Provided by: libpdf-builder-perl_3.025-1_all 
NAME
PDF::Builder::Content - Methods for adding graphics and text to a PDF
SYNOPSIS
# Start with a PDF page (new or opened)
my $pdf = PDF::Builder->new();
my $page = $pdf->page();
# Add new content object(s)
my $content = $page->graphics(); # or gfx()
# and/or (as separate object name)
my $content = $page->text();
# Then call the methods below to add graphics and text to the page.
# Note that negative coordinates can have unpredictable effects, so
# keep your coordinates non-negative!
These methods add content to streams output for text or graphics objects. Unless
otherwise restricted by a check that we are in or out of text mode, many methods listed
here apply equally to text and graphics streams. It is possible that there are some which
have no effect in one stream type or the other, but are currently lacking a check to
prevent them from being inserted into an inapplicable stream.
METHODS
All public methods listed, except as otherwise noted, return $self, for ease of chaining
calls.
Coordinate Transformations
The methods in this section change the coordinate system for the current content object
relative to the rest of the document. Note: the changes are relative to the original page
coordinates (and thus, absolute), not to the previous position! Thus, "translate(10, 10);
translate(10, 10);" ends up only moving the origin to "[10, 10]", rather than to "[20,
20]". There is one call, "transform_rel()", which makes your changes relative to the
previous position.
If you call more than one of these methods, the PDF specification recommends calling them
in the following order: translate, rotate, scale, skew. Each change builds on the last,
and you can get unexpected results when calling them in a different order.
CAUTION: a text object ($content) behaves a bit differently. Individual translate, rotate,
scale, and skew calls cancel out any previous settings. If you want to combine multiple
transformations for text, use the "transform" call.
$content->translate($dx,$dy)
Moves the origin along the x and y axes by $dx and $dy respectively.
$content->rotate($degrees)
Rotates the coordinate system counter-clockwise (anti-clockwise) around the current
origin. Use a negative argument to rotate clockwise. Note that 360 degrees will be
treated as 0 degrees.
Note: Unless you have already moved (translated) the origin, it is, and will remain,
at the lower left corner of the visible sheet. It will not automatically shift to
another corner. For example, a rotation of +90 degrees (counter-clockwise) will leave
the entire visible sheet in negative Y territory (0 at the left edge, -original_width
at the right edge), while X remains in positive territory (0 at bottom,
+original_height at the top edge).
This "rotate()" call permits any angle. Do not confuse it with the page rotation
"rotate" call, which only permits increments of 90 degrees (with opposite sign!), but
does shift the origin to another corner of the sheet.
$content->scale($sx,$sy)
Scales (stretches) the coordinate systems along the x and y axes. Separate
multipliers are provided for x and y.
$content->skew($skx,$sky)
Skews the coordinate system by $skx degrees (counter-clockwise/anti-clockwise) from
the x axis and $sky degrees (clockwise) from the y axis. Note that 360 degrees will
be treated the same as 0 degrees.
$content->transform(%opts)
Use one or more of the given %opts:
$content->transform(
'translate' => [$dx,$dy],
'rotate' => $degrees,
'scale' => [$sx,$sy],
'skew' => [$skx,$sky],
'matrix' => [$a, $b, $c, $d, $e, $f],
'point' => [$x,$y]
'repeat' => $boolean
)
A six element list may be given ("matrix") for a further transformation matrix:
$a = cos(rot) * scale factor for X
$b = sin(rot) * tan(skew for X)
$c = -sin(rot) * tan(skew for Y)
$d = cos(rot) * scale factor for Y
$e = translation for X
$f = translation for Y
Performs multiple coordinate transformations in one call, in the order recommended by
the PDF specification (translate, rotate, scale, skew). This is equivalent to making
each transformation separately, in the indicated order. A matrix of 6 values may also
be given ("matrix"). The transformation matrix is updated. A "point" may be given (a
point to be multiplied [transformed] by the completed matrix). Omitted options will
be unchanged.
If "repeat" is true, and if this is not the first call to a transformation method, the
previous transformation will be performed again, modified by any other provided
arguments.
$content->transform_rel(%opts)
Makes transformations similarly to "transform", except that it adds to the previously
set values, rather than replacing them (except for scale, which multiplies the new
values with the old).
Unlike "transform", "matrix" and "point" are not supported.
$content->matrix($a, $b, $c, $d, $e, $f)
(Advanced) Sets the current transformation matrix manually. Unless you have a
particular need to enter transformations manually, you should use the "transform"
method instead.
$a = cos(rot) * scale factor for X
$b = sin(rot) * tan(skew for X)
$c = -sin(rot) * tan(skew for Y)
$d = cos(rot) * scale factor for Y
$e = translation for X
$f = translation for Y
In text mode, the text matrix is returned. In graphics mode, $self is returned.
Graphics State Parameters
The following calls also affect the text state.
$content->linewidth($width)
Sets the width of the stroke (in points). This is the line drawn in graphics mode, or
the outline of a character in text mode (with appropriate "render" mode). If no $width
is given, the current setting is returned. If the width is being set, $self is
returned so that calls may be chained.
Alternate name: "line_width"
This is provided for compatibility with PDF::API2.
$content->linecap($style)
Sets the style to be used at the end of a stroke. This applies to lines which come to
a free-floating end, not to "joins" ("corners") in polylines (see "linejoin").
Alternate name: "line_cap"
This is provided for compatibility with PDF::API2.
"butt" or "b" or 0 = Butt Cap (default)
The stroke ends at the end of the path, with no projection.
"round" or "r" or 1 = Round Cap
A semicircular arc is drawn around the end of the path with a diameter equal to
the line width, and is filled in.
"square" or "s" or 2 = Projecting Square Cap
The stroke continues past the end of the path for half the line width.
If no $style is given, the current setting is returned. If the style is being set,
$self is returned so that calls may be chained.
Either a number or a string (case-insensitive) may be given.
$content->linejoin($style)
Sets the style of join to be used at corners of a path (within a multisegment
polyline).
Alternate name: "line_join"
This is provided for compatibility with PDF::API2.
"miter" or "m" or 0 = Miter Join, default
The outer edges of the strokes extend until they meet, up to the limit specified
by miterlimit. If the limit would be surpassed, a bevel join is used instead. For
a given linewidth, the more acute the angle is (closer to 0 degrees), the higher
the ratio of miter length to linewidth will be, and that's what miterlimit
controls -- a very "pointy" join is replaced by a bevel.
"round" or "r" or 1 = Round Join
A filled circle with a diameter equal to the linewidth is drawn around the corner
point, producing a rounded corner. The arc will meet up with the sides of the line
in a smooth tangent.
"bevel" or "b" or 2 = Bevel Join
A filled triangle is drawn to fill in the notch between the two strokes.
If no $style is given, the current setting is returned. If the style is being set,
$self is returned so that calls may be chained.
Either a number or a string (case-insensitive) may be given.
$content->miterlimit($ratio)
Sets the miter limit when the line join style is a miter join.
The ratio is the maximum length of the miter (inner to outer corner) divided by the
line width. Any miter above this ratio will be converted to a bevel join. The
practical effect is that lines meeting at shallow angles are chopped off instead of
producing long pointed corners.
The default miter limit is 10.0 (approximately 11.5 degree cutoff angle). The smaller
the limit, the larger the cutoff angle.
If no $ratio is given, the current setting is returned. If the ratio is being set,
$self is returned so that calls may be chained.
Alternate name: "miter_limit"
This is provided for compatibility with PDF::API2. Long ago, in a distant galaxy,
this method was misnamed meterlimit, but that was removed a while ago. Any code using
that name should be updated!
$content->linedash()
$content->linedash($length)
$content->linedash($dash_length, $gap_length, ...)
$content->linedash('pattern' => [$dash_length, $gap_length, ...], 'shift' => $offset)
Sets the line dash pattern.
If called without any arguments, a solid line will be drawn.
If called with one argument, the dashes and gaps (strokes and spaces) will have equal
lengths.
If called with two or more arguments, the arguments represent alternating dash and gap
lengths.
If called with a hash of arguments, the pattern array may have one or more elements,
specifying the dash and gap lengths. A dash phase may be set (shift), which is a
positive integer specifying the distance into the pattern at which to start the dashed
line. Note that if you wish to give a shift amount, using "shift", you need to use
"pattern" instead of one or two elements.
If an odd number of dash array elements are given, the list is repeated by the reader
software to form an even number of elements (pairs).
If a single argument of -1 is given, the current setting is returned. This is an
array consisting of two elements: an anonymous array containing the dash pattern
(default: empty), and the shift (offset) amount (default: 0). If the dash pattern is
being set, $self is returned so that calls may be chained.
Alternate name: "line_dash_pattern"
This is provided for compatibility with PDF::API2.
$content->flatness($tolerance)
(Advanced) Sets the maximum variation in output pixels when drawing curves. The
defined range of $tolerance is 0 to 100, with 0 meaning use the device default
flatness. According to the PDF specification, you should not try to force visible line
segments (the curve's approximation); results will be unpredictable. Usually, results
for different flatness settings will be indistinguishable to the eye.
The $tolerance value is silently clamped to be between 0 and 100.
If no $tolerance is given, the current setting is returned. If the tolerance is being
set, $self is returned so that calls may be chained.
Alternate name: "flatness_tolerance"
This is provided for compatibility with PDF::API2.
$content->egstate($object)
(Advanced) Adds an Extended Graphic State object containing additional state
parameters.
Path Construction (Drawing)
$content->move($x,$y)
Starts a new path at the specified coordinates. Note that multiple x,y pairs can be
given, although this isn't that useful (only the last pair would have an effect).
$content->close()
Closes and ends the current path by extending a line from the current position to the
starting position.
$content->endpath()
Ends the current path without explicitly enclosing it. That is, unlike "close", there
is no line segment drawn back to the starting position.
Alternate name: "end"
This is provided for compatibility with PDF::API2. Do not confuse it with the
"$pdf->end()" method!
Straight line constructs
Note: None of these will actually be visible until you call "stroke" or "fill". They are
merely setting up the path to draw.
$content->line($x,$y)
$content->line($x,$y, $x2,$y2,...)
Extends the path in a line from the current coordinates to the specified coordinates,
and updates the current position to be the new coordinates.
Multiple additional "[$x,$y]" pairs are permitted, to draw joined multiple line
segments. Note that this is not equivalent to a polyline (see "poly"), because the
first "[$x,$y]" pair in a polyline is a move operation. Also, the "linecap" setting
will be used rather than the "linejoin" setting for treating the ends of segments.
$content->hline($x)
$content->vline($y)
Shortcuts for drawing horizontal and vertical lines from the current position. They
are like "line()", but to the new x and current y ("hline"), or to the the current x
and new y ("vline").
$content->polyline($x1,$y1, ..., $xn,$yn)
This is a shortcut for creating a polyline path from the current position. It extends
the path in line segments along the specified coordinates. The current position is
changed to the last "[$x,$y]" pair given.
A critical distinction between the "polyline" method and the "poly" method is that in
this ("polyline"), the first pair of coordinates are treated as a draw order (unlike
the move order in "poly").
Thus, while this is provided for compatibility with PDF::API2, it is not really an
alias or alternate name for "poly"!
$content->poly($x1,$y1, ..., $xn,$yn)
This is a shortcut for creating a polyline path. It moves to "[$x1,$y1]", and then
extends the path in line segments along the specified coordinates. The current
position is changed to the last "[$x,$y]" pair given.
The difference between a polyline and a "line" with multiple "[$x,$y]" pairs is that
the first pair in a polyline are a move, while in a line they are a draw. Also,
"line_join" instead of "line_cap" is used to control the appearance of the ends of
line segments.
A critical distinction between the "polyline" method and the "poly" method is that in
this ("poly"), the first pair of coordinates are treated as a move order.
$content = $content->rectangle($x1, $y1, $x2, $y2)
Creates a new rectangle-shaped path, between the two corner points "[$x1, $y1]" and
"[$x2, $y2]". The corner points are swapped if necessary, to make "1" the lower left
and "2" the upper right (x2 > x1 and y2 > y1). The object (here, $content) is
returned, to permit chaining.
Note that this is not an alias or alternate name for "rect". It handles only one
rectangle, and takes corner coordinates for corner "2", rather than the width and
height.
$content = $content->rect($x,$y, $w,$h)
$content = $content->rect($x1,$y1, $w1,$h1, ..., $xn,$yn, $wn,$hn)
This creates paths for one or more rectangles, with their lower left points at
"[$x,$y]" and specified widths (+x direction) and heights (+y direction). Negative
widths and heights are permitted, which draw to the left (-x) and below (-y) the given
corner point, respectively. The current position is changed to the "[$x,$y]" of the
last rectangle given. Note that this is the starting point of the rectangle, not the
end point. The object (here, $content) is returned, to permit chaining.
Note that this differs from the "rectangle" method in that multiple rectangles may be
drawn in one call, and the second pair for each rectangle are the width and height,
not the opposite corner coordinates.
$content->rectxy($x1,$y1, $x2,$y2)
This creates a rectangular path, with "[$x1,$y1]" and "[$x2,$y2]" specifying opposite
corners. They can be Lower Left and Upper Right, or Upper Left and Lower Right, in
either order, so long as they are diagonally opposite each other. The current
position is changed to the "[$x1,$y1]" (first) pair.
This is not quite an alias or alternate name for "rectangle", as it permits the corner
points to be specified in any order.
Curved line constructs
Note: None of these will actually be visible until you call "stroke" or "fill". They are
merely setting up the path to draw.
$content->circle($xc,$yc, $radius)
This creates a circular path centered on "[$xc,$yc]" with the specified radius. It
does not change the current position.
$content->ellipse($xc,$yc, $rx,$ry)
This creates a closed elliptical path centered on "[$xc,$yc]", with axis radii
(semidiameters) specified by $rx (x axis) and $ry (y axis), respectively. It does not
change the current position.
$content->arc($xc,$yc, $rx,$ry, $alpha,$beta, $move, $dir)
$content->arc($xc,$yc, $rx,$ry, $alpha,$beta, $move)
This extends the path along an arc of an ellipse centered at "[$xc,$yc]". The
semidiameters of the elliptical curve are $rx (x axis) and $ry (y axis), respectively,
and the arc sweeps from $alpha degrees to $beta degrees. The current position is then
set to the endpoint of the arc.
Set $move to a true value if this arc is the beginning of a new path instead of the
continuation of an existing path. Either way, the current position will be updated to
the end of the arc. Use "$rx == $ry" for a circular arc.
The optional $dir arc sweep direction defaults to 0 (false), for a
counter-clockwise/anti-clockwise sweep. Set to 1 (true) for a clockwise sweep.
$content->pie($xc,$yc, $rx,$ry, $alpha,$beta, $dir)
$content->pie($xc,$yc, $rx,$ry, $alpha,$beta)
Creates a pie-shaped path from an ellipse centered on "[$xc,$yc]". The x-axis and
y-axis semidiameters of the ellipse are $rx and $ry, respectively, and the arc sweeps
from $alpha degrees to $beta degrees. It does not change the current position.
Depending on the sweep angles and direction, this can draw either the pie "slice" or
the remaining pie (with slice removed). Use "$rx == $ry" for a circular pie. Use a
different "[$xc,$yc]" for the slice, to offset it from the remaining pie.
The optional $dir arc sweep direction defaults to 0 (false), for a
counter-clockwise/anti-clockwise sweep. Set to 1 (true) for a clockwise sweep.
This is a shortcut to draw a section of elliptical (or circular) arc and connect it to
the center of the ellipse or circle, to form a pie shape.
$content->curve($cx1,$cy1, $cx2,$cy2, $x,$y)
This extends the path in a curve from the current point to "[$x,$y]", using the two
specified control points to create a cubic Bezier curve, and updates the current
position to be the new point ("[$x,$y]").
Within a text object, the text's baseline follows the Bezier curve.
Note that while multiple sets of three "[x,y]" pairs are permitted, these are treated
as independent cubic Bezier curves. There is no attempt made to smoothly blend one
curve into the next!
$content->qbspline($cx1,$cy1, $x,$y)
This extends the path in a curve from the current point to "[$x,$y]", using the two
specified points to create a quadratic Bezier curve, and updates the current position
to be the new point.
Internally, these splines are one or more cubic Bezier curves (see "curve") with the
two control points synthesized from the two given points (a control point and the end
point of a quadratic Bezier curve).
Note that while multiple sets of two "[x,y]" pairs are permitted, these are treated as
independent quadratic Bezier curves. There is no attempt made to smoothly blend one
curve into the next!
Further note that this "spline" does not match the common definition of a spline being
a continuous curve passing through all the given points! It is a piecewise non-
continuous cubic Bezier curve. Use with care, and do not make assumptions about
splines for you or your readers. You may wish to use the "bspline" call to have a
continuously smooth spline to pass through all given points.
Pairs of points (control point and end point) are consumed in a loop. If one point or
coordinate is left over at the end, it is discarded (as usual practice for excess data
to a routine). There is no check for duplicate points or other degeneracies.
Alternate name: "spline"
This method is still named "spline" in PDF::API2, so for compatibility, that name is
usable here. Since there are both quadratic and cubic splines available in PDF, it is
preferred to use more descriptive names such as "qbspline" and "cbspline" to minimize
confusion.
$content->bspline($ptsRef, %opts)
This extends the path in a curve from the current point to the end of a list of
coordinate pairs in the array referenced by $ptsRef. Smoothly continuous cubic Bezier
splines are used to create a curve that passes through all the given points. Multiple
control points are synthesized; they are not supplied in the call. The current
position is updated to the last point.
Internally, these splines are one cubic Bezier curve (see "curve") per pair of input
points, with the two control points synthesized from the tangent through each point as
set by the polyline that would connect each point to its neighbors. The intent is that
the resulting curve should follow reasonably closely a polyline that would connect the
points, and should avoid any major excursions. See the discussions below for the
handling of the control points at the endpoints (current point and last input point).
The point at the end of the last line or curve drawn becomes the new current point.
Options %opts:
'firstseg' => 'mode'
where mode is
curve
This is the default behavior. This forces the first segment (from the current
point to the first given point) to be drawn as a cubic Bezier curve. This
means that the direction of the curve coming off the current point is
unconstrained (it will end up being a reflection of the tangent at the first
given point).
line1
This forces the first segment (from the current point to the first given
point) to be drawn as a curve, with the tangent at the current point to be
constrained as parallel to the polyline segment.
line2
This forces the first segment (from the current point to the first given
point) to be drawn as a line segment. This also sets the tangent through the
first given point as a continuation of the line, as well as constraining the
direction of the line at the current point.
constraint1
This forces the first segment (from the current point to the first given
point) to not be drawn, but to be an invisible curve (like mode=line1) to
leave the tangent at the first given point unconstrained. A move will be made
to the first given point, and the current point is otherwise ignored.
constraint2
This forces the first segment (from the current point to the first given
point) to not be drawn, but to be an invisible line (like mode=line2) to
constrain the tangent at the first given point. A move will be made to the
first given point, and the current point is otherwise ignored.
'lastseg' => 'mode'
where mode is
curve
This is the default behavior. This forces the last segment (to the last given
input point) to be drawn as a cubic Bezier curve. This means that the
direction of the curve goin to the last point is unconstrained (it will end up
being a reflection of the tangent at the next-to-last given point).
line1
This forces the last segment (to the last given input point) to be drawn as a
curve with the the tangent through the last given point parallel to the
polyline segment, thus constraining the direction of the line at the last
point.
line2
This forces the last segment (to the last given input point) to be drawn as a
line segment. This also sets the tangent through the next-to-last given point
as a back continuation of the line, as well as constraining the direction of
the line at the last point.
constraint1
This forces the last segment (to the last given input point) to not be drawn,
but to be an invisible curve (like mode=line1) to leave the tangent at the
next-to-last given point unconstrained. The last given input point is ignored,
and next-to-last point becomes the new current point.
constraint2
This forces the last segment (to the last given input point) to not be drawn,
but to be an invisible line (like mode=line2) to constrain the tangent at the
next-to-last given point. The last given input point is ignored, and next-to-
last point becomes the new current point.
'ratio' => n
n is the ratio of the length from a point to a control point to the length of the
polyline segment on that side of the given point. It must be greater than 0.1, and
the default is 0.3333 (1/3).
'colinear' => 'mode'
This describes how to handle the middle segment when there are four or more
colinear points in the input set. A mode of 'line' specifies that a line segment
will be drawn between each of the interior colinear points. A mode of 'curve'
(this is the default) will draw a Bezier curve between each of those points.
"colinear" applies only to interior runs of colinear points, between curves. It
does not apply to runs at the beginning or end of the point list, which are drawn
as line segments or linear constraints regardless of firstseg and lastseg
settings.
'debug' => N
If N is 0 (the default), only the spline is returned. If it is greater than 0, a
number of additional items will be drawn: (N>0) the points, (N>1) a green solid
polyline connecting them, (N>2) blue original tangent lines at each interior
point, and (N>3) red dashed lines and hollow points representing the Bezier
control points.
Special cases
Adjacent points which are duplicates are consolidated. An extra coordinate at the end of
the input point list (not a full "[x,y]" pair) will, as usual, be ignored.
0 given points (after duplicate consolidation)
This leaves only the current point (unchanged), so it is a no-op.
1 given point (after duplicate consolidation)
This leaves the current point and one point, so it is rendered as a line, regardless
of %opt flags.
2 given points (after duplicate consolidation)
This leaves the current point, an intermediate point, and the end point. If the three
points are colinear, two line segments will be drawn. Otherwise, both segments are
curves (through the tangent at the intermediate point). If either end segment mode is
requested to be a line or constraint, it is treated as a line1 mode request instead.
N colinear points at beginning or end
N colinear points at beginning or end of the point set causes N-1 line segments
("line2" or "constraint2", regardless of the settings of "firstseg", "lastseg", and
"colinear".
Alternate name: "cbspline"
This is to emphasize that it is a cubic Bezier spline, as opposed to a quadratic Bezier
spline (see "qbspline" above).
$content->bogen($x1,$y1, $x2,$y2, $radius, $move, $larger, $reverse)
$content->bogen($x1,$y1, $x2,$y2, $radius, $move, $larger)
$content->bogen($x1,$y1, $x2,$y2, $radius, $move)
$content->bogen($x1,$y1, $x2,$y2, $radius)
(German for bow, as in a segment (arc) of a circle. This is a segment of a circle
defined by the intersection of two circles of a given radius, with the two
intersection points as inputs. There are four possible resulting arcs, which can be
selected with $larger and $reverse.)
This extends the path along an arc of a circle of the specified radius between
"[$x1,$y1]" to "[$x2,$y2]". The current position is then set to the endpoint of the
arc ("[$x2,$y2]").
Set $move to a true value if this arc is the beginning of a new path instead of the
continuation of an existing path. Note that the default ($move = false) is not a
straight line to P1 and then the arc, but a blending into the curve from the current
point. It will often not pass through P1!
Set $larger to a true value to draw the larger ("outer") arc between the two points,
instead of the smaller one. Both arcs are drawn clockwise from P1 to P2. The default
value of false draws the smaller arc.
Set $reverse to a true value to draw the mirror image of the specified arc (flip it
over, so that its center point is on the other side of the line connecting the two
points). Both arcs are drawn counter-clockwise from P1 to P2. The default (false)
draws clockwise arcs.
The $radius value cannot be smaller than half the distance from "[$x1,$y1]" to
"[$x2,$y2]". If it is too small, the radius will be set to half the distance between
the points (resulting in an arc that is a semicircle). This is a silent error.
Path Painting (Drawing)
$content->stroke()
Strokes the current path.
$content->fill($use_even_odd_fill)
$content->fill('rule' => $rule)
$content->fill() # use default nonzero rule
Fill the current path's enclosed area. It does not stroke the enclosing path around
the area.
$user_even_odd_fill = 0 or false (default)
$rule = 'nonzero'
If the path intersects with itself, the nonzero winding rule will be used to
determine which part of the path is filled in. This basically fills in everything
inside the path, except in some situations depending on the direction of the path.
$user_even_odd_fill = 1 (non-zero value) or true
$rule = 'even-odd'
If the path intersects with itself, the even-odd winding rule will be used to
determine which part of the path is filled in. In most cases, this means that the
filling state alternates each time the path is intersected. This basically will
fill alternating closed sub-areas.
See the PDF Specification, section 8.5.3.3 (in version 1.7), for more details on
filling.
The "rule" parameter is added for PDF::API2 compatibility.
$content->fillstroke($use_even_odd_fill)
$content->fillstroke('rule' => $rule)
$content->fillstroke() # use default nonzero rule
Fill the current path's enclosed area and then stroke the enclosing path around the
area (possibly with a different color).
$user_even_odd_fill = 0 or false (default)
$rule = 'nonzero'
If the path intersects with itself, the nonzero winding rule will be used to
determine which part of the path is filled in. This basically fills in everything
inside the path, except in some situations depending on the direction of the path.
$user_even_odd_fill = 1 (non-zero value) or true
$rule = 'even-odd'
If the path intersects with itself, the even-odd winding rule will be used to
determine which part of the path is filled in. In most cases, this means that the
filling state alternates each time the path is intersected. This basically will
fill alternating closed sub-areas.
See the PDF Specification, section 8.5.3.3 (in version 1.7), for more details on
filling.
The "rule" parameter is added for PDF::API2 compatibility.
Alternate names: "paint" and "fill_stroke"
"paint" is for compatibility with PDF::API2, while "fill_stroke" is added for
compatibility with many other PDF::API2-related renamed methods.
$content->clip($use_even_odd_fill)
$content->clip('rule' => $rule)
$content->clip() # use default nonzero rule
Modifies the current clipping path by intersecting it with the current path. Initially
(a fresh page), the clipping path is the entire media. Each definition of a path, and
a "clip()" call, intersects the new path with the existing clip path, so the resulting
clip path is no larger than the new path, and may even be empty if the intersection is
null.
$user_even_odd_fill = 0 or false (default)
$rule = 'nonzero'
If the path intersects with itself, the nonzero winding rule will be used to
determine which part of the path is included (clipped in or out). This basically
includes everything inside the path, except in some situations depending on the
direction of the path.
$user_even_odd_fill = 1 (non-zero value) or true
$rule = 'even-odd'
If the path intersects with itself, the even-odd winding rule will be used to
determine which part of the path is included. In most cases, this means that the
inclusion state alternates each time the path is intersected. This basically will
include alternating closed sub-areas.
It is common usage to make the "endpath()" call (n) after the "clip()" call, to clear
the path (unless you want to reuse that path, such as to fill and/or stroke it to show
the clip path). If you want to clip text glyphs, it gets rather complicated, as a clip
port cannot be created within a text object (that will have an effect on text). See
the object discussion in "Rendering Order" in PDF::Builder::Docs.
my $grfxC1 = $page->gfx();
my $textC = $page->text();
my $grfxC2 = $page->gfx();
...
$grfxC1->save();
$grfxC1->endpath();
$grfxC1->rect(...);
$grfxC1->clip();
$grfxC1->endpath();
...
$textC-> output text to be clipped
...
$grfxC2->restore();
The "rule" parameter is added for PDF::API2 compatibility.
$content->shade($shade, @coord)
Sets the shading matrix.
$shade
A hash reference that includes a "name()" method for the shade name.
@coord
An array of 4 items: X-translation, Y-translation, X-scaled and translated,
Y-scaled and translated.
Colors
$content->fillcolor($color)
$content->strokecolor($color)
Sets the fill (enclosed area) or stroke (path) color. The interior of text characters
are filled, and (if ordered by "render") the outline is stroked.
# Use a named color
# -> RGB color model
# there are many hundreds of named colors defined in
# PDF::Builder::Resource::Colors
$content->fillcolor('blue');
# Use an RGB color (# followed by 3, 6, 9, or 12 hex digits)
# -> RGB color model
# This maps to 0-1.0 values for red, green, and blue
$content->fillcolor('#FF0000'); # red
# Use a CMYK color (% followed by 4, 8, 12, or 16 hex digits)
# -> CMYK color model
# This maps to 0-1.0 values for cyan, magenta, yellow, and black
$content->fillcolor('%FF000000'); # cyan
# Use an HSV color (! followed by 3, 6, 9, or 12 hex digits)
# -> RGB color model
# This maps to 0-360 degrees for the hue, and 0-1.0 values for
# saturation and value
$content->fillcolor('!FF0000');
# Use an HSL color (& followed by 3, 6, 9, or 12 hex digits)
# -> L*a*b color model
# This maps to 0-360 degrees for the hue, and 0-1.0 values for
# saturation and lightness. Note that 360 degrees = 0 degrees (wraps)
$content->fillcolor('&FF0000');
# Use an L*a*b color ($ followed by 3, 6, 9, or 12 hex digits)
# -> L*a*b color model
# This maps to 0-100 for L, -100 to 100 for a and b
$content->fillcolor('$FF0000');
In all cases, if too few digits are given, the given digits are silently right-padded
with 0's (zeros). If an incorrect number of digits are given, the next lowest number
of expected digits are used, and the remaining digits are silently ignored.
# A single number between 0.0 (black) and 1.0 (white) is an alternate way
# of specifying a gray scale.
$content->fillcolor(0.5);
# Three array elements between 0.0 and 1.0 is an alternate way of specifying
# an RGB color.
$content->fillcolor(0.3, 0.59, 0.11);
# Four array elements between 0.0 and 1.0 is an alternate way of specifying
# a CMYK color.
$content->fillcolor(0.1, 0.9, 0.3, 1.0);
In all cases, if a number is less than 0, it is silently turned into a 0. If a number
is greater than 1, it is silently turned into a 1. This "clamps" all values to the
range 0.0-1.0.
# A single reference is treated as a pattern or shading space.
# Two or more entries with the first element a Perl reference, is treated
# as either an indexed colorspace reference plus color-index(es), or
# as a custom colorspace reference plus parameter(s).
If no value was passed in, the current fill color (or stroke color) array is returned,
otherwise $self is returned.
Alternate names: "fill_color" and "stroke_color".
These are provided for PDF::API2 compatibility.
External Objects
$content->image($image_object, $x,$y, $width,$height)
$content->image($image_object, $x,$y, $scale)
$content->image($image_object, $x,$y)
$content->image($image_object)
# Example
my $image_object = $pdf->image_jpeg($my_image_file);
$content->image($image_object, 100, 200);
Places an image on the page in the specified location (specifies the lower left corner
of the image). The default location is "[0,0]".
If coordinate transformations have been made (see Coordinate Transformations above),
the position and scale will be relative to the updated coordinates. Otherwise, "[0,0]"
will represent the bottom left corner of the page, and $width and $height will be
measured at 72dpi.
For example, if you have a 600x600 image that you would like to be shown at 600dpi
(i.e., one inch square), set the width and height to 72. (72 Big Points is one inch)
$content->formimage($form_object, $x,$y, $scaleX, $scaleY)
$content->formimage($form_object, $x,$y, $scale)
$content->formimage($form_object, $x,$y)
$content->formimage($form_object)
Places an XObject on the page in the specified location (giving the lower left corner
of the image) and scale (applied to the image's native height and width). If no scale
is given, use 1 for both X and Y. If one scale is given, use for both X and Y. If two
scales given, they are for (separately) X and Y. In general, you should not greatly
distort an image by using greatly different scaling factors in X and Y, although it is
now possible for when that effect is desirable. The "$x,$y" default is "[0,0]".
Note that while this method is named form image, it is also used for the pseudoimages
created by the barcode routines. Images are naturally dimensionless (1 point square)
and need at some point to be scaled up to the desired point size. Barcodes are
naturally sized in points, and should be scaled at approximately 1. Therefore, it
would greatly overscale barcodes to multiply by image width and height within
"formimage", and require scaling of 1/width and 1/height in the call. So, we leave
scaling alone within "formimage" and have the user manually scale images by the image
width and height (in pixels) in the call to "formimage".
$content = $content->object($object, $x,$y, $scale_x,$scale_y)
Places an image or other external object (a.k.a. XObject) on the page in the specified
location.
For images, $scale_x and $scale_y represent the width and height of the image on the
page, in points. If $scale_x is omitted, it will default to 72 pixels per inch. If
$scale_y is omitted, the image will be scaled proportionally, based on the image
dimensions.
For other external objects, the scale is a multiplier, where 1 (the default)
represents 100% (i.e. no change).
If coordinate transformations have been made (see Coordinate Transformations above),
the position and scale will be relative to the updated coordinates.
If no coordinate transformations are needed, this method can be called directly from
the PDF::Builder::Page object instead.
Text
Text State Parameters
All of the following parameters that take a size are applied before any scaling takes
place, so you don't need to adjust values to counteract scaling.
$spacing = $content->charspace($spacing)
Sets additional spacing between characters in a line. This is in points, and is
initially zero. It may be positive to give an expanded effect to words, or it may be
negative to give a condensed effect to words. If $spacing is given, the current
setting is replaced by that value and $self is returned (to permit chaining). If
$spacing is not given, the current setting is returned.
CAUTION: be careful about using "charspace" if you are using a connected font. This
might include Arabic, Devanagari, Latin cursive handwriting, and so on. You don't want
to leave gaps between characters, or cause overlaps. For such fonts and typefaces, set
the "charspace" spacing to 0.
Alternate names: "character_spacing" and "char_space"
character_spacing is provided for compatibility with PDF::API2, while char_space is
provided to be consistent with many other method name changes in PDF::API2.
$spacing = $content->wordspace($spacing)
Sets additional spacing between words in a line. This is in points and is initially
zero (i.e., just the width of the space, without anything extra). It may be negative
to close up sentences a bit. If $spacing is given, the current setting is replaced by
that value and $self is returned (to permit chaining). If $spacing is not given, the
current setting is returned.
Note that it is a limitation of the PDF specification (as of version 1.7, section
9.3.3) that only spacing with an ASCII space (x20) is adjusted. Neither required
blanks (xA0) nor any multiple-byte spaces (including thin and wide spaces) are
currently adjusted.
alternate names: "word_spacing" and "word_space"
word_spacing is provided for compatibility with PDF::API2, while word_space is
provided to be consistent with many other method name changes in PDF::API2.
$scale = $content->hscale($scale)
Sets the percentage of horizontal text scaling (relative sizing, not spacing). This is
initally 100 (percent, i.e., no scaling). A scale of greater than 100 will stretch the
text, while less than 100 will compress it. If $scale is given, the current setting
is replaced by that value and $self is returned (to permit chaining). If $scale is
not given, the current setting is returned.
Note that scaling affects all of the character widths, interletter spacing, and
interword spacing. It is inadvisable to stretch or compress text by a large amount, as
it will quickly make the text unreadable. If your objective is to justify text, you
will usually be better off using "charspace" and "wordspace" to expand (or slightly
condense) a line to fill a desired width. Also see the "text_justify()" calls for this
purpose.
$leading = $content->leading($leading)
$leading = $content->leading()
Sets the text leading, which is the distance between baselines. This is initially zero
(i.e., the lines will be printed on top of each other). The unit of leading is points.
If $leading is given, the current setting is replaced by that value and $self is
returned (to permit chaining). If $leading is not given, the current setting is
returned.
Note that "leading" here is defined as used in electronic typesetting and the PDF
specification, which is the full interline spacing (text baseline to text baseline
distance, in points). In cold metal typesetting, leading was usually the extra spacing
between lines beyond the font height itself, created by inserting lead (type alloy)
shims.
$leading = $content->lead($leading)
$leading = $content->lead()
Deprecated, to be removed after March 2023. Use "leading()" now.
Note that the "$self->{' lead'}" internal variable is no longer available, having been
replaced by "$self->{' leading'}".
$mode = $content->render($mode)
Sets the text rendering mode.
0 = Fill text
1 = Stroke text (outline)
2 = Fill, then stroke text
3 = Neither fill nor stroke text (invisible)
4 = Fill text and add to path for clipping
5 = Stroke text and add to path for clipping
6 = Fill, then stroke text and add to path for clipping
7 = Add text to path for clipping
If $mode is given, the current setting is replaced by that value and $self is returned
(to permit chaining). If $mode is not given, the current setting is returned.
$dist = $content->rise($dist)
Adjusts the baseline up or down from its current location. This is initially zero. A
$dist greater than 0 moves the baseline up the page (y increases).
Use this for creating superscripts or subscripts (usually along with an adjustment to
the font size). If $dist is given, the current setting is replaced by that value and
$self is returned (to permit chaining). If $dist is not given, the current setting is
returned.
%state = $content->textstate(charspace => $value, wordspace => $value, ...)
This is a shortcut for setting multiple text state parameters at once. If any
parameters are set, an empty hash is returned. This can also be used without
arguments to retrieve the current text state settings (a hash of the state is
returned).
Note: This does not work with the "save" and "restore" commands.
$content->font($font_object, $size)
Sets the font and font size. $font is an object created by calling "font" in
PDF::Builder to add the font to the document.
# Example (12 point Helvetica)
my $pdf = PDF::Builder->new();
my $font = $pdf->font('Helvetica');
$text->font($font, 24);
$text->position(72, 720);
$text->text('Hello, World!');
$pdf->save('sample.pdf');
Positioning Text
$content = $content->position($x, $y) # Set (also returns object, for ease of chaining)
($x, $y) = $content->position() # Get
If called with arguments (Set), moves to the start of the current line of text, offset
by $x and $y (right and up for positive values).
If called without arguments (Get), returns the current position of the cursor (before
the effects of any coordinate transformation methods).
Note that this is very similar in function to "distance()", added recently to
PDF::API2 and added here for compatibility.
($tx,$ty) = $content->textpos()
Returns the current text position on the page (where next write will happen) as an
array.
Note: This does not affect the PDF in any way. It only tells you where the the next
write will occur.
Alternate name: "position" (added for compatibility with PDF::API2)
$content->distance($dx,$dy)
This moves to the start of the previously-written line, plus an offset by the given
amounts, which are both required. "[0,0]" would overwrite the previous line, while
"[0,36]" would place the new line 36pt above the old line (higher y). The $dx moves to
the right, if positive.
"distance" is analogous to graphic's "move", except that it is relative to the
beginning of the previous text write, not to the coordinate origin. Note that
subsequent text writes will be relative to this new starting (left) point and Y
position! E.g., if you give a non-zero $dx, subsequent lines will be indented by that
amount.
$content->cr()
$content->cr($vertical_offset)
$content->cr(0)
If passed without an argument, moves (down) to the start of the next line (distance
set by "leading"). This is similar to "nl()".
If passed with an argument, the "leading" distance is ignored and the next line starts
that far up the page (positive value) or down the page (negative value) from the
current line. "Y" increases upward, so a negative value would normally be used to get
to the next line down.
An argument of 0 would simply return to the start of the present line, overprinting it
with new text. That is, it acts as a simple carriage return, without a linefeed.
Note that any setting for "leading" is ignored. If you wish to account for the
"leading" setting, you may wish to use the "crlf" method instead.
$content->nl()
$content->nl($indent)
$content->nl(0)
Moves to the start of the next line (see "leading"). If $indent is not given, or is 0,
there is no indentation. Otherwise, indent by that amount (outdent if a negative
value). The unit of measure is hundredths of a "unit of text space", or roughly 88 per
em.
Note that any setting for "leading" is ignored. If you wish to account for the
"leading" setting, you may wish to use the "crlf" method instead.
$content = $content->crlf()
Moves to the start of the next line, based on the "leading" setting. It returns its
own object, for ease of chaining.
If leading isn't set, a default distance of 120% of the font size will be used.
Added for compatibility with PDF::API2 changes; may be used to replace both "cr" and
"nl" methods.
$width = $content->advancewidth($string, %opts)
Options %opts:
'font' => $f3_TimesRoman
Change the font used, overriding $self->{' font'}. The font must have been
previously created (i.e., is not the name). Example: use Times-Roman.
'fontsize' => 12
Change the font size, overriding $self->{' fontsize'}. Example: 12 pt font.
'wordspace' => 0.8
Change the additional word spacing, overriding $self->wordspace(). Example: add
0.8 pt between words.
'charspace' => -2.1
Change the additional character spacing, overriding $self->charspace(). Example:
subtract 2.1 pt between letters, to condense the text.
'hscale' => 125
Change the horizontal scaling factor, overriding $self->hscale(). Example:
stretch text to 125% of its natural width.
Returns the width of the $string (when set as a line of type), based on all currently
set text-state attributes. These can optionally be overridden with %opts. Note that
these values temporarily replace the existing values, not scaling them up or down. For
example, if the existing charspace is 2, and you give in options a value of 3, the
value used is 3, not 5.
Note: This does not affect the PDF in any way. It only tells you how much horizontal
space a text string will take up.
Alternate name: "text_width"
This is provided for compatibility with PDF::API2.
Rendering Text
Single Lines
$width = $content->text($text, %opts)
Adds text to the page (left justified). The width used (in points) is returned.
Options:
'indent' => $distance
Indents the text by the number of points (A value less than 0 gives an outdent).
'underline' => 'none'
'underline' => 'auto'
'underline' => $distance
'underline' => [$distance, $thickness, ...]
Underlines the text. $distance is the number of units beneath the baseline, and
$thickness is the width of the line. Multiple underlines can be made by passing
several distances and thicknesses. A value of 'none' means no underlining (is the
default).
Example:
# 3 underlines:
# distance 4, thickness 1, color red
# distance 7, thickness 1.5, color yellow
# distance 11, thickness 2, color (strokecolor default)
'underline' => [4,[1,'red'],7,[1.5,'yellow'],11,2],
'strikethru' => 'none'
'strikethru' => 'auto'
'strikethru' => $distance
'strikethru' => [$distance, $thickness, ...]
Strikes through the text (like HTML s tag). A value of 'auto' places the line
about 30% of the font size above the baseline, or a specified $distance (above the
baseline) and $thickness (in points). Multiple strikethroughs can be made by
passing several distances and thicknesses. A value of 'none' means no
strikethrough. It is the default.
Example:
# 2 strikethroughs:
# distance 4, thickness 1, color red
# distance 7, thickness 1.5, color yellow
'strikethru' => [4,[1,'red'],7,[1.5,'yellow']],
$width = $content->textHS($HSarray, $settings, %opts)
Takes an array of hashes produced by HarfBuzz::Shaper and outputs them to the PDF
output file. HarfBuzz outputs glyph CIDs and positioning information. It may
rearrange and swap characters (glyphs), and the result may bear no resemblance to the
original Unicode point list. You should see examples/HarfBuzz.pl, which shows a number
of examples with Latin and non-Latin text, as well as vertical writing.
https://www.catskilltech.com/Examples has a sample available in case you want to see
some examples of what HarfBuzz can do, and don't yet have HarfBuzz::Shaper installed.
$HSarray
This is the reference to array of hashes produced by HarfBuzz::Shaper, normally
unchanged after being created (but can be modified). See "Using Shaper" in
PDF::Builder::Docs for some things that can be done.
$settings
This a reference to a hash of various pieces of information that "textHS()" needs
in order to function. They include:
'script' => 'script_name'
This is the standard 4 letter code (e.g., 'Latn') for the script (alphabet and
writing system) you're using. Currently, only Latn (Western writing systems)
do kerning, and 'Latn' is the default. HarfBuzz::Shaper will usually be able
to figure out from the Unicode points used what the script is, and you might
be able to use the "set_script()" call to override its guess. However,
PDF::Builder and HarfBuzz::Shaper do not talk to each other about the script
being used.
'features' => array_of_features
This item is required, but may be empty, e.g., "$settings->{'features'} =
();". It can include switches using the standard HarfBuzz naming, and a + or
- switch, such as '-liga' to turn off ligatures. '-liga' and '-kern', to turn
off ligatures and kerning, are the only features supported currently. Note
that this is separate from any switches for features that you send to
HarfBuzz::Shaper (with "$hb->add_features()", etc.) when you run it (before
"textHS()").
'language' => 'language_code'
This item is optional and currently does not appear to have any substantial
effect with HarfBuzz::Shaper. It is the standard code for the language to be
used, such as 'en' or 'en_US'. You might need to define this for
HarfBuzz::Shaper, in case that system can't surmise the language rules to be
used.
'dir' => 'flag'
Tell "textHS()" whether this text is to be written in a Left-To-Right manner
(L, the default), Right-To-Left (R), Top-To-Bottom (T), or Bottom-To-Top (B).
From the script used (Unicode points), HarfBuzz::Shaper can usually figure out
what direction to write text in. Also, HarfBuzz::Shaper does not share its
information with PDF::Builder -- you need to separately specify the direction,
unless you want to accept the default LTR direction. You can use
HarfBuzz::Shaper's "get_direction()" call (in addition to "get_language()" and
"get_script()") to see what HarfBuzz thinks is the correct text direction.
"set_direction()" may be used to override Shaper's guess as to the direction.
By the way, if the direction is RTL, HarfBuzz will reverse the text and return
an array with the last character first (to be written LTR). Likewise, for BTT,
HarfBuzz will reverse the text and return a string to be written from the top
down. Languages which are normally written horizontally are usually set
vertically with direction TTB. If setting text vertically, ligatures and
kerning, as well as character connectivity for cursive scripts, are
automatically turned off, so don't let the direction default to LTR or RTL in
the Shaper call, and then try to fix it up in "textHS()".
align => 'flag'
Given the current output location, align the text at the Beginning of the line
(left for LTR, right for RTL), Centered at the location, or at the End of the
line (right for LTR, left for RTL). The default is B. Centered is analogous
to using "text_center()", and End is analogous to using "text_right()".
Similar alignments are done for TTB and BTT.
'dump' => flag
Set to 1, it prints out positioning and glyph CID information (to STDOUT) for
each glyph in the chunk. The default is 0 (no information dump).
'minKern' => amount (default 1)
If the amount of kerning (font character width differs from glyph ax value) is
larger than this many character grid units, use the unaltered ax for the width
("textHS()" will output a kern amount in the TJ operation). Otherwise, ignore
kerning and use ax of the actual character width. The intent is to avoid
bloating the PDF code with unnecessary tiny kerning adjustments in the TJ
operation.
%opts
This a hash of options.
'underline' => underlining_instructions
See "text()" for available instructions.
'strikethru' => strikethrough_instructions
See "text()" for available instructions.
'strokecolor' => line_color
Color specification (e.g., 'green', '#FF3377') for underline or strikethrough,
if not given in an array with their instructions.
Text is sent separately to HarfBuzz::Shaper in 'chunks' ('segments') of a single
script (alphabet), a single direction (LTR, RTL, TTB, or BTT), a single font file, and
a single font size. A chunk may consist of a large amount of text, but at present,
"textHS()" can only output a single line. For long lines that need to be split into
column-width lines, the best way may be to take the array of hashes returned by
HarfBuzz::Shaper and split it into smaller chunks at spaces and other whitespace. You
may have to query the font to see what the glyph CIDs are for space and anything else
used.
It is expected that when "textHS()" is called, that the font and font size have
already been set in PDF::Builder code, as this information is needed to interpret what
HarfBuzz::Shaper is returning, and to write it to the PDF file. Needless to say, the
font should be opened from the same file as was given to HarfBuzz::Shaper ("ttfont()"
only, with .ttf or .otf files), and the font size must be the same. The appropriate
location on the page must also already have been specified.
NOTE: as HarfBuzz::Shaper is still in its early days, it is possible that there will
be major changes in its API. We hope that all changes will be upwardly compatible, but
do not control this package and cannot guarantee that there will not be any
incompatible changes that in turn require changes to PDF::Builder ("textHS()").
$width = $content->advancewidthHS($HSarray, $settings, %opts)
Returns text chunk width (in points) for Shaper-defined glyph array. This is the
horizontal width for LTR and RTL direction, and the vertical height for TTB and BTT
direction. Note: You must define the font and font size before calling
"advancewidthHS()".
$HSarray
The array reference of glyphs created by the HarfBuzz::Shaper call. See
"textHS()" for details.
$settings
the hash reference of settings. See "textHS()" for details.
'dir' => 'L' etc.
the direction of the text, to know which "advance" value to sum up.
%opts
Options. Unlike "advancewidth()", you cannot override the font, font size, etc.
used by HarfBuzz::Shaper to calculate the glyph list.
'doKern' => flag (default 1)
If 1, cancel minor kerns per "minKern" setting. This flag should be 0 (false)
if -kern was passed to HarfBuzz::Shaper (do not kern text). This is treated
as 0 if an ax override setting is given.
'minKern' => amount (default 1)
If the amount of kerning (font character width differs from glyph ax value) is
larger than this many character grid units, use the unaltered ax for the width
("textHS()" will output a kern amount in the TJ operation). Otherwise, ignore
kerning and use ax of the actual character width. The intent is to avoid
bloating the PDF code with unnecessary tiny kerning adjustments in the TJ
operation.
Returns total width in points.
Alternate name: "text_widthHS"
Advanced Methods
$content->save()
Saves the current graphics state on a PDF stack. See PDF definition 8.4.2 through
8.4.4 for details. This includes the line width, the line cap style, line join style,
miter limit, line dash pattern, stroke color, fill color, current transformation
matrix, current clipping port, flatness, and dictname. This method applies to both
text and gfx/graphics objects.
$content->restore()
Restores the most recently saved graphics state (see "save"), removing it from the
stack. You cannot restore the graphics state (pop it off the stack) unless you have
done at least one save (pushed it on the stack). This method applies to both text and
gfx/graphics objects.
$content->add(@content)
Add raw content (arbitrary string(s)) to the PDF stream. You will generally want to
use the other methods in this class instead, unless this is in order to implement some
PDF operation that PDF::Builder does not natively support. An array of multiple
strings may be given; they will be concatenated with spaces between them.
Be careful when doing this, as you are dabbling in the black arts, directly setting
PDF operations!
One interesting use is to split up an overly long object stream that is giving your
editor problems when exploring a PDF file. Add a newline add("\n") every few hundred
bytes of output or so, to do this. Note that you must use double quotes (quotation
marks), rather than single quotes (apostrophes).
Use extreme care if inserting BT and ET markers into the PDF stream. You may want to
use "textstart()" and "textend()" calls instead, and even then, there are many side
effects either way. It is generally not useful to suspend text mode with ET/textend
and BT/textstart, but it is possible, if you really need to do it.
Another, useful, case is when your input PDF is from the Chrome browser printing a
page to PDF with headers and/or footers. In some versions, this leaves the PDF page
with a strange scaling (such as the page height in points divided by 3300) and the
Y-axis flipped so 0 is at the top. This causes problems when trying to add additional
text or graphics in a new text or graphics record, where text is flipped (mirrored)
upsidedown and at the wrong end of the page. If this happens, you might be able to
cure it by adding
$scale = .23999999; # example, 792/3300, examine PDF or experiment!
...
if ($scale != 1) {
my @pageDim = $page->mediabox(); # e.g., 0 0 612 792
my $size_page = $pageDim[3]/$scale; # 3300 = 792/.23999999
my $invScale = 1.0/$scale; # 4.16666684
$text->add("$invScale 0 0 -$invScale 0 $size_page cm");
}
as the first output to the $text stream. Unfortunately, it is difficult to predict
exactly what $scale should be, as it may be 3300 units per page, or a fixed amount.
You may need to examine an uncompressed PDF file stream to see what is being used. It
might be possible to get the input (original) PDF into a string and look for a certain
pattern of "cm" output
.2399999 0 0 -.23999999 0 792 cm
or similar, which is not within a save/restore (q/Q). If the stream is already
compressed, this might not be possible.
$content->addNS(@content)
Like "add()", but does not make sure there is a space between each element and before
and after the new content. It is up to you to ensure that any necessary spaces in the
PDF stream are placed there explicitly!
$content->compressFlate()
Marks content for compression on output. This is done automatically in nearly all
cases, so you shouldn't need to call this yourself.
The "new()" call can set the compress parameter to 'flate' (default) to compress all
object streams, or 'none' to suppress compression and allow you to examine the output
in an editor.
$content->textstart()
Starts a text object (ignored if already in a text object). You will likely want to
use the "text()" method (text context, not text output) instead.
Note that calling this method, besides outputting a BT marker, will reset most text
settings to their default values. In addition, BT itself will reset some
transformation matrices.
$content->textend()
Ends a text object (ignored if not in a text object).
Note that calling this method, besides outputting an ET marker, will output any
accumulated poststream content.