Provided by: libqwt-doc_6.0.0-1.2_all 
NAME
QwtPlotCanvas -
Canvas of a QwtPlot.
SYNOPSIS
#include <qwt_plot_canvas.h>
Public Types
enum PaintAttribute { BackingStore = 1, Opaque = 2, HackStyledBackground = 4, ImmediatePaint = 8 }
enum FocusIndicator { NoFocusIndicator, CanvasFocusIndicator, ItemFocusIndicator }
typedef QFlags< PaintAttribute > PaintAttributes
Public Member Functions
QwtPlotCanvas (QwtPlot *)
virtual ~QwtPlotCanvas ()
QwtPlot * plot ()
const QwtPlot * plot () const
void setFocusIndicator (FocusIndicator)
FocusIndicator focusIndicator () const
void setBorderRadius (double)
double borderRadius () const
QPainterPath borderPath (const QRect &rect) const
QBitmap borderMask (const QSize &) const
void setPaintAttribute (PaintAttribute, bool on=true)
bool testPaintAttribute (PaintAttribute) const
const QPixmap * backingStore () const
void invalidateBackingStore ()
void replot ()
virtual bool event (QEvent *)
Protected Member Functions
virtual void paintEvent (QPaintEvent *)
virtual void resizeEvent (QResizeEvent *)
virtual void drawFocusIndicator (QPainter *)
virtual void drawBorder (QPainter *)
void updateStyleSheetInfo ()
Detailed Description
Canvas of a QwtPlot.
See also:
QwtPlot
Member Typedef Documentation
typedef QFlags<PaintAttribute> QwtPlotCanvas::PaintAttributes
Paint attributes.
Member Enumeration Documentation
enum QwtPlotCanvas::FocusIndicator
Focus indicator. .IP "•" 2 NoFocusIndicator
Don't paint a focus indicator
• CanvasFocusIndicator
The focus is related to the complete canvas. Paint the focus indicator using paintFocus()
• ItemFocusIndicator
The focus is related to an item (curve, point, ...) on the canvas. It is up to the application to
display a focus indication using f.e. highlighting.
See also:
setFocusIndicator(), focusIndicator(), paintFocus()
enum QwtPlotCanvas::PaintAttribute
Paint attributes. The default setting enables BackingStore and Opaque.
See also:
setPaintAttribute(), testPaintAttribute()
Enumerator:
BackingStore
Paint double buffered reusing the content of the pixmap buffer when possible. Using a backing
store might improve the performance significantly, when workin with widget overlays ( like
rubberbands ). Disabling the cache might improve the performance for incremental paints (using
QwtPlotDirectPainter ).
See also:
backingStore(), invalidateBackingStore()
Opaque Try to fill the complete contents rectangle of the plot canvas. When using styled backgrounds Qt
assumes, that the canvas doesn't fill its area completely ( f.e because of rounded borders ) and
fills the area below the canvas. When this is done with gradients it might result in a serious
performance bottleneck - depending on the size.
When the Opaque attribute is enabled the canvas tries to identify the gaps with some heuristics and to
fill those only.
Warning:
Will not work for semitransparent backgrounds
HackStyledBackground
Try to improve painting of styled backgrounds. QwtPlotCanvas supports the box model attributes for
customizing the layout with style sheets. Unfortunately the design of Qt style sheets has no
concept how to handle backgrounds with rounded corners - beside of padding.
When HackStyledBackground is enabled the plot canvas tries to seperate the background from the background
border by reverse engeneering to paint the background before and the border after the plot items. In this
order the border gets prefectly antialiased and you can avoid some pixel artifacts in the corners.
ImmediatePaint
When ImmediatePaint is set replot() calls repaint() instead of update().
See also:
replot(), QWidget::repaint(), QWidget::update()
Constructor & Destructor Documentation
QwtPlotCanvas::QwtPlotCanvas (QwtPlot *plot) [explicit]
Sets a cross cursor, enables QwtPlotCanvas::BackingStore.
QwtPlotCanvas::~QwtPlotCanvas () [virtual]
Destructor.
Member Function Documentation
const QPixmap * QwtPlotCanvas::backingStore () const
Return the backing store, might be null.
QBitmap QwtPlotCanvas::borderMask (const QSize &size) const Calculate a mask, that can be used to clip away
the border frame
Parameters:
size Size including the frame
QPainterPath QwtPlotCanvas::borderPath (const QRect &rect) const Calculate the painter path for a styled or
rounded border
When the canvas has no styled background or rounded borders the painter path is empty.
Parameters:
rect Bounding rectangle of the canvas
Returns:
Painter path, that can be used for clipping
double QwtPlotCanvas::borderRadius () const Returns:
Radius for the corners of the border frame
See also:
setBorderRadius()
void QwtPlotCanvas::drawBorder (QPainter *painter) [protected, virtual] Draw the border of the plot canvas
Parameters:
painter Painter
See also:
setBorderRadius(), QFrame::drawFrame()
void QwtPlotCanvas::drawFocusIndicator (QPainter *painter) [protected, virtual] Draw the focus indication
Parameters:
painter Painter
bool QwtPlotCanvas::event (QEvent *event) [virtual] Qt event handler for QEvent::PolishRequest and
QEvent::StyleChange
Parameters:
event Qt Event
QwtPlotCanvas::FocusIndicator QwtPlotCanvas::focusIndicator () const Returns:
Focus indicator
See also:
FocusIndicator, setFocusIndicator()
void QwtPlotCanvas::invalidateBackingStore ()
Invalidate the internal backing store.
void QwtPlotCanvas::paintEvent (QPaintEvent *event) [protected, virtual] Paint event
Parameters:
event Paint event
QwtPlot * QwtPlotCanvas::plot ()
Return parent plot widget.
const QwtPlot * QwtPlotCanvas::plot () const
Return parent plot widget.
void QwtPlotCanvas::replot () Invalidate the paint cache and repaint the canvas
See also:
invalidatePaintCache()
void QwtPlotCanvas::resizeEvent (QResizeEvent *event) [protected, virtual] Resize event
Parameters:
event Resize event
void QwtPlotCanvas::setBorderRadius (doubleradius) Set the radius for the corners of the border frame
Parameters:
radius Radius of a rounded corner
See also:
borderRadius()
void QwtPlotCanvas::setFocusIndicator (FocusIndicatorfocusIndicator) Set the focus indicator
See also:
FocusIndicator, focusIndicator()
void QwtPlotCanvas::setPaintAttribute (PaintAttributeattribute, boolon = true)
Changing the paint attributes. Parameters:
attribute Paint attribute
on On/Off
See also:
testPaintAttribute(), backingStore()
bool QwtPlotCanvas::testPaintAttribute (PaintAttributeattribute) const Test wether a paint attribute is
enabled
Parameters:
attribute Paint attribute
Returns:
true if the attribute is enabled
See also:
setPaintAttribute()
void QwtPlotCanvas::updateStyleSheetInfo () [protected]
Update the cached informations about the current style sheet.
Author
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