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NAME
wxScrolledWindow - The wxScrolled (not implemented in wx) class manages scrolling for its
client area, transforming the coordinates according to the scrollbar positions, and
setting the scroll positions, thumb sizes and ranges according to the area in view.
DESCRIPTION
There are two commonly used (but not the only possible!) specializations of this class:
Note: See wxScrolled::Create() (not implemented in wx) if you want to use wxScrolled (not
implemented in wx) with a custom class.
Starting from version 2.4 of wxWidgets, there are several ways to use a ?wxScrolledWindow
(and now wxScrolled (not implemented in wx)). In particular, there are three ways to set
the size of the scrolling area:
One way is to set the scrollbars directly using a call to setScrollbars/6. This is the way
it used to be in any previous version of wxWidgets and it will be kept for backwards
compatibility.
An additional method of manual control, which requires a little less computation of your
own, is to set the total size of the scrolling area by calling either
wxWindow:setVirtualSize/3, or wxWindow:fitInside/1, and setting the scrolling increments
for it by calling setScrollRate/3. Scrolling in some orientation is enabled by setting a
non-zero increment for it.
The most automatic and newest way is to simply let sizers determine the scrolling area.
This is now the default when you set an interior sizer into a wxScrolled (not implemented
in wx) with wxWindow:setSizer/3. The scrolling area will be set to the size requested by
the sizer and the scrollbars will be assigned for each orientation according to the need
for them and the scrolling increment set by setScrollRate/3. As above, scrolling is only
enabled in orientations with a non-zero increment. You can influence the minimum size of
the scrolled area controlled by a sizer by calling wxWindow::SetVirtualSizeHints().
(Calling setScrollbars/6 has analogous effects in wxWidgets 2.4 - in later versions it may
not continue to override the sizer.)
Note that if maximum size hints are still supported by wxWindow::SetVirtualSizeHints(),
use them at your own dire risk. They may or may not have been removed for 2.4, but it
really only makes sense to set minimum size hints here. We should probably replace
wxWindow::SetVirtualSizeHints() with wxWindow::SetMinVirtualSize() or similar and remove
it entirely in future.
As with all windows, an application can draw onto a wxScrolled (not implemented in wx)
using a device context.
You have the option of handling the OnPaint handler or overriding the wxScrolled::OnDraw()
(not implemented in wx) function, which is passed a pre-scrolled device context (prepared
by doPrepareDC/2).
If you don't wish to calculate your own scrolling, you must call doPrepareDC/2 when not
drawing from within OnDraw() (not implemented in wx), to set the device origin for the
device context according to the current scroll position.
A wxScrolled (not implemented in wx) will normally scroll itself and therefore its child
windows as well. It might however be desired to scroll a different window than itself:
e.g. when designing a spreadsheet, you will normally only have to scroll the (usually
white) cell area, whereas the (usually grey) label area will scroll very differently. For
this special purpose, you can call setTargetWindow/2 which means that pressing the
scrollbars will scroll a different window.
Note that the underlying system knows nothing about scrolling coordinates, so that all
system functions (mouse events, expose events, refresh calls etc) as well as the position
of subwindows are relative to the "physical" origin of the scrolled window. If the user
insert a child window at position (10,10) and scrolls the window down 100 pixels (moving
the child window out of the visible area), the child window will report a position of
(10,-90).
Styles
This class supports the following styles:
Note: Don't confuse wxScrollWinEvents generated by this class with wxScrollEvent objects
generated by wxScrollBar and wxSlider.
Remark: Use wxScrolled (not implemented in wx) for applications where the user scrolls by
a fixed amount, and where a 'page' can be interpreted to be the current visible portion of
the window. For more sophisticated applications, use the wxScrolled (not implemented in
wx) implementation as a guide to build your own scroll behaviour or use wxVScrolledWindow
(not implemented in wx) or its variants.
Since: The wxScrolled (not implemented in wx) template exists since version 2.9.0. In
older versions, only ?wxScrolledWindow (equivalent of wxScrolled<wxPanel>) was available.
See: wxScrollBar, wxClientDC, wxPaintDC, wxVScrolledWindow (not implemented in wx),
wxHScrolledWindow (not implemented in wx), wxHVScrolledWindow (not implemented in wx)
This class is derived (and can use functions) from: wxPanel wxWindow wxEvtHandler
wxWidgets docs: wxScrolledWindow
EVENTS
Event types emitted from this class: scrollwin_top, scrollwin_bottom, scrollwin_lineup,
scrollwin_linedown, scrollwin_pageup, scrollwin_pagedown, scrollwin_thumbtrack,
scrollwin_thumbrelease
DATA TYPES
wxScrolledWindow() = wx:wx_object()
EXPORTS
new() -> wxScrolledWindow()
Default constructor.
new(Parent) -> wxScrolledWindow()
Types:
Parent = wxWindow:wxWindow()
new(Parent, Options :: [Option]) -> wxScrolledWindow()
Types:
Parent = wxWindow:wxWindow()
Option =
{winid, integer()} |
{pos, {X :: integer(), Y :: integer()}} |
{size, {W :: integer(), H :: integer()}} |
{style, integer()}
Constructor.
Remark: The window is initially created without visible scrollbars. Call
setScrollbars/6 to specify how big the virtual window size should be.
calcScrolledPosition(This, Pt) -> {X :: integer(), Y :: integer()}
Types:
This = wxScrolledWindow()
Pt = {X :: integer(), Y :: integer()}
calcScrolledPosition(This, X, Y) ->
{Xx :: integer(), Yy :: integer()}
Types:
This = wxScrolledWindow()
X = Y = integer()
Translates the logical coordinates to the device ones.
For example, if a window is scrolled 10 pixels to the bottom, the device
coordinates of the origin are (0, 0) (as always), but the logical coordinates are
(0, 10) and so the call to CalcScrolledPosition(0, 10, xx, yy) will return 0 in yy.
See: calcUnscrolledPosition/3
calcUnscrolledPosition(This, Pt) ->
{X :: integer(), Y :: integer()}
Types:
This = wxScrolledWindow()
Pt = {X :: integer(), Y :: integer()}
calcUnscrolledPosition(This, X, Y) ->
{Xx :: integer(), Yy :: integer()}
Types:
This = wxScrolledWindow()
X = Y = integer()
Translates the device coordinates to the logical ones.
For example, if a window is scrolled 10 pixels to the bottom, the device
coordinates of the origin are (0, 0) (as always), but the logical coordinates are
(0, 10) and so the call to CalcUnscrolledPosition(0, 0, xx, yy) will return 10 in
yy.
See: calcScrolledPosition/3
enableScrolling(This, XScrolling, YScrolling) -> ok
Types:
This = wxScrolledWindow()
XScrolling = YScrolling = boolean()
Enable or disable use of wxWindow:scrollWindow/4 for scrolling.
By default, when a scrolled window is logically scrolled, wxWindow:scrollWindow/4
is called on the underlying window which scrolls the window contents and only
invalidates the part of the window newly brought into view. If false is passed as
an argument, then this "physical scrolling" is disabled and the window is entirely
invalidated whenever it is scrolled by calling wxWindow:refresh/2.
It should be rarely necessary to disable physical scrolling, so this method
shouldn't be called in normal circumstances.
getScrollPixelsPerUnit(This) ->
{XUnit :: integer(), YUnit :: integer()}
Types:
This = wxScrolledWindow()
Get the number of pixels per scroll unit (line), in each direction, as set by
setScrollbars/6.
A value of zero indicates no scrolling in that direction.
See: setScrollbars/6, wxWindow:getVirtualSize/1
getViewStart(This) -> {X :: integer(), Y :: integer()}
Types:
This = wxScrolledWindow()
This is a simple overload of GetViewStart(int*,int*); see that function for more
info.
doPrepareDC(This, Dc) -> ok
Types:
This = wxScrolledWindow()
Dc = wxDC:wxDC()
Call this function to prepare the device context for drawing a scrolled image.
It sets the device origin according to the current scroll position. doPrepareDC/2
is called automatically within the default wxEVT_PAINT event handler, so your
OnDraw() (not implemented in wx) override will be passed an already 'pre-scrolled'
device context. However, if you wish to draw from outside of OnDraw() (not
implemented in wx) (e.g. from your own wxEVT_PAINT handler), you must call this
function yourself.
For example:
Notice that the function sets the origin by moving it relatively to the current
origin position, so you shouldn't change the origin before calling doPrepareDC/2
or, if you do, reset it to (0, 0) later. If you call doPrepareDC/2 immediately
after device context creation, as in the example above, this problem doesn't arise,
of course, so it is customary to do it like this.
prepareDC(This, Dc) -> ok
Types:
This = wxScrolledWindow()
Dc = wxDC:wxDC()
This function is for backwards compatibility only and simply calls doPrepareDC/2
now.
Notice that it is not called by the default paint event handle (doPrepareDC/2 is),
so overriding this method in your derived class is useless.
scroll(This, Pt) -> ok
Types:
This = wxScrolledWindow()
Pt = {X :: integer(), Y :: integer()}
This is an overload of scroll/3; see that function for more info.
scroll(This, X, Y) -> ok
Types:
This = wxScrolledWindow()
X = Y = integer()
Scrolls a window so the view start is at the given point.
Remark: The positions are in scroll units, not pixels, so to convert to pixels you
will have to multiply by the number of pixels per scroll increment. If either
parameter is ?wxDefaultCoord (-1), that position will be ignored (no change in that
direction).
See: setScrollbars/6, getScrollPixelsPerUnit/1
setScrollbars(This, PixelsPerUnitX, PixelsPerUnitY, NoUnitsX,
NoUnitsY) ->
ok
Types:
This = wxScrolledWindow()
PixelsPerUnitX = PixelsPerUnitY = NoUnitsX = NoUnitsY = integer()
setScrollbars(This, PixelsPerUnitX, PixelsPerUnitY, NoUnitsX,
NoUnitsY,
Options :: [Option]) ->
ok
Types:
This = wxScrolledWindow()
PixelsPerUnitX = PixelsPerUnitY = NoUnitsX = NoUnitsY = integer()
Option =
{xPos, integer()} | {yPos, integer()} | {noRefresh, boolean()}
Sets up vertical and/or horizontal scrollbars.
The first pair of parameters give the number of pixels per 'scroll step', i.e.
amount moved when the up or down scroll arrows are pressed. The second pair gives
the length of scrollbar in scroll steps, which sets the size of the virtual window.
xPos and yPos optionally specify a position to scroll to immediately.
For example, the following gives a window horizontal and vertical scrollbars with
20 pixels per scroll step, and a size of 50 steps (1000 pixels) in each direction:
wxScrolled (not implemented in wx) manages the page size itself, using the current
client window size as the page size.
Note that for more sophisticated scrolling applications, for example where scroll
steps may be variable according to the position in the document, it will be
necessary to derive a new class from wxWindow, overriding OnSize() and adjusting
the scrollbars appropriately.
See: wxWindow:setVirtualSize/3
setScrollRate(This, Xstep, Ystep) -> ok
Types:
This = wxScrolledWindow()
Xstep = Ystep = integer()
Set the horizontal and vertical scrolling increment only.
See the pixelsPerUnit parameter in setScrollbars/6.
setTargetWindow(This, Window) -> ok
Types:
This = wxScrolledWindow()
Window = wxWindow:wxWindow()
Call this function to tell wxScrolled (not implemented in wx) to perform the actual
scrolling on a different window (and not on itself).
This method is useful when only a part of the window should be scrolled. A typical
example is a control consisting of a fixed header and the scrollable contents
window: the scrollbars are attached to the main window itself, hence it, and not
the contents window must be derived from wxScrolled (not implemented in wx), but
only the contents window scrolls when the scrollbars are used. To implement such
setup, you need to call this method with the contents window as argument.
Notice that if this method is used, GetSizeAvailableForScrollTarget() (not
implemented in wx) method must be overridden.
destroy(This :: wxScrolledWindow()) -> ok
Destroys the object.