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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.
wxWidgets team. wx 2.2.2.1 wxScrolledWindow(3erl)