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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.