interface/scrolwin.h

   1 /////////////////////////////////////////////////////////////////////////////
   2 // Name:        scrolwin.h
   3 // Purpose:     documentation for wxScrolledWindow class
   4 // Author:      wxWidgets team
   5 // RCS-ID:      $Id$
   6 // Licence:     wxWindows license
   7 /////////////////////////////////////////////////////////////////////////////
   8
   9 /**
  10     @class wxScrolledWindow
  11     @wxheader{scrolwin.h}
  12
  13     The wxScrolledWindow class manages scrolling for its client area, transforming
  14     the coordinates according to the scrollbar positions, and setting the
  15     scroll positions, thumb sizes and ranges according to the area in view.
  16
  17     Starting from version 2.4 of wxWidgets, there are several ways to use a
  18     wxScrolledWindow. In particular, there are now three ways to set the
  19     size of the scrolling area:
  20
  21     One way is to set the scrollbars directly using a call to
  22     wxScrolledWindow::SetScrollbars.
  23     This is the way it used to be in any previous version of wxWidgets
  24     and it will be kept for backwards compatibility.
  25
  26     An additional method of manual control, which requires a little less
  27     computation of your own, is to set the total size of the scrolling area by
  28     calling either wxWindow::SetVirtualSize,
  29     or wxWindow::FitInside, and setting the
  30     scrolling increments for it by calling
  31     wxScrolledWindow::SetScrollRate.
  32     Scrolling in some orientation is enabled by setting a non-zero increment
  33     for it.
  34
  35     The most automatic and newest way is to simply let sizers determine the
  36     scrolling area. This is now the default when you set an interior sizer
  37     into a wxScrolledWindow with wxWindow::SetSizer.
  38     The scrolling area will be set to the size requested by the sizer and
  39     the scrollbars will be assigned for each orientation according to the need
  40     for them and the scrolling increment set by
  41     wxScrolledWindow::SetScrollRate.
  42     As above, scrolling is only enabled in orientations with a non-zero
  43     increment.  You can influence the minimum size of the scrolled area
  44     controlled by a sizer by calling
  45     wxWindow::SetVirtualSizeHints.
  46     (calling wxScrolledWindow::SetScrollbars
  47      has analogous effects in wxWidgets 2.4 -- in later versions it may not continue
  48      to override the sizer)
  49
  50     Note:  if Maximum size hints are still supported by SetVirtualSizeHints, use
  51     them at your own dire risk.  They may or may not have been removed for 2.4,
  52     but it really only makes sense to set minimum size hints here.  We should
  53     probably replace SetVirtualSizeHints with SetMinVirtualSize or similar
  54     and remove it entirely in future.
  55
  56     As with all windows, an application can draw onto a wxScrolledWindow using
  57     a @ref overview_dcoverview "device context".
  58
  59     You have the option of handling the OnPaint handler
  60     or overriding the wxScrolledWindow::OnDraw function, which is
  61     passed a pre-scrolled device context (prepared by
  62     wxScrolledWindow::DoPrepareDC).
  63
  64     If you don't wish to calculate your own scrolling, you must call DoPrepareDC
  65     when not drawing from
  66     within OnDraw, to set the device origin for the device context according to the
  67     current
  68     scroll position.
  69
  70     A wxScrolledWindow will normally scroll itself and therefore its child windows
  71     as well. It
  72     might however be desired to scroll a different window than itself: e.g. when
  73     designing a
  74     spreadsheet, you will normally only have to scroll the (usually white) cell
  75     area, whereas the
  76     (usually grey) label area will scroll very differently. For this special
  77     purpose, you can
  78     call wxScrolledWindow::SetTargetWindow which means that pressing
  79     the scrollbars will scroll a different window.
  80
  81     Note that the underlying system knows nothing about scrolling coordinates, so
  82     that all system
  83     functions (mouse events, expose events, refresh calls etc) as well as the
  84     position of subwindows
  85     are relative to the "physical" origin of the scrolled window. If the user
  86     insert a child window at
  87     position (10,10) and scrolls the window down 100 pixels (moving the child
  88     window out of the visible
  89     area), the child window will report a position of (10,-90).
  90
  91     @beginStyleTable
  92     @style{wxRETAINED}:
  93            Uses a backing pixmap to speed refreshes. Motif only.
  94     @endStyleTable
  95
  96     @library{wxcore}
  97     @category{miscwnd}
  98
  99     @seealso
 100     wxScrollBar, wxClientDC, wxPaintDC, wxVScrolledWindow
 101 */
 102 class wxScrolledWindow : public wxPanel
 103 {
 104 public:
 105     //@{
 106     /**
 107         Constructor.
 108
 109         @param parent
 110             Parent window.
 111         @param id
 112             Window identifier. The value wxID_ANY indicates a default value.
 113         @param pos
 114             Window position. If a position of (-1, -1) is specified then a default
 115         position
 116             is chosen.
 117         @param size
 118             Window size. If a size of (-1, -1) is specified then the window is sized
 119             appropriately.
 120         @param style
 121             Window style. See wxScrolledWindow.
 122         @param name
 123             Window name.
 124
 125         @remarks The window is initially created without visible scrollbars. Call
 126                  SetScrollbars() to specify how big the
 127                  virtual window size should be.
 128     */
 129     wxScrolledWindow();
 130     wxScrolledWindow(wxWindow* parent, wxWindowID id = -1,
 131                      const wxPoint& pos = wxDefaultPosition,
 132                      const wxSize& size = wxDefaultSize,
 133                      long style = wxHSCROLL | wxVSCROLL,
 134                      const wxString& name = "scrolledWindow");
 135     //@}
 136
 137     /**
 138         Destructor.
 139     */
 140     ~wxScrolledWindow();
 141
 142     /**
 143         Translates the logical coordinates to the device ones. For example, if a window
 144         is
 145         scrolled 10 pixels to the bottom, the device coordinates of the origin are (0,
 146         0)
 147         (as always), but the logical coordinates are (0, 10) and so the call to
 148         CalcScrolledPosition(0, 10, xx, yy) will return 0 in yy.
 149
 150         @see CalcUnscrolledPosition()
 151     */
 152     void CalcScrolledPosition(int x, int y, int* xx, int* yy);
 153
 154     /**
 155         Translates the device coordinates to the logical ones. For example, if a window
 156         is
 157         scrolled 10 pixels to the bottom, the device coordinates of the origin are (0,
 158         0)
 159         (as always), but the logical coordinates are (0, 10) and so the call to
 160         CalcUnscrolledPosition(0, 0, xx, yy) will return 10 in yy.
 161
 162         @see CalcScrolledPosition()
 163     */
 164     void CalcUnscrolledPosition(int x, int y, int* xx, int* yy);
 165
 166     /**
 167         Creates the window for two-step construction. Derived classes
 168         should call or replace this function. See wxScrolledWindow()
 169         for details.
 170     */
 171     bool Create(wxWindow* parent, wxWindowID id = -1,
 172                 const wxPoint& pos = wxDefaultPosition,
 173                 const wxSize& size = wxDefaultSize,
 174                 long style = wxHSCROLL | wxVSCROLL,
 175                 const wxString& name = "scrolledWindow");
 176
 177     /**
 178         Call this function to prepare the device context for drawing a scrolled image.
 179         It
 180         sets the device origin according to the current scroll position.
 181         DoPrepareDC is called automatically within the default OnPaint() event
 182         handler, so your OnDraw() override
 183         will be passed a 'pre-scrolled' device context. However, if you wish to draw
 184         from
 185         outside of OnDraw (via OnPaint), or you wish to implement OnPaint yourself, you
 186         must
 187         call this function yourself. For example:
 188     */
 189     void DoPrepareDC(wxDC& dc);
 190
 191     /**
 192         Enable or disable physical scrolling in the given direction. Physical
 193         scrolling is the physical transfer of bits up or down the
 194         screen when a scroll event occurs. If the application scrolls by a
 195         variable amount (e.g. if there are different font sizes) then physical
 196         scrolling will not work, and you should switch it off. Note that you
 197         will have to reposition child windows yourself, if physical scrolling
 198         is disabled.
 199
 200         @param xScrolling
 201             If @true, enables physical scrolling in the x direction.
 202         @param yScrolling
 203             If @true, enables physical scrolling in the y direction.
 204
 205         @remarks Physical scrolling may not be available on all platforms. Where
 206                  it is available, it is enabled by default.
 207     */
 208     void EnableScrolling(bool xScrolling, bool yScrolling);
 209
 210     /**
 211         Get the number of pixels per scroll unit (line), in each direction, as set
 212         by SetScrollbars(). A value of zero indicates no
 213         scrolling in that direction.
 214
 215         @param xUnit
 216             Receives the number of pixels per horizontal unit.
 217         @param yUnit
 218             Receives the number of pixels per vertical unit.
 219
 220         @see SetScrollbars(), GetVirtualSize()
 221     */
 222     void GetScrollPixelsPerUnit(int* xUnit, int* yUnit);
 223
 224     /**
 225         Get the position at which the visible portion of the window starts.
 226
 227         @param x
 228             Receives the first visible x position in scroll units.
 229         @param y
 230             Receives the first visible y position in scroll units.
 231
 232         @remarks If either of the scrollbars is not at the home position, x
 233                  and/or y will be greater than zero.  Combined with
 234                  wxWindow::GetClientSize, the application can use this
 235                  function to efficiently redraw only the visible portion
 236                  of the window.  The positions are in logical scroll
 237                  units, not pixels, so to convert to pixels you will
 238                  have to multiply by the number of pixels per scroll
 239                  increment.
 240
 241         @see SetScrollbars()
 242     */
 243     void GetViewStart(int* x, int* y);
 244
 245     /**
 246         Gets the size in device units of the scrollable window area (as
 247         opposed to the client size, which is the area of the window currently
 248         visible).
 249
 250         @param x
 251             Receives the length of the scrollable window, in pixels.
 252         @param y
 253             Receives the height of the scrollable window, in pixels.
 254
 255         @remarks Use wxDC::DeviceToLogicalX and wxDC::DeviceToLogicalY to
 256                  translate these units to logical units.
 257
 258         @see SetScrollbars(), GetScrollPixelsPerUnit()
 259     */
 260     void GetVirtualSize(int* x, int* y);
 261
 262     /**
 263         Motif only: @true if the window has a backing bitmap.
 264     */
 265     bool IsRetained();
 266
 267     /**
 268         Called by the default paint event handler to allow the application to define
 269         painting behaviour without having to worry about calling
 270         DoPrepareDC().
 271         Instead of overriding this function you may also just process the paint event
 272         in the derived class as usual, but then you will have to call DoPrepareDC()
 273         yourself.
 274     */
 275     virtual void OnDraw(wxDC& dc);
 276
 277     /**
 278         This function is for backwards compatibility only and simply calls
 279         DoPrepareDC() now. Notice that it is
 280         not called by the default paint event handle (DoPrepareDC() is), so
 281         overriding this method in your derived class is useless.
 282     */
 283     void PrepareDC(wxDC& dc);
 284
 285     /**
 286         Scrolls a window so the view start is at the given point.
 287
 288         @param x
 289             The x position to scroll to, in scroll units.
 290         @param y
 291             The y position to scroll to, in scroll units.
 292
 293         @remarks The positions are in scroll units, not pixels, so to convert to
 294                  pixels you will have to multiply by the number of
 295                  pixels per scroll increment. If either parameter is -1,
 296                  that position will be ignored (no change in that
 297                  direction).
 298
 299         @see SetScrollbars(), GetScrollPixelsPerUnit()
 300     */
 301     void Scroll(int x, int y);
 302
 303     /**
 304         Set the horizontal and vertical scrolling increment only. See the pixelsPerUnit
 305         parameter in SetScrollbars.
 306     */
 307     void SetScrollRate(int xstep, int ystep);
 308
 309     /**
 310         Sets up vertical and/or horizontal scrollbars.
 311
 312         @param pixelsPerUnitX
 313             Pixels per scroll unit in the horizontal direction.
 314         @param pixelsPerUnitY
 315             Pixels per scroll unit in the vertical direction.
 316         @param noUnitsX
 317             Number of units in the horizontal direction.
 318         @param noUnitsY
 319             Number of units in the vertical direction.
 320         @param xPos
 321             Position to initialize the scrollbars in the horizontal direction, in
 322         scroll units.
 323         @param yPos
 324             Position to initialize the scrollbars in the vertical direction, in scroll
 325         units.
 326         @param noRefresh
 327             Will not refresh window if @true.
 328
 329         @remarks The first pair of parameters give the number of pixels per
 330                  'scroll step', i.e. amount moved when the up or down
 331                  scroll arrows are pressed. The second pair gives the
 332                  length of scrollbar in scroll steps, which sets the
 333                  size of the virtual window.
 334
 335         @see wxWindow::SetVirtualSize
 336     */
 337     void SetScrollbars(int pixelsPerUnitX, int pixelsPerUnitY,
 338                        int noUnitsX,
 339                        int noUnitsY,
 340                        int xPos = 0,
 341                        int yPos = 0,
 342                        bool noRefresh = false);
 343
 344     /**
 345         Call this function to tell wxScrolledWindow to perform the actual scrolling on
 346         a different window (and not on itself).
 347     */
 348     void SetTargetWindow(wxWindow* window);
 349 };