interface/scrolwin.h

   1 /////////////////////////////////////////////////////////////////////////////
   2 // Name:        scrolwin.h
   3 // Purpose:     interface of wxScrolledWindow
   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     @see wxScrollBar, wxClientDC, wxPaintDC, wxVScrolledWindow
 100 */
 101 class wxScrolledWindow : public wxPanel
 102 {
 103 public:
 104     //@{
 105     /**
 106         Constructor.
 107
 108         @param parent
 109             Parent window.
 110         @param id
 111             Window identifier. The value wxID_ANY indicates a default value.
 112         @param pos
 113             Window position. If a position of (-1, -1) is specified then a default
 114         position
 115             is chosen.
 116         @param size
 117             Window size. If a size of (-1, -1) is specified then the window is sized
 118             appropriately.
 119         @param style
 120             Window style. See wxScrolledWindow.
 121         @param name
 122             Window name.
 123
 124         @remarks The window is initially created without visible scrollbars. Call
 125                  SetScrollbars() to specify how big the
 126                  virtual window size should be.
 127     */
 128     wxScrolledWindow();
 129     wxScrolledWindow(wxWindow* parent, wxWindowID id = -1,
 130                      const wxPoint& pos = wxDefaultPosition,
 131                      const wxSize& size = wxDefaultSize,
 132                      long style = wxHSCROLL | wxVSCROLL,
 133                      const wxString& name = "scrolledWindow");
 134     //@}
 135
 136     /**
 137         Destructor.
 138     */
 139     ~wxScrolledWindow();
 140
 141     /**
 142         Translates the logical coordinates to the device ones. For example, if a window
 143         is
 144         scrolled 10 pixels to the bottom, the device coordinates of the origin are (0,
 145         0)
 146         (as always), but the logical coordinates are (0, 10) and so the call to
 147         CalcScrolledPosition(0, 10, xx, yy) will return 0 in yy.
 148
 149         @see CalcUnscrolledPosition()
 150     */
 151     void CalcScrolledPosition(int x, int y, int* xx, int* yy) const;
 152
 153     /**
 154         Translates the device coordinates to the logical ones. For example, if a window
 155         is
 156         scrolled 10 pixels to the bottom, the device coordinates of the origin are (0,
 157         0)
 158         (as always), but the logical coordinates are (0, 10) and so the call to
 159         CalcUnscrolledPosition(0, 0, xx, yy) will return 10 in yy.
 160
 161         @see CalcScrolledPosition()
 162     */
 163     void CalcUnscrolledPosition(int x, int y, int* xx, int* yy) const;
 164
 165     /**
 166         Creates the window for two-step construction. Derived classes
 167         should call or replace this function. See wxScrolledWindow()
 168         for details.
 169     */
 170     bool Create(wxWindow* parent, wxWindowID id = -1,
 171                 const wxPoint& pos = wxDefaultPosition,
 172                 const wxSize& size = wxDefaultSize,
 173                 long style = wxHSCROLL | wxVSCROLL,
 174                 const wxString& name = "scrolledWindow");
 175
 176     /**
 177         Call this function to prepare the device context for drawing a scrolled image.
 178         It
 179         sets the device origin according to the current scroll position.
 180         DoPrepareDC is called automatically within the default OnPaint() event
 181         handler, so your OnDraw() override
 182         will be passed a 'pre-scrolled' device context. However, if you wish to draw
 183         from
 184         outside of OnDraw (via OnPaint), or you wish to implement OnPaint yourself, you
 185         must
 186         call this function yourself. For example:
 187     */
 188     void DoPrepareDC(wxDC& dc);
 189
 190     /**
 191         Enable or disable physical scrolling in the given direction. Physical
 192         scrolling is the physical transfer of bits up or down the
 193         screen when a scroll event occurs. If the application scrolls by a
 194         variable amount (e.g. if there are different font sizes) then physical
 195         scrolling will not work, and you should switch it off. Note that you
 196         will have to reposition child windows yourself, if physical scrolling
 197         is disabled.
 198
 199         @param xScrolling
 200             If @true, enables physical scrolling in the x direction.
 201         @param yScrolling
 202             If @true, enables physical scrolling in the y direction.
 203
 204         @remarks Physical scrolling may not be available on all platforms. Where
 205                  it is available, it is enabled by default.
 206     */
 207     void EnableScrolling(bool xScrolling, bool yScrolling);
 208
 209     /**
 210         Get the number of pixels per scroll unit (line), in each direction, as set
 211         by SetScrollbars(). A value of zero indicates no
 212         scrolling in that direction.
 213
 214         @param xUnit
 215             Receives the number of pixels per horizontal unit.
 216         @param yUnit
 217             Receives the number of pixels per vertical unit.
 218
 219         @see SetScrollbars(), GetVirtualSize()
 220     */
 221     void GetScrollPixelsPerUnit(int* xUnit, int* yUnit) const;
 222
 223     /**
 224         Get the position at which the visible portion of the window starts.
 225
 226         @param x
 227             Receives the first visible x position in scroll units.
 228         @param y
 229             Receives the first visible y position in scroll units.
 230
 231         @remarks If either of the scrollbars is not at the home position, x
 232                  and/or y will be greater than zero.  Combined with
 233                  wxWindow::GetClientSize, the application can use this
 234                  function to efficiently redraw only the visible portion
 235                  of the window.  The positions are in logical scroll
 236                  units, not pixels, so to convert to pixels you will
 237                  have to multiply by the number of pixels per scroll
 238                  increment.
 239
 240         @see SetScrollbars()
 241     */
 242     void GetViewStart(int* x, int* y) const;
 243
 244     /**
 245         Gets the size in device units of the scrollable window area (as
 246         opposed to the client size, which is the area of the window currently
 247         visible).
 248
 249         @param x
 250             Receives the length of the scrollable window, in pixels.
 251         @param y
 252             Receives the height of the scrollable window, in pixels.
 253
 254         @remarks Use wxDC::DeviceToLogicalX and wxDC::DeviceToLogicalY to
 255                  translate these units to logical units.
 256
 257         @see SetScrollbars(), GetScrollPixelsPerUnit()
 258     */
 259     void GetVirtualSize(int* x, int* y) const;
 260
 261     /**
 262         Motif only: @true if the window has a backing bitmap.
 263     */
 264     bool IsRetained() const;
 265
 266     /**
 267         Called by the default paint event handler to allow the application to define
 268         painting behaviour without having to worry about calling
 269         DoPrepareDC().
 270         Instead of overriding this function you may also just process the paint event
 271         in the derived class as usual, but then you will have to call DoPrepareDC()
 272         yourself.
 273     */
 274     virtual void OnDraw(wxDC& dc);
 275
 276     /**
 277         This function is for backwards compatibility only and simply calls
 278         DoPrepareDC() now. Notice that it is
 279         not called by the default paint event handle (DoPrepareDC() is), so
 280         overriding this method in your derived class is useless.
 281     */
 282     void PrepareDC(wxDC& dc);
 283
 284     /**
 285         Scrolls a window so the view start is at the given point.
 286
 287         @param x
 288             The x position to scroll to, in scroll units.
 289         @param y
 290             The y position to scroll to, in scroll units.
 291
 292         @remarks The positions are in scroll units, not pixels, so to convert to
 293                  pixels you will have to multiply by the number of
 294                  pixels per scroll increment. If either parameter is -1,
 295                  that position will be ignored (no change in that
 296                  direction).
 297
 298         @see SetScrollbars(), GetScrollPixelsPerUnit()
 299     */
 300     void Scroll(int x, int y);
 301
 302     /**
 303         Set the horizontal and vertical scrolling increment only. See the pixelsPerUnit
 304         parameter in SetScrollbars.
 305     */
 306     void SetScrollRate(int xstep, int ystep);
 307
 308     /**
 309         Sets up vertical and/or horizontal scrollbars.
 310
 311         @param pixelsPerUnitX
 312             Pixels per scroll unit in the horizontal direction.
 313         @param pixelsPerUnitY
 314             Pixels per scroll unit in the vertical direction.
 315         @param noUnitsX
 316             Number of units in the horizontal direction.
 317         @param noUnitsY
 318             Number of units in the vertical direction.
 319         @param xPos
 320             Position to initialize the scrollbars in the horizontal direction, in
 321         scroll units.
 322         @param yPos
 323             Position to initialize the scrollbars in the vertical direction, in scroll
 324         units.
 325         @param noRefresh
 326             Will not refresh window if @true.
 327
 328         @remarks The first pair of parameters give the number of pixels per
 329                  'scroll step', i.e. amount moved when the up or down
 330                  scroll arrows are pressed. The second pair gives the
 331                  length of scrollbar in scroll steps, which sets the
 332                  size of the virtual window.
 333
 334         @see wxWindow::SetVirtualSize
 335     */
 336     void SetScrollbars(int pixelsPerUnitX, int pixelsPerUnitY,
 337                        int noUnitsX,
 338                        int noUnitsY,
 339                        int xPos = 0,
 340                        int yPos = 0,
 341                        bool noRefresh = false);
 342
 343     /**
 344         Call this function to tell wxScrolledWindow to perform the actual scrolling on
 345         a different window (and not on itself).
 346     */
 347     void SetTargetWindow(wxWindow* window);
 348 };
 349