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
 112         @param id
 113         Window identifier. The value wxID_ANY indicates a default value.
 114
 115         @param pos
 116         Window position. If a position of (-1, -1) is specified then a default position
 117         is chosen.
 118
 119         @param size
 120         Window size. If a size of (-1, -1) is specified then the window is sized
 121         appropriately.
 122
 123         @param style
 124         Window style. See wxScrolledWindow.
 125
 126         @param name
 127         Window name.
 128
 129         @remarks The window is initially created without visible scrollbars. Call
 130                    SetScrollbars() to specify how big
 131                    the virtual window size should be.
 132     */
 133     wxScrolledWindow();
 134     wxScrolledWindow(wxWindow* parent, wxWindowID id = -1,
 135                      const wxPoint& pos = wxDefaultPosition,
 136                      const wxSize& size = wxDefaultSize,
 137                      long style = wxHSCROLL |  wxVSCROLL,
 138                      const wxString& name = "scrolledWindow");
 139     //@}
 140
 141     /**
 142         Destructor.
 143     */
 144     ~wxScrolledWindow();
 145
 146     /**
 147         Translates the logical coordinates to the device ones. For example, if a window
 148         is
 149         scrolled 10 pixels to the bottom, the device coordinates of the origin are (0,
 150         0)
 151         (as always), but the logical coordinates are (0, 10) and so the call to
 152         CalcScrolledPosition(0, 10, xx, yy) will return 0 in yy.
 153
 154         @sa CalcUnscrolledPosition()
 155     */
 156     void CalcScrolledPosition(int x, int y, int * xx, int * yy);
 157
 158     /**
 159         Translates the device coordinates to the logical ones. For example, if a window
 160         is
 161         scrolled 10 pixels to the bottom, the device coordinates of the origin are (0,
 162         0)
 163         (as always), but the logical coordinates are (0, 10) and so the call to
 164         CalcUnscrolledPosition(0, 0, xx, yy) will return 10 in yy.
 165
 166         @sa CalcScrolledPosition()
 167     */
 168     void CalcUnscrolledPosition(int x, int y, int * xx, int * yy);
 169
 170     /**
 171         Creates the window for two-step construction. Derived classes
 172         should call or replace this function. See wxScrolledWindow()
 173         for details.
 174     */
 175     bool Create(wxWindow* parent, wxWindowID id = -1,
 176                 const wxPoint& pos = wxDefaultPosition,
 177                 const wxSize& size = wxDefaultSize,
 178                 long style = wxHSCROLL |  wxVSCROLL,
 179                 const wxString& name = "scrolledWindow");
 180
 181     /**
 182         Call this function to prepare the device context for drawing a scrolled image.
 183         It
 184         sets the device origin according to the current scroll position.
 185
 186         DoPrepareDC is called automatically within the default OnPaint() event
 187         handler, so your OnDraw() override
 188         will be passed a 'pre-scrolled' device context. However, if you wish to draw
 189         from
 190         outside of OnDraw (via OnPaint), or you wish to implement OnPaint yourself, you
 191         must
 192         call this function yourself. For example:
 193     */
 194     void DoPrepareDC(wxDC& dc);
 195
 196     /**
 197         Enable or disable physical scrolling in the given direction. Physical
 198         scrolling is the physical transfer of bits up or down the
 199         screen when a scroll event occurs. If the application scrolls by a
 200         variable amount (e.g. if there are different font sizes) then physical
 201         scrolling will not work, and you should switch it off. Note that you
 202         will have to reposition child windows yourself, if physical scrolling
 203         is disabled.
 204
 205         @param xScrolling
 206         If @true, enables physical scrolling in the x direction.
 207
 208         @param yScrolling
 209         If @true, enables physical scrolling in the y direction.
 210
 211         @remarks Physical scrolling may not be available on all platforms. Where
 212                    it is available, it is enabled by default.
 213     */
 214     void EnableScrolling(bool xScrolling, bool yScrolling);
 215
 216     /**
 217         Get the number of pixels per scroll unit (line), in each direction, as set
 218         by SetScrollbars(). A value of zero indicates no
 219         scrolling in that direction.
 220
 221         @param xUnit
 222         Receives the number of pixels per horizontal unit.
 223
 224         @param yUnit
 225         Receives the number of pixels per vertical unit.
 226
 227         @sa SetScrollbars(), GetVirtualSize()
 228     */
 229     void GetScrollPixelsPerUnit(int* xUnit, int* yUnit);
 230
 231     /**
 232         Get the position at which the visible portion of the window starts.
 233
 234         @param x
 235         Receives the first visible x position in scroll units.
 236
 237         @param y
 238         Receives the first visible y position in scroll units.
 239
 240         @remarks If either of the scrollbars is not at the home position, x
 241                    and/or y will be greater than zero.  Combined with
 242                    wxWindow::GetClientSize, the application can use this
 243                    function to efficiently redraw only the visible
 244                    portion of the window.  The positions are in logical
 245                    scroll units, not pixels, so to convert to pixels you
 246                    will have to multiply by the number of pixels per
 247                    scroll increment.
 248
 249         @sa SetScrollbars()
 250     */
 251     void GetViewStart(int* x, int* y);
 252
 253     /**
 254         Gets the size in device units of the scrollable window area (as
 255         opposed to the client size, which is the area of the window currently
 256         visible).
 257
 258         @param x
 259         Receives the length of the scrollable window, in pixels.
 260
 261         @param y
 262         Receives the height of the scrollable window, in pixels.
 263
 264         @remarks Use wxDC::DeviceToLogicalX and wxDC::DeviceToLogicalY to
 265                    translate these units to logical units.
 266
 267         @sa SetScrollbars(), GetScrollPixelsPerUnit()
 268     */
 269     void GetVirtualSize(int* x, int* y);
 270
 271     /**
 272         Motif only: @true if the window has a backing bitmap.
 273     */
 274     bool IsRetained();
 275
 276     /**
 277         Called by the default paint event handler to allow the application to define
 278         painting behaviour without having to worry about calling
 279         DoPrepareDC().
 280
 281         Instead of overriding this function you may also just process the paint event
 282         in the derived class as usual, but then you will have to call DoPrepareDC()
 283         yourself.
 284     */
 285     virtual void OnDraw(wxDC& dc);
 286
 287     /**
 288         This function is for backwards compatibility only and simply calls
 289         DoPrepareDC() now. Notice that it is
 290         not called by the default paint event handle (DoPrepareDC() is), so
 291         overriding this method in your derived class is useless.
 292     */
 293     void PrepareDC(wxDC& dc);
 294
 295     /**
 296         Scrolls a window so the view start is at the given point.
 297
 298         @param x
 299         The x position to scroll to, in scroll units.
 300
 301         @param y
 302         The y position to scroll to, in scroll units.
 303
 304         @remarks The positions are in scroll units, not pixels, so to convert to
 305                    pixels you will have to multiply by the number of
 306                    pixels per scroll increment. If either parameter is
 307                    -1, that position will be ignored (no change in that
 308                    direction).
 309
 310         @sa SetScrollbars(), GetScrollPixelsPerUnit()
 311     */
 312     void Scroll(int x, int y);
 313
 314     /**
 315         Set the horizontal and vertical scrolling increment only. See the pixelsPerUnit
 316         parameter in SetScrollbars.
 317     */
 318     void SetScrollRate(int xstep, int ystep);
 319
 320     /**
 321         Sets up vertical and/or horizontal scrollbars.
 322
 323         @param pixelsPerUnitX
 324         Pixels per scroll unit in the horizontal direction.
 325
 326         @param pixelsPerUnitY
 327         Pixels per scroll unit in the vertical direction.
 328
 329         @param noUnitsX
 330         Number of units in the horizontal direction.
 331
 332         @param noUnitsY
 333         Number of units in the vertical direction.
 334
 335         @param xPos
 336         Position to initialize the scrollbars in the horizontal direction, in scroll
 337         units.
 338
 339         @param yPos
 340         Position to initialize the scrollbars in the vertical direction, in scroll
 341         units.
 342
 343         @param noRefresh
 344         Will not refresh window if @true.
 345
 346         @remarks The first pair of parameters give the number of pixels per
 347                    'scroll step', i.e. amount moved when the up or down
 348                    scroll arrows are pressed. The second pair gives the
 349                    length of scrollbar in scroll steps, which sets the
 350                    size of the virtual window.
 351
 352         @sa wxWindow::SetVirtualSize
 353     */
 354     void SetScrollbars(int pixelsPerUnitX, int pixelsPerUnitY,
 355                        int noUnitsX,
 356                        int noUnitsY,
 357                        int xPos = 0,
 358                        int yPos = 0,
 359                        bool noRefresh = @false);
 360
 361     /**
 362         Call this function to tell wxScrolledWindow to perform the actual scrolling on
 363         a different window (and not on itself).
 364     */
 365     void SetTargetWindow(wxWindow* window);
 366 };