interface/wx/scrolwin.h

   1 /////////////////////////////////////////////////////////////////////////////
   2 // Name:        scrolwin.h
   3 // Purpose:     interface of wxScrolled template
   4 // Author:      wxWidgets team
   5 // RCS-ID:      $Id$
   6 // Licence:     wxWindows license
   7 /////////////////////////////////////////////////////////////////////////////
   8
   9 /**
  10
  11     The wxScrolled class manages scrolling for its client area, transforming
  12     the coordinates according to the scrollbar positions, and setting the
  13     scroll positions, thumb sizes and ranges according to the area in view.
  14
  15     There are two commonly used (but not the only possible!) specializations of
  16     this class:
  17
  18     - ::wxScrolledWindow, aka wxScrolled<wxPanel>, is equivalent to
  19       ::wxScrolledWindow from earlier versions. Derived from wxPanel, it shares
  20       wxPanel's behaviour with regard to TAB traversal and focus handling. Use
  21       this if the scrolled window will have child controls.
  22
  23     - ::wxScrolledCanvas, aka wxScrolled<wxWindow>, derives from wxWindow and
  24       so doesn't handle children specially. This is suitable e.g. for
  25       implementating scrollable controls such as tree or list controls.
  26
  27     Starting from version 2.4 of wxWidgets, there are several ways to use a
  28     ::wxScrolledWindow (and now wxScrolled). In particular, there are
  29     three ways to set the size of the scrolling area:
  30
  31     One way is to set the scrollbars directly using a call to SetScrollbars().
  32     This is the way it used to be in any previous version of wxWidgets and it
  33     will be kept for backwards compatibility.
  34
  35     An additional method of manual control, which requires a little less
  36     computation of your own, is to set the total size of the scrolling area by
  37     calling either wxWindow::SetVirtualSize(), or wxWindow::FitInside(), and
  38     setting the scrolling increments for it by calling SetScrollRate().
  39     Scrolling in some orientation is enabled by setting a non-zero increment
  40     for it.
  41
  42     The most automatic and newest way is to simply let sizers determine the
  43     scrolling area. This is now the default when you set an interior sizer into
  44     a wxScrolled with wxWindow::SetSizer().  The scrolling area will be
  45     set to the size requested by the sizer and the scrollbars will be assigned
  46     for each orientation according to the need for them and the scrolling
  47     increment set by SetScrollRate().  As above, scrolling is only enabled in
  48     orientations with a non-zero increment.  You can influence the minimum size
  49     of the scrolled area controlled by a sizer by calling
  50     wxWindow::SetVirtualSizeHints(). (Calling SetScrollbars() has analogous
  51     effects in wxWidgets 2.4 -- in later versions it may not continue to
  52     override the sizer.)
  53
  54     Note that if maximum size hints are still supported by
  55     wxWindow::SetVirtualSizeHints(), use them at your own dire risk. They may
  56     or may not have been removed for 2.4, but it really only makes sense to set
  57     minimum size hints here.  We should probably replace
  58     wxWindow::SetVirtualSizeHints() with wxWindow::SetMinVirtualSize() or
  59     similar and remove it entirely in future.
  60
  61     As with all windows, an application can draw onto a wxScrolled using a
  62     @ref overview_dc "device context".
  63
  64     You have the option of handling the OnPaint handler or overriding the
  65     wxScrolled::OnDraw() function, which is passed a pre-scrolled device
  66     context (prepared by wxScrolled::DoPrepareDC()).
  67
  68     If you don't wish to calculate your own scrolling, you must call
  69     DoPrepareDC() when not drawing from within OnDraw(), to set the device
  70     origin for the device context according to the current scroll position.
  71
  72     A wxScrolled will normally scroll itself and therefore its child windows
  73     as well. It might however be desired to scroll a different window than
  74     itself: e.g. when designing a spreadsheet, you will normally only have to
  75     scroll the (usually white) cell area, whereas the (usually grey) label area
  76     will scroll very differently. For this special purpose, you can call
  77     SetTargetWindow() which means that pressing the scrollbars will scroll a
  78     different window.
  79
  80     Note that the underlying system knows nothing about scrolling coordinates,
  81     so that all system functions (mouse events, expose events, refresh calls
  82     etc) as well as the position of subwindows are relative to the "physical"
  83     origin of the scrolled window. If the user insert a child window at
  84     position (10,10) and scrolls the window down 100 pixels (moving the child
  85     window out of the visible area), the child window will report a position
  86     of (10,-90).
  87
  88     @beginStyleTable
  89     @style{wxRETAINED}
  90            Uses a backing pixmap to speed refreshes. Motif only.
  91     @endStyleTable
  92
  93     @remarks
  94     Use wxScrolled for applications where the user scrolls by a fixed amount,
  95     and where a 'page' can be interpreted to be the current visible portion of
  96     the window. For more sophisticated applications, use the wxScrolled
  97     implementation as a guide to build your own scroll behaviour or use
  98     wxVScrolledWindow or its variants.
  99
 100     @since The wxScrolled template exists since version 2.9.0. In older versions,
 101            only ::wxScrolledWindow (equivalent of wxScrolled<wxPanel>) was
 102            available.
 103
 104     @library{wxcore}
 105     @category{miscwnd}
 106
 107     @see wxScrollBar, wxClientDC, wxPaintDC,
 108          wxVScrolledWindow, wxHScrolledWindow, wxHVScrolledWindow,
 109 */
 110 template<class T>
 111 class wxScrolled : public T
 112 {
 113 public:
 114     /// Default constructor.
 115     wxScrolled();
 116
 117     /**
 118         Constructor.
 119
 120         @param parent
 121             Parent window.
 122         @param id
 123             Window identifier. The value @c wxID_ANY indicates a default value.
 124         @param pos
 125             Window position. If a position of @c wxDefaultPosition is specified
 126             then a default position is chosen.
 127         @param size
 128             Window size. If a size of @c wxDefaultSize is specified then the
 129             window is sized appropriately.
 130         @param style
 131             Window style. See wxScrolled.
 132         @param name
 133             Window name.
 134
 135         @remarks The window is initially created without visible scrollbars.
 136                  Call SetScrollbars() to specify how big the virtual window
 137                  size should be.
 138     */
 139     wxScrolled(wxWindow* parent, wxWindowID id = -1,
 140                const wxPoint& pos = wxDefaultPosition,
 141                const wxSize& size = wxDefaultSize,
 142                long style = wxHSCROLL | wxVSCROLL,
 143                const wxString& name = "scrolledWindow");
 144
 145
 146     /**
 147         Translates the logical coordinates to the device ones. For example, if
 148         a window is scrolled 10 pixels to the bottom, the device coordinates of
 149         the origin are (0, 0) (as always), but the logical coordinates are (0,
 150         10) and so the call to CalcScrolledPosition(0, 10, xx, yy) will return
 151         0 in yy.
 152
 153         @see CalcUnscrolledPosition()
 154     */
 155     void CalcScrolledPosition(int x, int y, int* xx, int* yy) const;
 156
 157     /**
 158         Translates the device coordinates to the logical ones. For example, if
 159         a window is scrolled 10 pixels to the bottom, the device coordinates of
 160         the origin are (0, 0) (as always), but the logical coordinates are (0,
 161         10) and so the call to CalcUnscrolledPosition(0, 0, xx, yy) will return
 162         10 in yy.
 163
 164         @see CalcScrolledPosition()
 165     */
 166     void CalcUnscrolledPosition(int x, int y, int* xx, int* yy) const;
 167
 168     /**
 169         Creates the window for two-step construction. Derived classes
 170         should call or replace this function. See wxScrolled::wxScrolled()
 171         for details.
 172     */
 173     bool Create(wxWindow* parent, wxWindowID id = -1,
 174                 const wxPoint& pos = wxDefaultPosition,
 175                 const wxSize& size = wxDefaultSize,
 176                 long style = wxHSCROLL | wxVSCROLL,
 177                 const wxString& name = "scrolledWindow");
 178
 179     /**
 180         Call this function to prepare the device context for drawing a scrolled
 181         image.
 182
 183         It sets the device origin according to the current scroll position.
 184         DoPrepareDC() is called automatically within the default OnPaint()
 185         event handler, so your OnDraw() override will be passed a
 186         'pre-scrolled' device context. However, if you wish to draw from
 187         outside of OnDraw() (via OnPaint()), or you wish to implement OnPaint()
 188         yourself, you must call this function yourself.
 189
 190         For example:
 191         @code
 192         void MyWindow::OnEvent(wxMouseEvent& event)
 193         {
 194           wxClientDC dc(this);
 195           DoPrepareDC(dc);
 196
 197           dc.SetPen(*wxBLACK_PEN);
 198           float x, y;
 199           event.Position(&x, &y);
 200           if (xpos > -1 && ypos > -1 && event.Dragging())
 201           {
 202             dc.DrawLine(xpos, ypos, x, y);
 203           }
 204           xpos = x;
 205           ypos = y;
 206         }
 207         @endcode
 208
 209     */
 210     void DoPrepareDC(wxDC& dc);
 211
 212     /**
 213         Enable or disable physical scrolling in the given direction. Physical
 214         scrolling is the physical transfer of bits up or down the
 215         screen when a scroll event occurs. If the application scrolls by a
 216         variable amount (e.g. if there are different font sizes) then physical
 217         scrolling will not work, and you should switch it off. Note that you
 218         will have to reposition child windows yourself, if physical scrolling
 219         is disabled.
 220
 221         @param xScrolling
 222             If @true, enables physical scrolling in the x direction.
 223         @param yScrolling
 224             If @true, enables physical scrolling in the y direction.
 225
 226         @remarks Physical scrolling may not be available on all platforms. Where
 227                  it is available, it is enabled by default.
 228     */
 229     void EnableScrolling(bool xScrolling, bool yScrolling);
 230
 231     /**
 232         Get the number of pixels per scroll unit (line), in each direction, as
 233         set by SetScrollbars(). A value of zero indicates no scrolling in that
 234         direction.
 235
 236         @param xUnit
 237             Receives the number of pixels per horizontal unit.
 238         @param yUnit
 239             Receives the number of pixels per vertical unit.
 240
 241         @see SetScrollbars(), GetVirtualSize()
 242     */
 243     void GetScrollPixelsPerUnit(int* xUnit, int* yUnit) const;
 244
 245     /**
 246         Get the position at which the visible portion of the window starts.
 247
 248         @param x
 249             Receives the first visible x position in scroll units.
 250         @param y
 251             Receives the first visible y position in scroll units.
 252
 253         @remarks If either of the scrollbars is not at the home position, x
 254                  and/or y will be greater than zero.  Combined with
 255                  wxWindow::GetClientSize(), the application can use this
 256                  function to efficiently redraw only the visible portion
 257                  of the window.  The positions are in logical scroll
 258                  units, not pixels, so to convert to pixels you will
 259                  have to multiply by the number of pixels per scroll
 260                  increment.
 261
 262         @see SetScrollbars()
 263     */
 264     void GetViewStart(int* x, int* y) const;
 265
 266     /**
 267         Gets the size in device units of the scrollable window area (as
 268         opposed to the client size, which is the area of the window currently
 269         visible).
 270
 271         @param x
 272             Receives the length of the scrollable window, in pixels.
 273         @param y
 274             Receives the height of the scrollable window, in pixels.
 275
 276         @remarks Use wxDC::DeviceToLogicalX() and wxDC::DeviceToLogicalY() to
 277                  translate these units to logical units.
 278
 279         @see SetScrollbars(), GetScrollPixelsPerUnit()
 280     */
 281     void GetVirtualSize(int* x, int* y) const;
 282
 283     /**
 284         Motif only: @true if the window has a backing bitmap.
 285     */
 286     bool IsRetained() const;
 287
 288     /**
 289         Called by the default paint event handler to allow the application to
 290         define painting behaviour without having to worry about calling
 291         DoPrepareDC().
 292
 293         Instead of overriding this function you may also just process the paint
 294         event in the derived class as usual, but then you will have to call
 295         DoPrepareDC() yourself.
 296     */
 297     virtual void OnDraw(wxDC& dc);
 298
 299     /**
 300         This function is for backwards compatibility only and simply calls
 301         DoPrepareDC() now. Notice that it is not called by the default paint
 302         event handle (DoPrepareDC() is), so overriding this method in your
 303         derived class is useless.
 304     */
 305     void PrepareDC(wxDC& dc);
 306
 307     /**
 308         Scrolls a window so the view start is at the given point.
 309
 310         @param x
 311             The x position to scroll to, in scroll units.
 312         @param y
 313             The y position to scroll to, in scroll units.
 314
 315         @remarks The positions are in scroll units, not pixels, so to convert to
 316                  pixels you will have to multiply by the number of
 317                  pixels per scroll increment. If either parameter is -1,
 318                  that position will be ignored (no change in that
 319                  direction).
 320
 321         @see SetScrollbars(), GetScrollPixelsPerUnit()
 322     */
 323     void Scroll(int x, int y);
 324
 325     /**
 326         Set the horizontal and vertical scrolling increment only. See the
 327         pixelsPerUnit parameter in SetScrollbars().
 328     */
 329     void SetScrollRate(int xstep, int ystep);
 330
 331     /**
 332         Sets up vertical and/or horizontal scrollbars.
 333
 334         The first pair of parameters give the number of pixels per 'scroll
 335         step', i.e. amount moved when the up or down scroll arrows are pressed.
 336         The second pair gives the length of scrollbar in scroll steps, which
 337         sets the size of the virtual window.
 338
 339         @a xPos and @a yPos optionally specify a position to scroll to
 340         immediately.
 341
 342         For example, the following gives a window horizontal and vertical
 343         scrollbars with 20 pixels per scroll step, and a size of 50 steps (1000
 344         pixels) in each direction:
 345         @code
 346         window->SetScrollbars(20, 20, 50, 50);
 347         @endcode
 348
 349         wxScrolled manages the page size itself, using the current client
 350         window size as the page size.
 351
 352         Note that for more sophisticated scrolling applications, for example
 353         where scroll steps may be variable according to the position in the
 354         document, it will be necessary to derive a new class from wxWindow,
 355         overriding OnSize() and adjusting the scrollbars appropriately.
 356
 357         @param pixelsPerUnitX
 358             Pixels per scroll unit in the horizontal direction.
 359         @param pixelsPerUnitY
 360             Pixels per scroll unit in the vertical direction.
 361         @param noUnitsX
 362             Number of units in the horizontal direction.
 363         @param noUnitsY
 364             Number of units in the vertical direction.
 365         @param xPos
 366             Position to initialize the scrollbars in the horizontal direction,
 367             in scroll units.
 368         @param yPos
 369             Position to initialize the scrollbars in the vertical direction, in
 370             scroll units.
 371         @param noRefresh
 372             Will not refresh window if @true.
 373
 374         @see wxWindow::SetVirtualSize()
 375     */
 376     void SetScrollbars(int pixelsPerUnitX, int pixelsPerUnitY,
 377                        int noUnitsX,
 378                        int noUnitsY,
 379                        int xPos = 0,
 380                        int yPos = 0,
 381                        bool noRefresh = false);
 382
 383     /**
 384         Call this function to tell wxScrolled to perform the actual
 385         scrolling on a different window (and not on itself).
 386     */
 387     void SetTargetWindow(wxWindow* window);
 388 };
 389
 390
 391 /**
 392     Scrolled window derived from wxPanel.
 393
 394     See wxScrolled for detailed description.
 395
 396     @note Note that because this class derives from wxPanel, it shares its
 397           behavior with regard to TAB traversal and focus handling (in
 398           particular, it forwards focus to its children). If you don't want
 399           this behaviour, use ::wxScrolledCanvas instead.
 400
 401     @note ::wxScrolledWindow is an alias for wxScrolled<wxPanel> since version
 402           2.9.0. In older versions, it was a standalone class.
 403
 404     @library{wxcore}
 405     @category{miscwnd}
 406
 407     @see wxScrolled, ::wxScrolledCanvas
 408 */
 409 typedef wxScrolled<wxPanel> wxScrolledWindow;
 410
 411 /**
 412     Alias for wxScrolled<wxWindow>. Scrolled window that doesn't have children
 413     and so doesn't need or want special handling of TAB traversal.
 414
 415     @since 2.9.0
 416
 417     @library{wxcore}
 418     @category{miscwnd}
 419
 420     @see wxScrolled, ::wxScrolledWindow
 421 */
 422 typedef wxScrolled<wxWindow> wxScrolledCanvas;