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 @c wxEVT_PAINT
 185         event handler, so your OnDraw() override will be passed an already
 186         'pre-scrolled' device context. However, if you wish to draw from
 187         outside of OnDraw() (e.g. from your own @c wxEVT_PAINT handler), you
 188         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         Notice that the function sets the origin by moving it relatively to the
 210         current origin position, so you shouldn't change the origin before
 211         calling DoPrepareDC() or, if you do, reset it to (0, 0) later. If you
 212         call DoPrepareDC() immediately after device context creation, as in the
 213         example above, this problem doesn't arise, of course, so it is
 214         customary to do it like this.
 215     */
 216     void DoPrepareDC(wxDC& dc);
 217
 218     /**
 219         Enable or disable physical scrolling in the given direction. Physical
 220         scrolling is the physical transfer of bits up or down the
 221         screen when a scroll event occurs. If the application scrolls by a
 222         variable amount (e.g. if there are different font sizes) then physical
 223         scrolling will not work, and you should switch it off. Note that you
 224         will have to reposition child windows yourself, if physical scrolling
 225         is disabled.
 226
 227         @param xScrolling
 228             If @true, enables physical scrolling in the x direction.
 229         @param yScrolling
 230             If @true, enables physical scrolling in the y direction.
 231
 232         @remarks Physical scrolling may not be available on all platforms. Where
 233                  it is available, it is enabled by default.
 234     */
 235     void EnableScrolling(bool xScrolling, bool yScrolling);
 236
 237     /**
 238         Get the number of pixels per scroll unit (line), in each direction, as
 239         set by SetScrollbars(). A value of zero indicates no scrolling in that
 240         direction.
 241
 242         @param xUnit
 243             Receives the number of pixels per horizontal unit.
 244         @param yUnit
 245             Receives the number of pixels per vertical unit.
 246
 247         @see SetScrollbars(), GetVirtualSize()
 248     */
 249     void GetScrollPixelsPerUnit(int* xUnit, int* yUnit) const;
 250
 251     /**
 252         Get the position at which the visible portion of the window starts.
 253
 254         @param x
 255             Receives the first visible x position in scroll units.
 256         @param y
 257             Receives the first visible y position in scroll units.
 258
 259         @remarks If either of the scrollbars is not at the home position, x
 260                  and/or y will be greater than zero.  Combined with
 261                  wxWindow::GetClientSize(), the application can use this
 262                  function to efficiently redraw only the visible portion
 263                  of the window.  The positions are in logical scroll
 264                  units, not pixels, so to convert to pixels you will
 265                  have to multiply by the number of pixels per scroll
 266                  increment.
 267
 268         @see SetScrollbars()
 269     */
 270     void GetViewStart(int* x, int* y) const;
 271
 272     /**
 273         Gets the size in device units of the scrollable window area (as
 274         opposed to the client size, which is the area of the window currently
 275         visible).
 276
 277         @param x
 278             Receives the length of the scrollable window, in pixels.
 279         @param y
 280             Receives the height of the scrollable window, in pixels.
 281
 282         @remarks Use wxDC::DeviceToLogicalX() and wxDC::DeviceToLogicalY() to
 283                  translate these units to logical units.
 284
 285         @see SetScrollbars(), GetScrollPixelsPerUnit()
 286     */
 287     void GetVirtualSize(int* x, int* y) const;
 288
 289     /**
 290         Motif only: @true if the window has a backing bitmap.
 291     */
 292     bool IsRetained() const;
 293
 294     /**
 295         Called by the default paint event handler to allow the application to
 296         define painting behaviour without having to worry about calling
 297         DoPrepareDC().
 298
 299         Instead of overriding this function you may also just process the paint
 300         event in the derived class as usual, but then you will have to call
 301         DoPrepareDC() yourself.
 302     */
 303     virtual void OnDraw(wxDC& dc);
 304
 305     /**
 306         This function is for backwards compatibility only and simply calls
 307         DoPrepareDC() now. Notice that it is not called by the default paint
 308         event handle (DoPrepareDC() is), so overriding this method in your
 309         derived class is useless.
 310     */
 311     void PrepareDC(wxDC& dc);
 312
 313     /**
 314         Scrolls a window so the view start is at the given point.
 315
 316         @param x
 317             The x position to scroll to, in scroll units.
 318         @param y
 319             The y position to scroll to, in scroll units.
 320
 321         @remarks The positions are in scroll units, not pixels, so to convert to
 322                  pixels you will have to multiply by the number of
 323                  pixels per scroll increment. If either parameter is -1,
 324                  that position will be ignored (no change in that
 325                  direction).
 326
 327         @see SetScrollbars(), GetScrollPixelsPerUnit()
 328     */
 329     void Scroll(int x, int y);
 330
 331     /**
 332         Set the horizontal and vertical scrolling increment only. See the
 333         pixelsPerUnit parameter in SetScrollbars().
 334     */
 335     void SetScrollRate(int xstep, int ystep);
 336
 337     /**
 338         Sets up vertical and/or horizontal scrollbars.
 339
 340         The first pair of parameters give the number of pixels per 'scroll
 341         step', i.e. amount moved when the up or down scroll arrows are pressed.
 342         The second pair gives the length of scrollbar in scroll steps, which
 343         sets the size of the virtual window.
 344
 345         @a xPos and @a yPos optionally specify a position to scroll to
 346         immediately.
 347
 348         For example, the following gives a window horizontal and vertical
 349         scrollbars with 20 pixels per scroll step, and a size of 50 steps (1000
 350         pixels) in each direction:
 351         @code
 352         window->SetScrollbars(20, 20, 50, 50);
 353         @endcode
 354
 355         wxScrolled manages the page size itself, using the current client
 356         window size as the page size.
 357
 358         Note that for more sophisticated scrolling applications, for example
 359         where scroll steps may be variable according to the position in the
 360         document, it will be necessary to derive a new class from wxWindow,
 361         overriding OnSize() and adjusting the scrollbars appropriately.
 362
 363         @param pixelsPerUnitX
 364             Pixels per scroll unit in the horizontal direction.
 365         @param pixelsPerUnitY
 366             Pixels per scroll unit in the vertical direction.
 367         @param noUnitsX
 368             Number of units in the horizontal direction.
 369         @param noUnitsY
 370             Number of units in the vertical direction.
 371         @param xPos
 372             Position to initialize the scrollbars in the horizontal direction,
 373             in scroll units.
 374         @param yPos
 375             Position to initialize the scrollbars in the vertical direction, in
 376             scroll units.
 377         @param noRefresh
 378             Will not refresh window if @true.
 379
 380         @see wxWindow::SetVirtualSize()
 381     */
 382     void SetScrollbars(int pixelsPerUnitX, int pixelsPerUnitY,
 383                        int noUnitsX,
 384                        int noUnitsY,
 385                        int xPos = 0,
 386                        int yPos = 0,
 387                        bool noRefresh = false);
 388
 389     /**
 390         Call this function to tell wxScrolled to perform the actual
 391         scrolling on a different window (and not on itself).
 392     */
 393     void SetTargetWindow(wxWindow* window);
 394 };
 395
 396
 397 /**
 398     Scrolled window derived from wxPanel.
 399
 400     See wxScrolled for detailed description.
 401
 402     @note Note that because this class derives from wxPanel, it shares its
 403           behavior with regard to TAB traversal and focus handling (in
 404           particular, it forwards focus to its children). If you don't want
 405           this behaviour, use ::wxScrolledCanvas instead.
 406
 407     @note ::wxScrolledWindow is an alias for wxScrolled<wxPanel> since version
 408           2.9.0. In older versions, it was a standalone class.
 409
 410     @library{wxcore}
 411     @category{miscwnd}
 412
 413     @see wxScrolled, ::wxScrolledCanvas
 414 */
 415 typedef wxScrolled<wxPanel> wxScrolledWindow;
 416
 417 /**
 418     Alias for wxScrolled<wxWindow>. Scrolled window that doesn't have children
 419     and so doesn't need or want special handling of TAB traversal.
 420
 421     @since 2.9.0
 422
 423     @library{wxcore}
 424     @category{miscwnd}
 425
 426     @see wxScrolled, ::wxScrolledWindow
 427 */
 428 typedef wxScrolled<wxWindow> wxScrolledCanvas;