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