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     @todo review docs for this class replacing SetVirtualSizeHints() with
  62           SetMinClientSize().
  63
  64     As with all windows, an application can draw onto a wxScrolled using a
  65     @ref overview_dc "device context".
  66
  67     You have the option of handling the OnPaint handler or overriding the
  68     wxScrolled::OnDraw() function, which is passed a pre-scrolled device
  69     context (prepared by wxScrolled::DoPrepareDC()).
  70
  71     If you don't wish to calculate your own scrolling, you must call
  72     DoPrepareDC() when not drawing from within OnDraw(), to set the device
  73     origin for the device context according to the current scroll position.
  74
  75     A wxScrolled will normally scroll itself and therefore its child windows
  76     as well. It might however be desired to scroll a different window than
  77     itself: e.g. when designing a spreadsheet, you will normally only have to
  78     scroll the (usually white) cell area, whereas the (usually grey) label area
  79     will scroll very differently. For this special purpose, you can call
  80     SetTargetWindow() which means that pressing the scrollbars will scroll a
  81     different window.
  82
  83     Note that the underlying system knows nothing about scrolling coordinates,
  84     so that all system functions (mouse events, expose events, refresh calls
  85     etc) as well as the position of subwindows are relative to the "physical"
  86     origin of the scrolled window. If the user 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 area), the child window will report a position
  89     of (10,-90).
  90
  91     @beginStyleTable
  92     @style{wxRETAINED}
  93            Uses a backing pixmap to speed refreshes. Motif only.
  94     @endStyleTable
  95
  96     @remarks
  97     Use wxScrolled for applications where the user scrolls by a fixed amount,
  98     and where a 'page' can be interpreted to be the current visible portion of
  99     the window. For more sophisticated applications, use the wxScrolled
 100     implementation as a guide to build your own scroll behaviour or use
 101     wxVScrolledWindow or its variants.
 102
 103     @since The wxScrolled template exists since version 2.9.0. In older versions,
 104            only ::wxScrolledWindow (equivalent of wxScrolled<wxPanel>) was
 105            available.
 106
 107     @library{wxcore}
 108     @category{miscwnd}
 109
 110     @see wxScrollBar, wxClientDC, wxPaintDC,
 111          wxVScrolledWindow, wxHScrolledWindow, wxHVScrolledWindow,
 112 */
 113 template<class T>
 114 class wxScrolled : public T
 115 {
 116 public:
 117     /// Default constructor.
 118     wxScrolled();
 119
 120     /**
 121         Constructor.
 122
 123         @param parent
 124             Parent window.
 125         @param id
 126             Window identifier. The value @c wxID_ANY indicates a default value.
 127         @param pos
 128             Window position. If a position of @c wxDefaultPosition is specified
 129             then a default position is chosen.
 130         @param size
 131             Window size. If a size of @c wxDefaultSize is specified then the
 132             window is sized appropriately.
 133         @param style
 134             Window style. See wxScrolled.
 135         @param name
 136             Window name.
 137
 138         @remarks The window is initially created without visible scrollbars.
 139                  Call SetScrollbars() to specify how big the virtual window
 140                  size should be.
 141     */
 142     wxScrolled(wxWindow* parent, wxWindowID id = -1,
 143                const wxPoint& pos = wxDefaultPosition,
 144                const wxSize& size = wxDefaultSize,
 145                long style = wxHSCROLL | wxVSCROLL,
 146                const wxString& name = "scrolledWindow");
 147
 148
 149     /**
 150         Translates the logical coordinates to the device ones. For example, if
 151         a window is scrolled 10 pixels to the bottom, the device coordinates of
 152         the origin are (0, 0) (as always), but the logical coordinates are (0,
 153         10) and so the call to CalcScrolledPosition(0, 10, xx, yy) will return
 154         0 in yy.
 155
 156         @see CalcUnscrolledPosition()
 157     */
 158     void CalcScrolledPosition(int x, int y, int* xx, int* yy) const;
 159
 160     /**
 161         Translates the device coordinates to the logical ones. For example, if
 162         a window is scrolled 10 pixels to the bottom, the device coordinates of
 163         the origin are (0, 0) (as always), but the logical coordinates are (0,
 164         10) and so the call to CalcUnscrolledPosition(0, 0, xx, yy) will return
 165         10 in yy.
 166
 167         @see CalcScrolledPosition()
 168     */
 169     void CalcUnscrolledPosition(int x, int y, int* xx, int* yy) const;
 170
 171     /**
 172         Creates the window for two-step construction. Derived classes
 173         should call or replace this function. See wxScrolled::wxScrolled()
 174         for details.
 175     */
 176     bool Create(wxWindow* parent, wxWindowID id = -1,
 177                 const wxPoint& pos = wxDefaultPosition,
 178                 const wxSize& size = wxDefaultSize,
 179                 long style = wxHSCROLL | wxVSCROLL,
 180                 const wxString& name = "scrolledWindow");
 181
 182     /**
 183         Call this function to prepare the device context for drawing a scrolled
 184         image.
 185
 186         It sets the device origin according to the current scroll position.
 187         DoPrepareDC() is called automatically within the default @c wxEVT_PAINT
 188         event handler, so your OnDraw() override will be passed an already
 189         'pre-scrolled' device context. However, if you wish to draw from
 190         outside of OnDraw() (e.g. from your own @c wxEVT_PAINT handler), you
 191         must call this function yourself.
 192
 193         For example:
 194         @code
 195         void MyWindow::OnEvent(wxMouseEvent& event)
 196         {
 197           wxClientDC dc(this);
 198           DoPrepareDC(dc);
 199
 200           dc.SetPen(*wxBLACK_PEN);
 201           float x, y;
 202           event.Position(&x, &y);
 203           if (xpos > -1 && ypos > -1 && event.Dragging())
 204           {
 205             dc.DrawLine(xpos, ypos, x, y);
 206           }
 207           xpos = x;
 208           ypos = y;
 209         }
 210         @endcode
 211
 212         Notice that the function sets the origin by moving it relatively to the
 213         current origin position, so you shouldn't change the origin before
 214         calling DoPrepareDC() or, if you do, reset it to (0, 0) later. If you
 215         call DoPrepareDC() immediately after device context creation, as in the
 216         example above, this problem doesn't arise, of course, so it is
 217         customary to do it like this.
 218     */
 219     void DoPrepareDC(wxDC& dc);
 220
 221     /**
 222         Enable or disable physical scrolling in the given direction. Physical
 223         scrolling is the physical transfer of bits up or down the
 224         screen when a scroll event occurs. If the application scrolls by a
 225         variable amount (e.g. if there are different font sizes) then physical
 226         scrolling will not work, and you should switch it off. Note that you
 227         will have to reposition child windows yourself, if physical scrolling
 228         is disabled.
 229
 230         @param xScrolling
 231             If @true, enables physical scrolling in the x direction.
 232         @param yScrolling
 233             If @true, enables physical scrolling in the y direction.
 234
 235         @remarks Physical scrolling may not be available on all platforms. Where
 236                  it is available, it is enabled by default.
 237     */
 238     void EnableScrolling(bool xScrolling, bool yScrolling);
 239
 240     /**
 241         Get the number of pixels per scroll unit (line), in each direction, as
 242         set by SetScrollbars(). A value of zero indicates no scrolling in that
 243         direction.
 244
 245         @param xUnit
 246             Receives the number of pixels per horizontal unit.
 247         @param yUnit
 248             Receives the number of pixels per vertical unit.
 249
 250         @see SetScrollbars(), GetVirtualSize()
 251     */
 252     void GetScrollPixelsPerUnit(int* xUnit, int* yUnit) const;
 253
 254     /**
 255         Get the position at which the visible portion of the window starts.
 256
 257         @param x
 258             Receives the first visible x position in scroll units.
 259         @param y
 260             Receives the first visible y position in scroll units.
 261
 262         @remarks If either of the scrollbars is not at the home position, x
 263                  and/or y will be greater than zero.  Combined with
 264                  wxWindow::GetClientSize(), the application can use this
 265                  function to efficiently redraw only the visible portion
 266                  of the window.  The positions are in logical scroll
 267                  units, not pixels, so to convert to pixels you will
 268                  have to multiply by the number of pixels per scroll
 269                  increment.
 270
 271         @see SetScrollbars()
 272     */
 273     void GetViewStart(int* x, int* y) const;
 274
 275     /**
 276         Gets the size in device units of the scrollable window area (as
 277         opposed to the client size, which is the area of the window currently
 278         visible).
 279
 280         @param x
 281             Receives the length of the scrollable window, in pixels.
 282         @param y
 283             Receives the height of the scrollable window, in pixels.
 284
 285         @remarks Use wxDC::DeviceToLogicalX() and wxDC::DeviceToLogicalY() to
 286                  translate these units to logical units.
 287
 288         @see SetScrollbars(), GetScrollPixelsPerUnit()
 289     */
 290     void GetVirtualSize(int* x, int* y) const;
 291
 292     /**
 293         Motif only: @true if the window has a backing bitmap.
 294     */
 295     bool IsRetained() const;
 296
 297     /**
 298         Called by the default paint event handler to allow the application to
 299         define painting behaviour without having to worry about calling
 300         DoPrepareDC().
 301
 302         Instead of overriding this function you may also just process the paint
 303         event in the derived class as usual, but then you will have to call
 304         DoPrepareDC() yourself.
 305     */
 306     virtual void OnDraw(wxDC& dc);
 307
 308     /**
 309         This function is for backwards compatibility only and simply calls
 310         DoPrepareDC() now. Notice that it is not called by the default paint
 311         event handle (DoPrepareDC() is), so overriding this method in your
 312         derived class is useless.
 313     */
 314     void PrepareDC(wxDC& dc);
 315
 316     /**
 317         Scrolls a window so the view start is at the given point.
 318
 319         @param x
 320             The x position to scroll to, in scroll units.
 321         @param y
 322             The y position to scroll to, in scroll units.
 323
 324         @remarks The positions are in scroll units, not pixels, so to convert to
 325                  pixels you will have to multiply by the number of
 326                  pixels per scroll increment. If either parameter is -1,
 327                  that position will be ignored (no change in that
 328                  direction).
 329
 330         @see SetScrollbars(), GetScrollPixelsPerUnit()
 331     */
 332     void Scroll(int x, int y);
 333
 334     /**
 335         Set the horizontal and vertical scrolling increment only. See the
 336         pixelsPerUnit parameter in SetScrollbars().
 337     */
 338     void SetScrollRate(int xstep, int ystep);
 339
 340     /**
 341         Sets up vertical and/or horizontal scrollbars.
 342
 343         The first pair of parameters give the number of pixels per 'scroll
 344         step', i.e. amount moved when the up or down scroll arrows are pressed.
 345         The second pair gives the length of scrollbar in scroll steps, which
 346         sets the size of the virtual window.
 347
 348         @a xPos and @a yPos optionally specify a position to scroll to
 349         immediately.
 350
 351         For example, the following gives a window horizontal and vertical
 352         scrollbars with 20 pixels per scroll step, and a size of 50 steps (1000
 353         pixels) in each direction:
 354         @code
 355         window->SetScrollbars(20, 20, 50, 50);
 356         @endcode
 357
 358         wxScrolled manages the page size itself, using the current client
 359         window size as the page size.
 360
 361         Note that for more sophisticated scrolling applications, for example
 362         where scroll steps may be variable according to the position in the
 363         document, it will be necessary to derive a new class from wxWindow,
 364         overriding OnSize() and adjusting the scrollbars appropriately.
 365
 366         @param pixelsPerUnitX
 367             Pixels per scroll unit in the horizontal direction.
 368         @param pixelsPerUnitY
 369             Pixels per scroll unit in the vertical direction.
 370         @param noUnitsX
 371             Number of units in the horizontal direction.
 372         @param noUnitsY
 373             Number of units in the vertical direction.
 374         @param xPos
 375             Position to initialize the scrollbars in the horizontal direction,
 376             in scroll units.
 377         @param yPos
 378             Position to initialize the scrollbars in the vertical direction, in
 379             scroll units.
 380         @param noRefresh
 381             Will not refresh window if @true.
 382
 383         @see wxWindow::SetVirtualSize()
 384     */
 385     void SetScrollbars(int pixelsPerUnitX, int pixelsPerUnitY,
 386                        int noUnitsX,
 387                        int noUnitsY,
 388                        int xPos = 0,
 389                        int yPos = 0,
 390                        bool noRefresh = false);
 391
 392     /**
 393         Call this function to tell wxScrolled to perform the actual scrolling
 394         on a different window (and not on itself).
 395
 396         This method is useful when only a part of the window should be
 397         scrolled. A typical example is a control consisting of a fixed header
 398         and the scrollable contents window: the scrollbars are attached to the
 399         main window itself, hence it, and not the contents window must be
 400         derived from wxScrolled, but only the contents window scrolls when the
 401         scrollbars are used. To implement such setup, you need to call this
 402         method with the contents window as argument.
 403
 404         Notice that if this method is used, GetSizeAvailableForScrollTarget()
 405         method must be overridden.
 406     */
 407     void SetTargetWindow(wxWindow *window);
 408
 409 protected:
 410     /**
 411         Function which must be overridden to implement the size available for
 412         the scroll target for the given size of the main window.
 413
 414         This method must be overridden if SetTargetWindow() is used (it is
 415         never called otherwise). The implementation should decrease the @a size
 416         to account for the size of the non-scrollable parts of the main window
 417         and return only the size available for the scrollable window itself.
 418         E.g. in the example given in SetTargetWindow() documentation the
 419         function would subtract the height of the header window from the
 420         vertical component of @a size.
 421      */
 422     virtual wxSize GetSizeAvailableForScrollTarget(const wxSize& size);
 423 };
 424
 425
 426 /**
 427     Scrolled window derived from wxPanel.
 428
 429     See wxScrolled for detailed description.
 430
 431     @note Note that because this class derives from wxPanel, it shares its
 432           behavior with regard to TAB traversal and focus handling (in
 433           particular, it forwards focus to its children). If you don't want
 434           this behaviour, use ::wxScrolledCanvas instead.
 435
 436     @note ::wxScrolledWindow is an alias for wxScrolled<wxPanel> since version
 437           2.9.0. In older versions, it was a standalone class.
 438
 439     @library{wxcore}
 440     @category{miscwnd}
 441
 442     @see wxScrolled, ::wxScrolledCanvas
 443 */
 444 typedef wxScrolled<wxPanel> wxScrolledWindow;
 445
 446 /**
 447     Alias for wxScrolled<wxWindow>. Scrolled window that doesn't have children
 448     and so doesn't need or want special handling of TAB traversal.
 449
 450     @since 2.9.0
 451
 452     @library{wxcore}
 453     @category{miscwnd}
 454
 455     @see wxScrolled, ::wxScrolledWindow
 456 */
 457 typedef wxScrolled<wxWindow> wxScrolledCanvas;