docs/latex/wx/scrolwin.tex

   1 \section{\class{wxScrolledWindow}}\label{wxscrolledwindow}
   2
   3 The wxScrolledWindow class manages scrolling for its client area, transforming
   4 the coordinates according to the scrollbar positions, and setting the
   5 scroll positions, thumb sizes and ranges according to the area in view.
   6
   7 As with all windows, an application can draw onto a wxScrolledWindow using a \helpref{device context}{dcoverview}.
   8
   9 You have the option of handling the \helpref{OnPaint}{wxscrolledwindowonpaint} handler
  10 or overriding the \helpref{OnDraw}{wxscrolledwindowondraw} function, which is passed
  11 a pre-scrolled device context (prepared by \helpref{PrepareDC}{wxscrolledwindowpreparedc}).
  12
  13 If you don't wish to calculate your own scrolling, you must call PrepareDC when not drawing from
  14 within OnDraw, to set the device origin for the device context according to the current
  15 scroll position.
  16
  17 \wxheading{Derived from}
  18
  19 \helpref{wxWindow}{wxwindow}\\
  20 \helpref{wxEvtHandler}{wxevthandler}\\
  21 \helpref{wxObject}{wxobject}
  22
  23 \wxheading{Window styles}
  24
  25 \twocolwidtha{5cm}
  26 \begin{twocollist}\itemsep=0pt
  27 \twocolitem{\windowstyle{wxRETAINED}}{Uses a backing pixmap to speed refreshes. Motif only.}
  28 \end{twocollist}
  29
  30 See also \helpref{window styles overview}{windowstyles}.
  31
  32 \wxheading{Remarks}
  33
  34 Use wxScrolledWindow for applications where the user scrolls by a fixed amount, and
  35 where a `page' can be interpreted to be the current visible portion of the window. For
  36 more sophisticated applications, use the wxScrolledWindow implementation as a guide
  37 to build your own scroll behaviour.
  38
  39 \wxheading{See also}
  40
  41 \helpref{wxScrollBar}{wxscrollbar}, \helpref{wxClientDC}{wxclientdc}, \helpref{wxPaintDC}{wxpaintdc}
  42
  43 \latexignore{\rtfignore{\wxheading{Members}}}
  44
  45 \membersection{wxScrolledWindow::wxScrolledWindow}\label{wxscrolledwindowconstr}
  46
  47 \func{}{wxScrolledWindow}{\void}
  48
  49 Default constructor.
  50
  51 \func{}{wxScrolledWindow}{\param{wxWindow*}{ parent}, \param{wxWindowID }{id = -1},\rtfsp
  52 \param{const wxPoint\& }{pos = wxDefaultPosition}, \param{const wxSize\& }{size = wxDefaultSize},\rtfsp
  53 \param{long}{ style = wxHSCROLL \pipe wxVSCROLL}, \param{const wxString\& }{name = ``scrolledWindow"}}
  54
  55 Constructor.
  56
  57 \wxheading{Parameters}
  58
  59 \docparam{parent}{Parent window.}
  60
  61 \docparam{id}{Window identifier. A value of -1 indicates a default value.}
  62
  63 \docparam{pos}{Window position. If a position of (-1, -1) is specified then a default position
  64 is chosen.}
  65
  66 \docparam{size}{Window size. If a size of (-1, -1) is specified then the window is sized
  67 appropriately.}
  68
  69 \docparam{style}{Window style. See \helpref{wxScrolledWindow}{wxscrolledwindow}.}
  70
  71 \docparam{name}{Window name.}
  72
  73 \wxheading{Remarks}
  74
  75 The window is initially created without visible scrollbars.
  76 Call \helpref{wxScrolledWindow::SetScrollbars}{wxscrolledwindowsetscrollbars} to
  77 specify how big the virtual window size should be.
  78
  79 \membersection{wxScrolledWindow::\destruct{wxScrolledWindow}}
  80
  81 \func{}{\destruct{wxScrolledWindow}}{\void}
  82
  83 Destructor.
  84
  85 \membersection{wxScrolledWindow::Create}\label{wxscrolledwindowcreate}
  86
  87 \func{bool}{Create}{\param{wxWindow*}{ parent}, \param{wxWindowID }{id = -1},\rtfsp
  88 \param{const wxPoint\& }{pos = wxDefaultPosition}, \param{const wxSize\& }{size = wxDefaultSize},\rtfsp
  89 \param{long}{ style = wxHSCROLL \pipe wxVSCROLL}, \param{const wxString\& }{name = ``scrolledWindow"}}
  90
  91 Creates the window for two-step construction. Derived classes
  92 should call or replace this function. See \helpref{wxScrolledWindow::wxScrolledWindow}{wxscrolledwindowconstr}\rtfsp
  93 for details.
  94
  95 \membersection{wxScrolledWindow::EnableScrolling}\label{wxscrolledwindowenablescrolling}
  96
  97 \func{void}{EnableScrolling}{\param{const bool}{ xScrolling}, \param{const bool}{ yScrolling}}
  98
  99 Enable or disable physical scrolling in the given direction. Physical
 100 scrolling is the physical transfer of bits up or down the
 101 screen when a scroll event occurs. If the application scrolls by a
 102 variable amount (e.g. if there are different font sizes) then physical
 103 scrolling will not work, and you should switch it off.
 104
 105 \wxheading{Parameters}
 106
 107 \docparam{xScrolling}{If TRUE, enables physical scrolling in the x direction.}
 108
 109 \docparam{yScrolling}{If TRUE, enables physical scrolling in the y direction.}
 110
 111 \wxheading{Remarks}
 112
 113 Physical scrolling may not be available on all platforms. Where it is available, it is enabled
 114 by default.
 115
 116 \membersection{wxScrolledWindow::GetScrollPixelsPerUnit}\label{wxscrolledwindowgetscrollpixelsperunit}
 117
 118 \constfunc{void}{GetScrollPixelsPerUnit}{\param{int* }{xUnit}, \param{int* }{yUnit}}
 119
 120 Get the number of pixels per scroll unit (line), in each direction, as set
 121 by \helpref{wxScrolledWindow::SetScrollbars}{wxscrolledwindowsetscrollbars}. A value of zero indicates no
 122 scrolling in that direction.
 123
 124 \wxheading{Parameters}
 125
 126 \docparam{xUnit}{Receives the number of pixels per horizontal unit.}
 127
 128 \docparam{yUnit}{Receives the number of pixels per vertical unit.}
 129
 130 \wxheading{See also}
 131
 132 \helpref{wxScrolledWindow::SetScrollbars}{wxscrolledwindowsetscrollbars},\rtfsp
 133 \helpref{wxScrolledWindow::GetVirtualSize}{wxscrolledwindowgetvirtualsize}
 134
 135 \membersection{wxScrolledWindow::GetVirtualSize}\label{wxscrolledwindowgetvirtualsize}
 136
 137 \constfunc{void}{GetVirtualSize}{\param{int* }{x}, \param{int* }{y}}
 138
 139 Gets the size in device units of the scrollable window area (as
 140 opposed to the client size, which is the area of the window currently
 141 visible).
 142
 143 \wxheading{Parameters}
 144
 145 \docparam{x}{Receives the length of the scrollable window, in pixels.}
 146
 147 \docparam{y}{Receives the height of the scrollable window, in pixels.}
 148
 149 \wxheading{Remarks}
 150
 151 Use \helpref{wxDC::DeviceToLogicalX}{wxdcdevicetologicalx} and \helpref{wxDC::DeviceToLogicalY}{wxdcdevicetologicaly}\rtfsp
 152 to translate these units to logical units.
 153
 154 \wxheading{See also}
 155
 156 \helpref{wxScrolledWindow::SetScrollbars}{wxscrolledwindowsetscrollbars},\rtfsp
 157 \helpref{wxScrolledWindow::GetScrollPixelsPerUnit}{wxscrolledwindowgetscrollpixelsperunit}
 158
 159 \membersection{wxScrolledWindow::IsRetained}\label{wxscrolledwindowisretained}
 160
 161 \constfunc{bool}{IsRetained}{\void}
 162
 163 TRUE if the window has a backing bitmap.
 164
 165 \membersection{wxScrolledWindow::PrepareDC}\label{wxscrolledwindowpreparedc}
 166
 167 \func{void}{PrepareDC}{\param{wxDC\& }{dc}}
 168
 169 Call this function to prepare the device context for drawing a scrolled image. It
 170 sets the device origin according to the current scroll position.
 171
 172 PrepareDC is called automatically within the default \helpref{wxScrolledWindow::OnPaint}{wxscrolledwindowonpaint} event
 173 handler, so your \helpref{wxScrolledWindow::OnDraw}{wxscrolledwindowondraw} override
 174 will be passed a 'pre-scrolled' device context. However, if you wish to draw from
 175 outside of OnDraw (via OnPaint), or you wish to implement OnPaint yourself, you must
 176 call this function yourself. For example:
 177
 178 \begin{verbatim}
 179 void MyWindow::OnEvent(wxMouseEvent& event)
 180 {
 181   wxClientDC dc(this);
 182   PrepareDC(dc);
 183
 184   dc.SetPen(*wxBLACK_PEN);
 185   float x, y;
 186   event.Position(&x, &y);
 187   if (xpos > -1 && ypos > -1 && event.Dragging())
 188   {
 189     dc.DrawLine(xpos, ypos, x, y);
 190   }
 191   xpos = x;
 192   ypos = y;
 193 }
 194 \end{verbatim}
 195
 196 \membersection{wxScrolledWindow::OnDraw}\label{wxscrolledwindowondraw}
 197
 198 \func{virtual void}{OnDraw}{\param{wxDC\& }{dc}}
 199
 200 Called by the default \helpref{wxScrolledWindow::OnPaint}{wxscrolledwindowonpaint} implementation
 201 to allow the application to define painting behaviour without having to worry about
 202 calling \helpref{wxScrolledWindow::PrepareDC}{wxscrolledwindowpreparedc}.
 203
 204 \membersection{wxScrolledWindow::OnPaint}\label{wxscrolledwindowonpaint}
 205
 206 \func{void}{OnPaint}{\param{wxPaintEvent\& }{event}}
 207
 208 Sent to the window when the window must be refreshed.
 209
 210 For more details, see \helpref{wxWindow::OnPaint}{wxwindowonpaint}.
 211
 212 The default implementation for wxScrolledWindow's OnPaint handler is simply:
 213
 214 \begin{verbatim}
 215 void wxScrolledWindow::OnPaint(wxPaintEvent& event)
 216 {
 217         wxPaintDC dc(this);
 218         PrepareDC(dc);
 219
 220         OnDraw(dc);
 221 }
 222 \end{verbatim}
 223
 224 \membersection{wxScrolledWindow::OnScroll}\label{wxscrolledwindowonscroll}
 225
 226 \func{void}{OnScroll}{\param{wxScrollEvent\& }{event}}
 227
 228 Override this function to intercept scroll events. This
 229 member function implements the default scroll behaviour. If
 230 you do not call the default function, you will have to manage
 231 all scrolling behaviour including drawing the window contents
 232 at an appropriate position relative to the scrollbars.
 233
 234 For more details, see \helpref{wxWindow::OnScroll}{wxwindowonscroll}.
 235
 236 \wxheading{See also}
 237
 238 \helpref{wxScrollEvent}{wxscrollevent}
 239
 240 \membersection{wxScrolledWindow::Scroll}\label{wxscrolledwindowscroll}
 241
 242 \func{void}{Scroll}{\param{int}{ x}, \param{int}{ y}}
 243
 244 Scrolls a window so the view start is at the given point.
 245
 246 \wxheading{Parameters}
 247
 248 \docparam{x}{The x position to scroll to, in scroll units.}
 249
 250 \docparam{y}{The y position to scroll to, in scroll units.}
 251
 252 \wxheading{Remarks}
 253
 254 The positions are in scroll units, not pixels, so to convert to pixels you
 255 will have to multiply by the number of pixels per scroll increment.
 256 If either parameter is -1, that position will be ignored (no change in
 257 that direction).
 258
 259 \wxheading{See also}
 260
 261 \helpref{wxScrolledWindow::SetScrollbars}{wxscrolledwindowsetscrollbars},\rtfsp
 262 \helpref{wxScrolledWindow::GetScrollPixelsPerUnit}{wxscrolledwindowgetscrollpixelsperunit}
 263
 264 \membersection{wxScrolledWindow::SetScrollbars}\label{wxscrolledwindowsetscrollbars}
 265
 266 \func{void}{SetScrollbars}{\param{int}{ pixelsPerUnitX}, \param{int}{ pixelsPerUnitY},\rtfsp
 267 \param{int}{ noUnitsX}, \param{int}{ noUnitsY},\rtfsp
 268 \param{int }{xPos = 0}, \param{int}{ yPos = 0}}
 269
 270 Sets up vertical and/or horizontal scrollbars.
 271
 272 \wxheading{Parameters}
 273
 274 \docparam{pixelsPerUnitX}{Pixels per scroll unit in the horizontal direction.}
 275
 276 \docparam{pixelsPerUnitY}{Pixels per scroll unit in the vertical direction.}
 277
 278 \docparam{noUnitsX}{Number of units in the horizontal direction.}
 279
 280 \docparam{noUnitsY}{Number of units in the vertical direction.}
 281
 282 \docparam{xPos}{Position to initialize the scrollbars in the horizontal direction, in scroll units.}
 283
 284 \docparam{yPos}{Position to initialize the scrollbars in the vertical direction, in scroll units.}
 285
 286 \wxheading{Remarks}
 287
 288 The first pair of parameters give the number of pixels per `scroll step', i.e. amount
 289 moved when the up or down scroll arrows are pressed.
 290 The second pair gives the length of scrollbar in scroll steps, which sets the size of the virtual
 291 window.
 292
 293 {\it xPos} and {\it yPos} optionally specify a position to scroll to immediately.
 294
 295 For example, the following gives a window horizontal and vertical
 296 scrollbars with 20 pixels per scroll step, and a size of 50 steps (1000
 297 pixels) in each direction.
 298
 299 \begin{verbatim}
 300   window->SetScrollbars(20, 20, 50, 50);
 301 \end{verbatim}
 302
 303 wxScrolledWindow manages the page size itself,
 304 using the current client window size as the page size.
 305
 306 Note that for more sophisticated scrolling applications, for example where
 307 scroll steps may be variable according to the position in the document, it will be
 308 necessary to derive a new class from wxWindow, overriding {\bf OnSize} and
 309 adjusting the scrollbars appropriately.
 310
 311 \membersection{wxScrolledWindow::ViewStart}\label{wxscrolledwindowviewstart}
 312
 313 \constfunc{void}{ViewStart}{\param{int* }{x}, \param{int* }{ y}}
 314
 315 Get the position at which the visible portion of the window starts.
 316
 317 \wxheading{Parameters}
 318
 319 \docparam{x}{Receives the first visible x position in scroll units.}
 320
 321 \docparam{y}{Receives the first visible y position in scroll units.}
 322
 323 \wxheading{Remarks}
 324
 325 If either of the scrollbars is not at the home position, {\it x} and/or
 326 \rtfsp{\it y} will be greater than zero.  Combined with \helpref{wxWindow::GetClientSize}{wxwindowgetclientsize},
 327 the application can use this function to efficiently redraw only the
 328 visible portion of the window.  The positions are in logical scroll
 329 units, not pixels, so to convert to pixels you will have to multiply
 330 by the number of pixels per scroll increment.
 331
 332 \wxheading{See also}
 333
 334 \helpref{wxScrolledWindow::SetScrollbars}{wxscrolledwindowsetscrollbars}
 335