docs/latex/wx/vscroll.tex

   1 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
   2 %% Name:        vscroll.tex
   3 %% Purpose:     wxVScrolledWindow documentation
   4 %% Author:      Vadim Zeitlin
   5 %% Modified by:
   6 %% Created:     30.05.03
   7 %% RCS-ID:      $Id$
   8 %% Copyright:   (c) 2003 Vadim Zeitlin <vadim@wxwindows.org>
   9 %% License:     wxWindows license
  10 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
  11
  12 \section{\class{wxVScrolledWindow}}\label{wxvscrolledwindow}
  13
  14 In the name of this class, "V" may stand for "variable" because it can be
  15 used for scrolling lines of variable heights; "virtual" because it is not
  16 necessary to know the heights of all lines in advance -- only those which
  17 are shown on the screen need to be measured; or, even, "vertical" because
  18 this class only supports scrolling in one direction currently (this could
  19 and probably will change in the future however).
  20
  21 In any case, this is a generalization of the
  22 \helpref{wxScrolledWindow}{wxscrolledwindow} class which can be only used when
  23 all lines have the same height. It lacks some other wxScrolledWindow features
  24 however, notably there is currently no support for horizontal scrolling; it
  25 can't scroll another window nor only a rectangle of the window and not its
  26 entire client area.
  27
  28 To use this class, you need to derive from it and implement
  29 \helpref{OnGetLineHeight()}{wxvscrolledwindowongetlineheight} pure virtual
  30 method. You also must call \helpref{SetLineCount}{wxvscrolledwindowsetlinecount}
  31 to let the base class know how many lines it should display but from that
  32 moment on the scrolling is handled entirely by wxVScrolledWindow, you only
  33 need to draw the visible part of contents in your {\tt OnPaint()} method as
  34 usual. You should use \helpref{GetFirstVisibleLine()}{wxvscrolledwindowgetfirstvisibleline}
  35 and \helpref{GetLastVisibleLine()}{wxvscrolledwindowgetlastvisibleline} to
  36 select the lines to display. Note that the device context origin is not shifted
  37 so the first visible line always appears at the point $(0, 0)$ in physical as
  38 well as logical coordinates.
  39
  40 \wxheading{Derived from}
  41
  42 \helpref{wxPanel}{wxpanel}
  43
  44 \wxheading{Include files}
  45
  46 <wx/vscroll.h>
  47
  48
  49 \latexignore{\rtfignore{\wxheading{Members}}}
  50
  51
  52 \membersection{wxVScrolledWindow::wxVScrolledWindow}\label{wxvscrolledwindowctor}
  53
  54 \func{}{wxVScrolledWindow}{\param{wxWindow* }{parent}, \param{wxWindowID }{id = wxID\_ANY}, \param{const wxPoint\& }{pos = wxDefaultPosition}, \param{const wxSize\& }{size = wxDefaultSize}, \param{long }{style = 0}, \param{const wxString\& }{name = wxPanelNameStr}}
  55
  56 This is the normal constructor, no need to call Create() after using this one.
  57
  58 Note that {\tt wxVSCROLL} is always automatically added to our style, there is
  59 no need to specify it explicitly.
  60
  61 \func{}{wxVScrolledWindow}{\void}
  62
  63 Default constructor, you must call \helpref{Create()}{wxvscrolledwindowcreate}
  64 later.
  65
  66 \wxheading{Parameters}
  67
  68 \docparam{parent}{The parent window, must not be {\tt NULL}}
  69
  70 \docparam{id}{The identifier of this window, {\tt wxID\_ANY} by default}
  71
  72 \docparam{pos}{The initial window position}
  73
  74 \docparam{size}{The initial window size}
  75
  76 \docparam{style}{The window style. There are no special style bits defined for
  77 this class.}
  78
  79 \docparam{name}{The name for this window; usually not used}
  80
  81
  82 \membersection{wxVScrolledWindow::Create}\label{wxvscrolledwindowcreate}
  83
  84 \func{bool}{Create}{\param{wxWindow* }{parent}, \param{wxWindowID }{id = wxID\_ANY}, \param{const wxPoint\& }{pos = wxDefaultPosition}, \param{const wxSize\& }{size = wxDefaultSize}, \param{long }{style = 0}, \param{const wxString\& }{name = wxPanelNameStr}}
  85
  86 Same as the \helpref{non default ctor}{wxvscrolledwindowctor} but returns
  87 status code: {\tt true} if ok, {\tt false} if the window couldn't have been created.
  88
  89 Just as with the ctor above, {\tt wxVSCROLL} style is always used, there is no
  90 need to specify it explicitly.
  91
  92
  93 \membersection{wxVScrolledWindow::EstimateTotalHeight}\label{wxvscrolledwindowestimatetotalheight}
  94
  95 \constfunc{virtual wxCoord}{EstimateTotalHeight}{\void}
  96
  97 This protected function is used internally by wxVScrolledWindow to estimate the
  98 total height of the window when \helpref{SetLineCount}{wxvscrolledwindowsetlinecount}
  99 is called. The default implementation uses the brute force approach if the
 100 number of the items in the control is small enough. Otherwise, it tries to find
 101 the average line height using some lines in the beginning, middle and the end.
 102
 103 If it is undesirable to access all these lines (some of which might be never
 104 shown) just for the total height calculation, you may override the function and
 105 provide your own guess better and/or faster.
 106
 107 Note that although returning a totally wrong value would still work, it risks
 108 to result in very strange scrollbar behaviour so this function should really
 109 try to make the best guess possible.
 110
 111
 112 \membersection{wxVScrolledWindow::GetFirstVisibleLine}\label{wxvscrolledwindowgetfirstvisibleline}
 113
 114 \constfunc{size\_t}{GetFirstVisibleLine}{\void}
 115
 116 Returns the index of the first currently visible line.
 117
 118 This is same as \helpref{GetVisibleBegin}{wxvscrolledwindowgetvisiblebegin} and
 119 exists only for symmetry with \helpref{GetLastVisibleLine}{wxvscrolledwindowgetlastvisibleline}.
 120
 121
 122 \membersection{wxVScrolledWindow::GetLastVisibleLine}\label{wxvscrolledwindowgetlastvisibleline}
 123
 124 \constfunc{size\_t}{GetLastVisibleLine}{\void}
 125
 126 Returns the index of the last currently visible line. Note that this method
 127 returns \texttt{(size\_t)-1} (i.e. a huge positive number) if the control is
 128 empty so if this is possible you should use \helpref{GetVisibleEnd}{wxvscrolledwindowgetvisibleend}
 129 instead.
 130
 131 \wxheading{See also}
 132
 133 \helpref{GetFirstVisibleLine}{wxvscrolledwindowgetfirstvisibleline}
 134
 135
 136 \membersection{wxVScrolledWindow::GetLineCount}\label{wxvscrolledwindowgetlinecount}
 137
 138 \constfunc{size\_t}{GetLineCount}{\void}
 139
 140 Get the number of lines this window contains (previously set by
 141 \helpref{SetLineCount()}{wxvscrolledwindowsetlinecount})
 142
 143
 144 \membersection{wxVScrolledWindow::GetVisibleBegin}\label{wxvscrolledwindowgetvisiblebegin}
 145
 146 \constfunc{size\_t}{GetVisibleBegin}{\void}
 147
 148 Returns the index of the first currently visible line.
 149
 150 \wxheading{See also}
 151
 152 \helpref{GetVisibleEnd}{wxvscrolledwindowgetvisibleend}
 153
 154
 155 \membersection{wxVScrolledWindow::GetVisibleEnd}\label{wxvscrolledwindowgetvisibleend}
 156
 157 \constfunc{size\_t}{GetVisibleEnd}{\void}
 158
 159 Returns the index of the first line after the currently visible one. If the
 160 return value is $0$ it means that no lines are currently shown (which only
 161 happens if the control is empty). Note that the index returned by this method
 162 is not always a valid index as it may be equal to \helpref{GetLineCount}{wxvscrolledwindowsetlinecount}.
 163
 164 \wxheading{See also}
 165
 166 \helpref{GetVisibleBegin}{wxvscrolledwindowgetvisiblebegin}
 167
 168
 169 \membersection{wxVScrolledWindow::HitTest}\label{wxvscrolledwindowhittest}
 170
 171 \constfunc{int}{HitTest}{\param{wxCoord }{x}, \param{wxCoord }{y}}
 172
 173 \constfunc{int}{HitTest}{\param{const wxPoint\& }{pt}}
 174
 175 Return the item at the specified (in physical coordinates) position or
 176 {\tt wxNOT\_FOUND} if none, i.e. if it is below the last item.
 177
 178
 179 \membersection{wxVScrolledWindow::IsVisible}\label{wxvscrolledwindowisvisible}
 180
 181 \constfunc{bool}{IsVisible}{\param{size\_t }{line}}
 182
 183 Returns {\tt true} if the given line is (at least partially) visible or
 184 {\tt false} otherwise.
 185
 186
 187 \membersection{wxVScrolledWindow::OnGetLineHeight}\label{wxvscrolledwindowongetlineheight}
 188
 189 \constfunc{wxCoord}{OnGetLineHeight}{\param{size\_t }{n}}
 190
 191 This protected virtual function must be overridden in the derived class and it
 192 should return the height of the given line in pixels.
 193
 194 \wxheading{See also}
 195
 196 \helpref{OnGetLinesHint}{wxvscrolledwindowongetlineshint}
 197
 198
 199 \membersection{wxVScrolledWindow::OnGetLinesHint}\label{wxvscrolledwindowongetlineshint}
 200
 201 \constfunc{void}{OnGetLinesHint}{\param{size\_t }{lineMin}, \param{size\_t }{lineMax}}
 202
 203 This function doesn't have to be overridden but it may be useful to do
 204 it if calculating the lines heights is a relatively expensive operation
 205 as it gives the user code a possibility to calculate several of them at
 206 once.
 207
 208 {\tt OnGetLinesHint()} is normally called just before
 209 \helpref{OnGetLineHeight()}{wxvscrolledwindowongetlineheight} but you
 210 shouldn't rely on the latter being called for all lines in the interval
 211 specified here. It is also possible that OnGetLineHeight() will be
 212 called for the lines outside of this interval, so this is really just a
 213 hint, not a promise.
 214
 215 Finally note that {\it lineMin} is inclusive, while {\it lineMax} is exclusive,
 216 as usual.
 217
 218
 219 \membersection{wxVScrolledWindow::RefreshLine}\label{wxvscrolledwindowrefreshline}
 220
 221 \func{void}{RefreshLine}{\param{size\_t }{line}}
 222
 223 Refreshes the specified line -- it will be redrawn during the next main loop
 224 iteration.
 225
 226 \wxheading{See also}
 227
 228 \helpref{RefreshLines}{wxvscrolledwindowrefreshlines}
 229
 230
 231 \membersection{wxVScrolledWindow::RefreshLines}\label{wxvscrolledwindowrefreshlines}
 232
 233 \func{void}{RefreshLines}{\param{size\_t }{from}, \param{size\_t }{to}}
 234
 235 Refreshes all lines between {\it from} and {\it to}, inclusive. {\it from}
 236 should be less than or equal to {\it to}.
 237
 238 \wxheading{See also}
 239
 240 \helpref{RefreshLine}{wxvscrolledwindowrefreshline}
 241
 242
 243 \membersection{wxVScrolledWindow::RefreshAll}\label{wxvscrolledwindowrefreshall}
 244
 245 \func{void}{RefreshAll}{\void}
 246
 247 This function completely refreshes the control, recalculating the number of
 248 items shown on screen and repainting them. It should be called when the values
 249 returned by \helpref{OnGetLineHeight}{wxvscrolledwindowongetlineheight} change
 250 for some reason and the window must be updated to reflect this.
 251
 252
 253 \membersection{wxVScrolledWindow::ScrollLines}\label{wxvscrolledwindowscrolllines}
 254
 255 \func{bool}{ScrollLines}{\param{int }{lines}}
 256
 257 Scroll by the specified number of lines which may be positive (to scroll down)
 258 or negative (to scroll up).
 259
 260 Returns {\tt true} if the window was scrolled, {\tt false} otherwise (for
 261 example if we're trying to scroll down but we are already showing the last
 262 line).
 263
 264 \wxheading{See also}
 265
 266 \helpref{LineUp}{wxwindowlineup}, \helpref{LineDown}{wxwindowlinedown}
 267
 268
 269 \membersection{wxVScrolledWindow::ScrollPages}\label{wxvscrolledwindowscrollpages}
 270
 271 \func{bool}{ScrollPages}{\param{int }{pages}}
 272
 273 Scroll by the specified number of pages which may be positive (to scroll down)
 274 or negative (to scroll up).
 275
 276 \wxheading{See also}
 277
 278 \helpref{ScrollLines}{wxvscrolledwindowscrolllines},\\
 279 \helpref{PageUp}{wxwindowpageup}, \helpref{PageDown}{wxwindowpagedown}
 280
 281
 282 \membersection{wxVScrolledWindow::ScrollToLine}\label{wxvscrolledwindowscrolltoline}
 283
 284 \func{bool}{ScrollToLine}{\param{size\_t }{line}}
 285
 286 Scroll to the specified line: it will become the first visible line in
 287 the window.
 288
 289 Return {\tt true} if we scrolled the window, {\tt false} if nothing was done.
 290
 291
 292 \membersection{wxVScrolledWindow::SetLineCount}\label{wxvscrolledwindowsetlinecount}
 293
 294 \func{void}{SetLineCount}{\param{size\_t }{count}}
 295
 296 Set the number of lines the window contains: the derived class must
 297 provide the heights for all lines with indices up to the one given here
 298 in its \helpref{OnGetLineHeight()}{wxvscrolledwindowongetlineheight}.
 299
 300