docs/latex/wx/brush.tex

   1 \section{\class{wxBrush}}\label{wxbrush}
   2
   3 A brush is a drawing tool for filling in areas. It is used for painting
   4 the background of rectangles, ellipses, etc. It has a colour and a
   5 style.
   6
   7 \wxheading{Derived from}
   8
   9 \helpref{wxGDIObject}{wxgdiobject}\\
  10 \helpref{wxObject}{wxobject}
  11
  12 \wxheading{Remarks}
  13
  14 On a monochrome display, wxWindows shows
  15 all brushes as white unless the colour is really black.
  16
  17 Do not initialize objects on the stack before the program commences,
  18 since other required structures may not have been set up yet. Instead,
  19 define global pointers to objects and create them in \helpref{wxApp::OnInit}{wxapponinit} or
  20 when required.
  21
  22 An application may wish to create brushes with different
  23 characteristics dynamically, and there is the consequent danger that a
  24 large number of duplicate brushes will be created. Therefore an
  25 application may wish to get a pointer to a brush by using the global
  26 list of brushes {\bf wxTheBrushList}, and calling the member function
  27 \rtfsp{\bf FindOrCreateBrush}.
  28
  29 wxBrush uses a reference counting system, so assignments between brushes are very
  30 cheap. You can therefore use actual wxBrush objects instead of pointers without
  31 efficiency problems. Once one wxBrush object changes its data it will create its
  32 own brush data internally so that other brushes, which previously shared the
  33 data using the reference counting, are not affected.
  34
  35 TODO: an overview for wxBrush.
  36
  37 \wxheading{See also}
  38
  39 \helpref{wxBrushList}{wxbrushlist}, \helpref{wxDC}{wxdc}, \helpref{wxDC::SetBrush}{wxdcsetbrush}
  40
  41 \latexignore{\rtfignore{\wxheading{Members}}}
  42
  43 \membersection{wxBrush::wxBrush}
  44
  45 \func{}{wxBrush}{\void}
  46
  47 Default constructor. The brush will be uninitialised, and \helpref{wxBrush::Ok}{wxbrushok} will
  48 return FALSE.
  49
  50 \func{}{wxBrush}{\param{const wxColour\&}{ colour}, \param{int}{ style}}
  51
  52 Constructs a brush from a colour object and style.
  53
  54 \func{}{wxBrush}{\param{const wxString\& }{colourName}, \param{int}{ style}}
  55
  56 Constructs a brush from a colour name and style.
  57
  58 \func{}{wxBrush}{\param{const wxBitmap\& }{stippleBitmap}}
  59
  60 Constructs a stippled brush using a bitmap.
  61
  62 \func{}{wxBrush}{\param{const wxBrush\&}{ brush}}
  63
  64 Copy constructor. This uses reference counting so is a cheap operation.
  65
  66 \wxheading{Parameters}
  67
  68 \docparam{colour}{Colour object.}
  69
  70 \docparam{colourName}{Colour name. The name will be looked up in the colour database.}
  71
  72 \docparam{style}{One of:
  73
  74 \begin{twocollist}\itemsep=0pt
  75 \twocolitem{{\bf wxTRANSPARENT}}{Transparent (no fill).}
  76 \twocolitem{{\bf wxSOLID}}{Solid.}
  77 \twocolitem{{\bf wxBDIAGONAL\_HATCH}}{Backward diagonal hatch.}
  78 \twocolitem{{\bf wxCROSSDIAG\_HATCH}}{Cross-diagonal hatch.}
  79 \twocolitem{{\bf wxFDIAGONAL\_HATCH}}{Forward diagonal hatch.}
  80 \twocolitem{{\bf wxCROSS\_HATCH}}{Cross hatch.}
  81 \twocolitem{{\bf wxHORIZONTAL\_HATCH}}{Horizontal hatch.}
  82 \twocolitem{{\bf wxVERTICAL\_HATCH}}{Vertical hatch.}
  83 \end{twocollist}}
  84
  85 \docparam{brush}{Pointer or reference to a brush to copy.}
  86
  87 \docparam{stippleBitmap}{A bitmap to use for stippling.}
  88
  89 \wxheading{Remarks}
  90
  91 If a stipple brush is created, the brush style will be set to wxSTIPPLE.
  92
  93 \wxheading{See also}
  94
  95 \helpref{wxBrushList}{wxbrushlist}, \helpref{wxColour}{wxcolour}, \helpref{wxColourDatabase}{wxcolourdatabase}
  96
  97 \membersection{wxBrush::\destruct{wxBrush}}
  98
  99 \func{void}{\destruct{wxBrush}}{\void}
 100
 101 Destructor.
 102
 103 \wxheading{Remarks}
 104
 105 The destructor may not delete the underlying brush object of the native windowing
 106 system, since wxBrush uses a reference counting system for efficiency.
 107
 108 Although all remaining brushes are deleted when the application exits,
 109 the application should try to clean up all brushes itself. This is because
 110 wxWindows cannot know if a pointer to the brush object is stored in an
 111 application data structure, and there is a risk of double deletion.
 112
 113 \membersection{wxBrush::GetColour}\label{wxbrushgetcolour}
 114
 115 \constfunc{wxColour\&}{GetColour}{\void}
 116
 117 Returns a reference to the brush colour.
 118
 119 \wxheading{See also}
 120
 121 \helpref{wxBrush::SetColour}{wxbrushsetcolour}
 122
 123 \membersection{wxBrush::GetStipple}\label{wxbrushgetstipple}
 124
 125 \constfunc{wxBitmap *}{GetStipple}{\void}
 126
 127 Gets a pointer to the stipple bitmap. If the brush does not have a wxSTIPPLE style,
 128 this bitmap may be non-NULL but uninitialised (\helpref{wxBitmap::Ok}{wxbitmapok} returns FALSE).
 129
 130 \wxheading{See also}
 131
 132 \helpref{wxBrush::SetStipple}{wxbrushsetstipple}
 133
 134 \membersection{wxBrush::GetStyle}\label{wxbrushgetstyle}
 135
 136 \constfunc{int}{GetStyle}{\void}
 137
 138 Returns the brush style, one of:
 139
 140 \begin{twocollist}\itemsep=0pt
 141 \twocolitem{{\bf wxTRANSPARENT}}{Transparent (no fill).}
 142 \twocolitem{{\bf wxSOLID}}{Solid.}
 143 \twocolitem{{\bf wxBDIAGONAL\_HATCH}}{Backward diagonal hatch.}
 144 \twocolitem{{\bf wxCROSSDIAG\_HATCH}}{Cross-diagonal hatch.}
 145 \twocolitem{{\bf wxFDIAGONAL\_HATCH}}{Forward diagonal hatch.}
 146 \twocolitem{{\bf wxCROSS\_HATCH}}{Cross hatch.}
 147 \twocolitem{{\bf wxHORIZONTAL\_HATCH}}{Horizontal hatch.}
 148 \twocolitem{{\bf wxVERTICAL\_HATCH}}{Vertical hatch.}
 149 \twocolitem{{\bf wxSTIPPLE}}{Stippled using a bitmap.}
 150 \end{twocollist}
 151
 152 \wxheading{See also}
 153
 154 \helpref{wxBrush::SetStyle}{wxbrushsetstyle}, \helpref{wxBrush::SetColour}{wxbrushsetcolour},\rtfsp
 155 \helpref{wxBrush::SetStipple}{wxbrushsetstipple}
 156
 157 \membersection{wxBrush::Ok}\label{wxbrushok}
 158
 159 \constfunc{bool}{Ok}{\void}
 160
 161 Returns TRUE if the brush is initialised. It will return FALSE if the default
 162 constructor has been used (for example, the brush is a member of a class, or
 163 NULL has been assigned to it).
 164
 165 \membersection{wxBrush::SetColour}\label{wxbrushsetcolour}
 166
 167 \func{void}{SetColour}{\param{wxColour\& }{colour}}
 168
 169 Sets the brush colour using a reference to a colour object.
 170
 171 \func{void}{SetColour}{\param{const wxString\& }{colourName}}
 172
 173 Sets the brush colour using a colour name from the colour database.
 174
 175 \func{void}{SetColour}{\param{const unsigned char}{ red}, \param{const unsigned char}{ green}, \param{const unsigned char}{ blue}}
 176
 177 Sets the brush colour using red, green and blue values.
 178
 179 \wxheading{See also}
 180
 181 \helpref{wxBrush::GetColour}{wxbrushgetcolour}
 182
 183 \membersection{wxBrush::SetStipple}\label{wxbrushsetstipple}
 184
 185 \func{void}{SetStipple}{\param{const wxBitmap\&}{ bitmap}}
 186
 187 Sets the stipple bitmap.
 188
 189 \wxheading{Parameters}
 190
 191 \docparam{bitmap}{The bitmap to use for stippling.}
 192
 193 \wxheading{Remarks}
 194
 195 The style will be set to wxSTIPPLE.
 196
 197 Note that there is a big difference between stippling in X and Windows.
 198 On X, the stipple is a mask between the wxBitmap and current colour.
 199 On Windows, the current colour is ignored, and the bitmap colour is used.
 200 However, for pre-defined modes like wxCROSS\_HATCH, the behaviour is the
 201 same for both platforms.
 202
 203 \wxheading{See also}
 204
 205 \helpref{wxBitmap}{wxbitmap}
 206
 207 \membersection{wxBrush::SetStyle}\label{wxbrushsetstyle}
 208
 209 \func{void}{SetStyle}{\param{int}{ style}}
 210
 211 Sets the brush style.
 212
 213 \docparam{style}{One of:
 214
 215 \begin{twocollist}\itemsep=0pt
 216 \twocolitem{{\bf wxTRANSPARENT}}{Transparent (no fill).}
 217 \twocolitem{{\bf wxSOLID}}{Solid.}
 218 \twocolitem{{\bf wxBDIAGONAL\_HATCH}}{Backward diagonal hatch.}
 219 \twocolitem{{\bf wxCROSSDIAG\_HATCH}}{Cross-diagonal hatch.}
 220 \twocolitem{{\bf wxFDIAGONAL\_HATCH}}{Forward diagonal hatch.}
 221 \twocolitem{{\bf wxCROSS\_HATCH}}{Cross hatch.}
 222 \twocolitem{{\bf wxHORIZONTAL\_HATCH}}{Horizontal hatch.}
 223 \twocolitem{{\bf wxVERTICAL\_HATCH}}{Vertical hatch.}
 224 \twocolitem{{\bf wxSTIPPLE}}{Stippled using a bitmap.}
 225 \end{twocollist}}
 226
 227 \wxheading{See also}
 228
 229 \helpref{wxBrush::GetStyle}{wxbrushgetstyle}
 230
 231 \membersection{wxBrush::operator $=$}\label{wxbrushassignment}
 232
 233 \func{wxBrush\&}{operator $=$}{\param{const wxBrush\& }{brush}}
 234
 235 Assignment operator, using reference counting. Returns a reference
 236 to `this'.
 237
 238 \membersection{wxBrush::operator $==$}\label{wxbrushequals}
 239
 240 \func{bool}{operator $==$}{\param{const wxBrush\& }{brush}}
 241
 242 Equality operator. Two brushes are equal if they contain pointers
 243 to the same underlying brush data. It does not compare each attribute,
 244 so two independently-created brushes using the same parameters will
 245 fail the test.
 246
 247 \membersection{wxBrush::operator $!=$}\label{wxbrushnotequals}
 248
 249 \func{bool}{operator $!=$}{\param{const wxBrush\& }{brush}}
 250
 251 Inequality operator. Two brushes are not equal if they contain pointers
 252 to different underlying brush data. It does not compare each attribute.
 253
 254 \section{\class{wxBrushList}}\label{wxbrushlist}
 255
 256 A brush list is a list containing all brushes which have been created.
 257
 258 \wxheading{Derived from}
 259
 260 \helpref{wxList}{wxlist}\\
 261 \helpref{wxObject}{wxobject}
 262
 263 \wxheading{Remarks}
 264
 265 There is only one instance of this class: {\bf wxTheBrushList}.  Use
 266 this object to search for a previously created brush of the desired
 267 type and create it if not already found. In some windowing systems,
 268 the brush may be a scarce resource, so it can pay to reuse old
 269 resources if possible. When an application finishes, all brushes will
 270 be deleted and their resources freed, eliminating the possibility of
 271 `memory leaks'. However, it is best not to rely on this automatic
 272 cleanup because it can lead to double deletion in some circumstances.
 273
 274 There are two mechanisms in recent versions of wxWindows which make the
 275 brush list less useful than it once was. Under Windows, scarce resources
 276 are cleaned up internally if they are not being used. Also, a referencing
 277 counting mechanism applied to all GDI objects means that some sharing
 278 of underlying resources is possible. You don't have to keep track of pointers,
 279 working out when it is safe delete a brush, because the referencing counting does
 280 it for you. For example, you can set a brush in a device context, and then
 281 immediately delete the brush you passed, because the brush is `copied'.
 282
 283 So you may find it easier to ignore the brush list, and instead create
 284 and copy brushes as you see fit. If your Windows resource meter suggests
 285 your application is using too many resources, you can resort to using
 286 GDI lists to share objects explicitly.
 287
 288 The only compelling use for the brush list is for wxWindows to keep
 289 track of brushes in order to clean them up on exit. It is also kept for
 290 backward compatibility with earlier versions of wxWindows.
 291
 292 \wxheading{See also}
 293
 294 \helpref{wxBrush}{wxbrush}
 295
 296 \latexignore{\rtfignore{\wxheading{Members}}}
 297
 298 \membersection{wxBrushList::wxBrushList}\label{wxbrushlistconstr}
 299
 300 \func{void}{wxBrushList}{\void}
 301
 302 Constructor. The application should not construct its own brush list:
 303 use the object pointer {\bf wxTheBrushList}.
 304
 305 \membersection{wxBrushList::AddBrush}\label{wxbrushlistaddbrush}
 306
 307 \func{void}{AddBrush}{\param{wxBrush *}{brush}}
 308
 309 Used internally by wxWindows to add a brush to the list.
 310
 311 \membersection{wxBrushList::FindOrCreateBrush}\label{wxbrushlistfindorcreatebrush}
 312
 313 \func{wxBrush *}{FindOrCreateBrush}{\param{const wxColour\& }{colour}, \param{int}{ style}}
 314
 315 Finds a brush with the specified attributes and returns it, else creates a new brush, adds it
 316 to the brush list, and returns it.
 317
 318 \func{wxBrush *}{FindOrCreateBrush}{\param{const wxString\& }{colourName}, \param{int}{ style}}
 319
 320 Finds a brush with the specified attributes and returns it, else creates a new brush, adds it
 321 to the brush list, and returns it.
 322
 323 Finds a brush of the given specification, or creates one and adds it to the list.
 324
 325 \wxheading{Parameters}
 326
 327 \docparam{colour}{Colour object.}
 328
 329 \docparam{colourName}{Colour name, which should be in the colour database.}
 330
 331 \docparam{style}{Brush style. See \helpref{wxBrush::SetStyle}{wxbrushsetstyle} for a list of styles.}
 332
 333 \membersection{wxBrushList::RemoveBrush}\label{wxbrushlistremovebrush}
 334
 335 \func{void}{RemoveBrush}{\param{wxBrush *}{brush}}
 336
 337 Used by wxWindows to remove a brush from the list.
 338
 339