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{Include files}
  13
  14 <wx/brush.h>
  15
  16 \wxheading{Predefined objects}
  17
  18 Objects:
  19
  20 {\bf wxNullBrush}
  21
  22 Pointers:
  23
  24 {\bf wxBLUE\_BRUSH\\
  25 wxGREEN\_BRUSH\\
  26 wxWHITE\_BRUSH\\
  27 wxBLACK\_BRUSH\\
  28 wxGREY\_BRUSH\\
  29 wxMEDIUM\_GREY\_BRUSH\\
  30 wxLIGHT\_GREY\_BRUSH\\
  31 wxTRANSPARENT\_BRUSH\\
  32 wxCYAN\_BRUSH\\
  33 wxRED\_BRUSH}
  34
  35 \wxheading{Remarks}
  36
  37 On a monochrome display, wxWidgets shows
  38 all brushes as white unless the colour is really black.
  39
  40 Do not initialize objects on the stack before the program commences,
  41 since other required structures may not have been set up yet. Instead,
  42 define global pointers to objects and create them in \helpref{wxApp::OnInit}{wxapponinit} or
  43 when required.
  44
  45 An application may wish to create brushes with different
  46 characteristics dynamically, and there is the consequent danger that a
  47 large number of duplicate brushes will be created. Therefore an
  48 application may wish to get a pointer to a brush by using the global
  49 list of brushes {\bf wxTheBrushList}, and calling the member function
  50 \rtfsp{\bf FindOrCreateBrush}.
  51
  52 wxBrush uses a reference counting system, so assignments between brushes are very
  53 cheap. You can therefore use actual wxBrush objects instead of pointers without
  54 efficiency problems. Once one wxBrush object changes its data it will create its
  55 own brush data internally so that other brushes, which previously shared the
  56 data using the reference counting, are not affected.
  57
  58 %TODO: an overview for wxBrush.
  59 \wxheading{See also}
  60
  61 \helpref{wxBrushList}{wxbrushlist}, \helpref{wxDC}{wxdc}, \helpref{wxDC::SetBrush}{wxdcsetbrush}
  62
  63 \latexignore{\rtfignore{\wxheading{Members}}}
  64
  65 \membersection{wxBrush::wxBrush}\label{wxbrushctor}
  66
  67 \func{}{wxBrush}{\void}
  68
  69 Default constructor. The brush will be uninitialised, and \helpref{wxBrush::Ok}{wxbrushok} will
  70 return false.
  71
  72 \func{}{wxBrush}{\param{const wxColour\&}{ colour}, \param{int}{ style = {\tt wxSOLID}}}
  73
  74 Constructs a brush from a colour object and style.
  75
  76 \func{}{wxBrush}{\param{const wxString\& }{colourName}, \param{int}{ style}}
  77
  78 Constructs a brush from a colour name and style.
  79
  80 \func{}{wxBrush}{\param{const wxBitmap\& }{stippleBitmap}}
  81
  82 Constructs a stippled brush using a bitmap.
  83
  84 \func{}{wxBrush}{\param{const wxBrush\&}{ brush}}
  85
  86 Copy constructor. This uses reference counting so is a cheap operation.
  87
  88 \wxheading{Parameters}
  89
  90 \docparam{colour}{Colour object.}
  91
  92 \docparam{colourName}{Colour name. The name will be looked up in the colour database.}
  93
  94 \docparam{style}{One of:
  95
  96 \begin{twocollist}\itemsep=0pt
  97 \twocolitem{{\bf wxTRANSPARENT}}{Transparent (no fill).}
  98 \twocolitem{{\bf wxSOLID}}{Solid.}
  99 \twocolitem{{\bf wxSTIPPLE}}{Uses a bitmap as a stipple.}
 100 \twocolitem{{\bf wxBDIAGONAL\_HATCH}}{Backward diagonal hatch.}
 101 \twocolitem{{\bf wxCROSSDIAG\_HATCH}}{Cross-diagonal hatch.}
 102 \twocolitem{{\bf wxFDIAGONAL\_HATCH}}{Forward diagonal hatch.}
 103 \twocolitem{{\bf wxCROSS\_HATCH}}{Cross hatch.}
 104 \twocolitem{{\bf wxHORIZONTAL\_HATCH}}{Horizontal hatch.}
 105 \twocolitem{{\bf wxVERTICAL\_HATCH}}{Vertical hatch.}
 106 \end{twocollist}}
 107
 108 \docparam{brush}{Pointer or reference to a brush to copy.}
 109
 110 \docparam{stippleBitmap}{A bitmap to use for stippling.}
 111
 112 \wxheading{Remarks}
 113
 114 If a stipple brush is created, the brush style will be set to wxSTIPPLE.
 115
 116 \wxheading{See also}
 117
 118 \helpref{wxBrushList}{wxbrushlist}, \helpref{wxColour}{wxcolour}, \helpref{wxColourDatabase}{wxcolourdatabase}
 119
 120 \membersection{wxBrush::\destruct{wxBrush}}\label{wxbrushdtor}
 121
 122 \func{void}{\destruct{wxBrush}}{\void}
 123
 124 Destructor.
 125
 126 \wxheading{Remarks}
 127
 128 The destructor may not delete the underlying brush object of the native windowing
 129 system, since wxBrush uses a reference counting system for efficiency.
 130
 131 Although all remaining brushes are deleted when the application exits,
 132 the application should try to clean up all brushes itself. This is because
 133 wxWidgets cannot know if a pointer to the brush object is stored in an
 134 application data structure, and there is a risk of double deletion.
 135
 136 \membersection{wxBrush::GetColour}\label{wxbrushgetcolour}
 137
 138 \constfunc{wxColour\&}{GetColour}{\void}
 139
 140 Returns a reference to the brush colour.
 141
 142 \wxheading{See also}
 143
 144 \helpref{wxBrush::SetColour}{wxbrushsetcolour}
 145
 146 \membersection{wxBrush::GetStipple}\label{wxbrushgetstipple}
 147
 148 \constfunc{wxBitmap *}{GetStipple}{\void}
 149
 150 Gets a pointer to the stipple bitmap. If the brush does not have a wxSTIPPLE style,
 151 this bitmap may be non-NULL but uninitialised (\helpref{wxBitmap::Ok}{wxbitmapok} returns false).
 152
 153 \wxheading{See also}
 154
 155 \helpref{wxBrush::SetStipple}{wxbrushsetstipple}
 156
 157 \membersection{wxBrush::GetStyle}\label{wxbrushgetstyle}
 158
 159 \constfunc{int}{GetStyle}{\void}
 160
 161 Returns the brush style, one of:
 162
 163 \begin{twocollist}\itemsep=0pt
 164 \twocolitem{{\bf wxTRANSPARENT}}{Transparent (no fill).}
 165 \twocolitem{{\bf wxSOLID}}{Solid.}
 166 \twocolitem{{\bf wxBDIAGONAL\_HATCH}}{Backward diagonal hatch.}
 167 \twocolitem{{\bf wxCROSSDIAG\_HATCH}}{Cross-diagonal hatch.}
 168 \twocolitem{{\bf wxFDIAGONAL\_HATCH}}{Forward diagonal hatch.}
 169 \twocolitem{{\bf wxCROSS\_HATCH}}{Cross hatch.}
 170 \twocolitem{{\bf wxHORIZONTAL\_HATCH}}{Horizontal hatch.}
 171 \twocolitem{{\bf wxVERTICAL\_HATCH}}{Vertical hatch.}
 172 \twocolitem{{\bf wxSTIPPLE}}{Stippled using a bitmap.}
 173 \twocolitem{{\bf wxSTIPPLE\_MASK\_OPAQUE}}{Stippled using a bitmap's mask.}
 174 \end{twocollist}
 175
 176 \wxheading{See also}
 177
 178 \helpref{wxBrush::SetStyle}{wxbrushsetstyle}, \helpref{wxBrush::SetColour}{wxbrushsetcolour},\rtfsp
 179 \helpref{wxBrush::SetStipple}{wxbrushsetstipple}
 180
 181 \membersection{wxBrush::IsHatch}\label{wxbrushishatch}
 182
 183 \constfunc{bool}{IsHatch}{\void}
 184
 185 Returns true if the style of the brush is any of hatched fills.
 186
 187 \wxheading{See also}
 188
 189 \helpref{wxBrush::GetStyle}{wxbrushgetstyle}
 190
 191 \membersection{wxBrush::Ok}\label{wxbrushok}
 192
 193 \constfunc{bool}{Ok}{\void}
 194
 195 Returns true if the brush is initialised. It will return false if the default
 196 constructor has been used (for example, the brush is a member of a class, or
 197 NULL has been assigned to it).
 198
 199 \membersection{wxBrush::SetColour}\label{wxbrushsetcolour}
 200
 201 \func{void}{SetColour}{\param{wxColour\& }{colour}}
 202
 203 Sets the brush colour using a reference to a colour object.
 204
 205 \func{void}{SetColour}{\param{const wxString\& }{colourName}}
 206
 207 Sets the brush colour using a colour name from the colour database.
 208
 209 \func{void}{SetColour}{\param{const unsigned char}{ red}, \param{const unsigned char}{ green}, \param{const unsigned char}{ blue}}
 210
 211 Sets the brush colour using red, green and blue values.
 212
 213 \wxheading{See also}
 214
 215 \helpref{wxBrush::GetColour}{wxbrushgetcolour}
 216
 217 \membersection{wxBrush::SetStipple}\label{wxbrushsetstipple}
 218
 219 \func{void}{SetStipple}{\param{const wxBitmap\&}{ bitmap}}
 220
 221 Sets the stipple bitmap.
 222
 223 \wxheading{Parameters}
 224
 225 \docparam{bitmap}{The bitmap to use for stippling.}
 226
 227 \wxheading{Remarks}
 228
 229 The style will be set to wxSTIPPLE, unless the bitmap has a mask associated
 230 to it, in which case the style will be set to wxSTIPPLE\_MASK\_OPAQUE.
 231
 232 If the wxSTIPPLE variant is used, the bitmap will be used to fill out the
 233 area to be drawn. If the wxSTIPPLE\_MASK\_OPAQUE is used, the current
 234 text foreground and text background determine what colours are used for
 235 displaying and the bits in the mask (which is a mono-bitmap actually)
 236 determine where to draw what.
 237
 238 Note that under Windows 95, only 8x8 pixel large stipple bitmaps are
 239 supported, Windows 98 and NT as well as GTK support arbitrary bitmaps.
 240
 241 \wxheading{See also}
 242
 243 \helpref{wxBitmap}{wxbitmap}
 244
 245 \membersection{wxBrush::SetStyle}\label{wxbrushsetstyle}
 246
 247 \func{void}{SetStyle}{\param{int}{ style}}
 248
 249 Sets the brush style.
 250
 251 \docparam{style}{One of:
 252
 253 \begin{twocollist}\itemsep=0pt
 254 \twocolitem{{\bf wxTRANSPARENT}}{Transparent (no fill).}
 255 \twocolitem{{\bf wxSOLID}}{Solid.}
 256 \twocolitem{{\bf wxBDIAGONAL\_HATCH}}{Backward diagonal hatch.}
 257 \twocolitem{{\bf wxCROSSDIAG\_HATCH}}{Cross-diagonal hatch.}
 258 \twocolitem{{\bf wxFDIAGONAL\_HATCH}}{Forward diagonal hatch.}
 259 \twocolitem{{\bf wxCROSS\_HATCH}}{Cross hatch.}
 260 \twocolitem{{\bf wxHORIZONTAL\_HATCH}}{Horizontal hatch.}
 261 \twocolitem{{\bf wxVERTICAL\_HATCH}}{Vertical hatch.}
 262 \twocolitem{{\bf wxSTIPPLE}}{Stippled using a bitmap.}
 263 \twocolitem{{\bf wxSTIPPLE\_MASK\_OPAQUE}}{Stippled using a bitmap's mask.}
 264 \end{twocollist}}
 265
 266 \wxheading{See also}
 267
 268 \helpref{wxBrush::GetStyle}{wxbrushgetstyle}
 269
 270 \membersection{wxBrush::operator $=$}\label{wxbrushassignment}
 271
 272 \func{wxBrush\&}{operator $=$}{\param{const wxBrush\& }{brush}}
 273
 274 Assignment operator, using reference counting. Returns a reference
 275 to `this'.
 276
 277 \membersection{wxBrush::operator $==$}\label{wxbrushequals}
 278
 279 \func{bool}{operator $==$}{\param{const wxBrush\& }{brush}}
 280
 281 Equality operator. Two brushes are equal if they contain pointers
 282 to the same underlying brush data. It does not compare each attribute,
 283 so two independently-created brushes using the same parameters will
 284 fail the test.
 285
 286 \membersection{wxBrush::operator $!=$}\label{wxbrushnotequals}
 287
 288 \func{bool}{operator $!=$}{\param{const wxBrush\& }{brush}}
 289
 290 Inequality operator. Two brushes are not equal if they contain pointers
 291 to different underlying brush data. It does not compare each attribute.
 292
 293 \section{\class{wxBrushList}}\label{wxbrushlist}
 294
 295 A brush list is a list containing all brushes which have been created.
 296
 297 \wxheading{Derived from}
 298
 299 \helpref{wxList}{wxlist}\\
 300 \helpref{wxObject}{wxobject}
 301
 302 \wxheading{Include files}
 303
 304 <wx/gdicmn.h>
 305
 306 \wxheading{Remarks}
 307
 308 There is only one instance of this class: {\bf wxTheBrushList}.  Use
 309 this object to search for a previously created brush of the desired
 310 type and create it if not already found. In some windowing systems,
 311 the brush may be a scarce resource, so it can pay to reuse old
 312 resources if possible. When an application finishes, all brushes will
 313 be deleted and their resources freed, eliminating the possibility of
 314 `memory leaks'. However, it is best not to rely on this automatic
 315 cleanup because it can lead to double deletion in some circumstances.
 316
 317 There are two mechanisms in recent versions of wxWidgets which make the
 318 brush list less useful than it once was. Under Windows, scarce resources
 319 are cleaned up internally if they are not being used. Also, a referencing
 320 counting mechanism applied to all GDI objects means that some sharing
 321 of underlying resources is possible. You don't have to keep track of pointers,
 322 working out when it is safe delete a brush, because the referencing counting does
 323 it for you. For example, you can set a brush in a device context, and then
 324 immediately delete the brush you passed, because the brush is `copied'.
 325
 326 So you may find it easier to ignore the brush list, and instead create
 327 and copy brushes as you see fit. If your Windows resource meter suggests
 328 your application is using too many resources, you can resort to using
 329 GDI lists to share objects explicitly.
 330
 331 The only compelling use for the brush list is for wxWidgets to keep
 332 track of brushes in order to clean them up on exit. It is also kept for
 333 backward compatibility with earlier versions of wxWidgets.
 334
 335 \wxheading{See also}
 336
 337 \helpref{wxBrush}{wxbrush}
 338
 339 \latexignore{\rtfignore{\wxheading{Members}}}
 340
 341 \membersection{wxBrushList::wxBrushList}\label{wxbrushlistconstr}
 342
 343 \func{void}{wxBrushList}{\void}
 344
 345 Constructor. The application should not construct its own brush list:
 346 use the object pointer {\bf wxTheBrushList}.
 347
 348 \membersection{wxBrushList::AddBrush}\label{wxbrushlistaddbrush}
 349
 350 \func{void}{AddBrush}{\param{wxBrush *}{brush}}
 351
 352 Used internally by wxWidgets to add a brush to the list.
 353
 354 \membersection{wxBrushList::FindOrCreateBrush}\label{wxbrushlistfindorcreatebrush}
 355
 356 \func{wxBrush *}{FindOrCreateBrush}{\param{const wxColour\& }{colour}, \param{int}{ style}}
 357
 358 Finds a brush with the specified attributes and returns it, else creates a new brush, adds it
 359 to the brush list, and returns it.
 360
 361 \func{wxBrush *}{FindOrCreateBrush}{\param{const wxString\& }{colourName}, \param{int}{ style}}
 362
 363 Finds a brush with the specified attributes and returns it, else creates a new brush, adds it
 364 to the brush list, and returns it.
 365
 366 Finds a brush of the given specification, or creates one and adds it to the list.
 367
 368 \wxheading{Parameters}
 369
 370 \docparam{colour}{Colour object.}
 371
 372 \docparam{colourName}{Colour name, which should be in the colour database.}
 373
 374 \docparam{style}{Brush style. See \helpref{wxBrush::SetStyle}{wxbrushsetstyle} for a list of styles.}
 375
 376 \membersection{wxBrushList::RemoveBrush}\label{wxbrushlistremovebrush}
 377
 378 \func{void}{RemoveBrush}{\param{wxBrush *}{brush}}
 379
 380 Used by wxWidgets to remove a brush from the list.
 381
 382