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, wxWindows 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}
  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 wxBDIAGONAL\_HATCH}}{Backward diagonal hatch.}
 100 \twocolitem{{\bf wxCROSSDIAG\_HATCH}}{Cross-diagonal hatch.}
 101 \twocolitem{{\bf wxFDIAGONAL\_HATCH}}{Forward diagonal hatch.}
 102 \twocolitem{{\bf wxCROSS\_HATCH}}{Cross hatch.}
 103 \twocolitem{{\bf wxHORIZONTAL\_HATCH}}{Horizontal hatch.}
 104 \twocolitem{{\bf wxVERTICAL\_HATCH}}{Vertical hatch.}
 105 \end{twocollist}}
 106
 107 \docparam{brush}{Pointer or reference to a brush to copy.}
 108
 109 \docparam{stippleBitmap}{A bitmap to use for stippling.}
 110
 111 \wxheading{Remarks}
 112
 113 If a stipple brush is created, the brush style will be set to wxSTIPPLE.
 114
 115 \wxheading{See also}
 116
 117 \helpref{wxBrushList}{wxbrushlist}, \helpref{wxColour}{wxcolour}, \helpref{wxColourDatabase}{wxcolourdatabase}
 118
 119 \membersection{wxBrush::\destruct{wxBrush}}
 120
 121 \func{void}{\destruct{wxBrush}}{\void}
 122
 123 Destructor.
 124
 125 \wxheading{Remarks}
 126
 127 The destructor may not delete the underlying brush object of the native windowing
 128 system, since wxBrush uses a reference counting system for efficiency.
 129
 130 Although all remaining brushes are deleted when the application exits,
 131 the application should try to clean up all brushes itself. This is because
 132 wxWindows cannot know if a pointer to the brush object is stored in an
 133 application data structure, and there is a risk of double deletion.
 134
 135 \membersection{wxBrush::GetColour}\label{wxbrushgetcolour}
 136
 137 \constfunc{wxColour\&}{GetColour}{\void}
 138
 139 Returns a reference to the brush colour.
 140
 141 \wxheading{See also}
 142
 143 \helpref{wxBrush::SetColour}{wxbrushsetcolour}
 144
 145 \membersection{wxBrush::GetStipple}\label{wxbrushgetstipple}
 146
 147 \constfunc{wxBitmap *}{GetStipple}{\void}
 148
 149 Gets a pointer to the stipple bitmap. If the brush does not have a wxSTIPPLE style,
 150 this bitmap may be non-NULL but uninitialised (\helpref{wxBitmap::Ok}{wxbitmapok} returns false).
 151
 152 \wxheading{See also}
 153
 154 \helpref{wxBrush::SetStipple}{wxbrushsetstipple}
 155
 156 \membersection{wxBrush::GetStyle}\label{wxbrushgetstyle}
 157
 158 \constfunc{int}{GetStyle}{\void}
 159
 160 Returns the brush style, one of:
 161
 162 \begin{twocollist}\itemsep=0pt
 163 \twocolitem{{\bf wxTRANSPARENT}}{Transparent (no fill).}
 164 \twocolitem{{\bf wxSOLID}}{Solid.}
 165 \twocolitem{{\bf wxBDIAGONAL\_HATCH}}{Backward diagonal hatch.}
 166 \twocolitem{{\bf wxCROSSDIAG\_HATCH}}{Cross-diagonal hatch.}
 167 \twocolitem{{\bf wxFDIAGONAL\_HATCH}}{Forward diagonal hatch.}
 168 \twocolitem{{\bf wxCROSS\_HATCH}}{Cross hatch.}
 169 \twocolitem{{\bf wxHORIZONTAL\_HATCH}}{Horizontal hatch.}
 170 \twocolitem{{\bf wxVERTICAL\_HATCH}}{Vertical hatch.}
 171 \twocolitem{{\bf wxSTIPPLE}}{Stippled using a bitmap.}
 172 \twocolitem{{\bf wxSTIPPLE\_MASK\_OPAQUE}}{Stippled using a bitmap's mask.}
 173 \end{twocollist}
 174
 175 \wxheading{See also}
 176
 177 \helpref{wxBrush::SetStyle}{wxbrushsetstyle}, \helpref{wxBrush::SetColour}{wxbrushsetcolour},\rtfsp
 178 \helpref{wxBrush::SetStipple}{wxbrushsetstipple}
 179
 180 \membersection{wxBrush::Ok}\label{wxbrushok}
 181
 182 \constfunc{bool}{Ok}{\void}
 183
 184 Returns true if the brush is initialised. It will return false if the default
 185 constructor has been used (for example, the brush is a member of a class, or
 186 NULL has been assigned to it).
 187
 188 \membersection{wxBrush::SetColour}\label{wxbrushsetcolour}
 189
 190 \func{void}{SetColour}{\param{wxColour\& }{colour}}
 191
 192 Sets the brush colour using a reference to a colour object.
 193
 194 \func{void}{SetColour}{\param{const wxString\& }{colourName}}
 195
 196 Sets the brush colour using a colour name from the colour database.
 197
 198 \func{void}{SetColour}{\param{const unsigned char}{ red}, \param{const unsigned char}{ green}, \param{const unsigned char}{ blue}}
 199
 200 Sets the brush colour using red, green and blue values.
 201
 202 \wxheading{See also}
 203
 204 \helpref{wxBrush::GetColour}{wxbrushgetcolour}
 205
 206 \membersection{wxBrush::SetStipple}\label{wxbrushsetstipple}
 207
 208 \func{void}{SetStipple}{\param{const wxBitmap\&}{ bitmap}}
 209
 210 Sets the stipple bitmap.
 211
 212 \wxheading{Parameters}
 213
 214 \docparam{bitmap}{The bitmap to use for stippling.}
 215
 216 \wxheading{Remarks}
 217
 218 The style will be set to wxSTIPPLE, unless the bitmap has a mask associated
 219 to it, in which case the style will be set to wxSTIPPLE\_MASK\_OPAQUE.
 220
 221 If the wxSTIPPLE variant is used, the bitmap will be used to fill out the
 222 area to be drawn. If the wxSTIPPLE\_MASK\_OPAQUE is used, the current
 223 text foreground and text background determine what colours are used for
 224 displaying and the bits in the mask (which is a mono-bitmap actually)
 225 determine where to draw what.
 226
 227 Note that under Windows 95, only 8x8 pixel large stipple bitmaps are
 228 supported, Windows 98 and NT as well as GTK support arbitrary bitmaps.
 229
 230 \wxheading{See also}
 231
 232 \helpref{wxBitmap}{wxbitmap}
 233
 234 \membersection{wxBrush::SetStyle}\label{wxbrushsetstyle}
 235
 236 \func{void}{SetStyle}{\param{int}{ style}}
 237
 238 Sets the brush style.
 239
 240 \docparam{style}{One of:
 241
 242 \begin{twocollist}\itemsep=0pt
 243 \twocolitem{{\bf wxTRANSPARENT}}{Transparent (no fill).}
 244 \twocolitem{{\bf wxSOLID}}{Solid.}
 245 \twocolitem{{\bf wxBDIAGONAL\_HATCH}}{Backward diagonal hatch.}
 246 \twocolitem{{\bf wxCROSSDIAG\_HATCH}}{Cross-diagonal hatch.}
 247 \twocolitem{{\bf wxFDIAGONAL\_HATCH}}{Forward diagonal hatch.}
 248 \twocolitem{{\bf wxCROSS\_HATCH}}{Cross hatch.}
 249 \twocolitem{{\bf wxHORIZONTAL\_HATCH}}{Horizontal hatch.}
 250 \twocolitem{{\bf wxVERTICAL\_HATCH}}{Vertical hatch.}
 251 \twocolitem{{\bf wxSTIPPLE}}{Stippled using a bitmap.}
 252 \twocolitem{{\bf wxSTIPPLE\_MASK\_OPAQUE}}{Stippled using a bitmap's mask.}
 253 \end{twocollist}}
 254
 255 \wxheading{See also}
 256
 257 \helpref{wxBrush::GetStyle}{wxbrushgetstyle}
 258
 259 \membersection{wxBrush::operator $=$}\label{wxbrushassignment}
 260
 261 \func{wxBrush\&}{operator $=$}{\param{const wxBrush\& }{brush}}
 262
 263 Assignment operator, using reference counting. Returns a reference
 264 to `this'.
 265
 266 \membersection{wxBrush::operator $==$}\label{wxbrushequals}
 267
 268 \func{bool}{operator $==$}{\param{const wxBrush\& }{brush}}
 269
 270 Equality operator. Two brushes are equal if they contain pointers
 271 to the same underlying brush data. It does not compare each attribute,
 272 so two independently-created brushes using the same parameters will
 273 fail the test.
 274
 275 \membersection{wxBrush::operator $!=$}\label{wxbrushnotequals}
 276
 277 \func{bool}{operator $!=$}{\param{const wxBrush\& }{brush}}
 278
 279 Inequality operator. Two brushes are not equal if they contain pointers
 280 to different underlying brush data. It does not compare each attribute.
 281
 282 \section{\class{wxBrushList}}\label{wxbrushlist}
 283
 284 A brush list is a list containing all brushes which have been created.
 285
 286 \wxheading{Derived from}
 287
 288 \helpref{wxList}{wxlist}\\
 289 \helpref{wxObject}{wxobject}
 290
 291 \wxheading{Include files}
 292
 293 <wx/gdicmn.h>
 294
 295 \wxheading{Remarks}
 296
 297 There is only one instance of this class: {\bf wxTheBrushList}.  Use
 298 this object to search for a previously created brush of the desired
 299 type and create it if not already found. In some windowing systems,
 300 the brush may be a scarce resource, so it can pay to reuse old
 301 resources if possible. When an application finishes, all brushes will
 302 be deleted and their resources freed, eliminating the possibility of
 303 `memory leaks'. However, it is best not to rely on this automatic
 304 cleanup because it can lead to double deletion in some circumstances.
 305
 306 There are two mechanisms in recent versions of wxWindows which make the
 307 brush list less useful than it once was. Under Windows, scarce resources
 308 are cleaned up internally if they are not being used. Also, a referencing
 309 counting mechanism applied to all GDI objects means that some sharing
 310 of underlying resources is possible. You don't have to keep track of pointers,
 311 working out when it is safe delete a brush, because the referencing counting does
 312 it for you. For example, you can set a brush in a device context, and then
 313 immediately delete the brush you passed, because the brush is `copied'.
 314
 315 So you may find it easier to ignore the brush list, and instead create
 316 and copy brushes as you see fit. If your Windows resource meter suggests
 317 your application is using too many resources, you can resort to using
 318 GDI lists to share objects explicitly.
 319
 320 The only compelling use for the brush list is for wxWindows to keep
 321 track of brushes in order to clean them up on exit. It is also kept for
 322 backward compatibility with earlier versions of wxWindows.
 323
 324 \wxheading{See also}
 325
 326 \helpref{wxBrush}{wxbrush}
 327
 328 \latexignore{\rtfignore{\wxheading{Members}}}
 329
 330 \membersection{wxBrushList::wxBrushList}\label{wxbrushlistconstr}
 331
 332 \func{void}{wxBrushList}{\void}
 333
 334 Constructor. The application should not construct its own brush list:
 335 use the object pointer {\bf wxTheBrushList}.
 336
 337 \membersection{wxBrushList::AddBrush}\label{wxbrushlistaddbrush}
 338
 339 \func{void}{AddBrush}{\param{wxBrush *}{brush}}
 340
 341 Used internally by wxWindows to add a brush to the list.
 342
 343 \membersection{wxBrushList::FindOrCreateBrush}\label{wxbrushlistfindorcreatebrush}
 344
 345 \func{wxBrush *}{FindOrCreateBrush}{\param{const wxColour\& }{colour}, \param{int}{ style}}
 346
 347 Finds a brush with the specified attributes and returns it, else creates a new brush, adds it
 348 to the brush list, and returns it.
 349
 350 \func{wxBrush *}{FindOrCreateBrush}{\param{const wxString\& }{colourName}, \param{int}{ style}}
 351
 352 Finds a brush with the specified attributes and returns it, else creates a new brush, adds it
 353 to the brush list, and returns it.
 354
 355 Finds a brush of the given specification, or creates one and adds it to the list.
 356
 357 \wxheading{Parameters}
 358
 359 \docparam{colour}{Colour object.}
 360
 361 \docparam{colourName}{Colour name, which should be in the colour database.}
 362
 363 \docparam{style}{Brush style. See \helpref{wxBrush::SetStyle}{wxbrushsetstyle} for a list of styles.}
 364
 365 \membersection{wxBrushList::RemoveBrush}\label{wxbrushlistremovebrush}
 366
 367 \func{void}{RemoveBrush}{\param{wxBrush *}{brush}}
 368
 369 Used by wxWindows to remove a brush from the list.
 370
 371