qgraphicsshadereffect.cpp

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1 /**************************************************************************** -

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33 -

34 #include "qgraphicsshadereffect_p.h" -

35 -

36 #ifndef QT_NO_GRAPHICSEFFECT -

37 -

38 #include "qglshaderprogram.h" -

39 #include "gl2paintengineex/qglcustomshaderstage_p.h" -

40 #define QGL_HAVE_CUSTOM_SHADERS 1 -

41 #include <QtGui/qpainter.h> -

42 #include <QtWidgets/qgraphicsitem.h> -

43 #include <private/qgraphicseffect_p.h> -

44 -

45 QT_BEGIN_NAMESPACE -

46 -

47 /*# -

48 \class QGraphicsShaderEffect -

49 \inmodule QtOpenGL -

50 \brief The QGraphicsShaderEffect class is the base class for creating -

51 custom GLSL shader effects in a QGraphicsScene. -

52 \since 4.6 -

53 \ingroup multimedia -

54 \ingroup graphicsview-api -

55 -

56 The specific effect is defined by a fragment of GLSL source code -

57 supplied to setPixelShaderFragment(). This source code must define a -

58 function with the signature -

59 \c{lowp vec4 customShader(lowp sampler2D imageTexture, highp vec2 textureCoords)} -

60 that returns the source pixel value -

61 to use in the paint engine's shader program. The shader fragment -

62 is linked with the regular shader code used by the GL2 paint engine -

63 to construct a complete QGLShaderProgram. -

64 -

65 The following example shader converts the incoming pixmap to -

66 grayscale and then applies a colorize operation using the -

67 \c effectColor value: -

68 -

69 \code -

70 static char const colorizeShaderCode[] = -

71 "uniform lowp vec4 effectColor;\n" -

72 "lowp vec4 customShader(lowp sampler2D imageTexture, highp vec2 textureCoords) {\n" -

73 " vec4 src = texture2D(imageTexture, textureCoords);\n" -

74 " float gray = dot(src.rgb, vec3(0.212671, 0.715160, 0.072169));\n" -

75 " vec4 colorize = 1.0-((1.0-gray)*(1.0-effectColor));\n" -

76 " return vec4(colorize.rgb, src.a);\n" -

77 "}"; -

78 \endcode -

79 -

80 To use this shader code, it is necessary to define a subclass -

81 of QGraphicsShaderEffect as follows: -

82 -

83 \code -

84 class ColorizeEffect : public QGraphicsShaderEffect -

85 { -

86 Q_OBJECT -

87 public: -

88 ColorizeEffect(QObject *parent = 0) -

89 : QGraphicsShaderEffect(parent), color(Qt::black) -

90 { -

91 setPixelShaderFragment(colorizeShaderCode); -

92 } -

93 -

94 QColor effectColor() const { return color; } -

95 void setEffectColor(const QColor& c) -

96 { -

97 color = c; -

98 setUniformsDirty(); -

99 } -

100 -

101 protected: -

102 void setUniforms(QGLShaderProgram *program) -

103 { -

104 program->setUniformValue("effectColor", color); -

105 } -

106 -

107 private: -

108 QColor color; -

109 }; -

110 \endcode -

111 -

112 The setUniforms() function is called when the effect is about -

113 to be used for drawing to give the subclass the opportunity to -

114 set effect-specific uniform variables. -

115 -

116 QGraphicsShaderEffect is only supported when the GL2 paint engine -

117 is in use. When any other paint engine is in use (GL1, raster, etc), -

118 the drawItem() method will draw its item argument directly with -

119 no effect applied. -

120 -

121 \sa QGraphicsEffect -

122 */ -

123 -

124 static const char qglslDefaultImageFragmentShader[] = "\ -

125 lowp vec4 customShader(lowp sampler2D imageTexture, highp vec2 textureCoords) { \ -

126 return texture2D(imageTexture, textureCoords); \ -

127 }\n"; -

128 -

129 #ifdef QGL_HAVE_CUSTOM_SHADERS -

130 -

131 class QGLCustomShaderEffectStage : public QGLCustomShaderStage -

132 { -

133 public: -

134 QGLCustomShaderEffectStage -

135 (QGraphicsShaderEffect *e, const QByteArray& source) -

136 : QGLCustomShaderStage(), -

137 effect(e) -

138 { -

139 setSource(source); -

140

}

never executed: end of block

141 -

142 void setUniforms(QGLShaderProgram *program) Q_DECL_OVERRIDE; -

143 -

144 QGraphicsShaderEffect *effect; -

145 }; -

146 -

147 void QGLCustomShaderEffectStage::setUniforms(QGLShaderProgram *program) -

148 { -

149 effect->setUniforms(program); -

150

}

never executed: end of block

151 -

152 #endif -

153 -

154 class QGraphicsShaderEffectPrivate : public QGraphicsEffectPrivate -

155 { -

156 Q_DECLARE_PUBLIC(QGraphicsShaderEffect) -

157 public: -

158 QGraphicsShaderEffectPrivate() -

159 : pixelShaderFragment(qglslDefaultImageFragmentShader) -

160 #ifdef QGL_HAVE_CUSTOM_SHADERS -

161 , customShaderStage(0) -

162 #endif -

163 { -

164

}

never executed: end of block

165 -

166 QByteArray pixelShaderFragment; -

167 #ifdef QGL_HAVE_CUSTOM_SHADERS -

168 QGLCustomShaderEffectStage *customShaderStage; -

169 #endif -

170 }; -

171 -

172 /*# -

173 Constructs a shader effect and attaches it to \a parent. -

174 */ -

175 QGraphicsShaderEffect::QGraphicsShaderEffect(QObject *parent) -

176 : QGraphicsEffect(*new QGraphicsShaderEffectPrivate(), parent) -

177 { -

178

}

never executed: end of block

179 -

180 /*# -

181 Destroys this shader effect. -

182 */ -

183 QGraphicsShaderEffect::~QGraphicsShaderEffect() -

184 { -

185 #ifdef QGL_HAVE_CUSTOM_SHADERS -

186 Q_D(QGraphicsShaderEffect); -

187 delete d->customShaderStage; -

188 #endif -

189

}

never executed: end of block

190 -

191 /*# -

192 Returns the source code for the pixel shader fragment for -

193 this shader effect. The default is a shader that copies -

194 its incoming pixmap directly to the output with no effect -

195 applied. -

196 -

197 \sa setPixelShaderFragment() -

198 */ -

199 QByteArray QGraphicsShaderEffect::pixelShaderFragment() const -

200 { -

201 Q_D(const QGraphicsShaderEffect); -

202

return d->pixelShaderFragment;

never executed: return d->pixelShaderFragment;

203 } -

204 -

205 /*# -

206 Sets the source code for the pixel shader fragment for -

207 this shader effect to \a code. -

208 -

209 The \a code must define a GLSL function with the signature -

210 \c{lowp vec4 customShader(lowp sampler2D imageTexture, highp vec2 textureCoords)} -

211 that returns the source pixel value to use in the paint engine's -

212 shader program. The following is the default pixel shader fragment, -

213 which draws a pixmap with no effect applied: -

214 -

215 \code -

216 lowp vec4 customShader(lowp sampler2D imageTexture, highp vec2 textureCoords) { -

217 return texture2D(imageTexture, textureCoords); -

218 } -

219 \endcode -

220 -

221 \sa pixelShaderFragment(), setUniforms() -

222 */ -

223 void QGraphicsShaderEffect::setPixelShaderFragment(const QByteArray& code) -

224 { -

225 Q_D(QGraphicsShaderEffect); -

226

if (d->pixelShaderFragment != code) {

d->pixelShaderFragment != code	Description
TRUE	never evaluated
FALSE	never evaluated

227 d->pixelShaderFragment = code; -

228 #ifdef QGL_HAVE_CUSTOM_SHADERS -

229 delete d->customShaderStage; -

230 d->customShaderStage = 0; -

231 #endif -

232

}

never executed: end of block

233

}

never executed: end of block

234 -

235 /*# -

236 \reimp -

237 */ -

238 void QGraphicsShaderEffect::draw(QPainter *painter) -

239 { -

240 Q_D(QGraphicsShaderEffect); -

241 -

242 #ifdef QGL_HAVE_CUSTOM_SHADERS -

243 // Set the custom shader on the paint engine. The setOnPainter() -

244 // call may fail if the paint engine is not GL2. In that case, -

245 // we fall through to drawing the pixmap normally. -

246

if (!d->customShaderStage) {

!d->customShaderStage	Description
TRUE	never evaluated
FALSE	never evaluated

247 d->customShaderStage = new QGLCustomShaderEffectStage -

248 (this, d->pixelShaderFragment); -

249

}

never executed: end of block

250 bool usingShader = d->customShaderStage->setOnPainter(painter); -

251 -

252 QPoint offset; -

253

if (sourceIsPixmap()) {

sourceIsPixmap()	Description
TRUE	never evaluated
FALSE	never evaluated

254 // No point in drawing in device coordinates (pixmap will be scaled anyways). -

255 const QPixmap pixmap = sourcePixmap(Qt::LogicalCoordinates, &offset); -

256 painter->drawPixmap(offset, pixmap); -

257

} else {

never executed: end of block

258 // Draw pixmap in device coordinates to avoid pixmap scaling. -

259 const QPixmap pixmap = sourcePixmap(Qt::DeviceCoordinates, &offset); -

260 QTransform restoreTransform = painter->worldTransform(); -

261 painter->setWorldTransform(QTransform()); -

262 painter->drawPixmap(offset, pixmap); -

263 painter->setWorldTransform(restoreTransform); -

264

}

never executed: end of block

265 -

266 // Remove the custom shader to return to normal painting operations. -

267

if (usingShader)

usingShader	Description
TRUE	never evaluated
FALSE	never evaluated

268

d->customShaderStage->removeFromPainter(painter);

never executed: d->customShaderStage->removeFromPainter(painter);

269 #else -

270 drawSource(painter); -

271 #endif -

272

}

never executed: end of block

273 -

274 /*# -

275 Sets the custom uniform variables on this shader effect to -

276 be dirty. The setUniforms() function will be called the next -

277 time the shader program corresponding to this effect is used. -

278 -

279 This function is typically called by subclasses when an -

280 effect-specific parameter is changed by the application. -

281 -

282 \sa setUniforms() -

283 */ -

284 void QGraphicsShaderEffect::setUniformsDirty() -

285 { -

286 #ifdef QGL_HAVE_CUSTOM_SHADERS -

287 Q_D(QGraphicsShaderEffect); -

288

if (d->customShaderStage)

d->customShaderStage	Description
TRUE	never evaluated
FALSE	never evaluated

289

d->customShaderStage->setUniformsDirty();

never executed: d->customShaderStage->setUniformsDirty();

290 #endif -

291

}

never executed: end of block

292 -

293 /*# -

294 Sets custom uniform variables on the current GL context when -

295 \a program is about to be used by the paint engine. -

296 -

297 This function should be overridden if the shader set with -

298 setPixelShaderFragment() has additional parameters beyond -

299 those that the paint engine normally sets itself. -

300 -

301 \sa setUniformsDirty() -

302 */ -

303 void QGraphicsShaderEffect::setUniforms(QGLShaderProgram *program) -

304 { -

305 Q_UNUSED(program); -

306

}

never executed: end of block

307 -

308 QT_END_NAMESPACE -

309 -

310 #endif // QT_NO_GRAPHICSEFFECT -

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