qgraphicsshadereffect.cpp

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39 -

40 #include "qgraphicsshadereffect_p.h" -

41 -

42 #ifndef QT_NO_GRAPHICSEFFECT -

43 -

44 #include "qglshaderprogram.h" -

45 #include "gl2paintengineex/qglcustomshaderstage_p.h" -

46 #define QGL_HAVE_CUSTOM_SHADERS 1 -

47 #include <QtGui/qpainter.h> -

48 #include <QtWidgets/qgraphicsitem.h> -

49 #include <private/qgraphicseffect_p.h> -

50 -

51 QT_BEGIN_NAMESPACE -

52 -

53 /*# -

54 \class QGraphicsShaderEffect -

55 \inmodule QtOpenGL -

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

57 custom GLSL shader effects in a QGraphicsScene. -

58 \since 4.6 -

59 \ingroup multimedia -

60 \ingroup graphicsview-api -

61 -

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

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

64 function with the signature -

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

66 that returns the source pixel value -

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

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

69 to construct a complete QGLShaderProgram. -

70 -

71 The following example shader converts the incoming pixmap to -

72 grayscale and then applies a colorize operation using the -

73 \c effectColor value: -

74 -

75 \code -

76 static char const colorizeShaderCode[] = -

77 "uniform lowp vec4 effectColor;\n" -

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

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

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

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

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

83 "}"; -

84 \endcode -

85 -

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

87 of QGraphicsShaderEffect as follows: -

88 -

89 \code -

90 class ColorizeEffect : public QGraphicsShaderEffect -

91 { -

92 Q_OBJECT -

93 public: -

94 ColorizeEffect(QObject *parent = 0) -

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

96 { -

97 setPixelShaderFragment(colorizeShaderCode); -

98 } -

99 -

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

101 void setEffectColor(const QColor& c) -

102 { -

103 color = c; -

104 setUniformsDirty(); -

105 } -

106 -

107 protected: -

108 void setUniforms(QGLShaderProgram *program) -

109 { -

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

111 } -

112 -

113 private: -

114 QColor color; -

115 }; -

116 \endcode -

117 -

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

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

120 set effect-specific uniform variables. -

121 -

122 QGraphicsShaderEffect is only supported when the GL2 paint engine -

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

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

125 no effect applied. -

126 -

127 \sa QGraphicsEffect -

128 */ -

129 -

130 static const char qglslDefaultImageFragmentShader[] = "\ -

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

132 return texture2D(imageTexture, textureCoords); \ -

133 }\n"; -

134 -

135 #ifdef QGL_HAVE_CUSTOM_SHADERS -

136 -

137 class QGLCustomShaderEffectStage : public QGLCustomShaderStage -

138 { -

139 public: -

140 QGLCustomShaderEffectStage -

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

142 : QGLCustomShaderStage(), -

143 effect(e) -

144 { -

145 setSource(source); -

146

}

never executed: end of block

147 -

148 void setUniforms(QGLShaderProgram *program) Q_DECL_OVERRIDE; -

149 -

150 QGraphicsShaderEffect *effect; -

151 }; -

152 -

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

154 { -

155 effect->setUniforms(program); -

156

}

never executed: end of block

157 -

158 #endif -

159 -

160 class QGraphicsShaderEffectPrivate : public QGraphicsEffectPrivate -

161 { -

162 Q_DECLARE_PUBLIC(QGraphicsShaderEffect) -

163 public: -

164 QGraphicsShaderEffectPrivate() -

165 : pixelShaderFragment(qglslDefaultImageFragmentShader) -

166 #ifdef QGL_HAVE_CUSTOM_SHADERS -

167 , customShaderStage(0) -

168 #endif -

169 { -

170

}

never executed: end of block

171 -

172 QByteArray pixelShaderFragment; -

173 #ifdef QGL_HAVE_CUSTOM_SHADERS -

174 QGLCustomShaderEffectStage *customShaderStage; -

175 #endif -

176 }; -

177 -

178 /*# -

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

180 */ -

181 QGraphicsShaderEffect::QGraphicsShaderEffect(QObject *parent) -

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

183 { -

184

}

never executed: end of block

185 -

186 /*# -

187 Destroys this shader effect. -

188 */ -

189 QGraphicsShaderEffect::~QGraphicsShaderEffect() -

190 { -

191 #ifdef QGL_HAVE_CUSTOM_SHADERS -

192 Q_D(QGraphicsShaderEffect); -

193 delete d->customShaderStage; -

194 #endif -

195

}

never executed: end of block

196 -

197 /*# -

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

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

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

201 applied. -

202 -

203 \sa setPixelShaderFragment() -

204 */ -

205 QByteArray QGraphicsShaderEffect::pixelShaderFragment() const -

206 { -

207 Q_D(const QGraphicsShaderEffect); -

208

return d->pixelShaderFragment;

never executed: return d->pixelShaderFragment;

209 } -

210 -

211 /*# -

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

213 this shader effect to \a code. -

214 -

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

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

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

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

219 which draws a pixmap with no effect applied: -

220 -

221 \code -

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

223 return texture2D(imageTexture, textureCoords); -

224 } -

225 \endcode -

226 -

227 \sa pixelShaderFragment(), setUniforms() -

228 */ -

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

230 { -

231 Q_D(QGraphicsShaderEffect); -

232

if (d->pixelShaderFragment != code) {

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

233 d->pixelShaderFragment = code; -

234 #ifdef QGL_HAVE_CUSTOM_SHADERS -

235 delete d->customShaderStage; -

236 d->customShaderStage = 0; -

237 #endif -

238

}

never executed: end of block

239

}

never executed: end of block

240 -

241 /*# -

242 \reimp -

243 */ -

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

245 { -

246 Q_D(QGraphicsShaderEffect); -

247 -

248 #ifdef QGL_HAVE_CUSTOM_SHADERS -

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

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

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

252

if (!d->customShaderStage) {

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

253 d->customShaderStage = new QGLCustomShaderEffectStage -

254 (this, d->pixelShaderFragment); -

255

}

never executed: end of block

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

257 -

258 QPoint offset; -

259

if (sourceIsPixmap()) {

sourceIsPixmap()	Description
TRUE	never evaluated
FALSE	never evaluated

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

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

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

263

} else {

never executed: end of block

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

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

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

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

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

269 painter->setWorldTransform(restoreTransform); -

270

}

never executed: end of block

271 -

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

273

if (usingShader)

usingShader	Description
TRUE	never evaluated
FALSE	never evaluated

274

d->customShaderStage->removeFromPainter(painter);

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

275 #else -

276 drawSource(painter); -

277 #endif -

278

}

never executed: end of block

279 -

280 /*# -

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

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

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

284 -

285 This function is typically called by subclasses when an -

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

287 -

288 \sa setUniforms() -

289 */ -

290 void QGraphicsShaderEffect::setUniformsDirty() -

291 { -

292 #ifdef QGL_HAVE_CUSTOM_SHADERS -

293 Q_D(QGraphicsShaderEffect); -

294

if (d->customShaderStage)

d->customShaderStage	Description
TRUE	never evaluated
FALSE	never evaluated

295

d->customShaderStage->setUniformsDirty();

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

296 #endif -

297

}

never executed: end of block

298 -

299 /*# -

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

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

302 -

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

304 setPixelShaderFragment() has additional parameters beyond -

305 those that the paint engine normally sets itself. -

306 -

307 \sa setUniformsDirty() -

308 */ -

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

310 { -

311 Q_UNUSED(program); -

312

}

never executed: end of block

313 -

314 QT_END_NAMESPACE -

315 -

316 #endif // QT_NO_GRAPHICSEFFECT -

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