Implement QGraphicsShaderEffect for custom shader-based effects

3 files changed, 413 insertions, 0 deletions

diff --git a/src/opengl/opengl.pro b/src/opengl/opengl.pro
index 5a76cb1..b217949 100644
--- a/src/opengl/opengl.pro
+++ b/src/opengl/opengl.pro
@@ -37,6 +37,7 @@ SOURCES	+= qgl.cpp \
 !contains(QT_CONFIG, opengles1):!contains(QT_CONFIG, opengles1cl) {
     HEADERS +=  qglshaderprogram.h \
                 qglpixmapfilter_p.h  \
+                qgraphicsshadereffect.h \
                 qgraphicssystem_gl_p.h \
                 qwindowsurface_gl_p.h \
                 qpixmapdata_gl_p.h \
@@ -49,6 +50,7 @@ SOURCES	+= qgl.cpp \
 
     SOURCES +=  qglshaderprogram.cpp \
                 qglpixmapfilter.cpp \
+                qgraphicsshadereffect.cpp \
                 qgraphicssystem_gl.cpp \
                 qwindowsurface_gl.cpp \
                 qpixmapdata_gl.cpp \
diff --git a/src/opengl/qgraphicsshadereffect.cpp b/src/opengl/qgraphicsshadereffect.cpp
new file mode 100644
index 0000000..121dd90
--- /dev/null
+++ b/src/opengl/qgraphicsshadereffect.cpp
@@ -0,0 +1,319 @@
+/****************************************************************************
+**
+** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
+** Contact: Qt Software Information (qt-info@nokia.com)
+**
+** This file is part of the QtGui module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** No Commercial Usage
+** This file contains pre-release code and may not be distributed.
+** You may use this file in accordance with the terms and conditions
+** contained in the either Technology Preview License Agreement or the
+** Beta Release License Agreement.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 2.1 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU Lesser General Public License version 2.1 requirements
+** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** In addition, as a special exception, Nokia gives you certain
+** additional rights. These rights are described in the Nokia Qt LGPL
+** Exception version 1.0, included in the file LGPL_EXCEPTION.txt in this
+** package.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 3.0 as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU General Public License version 3.0 requirements will be
+** met: http://www.gnu.org/copyleft/gpl.html.
+**
+** If you are unsure which license is appropriate for your use, please
+** contact the sales department at qt-sales@nokia.com.
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include "qgraphicsshadereffect.h"
+#if !defined(QT_OPENGL_ES_1) && !defined(QT_OPENGL_ES_1_CL)
+#include "qglshaderprogram.h"
+#include "gl2paintengineex/qglcustomshaderstage_p.h"
+#define QGL_HAVE_CUSTOM_SHADERS 1
+#endif
+#include <QtGui/qpainter.h>
+#include <QtGui/qgraphicsitem.h>
+
+QT_BEGIN_NAMESPACE
+
+#if !defined(QT_NO_GRAPHICSVIEW) || (QT_EDITION & QT_MODULE_GRAPHICSVIEW) != QT_MODULE_GRAPHICSVIEW
+
+/*!
+    \class QGraphicsShaderEffect
+    \brief The QGraphicsShaderEffect class is the base class for creating
+    custom GLSL shader effects in a QGraphicsScene.
+    \since 4.6
+    \ingroup multimedia
+    \ingroup graphicsview-api
+
+    The specific effect is defined by a fragment of GLSL source code
+    supplied to setPixelShaderFragment().  This source code must define a
+    function called \c{srcPixel()} that returns the source pixel value
+    to use in the paint engine's shader program.  The shader fragment
+    is linked with the regular shader code used by the GL2 paint engine
+    to construct a complete QGLShaderProgram.
+
+    The following example shader converts the incoming pixmap to
+    grayscale and then applies a colorize operation using the
+    \c effectColor value:
+
+    \code
+    static char const colorizeShaderCode[] =
+        "varying highp vec2 textureCoords;\n"
+        "uniform sampler2D imageTexture;\n"
+        "uniform lowp vec4 effectColor;\n"
+        "lowp vec4 srcPixel() {\n"
+        "    vec4 src = texture2D(imageTexture, textureCoords);\n"
+        "    float gray = dot(src.rgb, vec3(0.212671, 0.715160, 0.072169));\n"
+        "    vec4 colorize = 1.0-((1.0-gray)*(1.0-effectColor));\n"
+        "    return vec4(colorize.rgb, src.a);\n"
+        "}";
+    \endcode
+
+    To use this shader code, it is necessary to define a subclass
+    of QGraphicsShaderEffect as follows:
+
+    \code
+    class ColorizeEffect : public QGraphicsShaderEffect
+    {
+        Q_OBJECT
+    public:
+        ColorizeEffect(QObject *parent = 0)
+            : QGraphicsShaderEffect(parent), color(Qt::black)
+        {
+            setPixelShaderFragment(colorizeShaderCode);
+        }
+
+        QColor effectColor() const { return color; }
+        void setEffectColor(const QColor& c)
+        {
+            color = c;
+            setUniformsDirty();
+        }
+
+    protected:
+        void setUniforms(QGLShaderProgram *program)
+        {
+            program->setUniformValue("effectColor", color);
+        }
+
+    private:
+        QColor color;
+    };
+    \endcode
+
+    The setUniforms() function is called when the effect is about
+    to be used for drawing to give the subclass the opportunity to
+    set effect-specific uniform variables.
+
+    QGraphicsShaderEffect is only supported when the GL2 paint engine
+    is in use.  When any other paint engine is in use (GL1, raster, etc),
+    the drawItem() method will draw its item argument directly with
+    no effect applied.
+
+    \sa QGrapicsEffect
+*/
+
+static const char qglslDefaultImageFragmentShader[] = "\
+    varying highp vec2 textureCoords; \
+    uniform sampler2D imageTexture; \
+    lowp vec4 srcPixel() { \
+        return texture2D(imageTexture, textureCoords); \
+    }\n";
+
+#ifdef QGL_HAVE_CUSTOM_SHADERS
+
+class QGLCustomShaderEffectStage : public QGLCustomShaderStage
+{
+public:
+    QGLCustomShaderEffectStage
+            (QGraphicsShaderEffect *e, const QByteArray& source)
+        : QGLCustomShaderStage(),
+          effect(e)
+    {
+        setSource(source);
+    }
+
+    void setUniforms(QGLShaderProgram *program);
+
+    QGraphicsShaderEffect *effect;
+};
+
+void QGLCustomShaderEffectStage::setUniforms(QGLShaderProgram *program)
+{
+    effect->setUniforms(program);
+}
+
+#endif
+
+class QGraphicsShaderEffectPrivate
+{
+public:
+    QGraphicsShaderEffectPrivate()
+        : pixelShaderFragment(qglslDefaultImageFragmentShader)
+#ifdef QGL_HAVE_CUSTOM_SHADERS
+          , customShaderStage(0)
+#endif
+    {
+    }
+
+    QByteArray pixelShaderFragment;
+#ifdef QGL_HAVE_CUSTOM_SHADERS
+    QGLCustomShaderEffectStage *customShaderStage;
+#endif
+};
+
+/*!
+    Constructs a shader effect and attaches it to \a parent.
+*/
+QGraphicsShaderEffect::QGraphicsShaderEffect(QObject *parent)
+    : QGraphicsEffect(parent)
+{
+    d_ptr = new QGraphicsShaderEffectPrivate();
+}
+
+/*!
+    Destroys this shader effect.
+*/
+QGraphicsShaderEffect::~QGraphicsShaderEffect()
+{
+#ifdef QGL_HAVE_CUSTOM_SHADERS
+    delete d_ptr->customShaderStage;
+#endif
+    delete d_ptr;
+}
+
+/*!
+    Returns the source code for the pixel shader fragment for
+    this shader effect.  The default is a shader that copies
+    its incoming pixmap directly to the output with no effect
+    applied.
+
+    \sa setPixelShaderFragment()
+*/
+QByteArray QGraphicsShaderEffect::pixelShaderFragment() const
+{
+    return d_ptr->pixelShaderFragment;
+}
+
+/*!
+    Sets the source code for the pixel shader fragment for
+    this shader effect to \a code.
+
+    The \a code must define a GLSL function called \c{srcPixel()}
+    that returns the source pixel value to use in the paint engine's
+    shader program.  The following is the default pixel shader fragment,
+    which draws a pixmap with no effect applied:
+
+    \code
+    varying highp vec2 textureCoords;
+    uniform sampler2D imageTexture;
+    lowp vec4 srcPixel() {
+        return texture2D(imageTexture, textureCoords);
+    }
+    \endcode
+
+    \sa pixelShaderFragment(), setUniforms()
+*/
+void QGraphicsShaderEffect::setPixelShaderFragment(const QByteArray& code)
+{
+    if (d_ptr->pixelShaderFragment != code) {
+        d_ptr->pixelShaderFragment = code;
+#ifdef QGL_HAVE_CUSTOM_SHADERS
+        delete d_ptr->customShaderStage;
+        d_ptr->customShaderStage = 0;
+#endif
+    }
+}
+
+/*!
+    \reimp
+*/
+void QGraphicsShaderEffect::drawItem
+    (QGraphicsItem *item, QPainter *painter,
+     const QStyleOptionGraphicsItem *option, QWidget *widget)
+{
+#ifdef QGL_HAVE_CUSTOM_SHADERS
+    // Find the item's bounds in device coordinates.
+    QRectF deviceBounds = painter->worldTransform().mapRect(item->boundingRect());
+    QRect deviceRect = deviceBounds.toRect().adjusted(-1, -1, 1, 1);
+    if (deviceRect.isEmpty())
+        return;
+
+    QPixmap *pixmap = QGraphicsEffect::drawItemOnPixmap(painter, item, option, widget, 0);
+    if (!pixmap)
+        return;
+
+    // Set the custom shader on the paint engine.  The setOnPainter()
+    // call may fail if the paint engine is not GL2.  In that case,
+    // we fall through to drawing the pixmap normally.
+    if (!d_ptr->customShaderStage) {
+        d_ptr->customShaderStage = new QGLCustomShaderEffectStage
+            (this, d_ptr->pixelShaderFragment);
+    }
+    bool usingShader = d_ptr->customShaderStage->setOnPainter(painter);
+
+    // Draw using an untransformed painter.
+    QTransform restoreTransform = painter->worldTransform();
+    painter->setWorldTransform(QTransform());
+    painter->drawPixmap(deviceRect.topLeft(), *pixmap);
+    painter->setWorldTransform(restoreTransform);
+
+    // Remove the custom shader to return to normal painting operations.
+    if (usingShader)
+        d_ptr->customShaderStage->removeFromPainter(painter);
+#else
+    item->paint(painter, option, widget);
+#endif
+}
+
+/*!
+    Sets the custom uniform variables on this shader effect to
+    be dirty.  The setUniforms() function will be called the next
+    time the shader program corresponding to this effect is used.
+
+    This function is typically called by subclasses when an
+    effect-specific parameter is changed by the application.
+
+    \sa setUniforms()
+*/
+void QGraphicsShaderEffect::setUniformsDirty()
+{
+#ifdef QGL_HAVE_CUSTOM_SHADERS
+    if (d_ptr->customShaderStage)
+        d_ptr->customShaderStage->setUniformsDirty();
+#endif
+}
+
+/*!
+    Sets custom uniform variables on the current GL context when
+    \a program is about to be used by the paint engine.
+
+    This function should be overridden if the shader set with
+    setPixelShaderFragment() has additional parameters beyond
+    those that the paint engine normally sets itself.
+
+    \sa setUniformsDirty()
+*/
+void QGraphicsShaderEffect::setUniforms(QGLShaderProgram *program)
+{
+    Q_UNUSED(program);
+}
+
+#endif // QT_NO_GRAPHICSVIEW
+
+QT_END_NAMESPACE
diff --git a/src/opengl/qgraphicsshadereffect.h b/src/opengl/qgraphicsshadereffect.h
new file mode 100644
index 0000000..124f30c
--- /dev/null
+++ b/src/opengl/qgraphicsshadereffect.h
@@ -0,0 +1,92 @@
+/****************************************************************************
+**
+** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
+** Contact: Qt Software Information (qt-info@nokia.com)
+**
+** This file is part of the QtGui module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** No Commercial Usage
+** This file contains pre-release code and may not be distributed.
+** You may use this file in accordance with the terms and conditions
+** contained in the either Technology Preview License Agreement or the
+** Beta Release License Agreement.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 2.1 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU Lesser General Public License version 2.1 requirements
+** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** In addition, as a special exception, Nokia gives you certain
+** additional rights. These rights are described in the Nokia Qt LGPL
+** Exception version 1.0, included in the file LGPL_EXCEPTION.txt in this
+** package.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 3.0 as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU General Public License version 3.0 requirements will be
+** met: http://www.gnu.org/copyleft/gpl.html.
+**
+** If you are unsure which license is appropriate for your use, please
+** contact the sales department at qt-sales@nokia.com.
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#ifndef QGRAPHICSSHADEREFFECT_H
+#define QGRAPHICSSHADEREFFECT_H
+
+#include <QtGui/qgraphicseffect.h>
+
+QT_BEGIN_HEADER
+
+QT_BEGIN_NAMESPACE
+
+QT_MODULE(OpenGL)
+
+#if !defined(QT_NO_GRAPHICSVIEW) || (QT_EDITION & QT_MODULE_GRAPHICSVIEW) != QT_MODULE_GRAPHICSVIEW
+
+class QGLShaderProgram;
+class QGLCustomShaderEffectStage;
+class QGraphicsShaderEffectPrivate;
+
+class Q_OPENGL_EXPORT QGraphicsShaderEffect : public QGraphicsEffect
+{
+    Q_OBJECT
+public:
+    QGraphicsShaderEffect(QObject *parent = 0);
+    virtual ~QGraphicsShaderEffect();
+
+    QByteArray pixelShaderFragment() const;
+    void setPixelShaderFragment(const QByteArray& code);
+
+    void drawItem(QGraphicsItem *item, QPainter *painter,
+                  const QStyleOptionGraphicsItem *option,
+                  QWidget *widget);
+
+protected:
+    void setUniformsDirty();
+    virtual void setUniforms(QGLShaderProgram *program);
+
+private:
+    QGraphicsShaderEffectPrivate *d_ptr;
+    Q_DISABLE_COPY(QGraphicsShaderEffect)
+
+    friend class QGLCustomShaderEffectStage;
+};
+
+Q_DECLARE_METATYPE(QGraphicsShaderEffect *)
+
+#endif // QT_NO_GRAPHICSVIEW
+
+QT_END_NAMESPACE
+
+QT_END_HEADER
+
+#endif // QGRAPHICSSHADEREFFECT_H