Fix for qml1shaderplugin GPU resource handling on Symbian

qml1shaderplugin now automatically recovers from situations when GL context is
destroyed and related FBOs and shaderprograms become invalid. Additionally the
shaderprograms are created lazily so that no GPU memory is used if items are
not visible.

Task-number: QTBUG-20724 QTBUG-20736
Reviewed-by: Jani Hautakangas

1 files changed, 85 insertions, 25 deletions

diff --git a/src/imports/shaders/shadereffectitem.cpp b/src/imports/shaders/shadereffectitem.cpp
index 056581c..04c81f5 100644..100755
--- a/src/imports/shaders/shadereffectitem.cpp
+++ b/src/imports/shaders/shadereffectitem.cpp
@@ -199,8 +199,13 @@ Rectangle {
 
 */
 
+#ifdef Q_OS_SYMBIAN
+#define OBSERVE_GL_CONTEXT_LOSS 1
+#endif
+
 ShaderEffectItem::ShaderEffectItem(QDeclarativeItem *parent)
     : QDeclarativeItem(parent)
+    , m_program(0)
     , m_meshResolution(1, 1)
     , m_geometry(QSGGeometry::defaultAttributes_TexturedPoint2D(), 4)
     , m_blending(true)
@@ -214,15 +219,21 @@ ShaderEffectItem::ShaderEffectItem(QDeclarativeItem *parent)
     , m_hasShaderPrograms(false)
     , m_mirrored(false)
     , m_defaultVertexShader(true)
+    , m_contextObserver(0)
 {
     setFlag(QGraphicsItem::ItemHasNoContents, false);
     connect(this, SIGNAL(visibleChanged()), this, SLOT(handleVisibilityChange()));
     m_active = isVisible();
+
+#ifndef OBSERVE_GL_CONTEXT_LOSS
+    m_program = new QGLShaderProgram(this);
+#endif
 }
 
 ShaderEffectItem::~ShaderEffectItem()
 {
     reset();
+    delete m_contextObserver;
 }
 
 
@@ -422,10 +433,38 @@ void ShaderEffectItem::renderEffect(QPainter *painter, const QMatrix4x4 &matrix)
     if (!painter || !painter->device())
         return;
 
-    if (!m_program.isLinked() || m_program_dirty)
+#ifdef OBSERVE_GL_CONTEXT_LOSS
+    QGLContext *context = const_cast <QGLContext*> (QGLContext::currentContext());
+    if (!m_program || !m_contextObserver || !m_contextObserver->isValid()) {
+        // Context has changed, re-create QGLShaderProgram
+        if (context) {
+            delete m_program;
+            m_program = 0;
+
+            delete m_contextObserver;
+            m_contextObserver = 0;
+
+            m_program = new QGLShaderProgram(this);
+            m_contextObserver = new QGLFramebufferObject(QSize(2,2));
+
+            if (!m_contextObserver || !m_program) {
+                delete m_program;
+                m_program = 0;
+                delete m_contextObserver;
+                m_contextObserver = 0;
+                qWarning() << "ShaderEffectItem::renderEffect - Creating QGLShaderProgram or QGLFrameBufferObject failed!";
+            }
+        }
+    }
+#endif
+
+    if (!m_program)
+        return;
+
+    if (!m_program->isLinked() || m_program_dirty)
         updateShaderProgram();
 
-    m_program.bind();
+    m_program->bind();
 
     QMatrix4x4 combinedMatrix;
     combinedMatrix.scale(2.0 / painter->device()->width(), -2.0 / painter->device()->height(), 1.0);
@@ -434,7 +473,7 @@ void ShaderEffectItem::renderEffect(QPainter *painter, const QMatrix4x4 &matrix)
     updateEffectState(combinedMatrix);
 
     for (int i = 0; i < m_attributeNames.size(); ++i) {
-        m_program.enableAttributeArray(m_geometry.attributes()[i].position);
+        m_program->enableAttributeArray(m_geometry.attributes()[i].position);
     }
 
     bindGeometry();
@@ -472,11 +511,14 @@ void ShaderEffectItem::renderEffect(QPainter *painter, const QMatrix4x4 &matrix)
     glDisable(GL_DEPTH_TEST);
 
    for (int i = 0; i < m_attributeNames.size(); ++i)
-        m_program.disableAttributeArray(m_geometry.attributes()[i].position);
+        m_program->disableAttributeArray(m_geometry.attributes()[i].position);
 }
 
 void ShaderEffectItem::updateEffectState(const QMatrix4x4 &matrix)
 {
+    if (!m_program)
+        return;
+
     for (int i = m_sources.size() - 1; i >= 0; --i) {
         const ShaderEffectItem::SourceData &source = m_sources.at(i);
         if (!source.source)
@@ -487,10 +529,10 @@ void ShaderEffectItem::updateEffectState(const QMatrix4x4 &matrix)
     }
 
     if (m_respectsOpacity)
-        m_program.setUniformValue("qt_Opacity", static_cast<float> (effectiveOpacity()));
+        m_program->setUniformValue("qt_Opacity", static_cast<float> (effectiveOpacity()));
 
     if (m_respectsMatrix){
-        m_program.setUniformValue("qt_ModelViewProjectionMatrix", matrix);
+        m_program->setUniformValue("qt_ModelViewProjectionMatrix", matrix);
     }
 
     QSet<QByteArray>::const_iterator it;
@@ -500,37 +542,37 @@ void ShaderEffectItem::updateEffectState(const QMatrix4x4 &matrix)
 
         switch (v.type()) {
         case QVariant::Color:
-            m_program.setUniformValue(name.constData(), qvariant_cast<QColor>(v));
+            m_program->setUniformValue(name.constData(), qvariant_cast<QColor>(v));
             break;
         case QVariant::Double:
-            m_program.setUniformValue(name.constData(), (float) qvariant_cast<double>(v));
+            m_program->setUniformValue(name.constData(), (float) qvariant_cast<double>(v));
             break;
         case QVariant::Transform:
-            m_program.setUniformValue(name.constData(), qvariant_cast<QTransform>(v));
+            m_program->setUniformValue(name.constData(), qvariant_cast<QTransform>(v));
             break;
         case QVariant::Int:
-            m_program.setUniformValue(name.constData(), v.toInt());
+            m_program->setUniformValue(name.constData(), GLint(v.toInt()));
             break;
         case QVariant::Bool:
-            m_program.setUniformValue(name.constData(), GLint(v.toBool()));
+            m_program->setUniformValue(name.constData(), GLint(v.toBool()));
             break;
         case QVariant::Size:
         case QVariant::SizeF:
-            m_program.setUniformValue(name.constData(), v.toSizeF());
+            m_program->setUniformValue(name.constData(), v.toSizeF());
             break;
         case QVariant::Point:
         case QVariant::PointF:
-            m_program.setUniformValue(name.constData(), v.toPointF());
+            m_program->setUniformValue(name.constData(), v.toPointF());
             break;
         case QVariant::Rect:
         case QVariant::RectF:
         {
             QRectF r = v.toRectF();
-            m_program.setUniformValue(name.constData(), r.x(), r.y(), r.width(), r.height());
+            m_program->setUniformValue(name.constData(), r.x(), r.y(), r.width(), r.height());
         }
             break;
         case QVariant::Vector3D:
-            m_program.setUniformValue(name.constData(), qvariant_cast<QVector3D>(v));
+            m_program->setUniformValue(name.constData(), qvariant_cast<QVector3D>(v));
             break;
         default:
             break;
@@ -558,6 +600,9 @@ static inline int size_of_type(GLenum type)
 
 void ShaderEffectItem::bindGeometry()
 {
+    if (!m_program)
+        return;
+
     char const *const *attrNames = m_attributeNames.constData();
     int offset = 0;
         for (int j = 0; j < m_attributeNames.size(); ++j) {
@@ -574,7 +619,7 @@ void ShaderEffectItem::bindGeometry()
         if (normalize)
             qWarning() << "ShaderEffectItem::bindGeometry() - non supported attribute type!";
 
-        m_program.setAttributeArray(a.position, (GLfloat*) (((char*) m_geometry.vertexData()) + offset), a.tupleSize, m_geometry.stride());
+        m_program->setAttributeArray(a.position, (GLfloat*) (((char*) m_geometry.vertexData()) + offset), a.tupleSize, m_geometry.stride());
         //glVertexAttribPointer(a.position, a.tupleSize, a.type, normalize, m_geometry.stride(), (char *) m_geometry.vertexData() + offset);
         offset += a.tupleSize * size_of_type(a.type);
     }
@@ -657,6 +702,16 @@ void ShaderEffectItem::setActive(bool enable)
         }
     }
 
+    // QGLShaderProgram is deleted when not active (to minimize GPU memory usage).
+#ifdef OBSERVE_GL_CONTEXT_LOSS
+    if (!m_active && m_program) {
+        delete m_program;
+        m_program = 0;
+        delete m_contextObserver;
+        m_contextObserver = 0;
+    }
+#endif
+
     emit activeChanged();
     markDirty();
 }
@@ -776,7 +831,9 @@ void ShaderEffectItem::reset()
 {
     disconnectPropertySignals();
 
-    m_program.removeAllShaders();
+    if (m_program)
+        m_program->removeAllShaders();
+
     m_attributeNames.clear();
     m_uniformNames.clear();
     for (int i = 0; i < m_sources.size(); ++i) {
@@ -821,6 +878,9 @@ void ShaderEffectItem::updateProperties()
 
 void ShaderEffectItem::updateShaderProgram()
 {
+    if (!m_program)
+        return;
+
     QString vertexCode = m_vertex_code;
     QString fragmentCode = m_fragment_code;
 
@@ -830,16 +890,16 @@ void ShaderEffectItem::updateShaderProgram()
     if (fragmentCode.isEmpty())
         fragmentCode = QString::fromLatin1(qt_default_fragment_code);
 
-    m_program.addShaderFromSourceCode(QGLShader::Vertex, vertexCode);
-    m_program.addShaderFromSourceCode(QGLShader::Fragment, fragmentCode);
+    m_program->addShaderFromSourceCode(QGLShader::Vertex, vertexCode);
+    m_program->addShaderFromSourceCode(QGLShader::Fragment, fragmentCode);
 
     for (int i = 0; i < m_attributeNames.size(); ++i) {
-        m_program.bindAttributeLocation(m_attributeNames.at(i), m_geometry.attributes()[i].position);
+        m_program->bindAttributeLocation(m_attributeNames.at(i), m_geometry.attributes()[i].position);
     }
 
-    if (!m_program.link()) {
+    if (!m_program->link()) {
         qWarning("ShaderEffectItem: Shader compilation failed:");
-        qWarning() << m_program.log();
+        qWarning() << m_program->log();
     }
 
     if (!m_attributeNames.contains(qt_postion_attribute_name))
@@ -849,10 +909,10 @@ void ShaderEffectItem::updateShaderProgram()
     if (!m_respectsMatrix)
         qWarning("ShaderEffectItem: Missing reference to \'qt_ModelViewProjectionMatrix\'.");
 
-    if (m_program.isLinked()) {
-        m_program.bind();
+    if (m_program->isLinked()) {
+        m_program->bind();
         for (int i = 0; i < m_sources.size(); ++i)
-            m_program.setUniformValue(m_sources.at(i).name.constData(), i);
+            m_program->setUniformValue(m_sources.at(i).name.constData(), (GLint) i);
     }
 
     m_program_dirty = false;