File 0013-Observe-GL-context-loss-in-ShaderEffectItem.patch of Package qt

From 9e79e82a2e363a8f7fcdfd34c9e64a15dd097d79 Mon Sep 17 00:00:00 2001
From: Chris Adams <chris.adams@jollamobile.com>
Date: Fri, 2 Nov 2012 13:50:58 +1000
Subject: [PATCH 13/29] Observe GL context loss in ShaderEffectItem

Recreate the shader program as required when the GL context
changes.  Also delete the shader program when the ShaderEffectItem
is deactivated, to save graphics memory.

Previously, this was done only for Symbian platforms, and in a
suboptimal fashion.  This patch implements the behaviour for all
platforms in a more optimal manner.

Signed-off-by: Chris Adams <chris.adams@jollamobile.com>
---
 src/imports/shaders/shadereffectitem.cpp |   43 +++++-------------------------
 src/imports/shaders/shadereffectitem.h   |    2 --
 2 files changed, 7 insertions(+), 38 deletions(-)

diff --git a/src/imports/shaders/shadereffectitem.cpp b/src/imports/shaders/shadereffectitem.cpp
index ac5a985..5c5aaeb 100644
--- a/src/imports/shaders/shadereffectitem.cpp
+++ b/src/imports/shaders/shadereffectitem.cpp
@@ -199,10 +199,6 @@ Rectangle {
 
 */
 
-#ifdef Q_OS_SYMBIAN
-#define OBSERVE_GL_CONTEXT_LOSS 1
-#endif
-
 ShaderEffectItem::ShaderEffectItem(QDeclarativeItem *parent)
     : QDeclarativeItem(parent)
     , m_program(0)
@@ -219,21 +215,15 @@ 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;
 }
 
 
@@ -413,30 +403,15 @@ void ShaderEffectItem::renderEffect(QPainter *painter, const QMatrix4x4 &matrix)
     if (!painter || !painter->device())
         return;
 
-#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;
-
+    if (!m_program || !m_program->programId()) {
+        // Deleted due to deactivation, to save GPU memory,
+        // or invalidated due to GL context change.
+        delete m_program;
+        if (QGLContext::currentContext())
             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!";
-            }
-        }
+        if (!m_program)
+            qWarning() << "ShaderEffectItem::renderEffect - Creating QGLShaderProgram failed!";
     }
-#endif
 
     if (!m_program)
         return;
@@ -683,14 +658,10 @@ 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();
diff --git a/src/imports/shaders/shadereffectitem.h b/src/imports/shaders/shadereffectitem.h
index 79af43b..5ef57da 100644
--- a/src/imports/shaders/shadereffectitem.h
+++ b/src/imports/shaders/shadereffectitem.h
@@ -143,8 +143,6 @@ private:
     bool m_hasShaderPrograms : 1;
     bool m_mirrored : 1;
     bool m_defaultVertexShader : 1;
-
-    QGLFramebufferObject* m_contextObserver;
 };
 
 QT_END_HEADER
-- 
1.7.10.3