From c23d4d6644bff2195fbb6aa84d3425dc2d31491a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Samuel=20R=C3=B8dal?= <sroedal@trolltech.com>
Date: Thu, 18 Jun 2009 12:10:12 +0200
Subject: Prevented unnecessary depth clip updates in OpenGL paint engine.

Keep track of whether the depth clip has actually changed between
states, so that when QPainter::restore() is called we don't call the
potentially expensive updateDepthClip() function when not needed.

Task-number: 254658
Reviewed-by: Trond
---
 src/opengl/qpaintengine_opengl.cpp | 10 +++++++++-
 src/opengl/qpaintengine_opengl_p.h |  1 +
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/src/opengl/qpaintengine_opengl.cpp b/src/opengl/qpaintengine_opengl.cpp
index 044090b..b594f5b 100644
--- a/src/opengl/qpaintengine_opengl.cpp
+++ b/src/opengl/qpaintengine_opengl.cpp
@@ -2222,6 +2222,8 @@ void QOpenGLPaintEnginePrivate::updateDepthClip()
 {
     Q_Q(QOpenGLPaintEngine);
 
+    ++q->state()->depthClipId;
+
     glDisable(GL_DEPTH_TEST);
     glDisable(GL_SCISSOR_TEST);
 
@@ -5504,6 +5506,9 @@ void QOpenGLPaintEngine::clip(const QVectorPath &path, Qt::ClipOperation op)
 void QOpenGLPaintEngine::setState(QPainterState *s)
 {
     Q_D(QOpenGLPaintEngine);
+    QOpenGLPaintEngineState *new_state = static_cast<QOpenGLPaintEngineState *>(s);
+    QOpenGLPaintEngineState *old_state = state();
+
     QPaintEngineEx::setState(s);
 
     // are we in a save() ?
@@ -5513,7 +5518,8 @@ void QOpenGLPaintEngine::setState(QPainterState *s)
     }
 
     if (isActive()) {
-        d->updateDepthClip();
+        if (old_state->depthClipId != new_state->depthClipId)
+            d->updateDepthClip();
         penChanged();
         brushChanged();
         opacityChanged();
@@ -5547,11 +5553,13 @@ QOpenGLPaintEngineState::QOpenGLPaintEngineState(QOpenGLPaintEngineState &other)
     clipRegion = other.clipRegion;
     hasClipping = other.hasClipping;
     fastClip = other.fastClip;
+    depthClipId = other.depthClipId;
 }
 
 QOpenGLPaintEngineState::QOpenGLPaintEngineState()
 {
     hasClipping = false;
+    depthClipId = 0;
 }
 
 QOpenGLPaintEngineState::~QOpenGLPaintEngineState()
diff --git a/src/opengl/qpaintengine_opengl_p.h b/src/opengl/qpaintengine_opengl_p.h
index 891cbd6..439782b 100644
--- a/src/opengl/qpaintengine_opengl_p.h
+++ b/src/opengl/qpaintengine_opengl_p.h
@@ -69,6 +69,7 @@ public:
     QRegion clipRegion;
     bool hasClipping;
     QRect fastClip;
+    uint depthClipId;
 };
 
 class QOpenGLPaintEngine : public QPaintEngineEx
-- 
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