From 8c33b798237b95d37fe4d60ae36f0d8067504429 Mon Sep 17 00:00:00 2001
From: Allan Sandfeld Jensen <allan.jensen@qt.io>
Date: Wed, 30 May 2018 15:51:32 +0200
Subject: Fix HDR format in QOpenGLFramebufferObject::toImage()

If the fbo had samples > 0 set, it would use a temporary fbo with
a default configuration losing the HDR precision.

Change-Id: I7e9966165b3100f148c4ad24738f3ee71273f29a
Reviewed-by: Laszlo Agocs <laszlo.agocs@qt.io>
---
 src/gui/opengl/qopenglframebufferobject.cpp |  7 +++++--
 tests/auto/other/lancelot/tst_lancelot.cpp  | 18 ++++++++++++++++++
 2 files changed, 23 insertions(+), 2 deletions(-)

diff --git a/src/gui/opengl/qopenglframebufferobject.cpp b/src/gui/opengl/qopenglframebufferobject.cpp
index 469f019a1c..91c25184b6 100644
--- a/src/gui/opengl/qopenglframebufferobject.cpp
+++ b/src/gui/opengl/qopenglframebufferobject.cpp
@@ -1424,14 +1424,17 @@ QImage QOpenGLFramebufferObject::toImage(bool flipped, int colorAttachmentIndex)
     // qt_gl_read_framebuffer doesn't work on a multisample FBO
     if (format().samples() != 0) {
         QRect rect(QPoint(0, 0), size());
+        QOpenGLFramebufferObjectFormat fmt;
         if (extraFuncs->hasOpenGLFeature(QOpenGLFunctions::MultipleRenderTargets)) {
-            QOpenGLFramebufferObject temp(d->colorAttachments[colorAttachmentIndex].size, QOpenGLFramebufferObjectFormat());
+            fmt.setInternalTextureFormat(d->colorAttachments[colorAttachmentIndex].internalFormat);
+            QOpenGLFramebufferObject temp(d->colorAttachments[colorAttachmentIndex].size, fmt);
             blitFramebuffer(&temp, rect, const_cast<QOpenGLFramebufferObject *>(this), rect,
                             GL_COLOR_BUFFER_BIT, GL_NEAREST,
                             colorAttachmentIndex, 0);
             image = temp.toImage(flipped);
         } else {
-            QOpenGLFramebufferObject temp(size(), QOpenGLFramebufferObjectFormat());
+            fmt.setInternalTextureFormat(d->colorAttachments[0].internalFormat);
+            QOpenGLFramebufferObject temp(size(), fmt);
             blitFramebuffer(&temp, rect, const_cast<QOpenGLFramebufferObject *>(this), rect);
             image = temp.toImage(flipped);
         }
diff --git a/tests/auto/other/lancelot/tst_lancelot.cpp b/tests/auto/other/lancelot/tst_lancelot.cpp
index 79d0f7c6cf..15267d256e 100644
--- a/tests/auto/other/lancelot/tst_lancelot.cpp
+++ b/tests/auto/other/lancelot/tst_lancelot.cpp
@@ -39,6 +39,10 @@
 
 #include <algorithm>
 
+#ifndef GL_RGB10
+#define GL_RGB10                          0x8052
+#endif
+
 class tst_Lancelot : public QObject
 {
 Q_OBJECT
@@ -85,6 +89,8 @@ private slots:
 #ifndef QT_NO_OPENGL
     void testOpenGL_data();
     void testOpenGL();
+    void testOpenGLBGR30_data();
+    void testOpenGLBGR30();
     void testCoreOpenGL_data();
     void testCoreOpenGL();
 private:
@@ -279,6 +285,16 @@ void tst_Lancelot::testOpenGL()
     runTestSuite(OpenGL, QImage::Format_RGB32);
 }
 
+void tst_Lancelot::testOpenGLBGR30_data()
+{
+    tst_Lancelot::testOpenGL_data();
+}
+
+void tst_Lancelot::testOpenGLBGR30()
+{
+    runTestSuite(OpenGL, QImage::Format_BGR30);
+}
+
 void tst_Lancelot::testCoreOpenGL_data()
 {
     if (!checkSystemCoreGLSupport())
@@ -329,6 +345,8 @@ void tst_Lancelot::runTestSuite(GraphicsEngine engine, QImage::Format format, co
         QOpenGLFramebufferObjectFormat fmt;
         fmt.setAttachment(QOpenGLFramebufferObject::CombinedDepthStencil);
         fmt.setSamples(4);
+        if (format == QImage::Format_BGR30)
+            fmt.setInternalTextureFormat(GL_RGB10);
         QOpenGLContext ctx;
         ctx.setFormat(contextFormat);
         QVERIFY(ctx.create());
-- 
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