From 5f484abc2d0176015c4286459162bbf40759e1ac Mon Sep 17 00:00:00 2001
From: Magne Sjaastad <magne.sjaastad@ceetronsolutions.com>
Date: Fri, 28 Oct 2016 19:16:27 +0200
Subject: [PATCH] #279 Create QImage from offscreen frame buffer object

---
 Fwk/AppFwk/cafViewer/cafViewer.cpp | 32 +++++++++++++++++++++++++++---
 Fwk/AppFwk/cafViewer/cafViewer.h   |  2 ++
 2 files changed, 31 insertions(+), 3 deletions(-)

diff --git a/Fwk/AppFwk/cafViewer/cafViewer.cpp b/Fwk/AppFwk/cafViewer/cafViewer.cpp
index 8af484e1c7..3a1907bb20 100644
--- a/Fwk/AppFwk/cafViewer/cafViewer.cpp
+++ b/Fwk/AppFwk/cafViewer/cafViewer.cpp
@@ -119,7 +119,9 @@ caf::Viewer::Viewer(const QGLFormat& format, QWidget* parent)
     m_releaseOGLResourcesEachFrame(false),
     m_paintCounter(0),
     m_navigationPolicyEnabled(true),
-    m_isOverlayPaintingEnabled(true)
+    m_isOverlayPaintingEnabled(true),
+    m_offscreenViewportWidth(0),
+    m_offscreenViewportHeight(0)
 {
     m_layoutWidget = parentWidget();
 
@@ -497,6 +499,9 @@ void caf::Viewer::resizeGL(int width, int height)
         m_offscreenFbo->resizeAttachedBuffers(width, height);
     
         m_quadRendering->camera()->viewport()->set(0, 0, width, height);
+
+        m_offscreenViewportWidth = width;
+        m_offscreenViewportHeight = height;
     }
 
     updateCamera(width, height);
@@ -810,9 +815,30 @@ bool caf::Viewer::isShadersSupported()
 QImage caf::Viewer::snapshotImage()
 {
     QImage image;
-    if (m_offscreenTexture.notNull() && m_offscreenTexture->image())
+    if (m_offscreenFbo.notNull() && m_offscreenViewportWidth > 0 && m_offscreenViewportHeight > 0)
     {
-        image = cvfqt::Utils::toQImage(*(m_offscreenTexture->image()));
+        cvf::ref<cvf::OpenGLContext> myOglContext = cvfOpenGLContext();
+
+        // TODO: Is this required???
+        //m_offscreenFbo->bind(myOglContext.p());
+
+        GLint iOldPackAlignment = 0;
+        glGetIntegerv(GL_PACK_ALIGNMENT, &iOldPackAlignment);
+        glPixelStorei(GL_PACK_ALIGNMENT, 1);
+        CVF_CHECK_OGL(myOglContext.p());
+
+        cvf::UByteArray arr(3 * m_offscreenViewportWidth * m_offscreenViewportHeight);
+
+        glReadPixels(0, 0, static_cast<GLsizei>(m_offscreenViewportWidth), static_cast<GLsizei>(m_offscreenViewportHeight), GL_RGB, GL_UNSIGNED_BYTE, arr.ptr());
+        CVF_CHECK_OGL(myOglContext.p());
+
+        glPixelStorei(GL_PACK_ALIGNMENT, iOldPackAlignment);
+        CVF_CHECK_OGL(myOglContext.p());
+
+        cvf::TextureImage texImage;
+        texImage.setFromRgb(arr.ptr(), m_offscreenViewportWidth, m_offscreenViewportHeight);
+
+        image = cvfqt::Utils::toQImage(texImage);
     }
     else
     {
diff --git a/Fwk/AppFwk/cafViewer/cafViewer.h b/Fwk/AppFwk/cafViewer/cafViewer.h
index 38dad95e5b..c90fb63721 100644
--- a/Fwk/AppFwk/cafViewer/cafViewer.h
+++ b/Fwk/AppFwk/cafViewer/cafViewer.h
@@ -231,6 +231,8 @@ private:
     // Offscreen render objects
     cvf::ref<cvf::FramebufferObject>    m_offscreenFbo;
     cvf::ref<cvf::Texture>              m_offscreenTexture;
+    int                                 m_offscreenViewportWidth;
+    int                                 m_offscreenViewportHeight;
     cvf::ref<cvf::Rendering>            m_quadRendering;
 };