From 345643bad10d9f539eebe0139fa69f11e3f14f09 Mon Sep 17 00:00:00 2001
From: Tats <info@sofianaudry.com>
Date: Thu, 17 Mar 2016 16:05:03 -0400
Subject: [PATCH] Fixed: Flickering video images when loading from the
 commandline (closes #218).

---
 Paint.cpp             |  9 +++++++++
 Paint.h               |  5 ++++-
 ShapeGraphicsItem.cpp | 18 ++++++++++++------
 3 files changed, 25 insertions(+), 7 deletions(-)

diff --git a/Paint.cpp b/Paint.cpp
index b4e6f52..580c12c 100644
--- a/Paint.cpp
+++ b/Paint.cpp
@@ -26,6 +26,14 @@ MM_BEGIN_NAMESPACE
 
 UidAllocator Paint::allocator;
 
+void Texture::update()
+{
+  if (textureId == 0)
+  {
+    glGenTextures(1, &textureId);
+  }
+}
+
 void Texture::read(const QDomElement& obj)
 {
   Paint::read(obj);
@@ -111,6 +119,7 @@ int Video::getHeight() const
 
 void Video::update() {
   _impl->update();
+  Texture::update();
 }
 
 void Video::play()
diff --git a/Paint.h b/Paint.h
index 9dfaabc..6203966 100644
--- a/Paint.h
+++ b/Paint.h
@@ -135,16 +135,19 @@ protected:
     x(0),
     y(0)
   {
-    glGenTextures(1, &textureId);
   }
 
 public:
   virtual ~Texture() {
+    // TODO: this needs to be fixed: it will not work unless it is executed from within a GL context
+    // see issue #229
     if (textureId != 0)
       glDeleteTextures(1, &textureId);
   }
 
 public:
+  virtual void update();
+
   GLuint getTextureId() const { return textureId; }
   virtual int getWidth() const = 0;
   virtual int getHeight() const = 0;
diff --git a/ShapeGraphicsItem.cpp b/ShapeGraphicsItem.cpp
index 6736f2a..c91745f 100644
--- a/ShapeGraphicsItem.cpp
+++ b/ShapeGraphicsItem.cpp
@@ -229,17 +229,16 @@ void TextureGraphicsItem::_prePaint(QPainter* painter,
                                     const QStyleOptionGraphicsItem *option)
 {
   Q_UNUSED(option);
+  QSharedPointer<Texture> texture = _texture.toStrongRef();
   painter->beginNativePainting();
 
-  QSharedPointer<Texture> texture = _texture.toStrongRef();
+  // Project source texture and sent it to destination.
+  texture->update();
 
   // Only works for similar shapes.
   // TODO:remettre
   //Q_ASSERT( _inputShape->nVertices() == outputShape->nVertices());
 
-  // Project source texture and sent it to destination.
-  texture->update();
-
   // Allow alpha blending.
   glEnable (GL_BLEND);
   glBlendFunc (GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
@@ -253,8 +252,14 @@ void TextureGraphicsItem::_prePaint(QPainter* painter,
   if (texture->bitsHaveChanged())
   {
     glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA,
-        texture->getWidth(), texture->getHeight(), 0, GL_RGBA,
-      GL_UNSIGNED_BYTE, texture->getBits());
+                 texture->getWidth(), texture->getHeight(), 0, GL_RGBA,
+                 GL_UNSIGNED_BYTE, texture->getBits());
+    // NOTE: We would gain in efficiency if we were able to just update the texture using glTexSubImage2D
+    // See: http://stackoverflow.com/questions/11217121/how-to-manage-memory-with-texture-in-opengl
+//    glTexSubImage2D(GL_TEXTURE_2D,
+//        0, 0,
+//        texture->getWidth(), texture->getHeight(), 0,
+//        GL_RGBA, GL_UNSIGNED_BYTE, texture->getBits());
   }
   texture->unlockMutex();
 
@@ -266,6 +271,7 @@ void TextureGraphicsItem::_prePaint(QPainter* painter,
   // Set texture color (apply opacity).
   glColor4f(1.0f, 1.0f, 1.0f,
             isOutput() ? getMapping()->getComputedOpacity() : getMapping()->getPaint()->getOpacity());
+
 }
 
 void TextureGraphicsItem::_postPaint(QPainter* painter,