From ca9ba386823c47721f6e0c7e184b5230a2c967fd Mon Sep 17 00:00:00 2001
From: Tats <info@sofianaudry.com>
Date: Sat, 26 Apr 2014 13:32:27 +0100
Subject: [PATCH] Performance improvement: copy texture bits to video card only
 if they have changed

---
 Mapper.cpp         | 10 +++++++---
 MediaImpl.cpp      | 17 ++++++++++++-----
 MediaImpl.h        |  3 ++-
 Paint.cpp          |  5 +++--
 Paint.h            | 19 ++++++++++++++-----
 SourceGLCanvas.cpp |  7 +++++--
 6 files changed, 43 insertions(+), 18 deletions(-)

diff --git a/Mapper.cpp b/Mapper.cpp
index e20584c..9d682ea 100644
--- a/Mapper.cpp
+++ b/Mapper.cpp
@@ -307,9 +307,13 @@ void TextureMapper::draw(QPainter* painter)
   glEnable (GL_TEXTURE_2D);
   glBindTexture(GL_TEXTURE_2D, texture->getTextureId());
 
-  glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA,
-    texture->getWidth(), texture->getHeight(), 0, GL_RGBA,
-    GL_UNSIGNED_BYTE, texture->getBits());
+  // Copy bits to texture iff necessary.
+  if (texture->bitsHaveChanged())
+  {
+    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA,
+      texture->getWidth(), texture->getHeight(), 0, GL_RGBA,
+      GL_UNSIGNED_BYTE, texture->getBits());
+  }
 
   glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP);
   glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP);
diff --git a/MediaImpl.cpp b/MediaImpl.cpp
index d63a6e2..aaccde2 100644
--- a/MediaImpl.cpp
+++ b/MediaImpl.cpp
@@ -404,13 +404,15 @@ bool MediaImpl::loadMovie(QString filename)
 }
 
 
-void MediaImpl::runVideo() {
+bool MediaImpl::runVideo() {
 
 //  if (!_VIDEO_OUT->connected())
 //    return;
 
   if (!_preRun())
-    return;
+    return false;
+
+  bool bitsChanged = false;
 
   if (_videoNewBufferCounter > 0) {
 
@@ -420,14 +422,19 @@ void MediaImpl::runVideo() {
       _setFinished(true);
 //      _FINISH_OUT->type()->setValue(1.0f);
 //      _VIDEO_OUT->sleeping(true);
-    } else
-//      _VIDEO_OUT->sleeping(false);
-
+    }
+    else
+    {
+      bitsChanged = true;
+      //      _VIDEO_OUT->sleeping(false);
+    }
 
     _videoNewBufferCounter--;
   }
 
   _postRun();
+
+  return bitsChanged;
 }
 
 
diff --git a/MediaImpl.h b/MediaImpl.h
index 5b006ec..e673e72 100644
--- a/MediaImpl.h
+++ b/MediaImpl.h
@@ -53,7 +53,8 @@ public:
   int getHeight() const;
   const uchar* getBits() const;
 
-  void runVideo();
+  /// Returns true if the image has changed.
+  bool runVideo();
 //  void runAudio();
 
 protected:
diff --git a/Paint.cpp b/Paint.cpp
index bed9291..04ae499 100644
--- a/Paint.cpp
+++ b/Paint.cpp
@@ -76,10 +76,11 @@ int Media::getHeight() const
 }
 
 void Media::update() {
-  impl_->runVideo();
+  if (impl_->runVideo())
+    bitsChanged = true;
 }
 
-const uchar* Media::getBits() const
+const uchar* Media::_getBits() const
 {
   return this->impl_->getBits();
 }
diff --git a/Paint.h b/Paint.h
index a80bc1d..fc7633f 100644
--- a/Paint.h
+++ b/Paint.h
@@ -103,12 +103,14 @@ protected:
   GLuint textureId;
   GLfloat x;
   GLfloat y;
+  mutable bool bitsChanged;
 
   Texture(uid id=NULL_UID) :
     Paint(id),
     textureId(0),
     x(0),
-    y(0)
+    y(0),
+    bitsChanged(true)
   {}
   virtual ~Texture() {
     if (textureId != 0)
@@ -123,7 +125,14 @@ public:
   }
   virtual int getWidth() const = 0;
   virtual int getHeight() const = 0;
-  virtual const uchar* getBits() const = 0;
+  virtual const uchar* getBits() const {
+    bitsChanged = false;
+    return _getBits();
+  }
+  virtual const uchar* _getBits() const = 0;
+
+  /// Returns true iff bits have changed since last call to getBits().
+  bool bitsHaveChanged() const { return bitsChanged; }
 
   virtual void setPosition(GLfloat xPos, GLfloat yPos) {
     x = xPos;
@@ -147,7 +156,6 @@ public:
     Texture(id),
     uri(uri_)
   {
-    image = QGLWidget::convertToGLFormat(QImage(uri));
   }
 
   virtual ~Image() {}
@@ -155,13 +163,14 @@ public:
   const QString getUri() const { return uri; }
 
   virtual void build() {
+    image = QGLWidget::convertToGLFormat(QImage(uri));
   }
 
   virtual QString getType() const { return "image"; }
 
   virtual int getWidth() const { return image.width(); }
   virtual int getHeight() const { return image.height(); }
-  virtual const uchar* getBits() const { return image.bits(); }
+  virtual const uchar* _getBits() const { return image.bits(); }
 };
 
 class MediaImpl; // forward declaration
@@ -188,7 +197,7 @@ public:
   }
   virtual int getWidth() const;
   virtual int getHeight() const;
-  virtual const uchar* getBits() const;
+  virtual const uchar* _getBits() const;
   /**
    * Checks whether or not video is supported on this platform.
    */
diff --git a/SourceGLCanvas.cpp b/SourceGLCanvas.cpp
index 1ac96e3..ce2152d 100644
--- a/SourceGLCanvas.cpp
+++ b/SourceGLCanvas.cpp
@@ -112,8 +112,11 @@ void SourceGLCanvas::_drawTexture(QPainter* painter, Paint::ptr paint, QMap<uid,
   glEnable (GL_TEXTURE_2D);
   glBindTexture(GL_TEXTURE_2D, texture->getTextureId());
 
-  glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, texture->getWidth(), texture->getHeight(), 0, GL_RGBA,
-               GL_UNSIGNED_BYTE, texture->getBits());
+  if (texture->bitsHaveChanged())
+  {
+    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, texture->getWidth(), texture->getHeight(), 0, GL_RGBA,
+                 GL_UNSIGNED_BYTE, texture->getBits());
+  }
 
   //std::cout << texture->getX() << "x" << texture->getY() << " : " << texture->getWidth() << "x" << texture->getHeight() << " " << texture->getTextureId() << std::endl;