Stage #3 - first cut at flushing the whole buffer across ...

vcl/inc/openglgdiimpl.hxx

@@ -160,6 +160,9 @@ protected:
     /// retrieve the default context for offscreen rendering
     static rtl::Reference<OpenGLContext> GetDefaultContext();
 
+    /// flush contents of the back-buffer to the screen & swap.
+    void FlushAndSwap();
+
     /// create a new context for rendering to the underlying window
     virtual rtl::Reference<OpenGLContext> CreateWinContext() = 0;
 
@@ -346,6 +349,7 @@ public:
     virtual bool drawGradient(const tools::PolyPolygon& rPolygon, const Gradient& rGradient) override;
 
     virtual OpenGLContext *beginPaint() override;
+    virtual void           endPaint() override;
 private:
 };
 

vcl/inc/salgdi.hxx

@@ -439,6 +439,7 @@ public:
                                     const OutputDevice *pOutDev );
 
     virtual OpenGLContext      *BeginPaint() { return nullptr; }
+    virtual void                EndPaint()   { }
 
     virtual SystemGraphicsData  GetGraphicsData() const = 0;
 

vcl/inc/salgdiimpl.hxx

@@ -213,6 +213,7 @@ public:
     virtual bool drawGradient(const tools::PolyPolygon& rPolygon, const Gradient& rGradient) = 0;
 
     virtual OpenGLContext *beginPaint() { return nullptr; }
+    virtual OpenGLContext *endPaint()   { }
 };
 
 #endif

vcl/opengl/gdiimpl.cxx

@@ -133,6 +133,10 @@ void OpenGLSalGraphicsImpl::Init()
         }
         maOffscreenTex = OpenGLTexture();
     }
+
+    if( mpWindowContext.is() )
+        mpWindowContext.reset();
+    mpWindowContext = CreateWinContext();
 }
 
 // Currently only used to get windows ordering right.
@@ -172,12 +176,6 @@ void OpenGLSalGraphicsImpl::PreDraw()
 
 void OpenGLSalGraphicsImpl::PostDraw()
 {
-    if( mpContext->mnPainting == 0 )
-    {
-        if (!IsOffscreen()) ...
-#warning "Trigger re-rendering of the window if we have one"
-        glFlush();
-    }
     if( mbUseScissor )
         glDisable( GL_SCISSOR_TEST );
     if( mbUseStencil )
@@ -191,6 +189,15 @@ void OpenGLSalGraphicsImpl::PostDraw()
 #endif
     }
 
+    if( mpContext->mnPainting == 0 )
+    {
+        if (!IsOffscreen())
+        {
+            SAL_DEBUG("PostDraw flush ?");
+            FlushAndSwap();
+        }
+    }
+
     CHECK_GL_ERROR();
     OpenGLZone::leave();
 }
@@ -1848,10 +1855,76 @@ bool OpenGLSalGraphicsImpl::drawGradient(const tools::PolyPolygon& rPolyPoly,
 
 OpenGLContext *OpenGLSalGraphicsImpl::beginPaint()
 {
+    SAL_DEBUG( "want to rid ourselves of this method" );
     AcquireContext();
     return mpContext.get();
 }
 
+void OpenGLSalGraphicsImpl::FlushAndSwap()
+{
+    assert( !IsOffscreen() );
+    assert( mpContext.is() );
+
+    OpenGLZone aZone;
+
+//    glFlush(); - not needed
+    mpWindowContext->makeCurrent();
+    CHECK_GL_ERROR();
+
+    mpWindowContext->AcquireDefaultFramebuffer();
+    CHECK_GL_ERROR();
+
+    glViewport( 0, 0, GetWidth(), GetHeight() );
+    ImplInitClipRegion();
+    CHECK_GL_ERROR();
+
+    SalTwoRect aPosAry(0, 0, maOffscreenTex.GetWidth(), maOffscreenTex.GetHeight(),
+                       0, 0, maOffscreenTex.GetWidth(), maOffscreenTex.GetHeight());
+
+    OpenGLProgram *pProgram =
+        mpContext->UseProgram( "textureVertexShader", "textureFragmentShader", "" );
+
+    pProgram->SetTexture( "sampler", maOffscreenTex );
+
+    GLfloat aTexCoord[8];
+    maOffscreenTex.GetCoord( aTexCoord, rPosAry, false );
+    pProgram->SetTextureCoord( aTexCoord );
+
+    long nX1( rPosAry.mnDestX );
+    long nY1( rPosAry.mnDestY );
+    long nX2( nX1 + rPosAry.mnDestWidth );
+    long nY2( nY1 + rPosAry.mnDestHeight );
+    const SalPoint aPoints[] = { { nX1, nY2 }, { nX1, nY1 },
+                                 { nX2, nY1 }, { nX2, nY2 }};
+
+    std::vector<GLfloat> aVertices(nPoints * 2);
+    sal_uInt32 i, j;
+
+    for( i = 0, j = 0; i < 4; i++, j += 2 )
+    {
+        aVertices[j]   = GLfloat(aPoints[i].mnX);
+        aVertices[j+1] = GLfloat(aPoints[i].mnY);
+    }
+
+    pProgram->ApplyMatrix(GetWidth(), GetHeight(), 0.0);
+    pProgram->SetVertices( &aVertices[0] );
+    glDrawArrays( GL_TRIANGLE_FAN, 0, nPoints );
+
+    pProgram->Clean();
+
+    mpContext->swapBuffers();
+}
+
+void OpenGLSalGraphicsImpl::endPaint()
+{
+    assert( !IsOffscreen() );
+
+    AcquireContext();
+    if( mpContext.is() &&
+        mpContext->mnPainting == 0 )
+        FlushAndSwap();
+}
+
 bool OpenGLSalGraphicsImpl::IsForeignContext(const rtl::Reference<OpenGLContext> &xContext)
 {
     // so far a blunt heuristic: vcl uses shiny new contexts.

vcl/source/opengl/OpenGLHelper.cxx

@@ -1086,13 +1086,15 @@ OutputDevice::PaintScope::PaintScope(OutputDevice *pDev)
     if( pDev->mpGraphics || pDev->AcquireGraphics() )
     {
         OpenGLContext *pContext = pDev->mpGraphics->BeginPaint();
+/*
         if( pContext )
         {
             assert( pContext->mnPainting >= 0 );
             pContext->mnPainting++;
             pContext->acquire();
             pHandle = static_cast<void *>( pContext );
         }
+*/
     }
 }
 
@@ -1101,6 +1103,10 @@ OutputDevice::PaintScope::PaintScope(OutputDevice *pDev)
  */
 void OutputDevice::PaintScope::flush()
 {
+    if( pDev->mpGraphics || pDev->AcquireGraphics() )
+        pDev->mpGraphics->EndPaint();
+
+#if 0
     if( pHandle )
     {
         OpenGLContext *pContext = static_cast<OpenGLContext *>( pHandle );
@@ -1117,6 +1123,7 @@ void OutputDevice::PaintScope::flush()
         }
         pContext->release();
     }
+#endif
 }
 
 OutputDevice::PaintScope::~PaintScope()