vcl: opengl - Kill the last glErrors on common paths.

Re-work the makeSomeOpenGLContextCurrent logic into a shared function
with the existing AcquireContext logic in the SalOpenGLGraphics impl.
Use an OpenGLVCLContextZone placeholder to do both context and zone
management - to include destructors into the zone.

Fix a number of error cases around SalBitmaps where we did not have
a GL context associated when allocating, and/or freeing textures..

Don't drag a (potentially) slower context around in the
OpenGLSalBitmap when we're going to check / fetch a better VCL
context anyway.

Change-Id: Ibbb2358c47156cd078ad28b6aad4f03af36aaf23
Reviewed-on: https://gerrit.libreoffice.org/21127
Reviewed-by: Michael Meeks <michael.meeks@collabora.com>
Tested-by: Michael Meeks <michael.meeks@collabora.com>

3 files changed, 11 insertions, 8 deletions

diff --git a/vcl/inc/opengl/salbmp.hxx b/vcl/inc/opengl/salbmp.hxx
index e9fd6f776719..19dfa3cf4339 100644
--- a/vcl/inc/opengl/salbmp.hxx
+++ b/vcl/inc/opengl/salbmp.hxx
@@ -37,7 +37,6 @@ class   BitmapPalette;
 class VCL_PLUGIN_PUBLIC OpenGLSalBitmap : public SalBitmap
 {
 private:
-    rtl::Reference<OpenGLContext>       mpContext;
     OpenGLTexture                       maTexture;
     bool                                mbDirtyTexture;
     BitmapPalette                       maPalette;
@@ -50,7 +49,6 @@ private:
     int                                 mnBufHeight;
     std::deque< OpenGLSalBitmapOp* >    maPendingOps;
 
-    void makeSomeOpenGLContextCurrent();
     virtual void updateChecksum() const override;
 
     bool calcChecksumGL(OpenGLTexture& rInputTexture, ChecksumType& rChecksum) const;
@@ -98,10 +96,11 @@ private:
 
 private:
 
-    bool ImplScaleFilter( const double& rScaleX, const double& rScaleY, GLenum nFilter );
+    bool ImplScaleFilter( const rtl::Reference< OpenGLContext > &xContext, const double& rScaleX, const double& rScaleY, GLenum nFilter );
     static void ImplCreateKernel( const double& fScale, const vcl::Kernel& rKernel, GLfloat*& pWeights, sal_uInt32& aKernelSize );
-    bool ImplScaleConvolution(const double& rScaleX, const double& rScaleY, const vcl::Kernel& rKernel);
-    bool ImplScaleArea( double rScaleX, double rScaleY );
+    bool ImplScaleConvolution(const rtl::Reference< OpenGLContext > &xContext, const double& rScaleX, const double& rScaleY, const vcl::Kernel& rKernel);
+    bool ImplScaleArea( const rtl::Reference< OpenGLContext > &xContext,
+                        double rScaleX, double rScaleY );
 
 public:
 
diff --git a/vcl/inc/opengl/zone.hxx b/vcl/inc/opengl/zone.hxx
index 44265c526693..c6ba0ccc7487 100644
--- a/vcl/inc/opengl/zone.hxx
+++ b/vcl/inc/opengl/zone.hxx
@@ -40,6 +40,13 @@ public:
     static void hardDisable();
 };
 
+/// Create this to not only enter the zone, but set VCL context.
+class OpenGLVCLContextZone {
+    OpenGLZone aZone;
+public:
+    OpenGLVCLContextZone();
+};
+
 #endif // INCLUDED_VCL_INC_OPENGL_ZONE_H
 
 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */
diff --git a/vcl/inc/openglgdiimpl.hxx b/vcl/inc/openglgdiimpl.hxx
index 63bebdcc991d..0220758e1fbd 100644
--- a/vcl/inc/openglgdiimpl.hxx
+++ b/vcl/inc/openglgdiimpl.hxx
@@ -162,9 +162,6 @@ protected:
     bool AcquireContext(bool bForceCreate = false);
     bool ReleaseContext();
 
-    /// retrieve the default context for offscreen rendering
-    static rtl::Reference<OpenGLContext> GetDefaultContext();
-
     /// create a new context for rendering to the underlying window
     virtual rtl::Reference<OpenGLContext> CreateWinContext() = 0;