tdf#118107 canvas opengl: avoid assertion failure with negative widths

In case an Impress shape has a "Fade in and Swivel" animation attached,
canvas calls OutputDevice::DrawBitmapEx() with a negative width. This
results in a call to OutputDevice::DrawDeviceAlphaBitmap(), which
asserts that the height/width is not negative.

Fix the problem by transforming the bitmap before calling
OutputDevice::DrawBitmapEx() in the GL case, similarly to how "complex"
transformations are handled already.

Change-Id: I65ccc8a984132c5921d6096bfe9c7a8fcfacd8dd
Reviewed-on: https://gerrit.libreoffice.org/57774Reviewed-by: Miklos Vajna <vmiklos@collabora.co.uk>
Tested-by: Jenkins

canvas/Library_vclcanvas.mk

@@ -21,7 +21,10 @@ $(eval $(call gb_Library_Library,vclcanvas))
 
 $(eval $(call gb_Library_set_componentfile,vclcanvas,canvas/source/vcl/vclcanvas))
 
-$(eval $(call gb_Library_use_external,vclcanvas,boost_headers))
+$(eval $(call gb_Library_use_externals,vclcanvas,\
+	boost_headers \
+	epoxy \
+))
 
 $(eval $(call gb_Library_use_sdk_api,vclcanvas))
 

canvas/source/vcl/spritehelper.cxx

@@ -38,6 +38,7 @@
 #include <vcl/canvastools.hxx>
 #include <vcl/outdev.hxx>
 #include <vcl/BitmapMonochromeFilter.hxx>
+#include <vcl/opengl/OpenGLHelper.hxx>
 
 #include <canvas/canvastools.hxx>
 
@@ -183,8 +184,11 @@ namespace vclcanvas
 
             if( !bIdentityTransform )
             {
+                // Avoid the trick with the negative width in the OpenGL case,
+                // OutputDevice::DrawDeviceAlphaBitmap() doesn't like it.
                 if( !::basegfx::fTools::equalZero( aTransform.get(0,1) ) ||
-                    !::basegfx::fTools::equalZero( aTransform.get(1,0) ) )
+                    !::basegfx::fTools::equalZero( aTransform.get(1,0) ) ||
+                    OpenGLHelper::isVCLOpenGLEnabled())
                 {
                     // "complex" transformation, employ affine
                     // transformator