opengl: when scaling, create a new texture with equal settings

Change-Id: Id0258fe0db89aa06b91233ae2052f018d606cc74
(cherry picked from commit 6d9ddfb9)
Reviewed-on: https://gerrit.libreoffice.org/17558Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Miklos Vajna <vmiklos@collabora.co.uk>

vcl/inc/opengl/salbmp.hxx

@@ -106,6 +106,8 @@ private:
     bool ImplScaleConvolution( const double& rScaleX, const double& rScaleY, const Kernel& aKernel );
     bool ImplScaleArea( double rScaleX, double rScaleY );
 
+    bool getFormatAndType(GLenum& nFormat, GLenum& nType);
+
 public:
 
     bool ImplScale( const double& rScaleX, const double& rScaleY, BmpScaleFlag nScaleFlag );

vcl/opengl/scale.cxx

@@ -43,6 +43,31 @@ public:
     void GetSize( Size& rSize ) const SAL_OVERRIDE;
 };
 
+bool OpenGLSalBitmap::getFormatAndType(GLenum& nFormat, GLenum& nType)
+{
+    switch(mnBits)
+    {
+    case  8:
+        nFormat = GL_LUMINANCE;
+        nType = GL_UNSIGNED_BYTE;
+        break;
+    case 16:
+        nFormat = GL_RGB;
+        nType = GL_UNSIGNED_SHORT_5_6_5;
+        break;
+    case 24:
+        nFormat = GL_RGB;
+        nType = GL_UNSIGNED_BYTE;
+        break;
+    case 32:
+    default:
+        nFormat = GL_RGBA;
+        nType = GL_UNSIGNED_BYTE;
+        break;
+    }
+    return true;
+}
+
 bool OpenGLSalBitmap::ImplScaleFilter(
     const double& rScaleX,
     const double& rScaleY,
@@ -59,7 +84,11 @@ bool OpenGLSalBitmap::ImplScaleFilter(
     if( !pProgram )
         return false;
 
-    OpenGLTexture aNewTex = OpenGLTexture( nNewWidth, nNewHeight );
+    GLenum nFormat;
+    GLenum nType;
+    getFormatAndType(nFormat, nType);
+
+    OpenGLTexture aNewTex = OpenGLTexture(nNewWidth, nNewHeight, nFormat, nType, nullptr);
     pFramebuffer = mpContext->AcquireFramebuffer( aNewTex );
 
     pProgram->SetTexture( "sampler", maTexture );
@@ -138,10 +167,15 @@ bool OpenGLSalBitmap::ImplScaleConvolution(
     if( pProgram == 0 )
         return false;
 
+    GLenum nFormat;
+    GLenum nType;
+    getFormatAndType(nFormat, nType);
+
     // horizontal scaling in scratch texture
     if( mnWidth != nNewWidth )
     {
-        OpenGLTexture aScratchTex = OpenGLTexture( nNewWidth, mnHeight );
+        OpenGLTexture aScratchTex = OpenGLTexture(nNewWidth, mnHeight, nFormat, nType, nullptr);
+
         pFramebuffer = mpContext->AcquireFramebuffer( aScratchTex );
 
         for( sal_uInt32 i = 0; i < 16; i++ )
@@ -163,7 +197,8 @@ bool OpenGLSalBitmap::ImplScaleConvolution(
     // vertical scaling in final texture
     if( mnHeight != nNewHeight )
     {
-        OpenGLTexture aScratchTex = OpenGLTexture( nNewWidth, nNewHeight );
+        OpenGLTexture aScratchTex = OpenGLTexture(nNewWidth, nNewHeight, nFormat, nType, nullptr);
+
         pFramebuffer = mpContext->AcquireFramebuffer( aScratchTex );
 
         for( sal_uInt32 i = 0; i < 16; i++ )
@@ -223,7 +258,12 @@ bool OpenGLSalBitmap::ImplScaleArea( double rScaleX, double rScaleY )
     if( pProgram == 0 )
         return false;
 
-    OpenGLTexture aScratchTex = OpenGLTexture( nNewWidth, nNewHeight );
+    GLenum nFormat;
+    GLenum nType;
+    getFormatAndType(nFormat, nType);
+
+    OpenGLTexture aScratchTex = OpenGLTexture(nNewWidth, nNewHeight, nFormat, nType, nullptr);
+
     OpenGLFramebuffer* pFramebuffer = mpContext->AcquireFramebuffer( aScratchTex );
 
     // NOTE: This setup is also done in OpenGLSalGraphicsImpl::DrawTransformedTexture().
@@ -325,7 +365,9 @@ void ScaleOp::GetSize( Size& rSize ) const
 
 bool OpenGLSalBitmap::Scale( const double& rScaleX, const double& rScaleY, BmpScaleFlag nScaleFlag )
 {
-    SAL_INFO( "vcl.opengl", "::Scale " << static_cast<int>(nScaleFlag) );
+    SAL_INFO("vcl.opengl", "::Scale " << int(nScaleFlag)
+             << " from " << mnWidth << "x" << mnHeight
+             << " to " << (mnWidth * rScaleX) << "x" << (mnHeight * rScaleY) );
 
     if( nScaleFlag == BmpScaleFlag::Fast ||
         nScaleFlag == BmpScaleFlag::BiLinear ||