vcl: Read back OpenGL FBO to create offscreen X11 pixmap

Change-Id: I330e7d62bf31b4a90b5866d9531f073f7c69c92a

2 files changed, 45 insertions, 7 deletions

diff --git a/vcl/opengl/gdiimpl.cxx b/vcl/opengl/gdiimpl.cxx
index 72387e22cbc1..65c4f3089017 100644
--- a/vcl/opengl/gdiimpl.cxx
+++ b/vcl/opengl/gdiimpl.cxx
@@ -503,14 +503,23 @@ void OpenGLSalGraphicsImpl::DrawPolyPolygon( const basegfx::B2DPolyPolygon& rPol
     glDisableVertexAttribArray( GL_ATTRIB_POS );
 }
 
-void OpenGLSalGraphicsImpl::DrawTextureRect( const Size& rSize, const SalTwoRect& rPosAry )
+void OpenGLSalGraphicsImpl::DrawTextureRect( const Size& rSize, const SalTwoRect& rPosAry, bool bInverted )
 {
     GLfloat aTexCoord[8];
 
     aTexCoord[0] = aTexCoord[2] = rPosAry.mnSrcX / (double) rSize.Width();
     aTexCoord[4] = aTexCoord[6] = (rPosAry.mnSrcX + rPosAry.mnSrcWidth) / (double) rSize.Width();
-    aTexCoord[3] = aTexCoord[5] = (rSize.Height() - rPosAry.mnSrcY) / (double) rSize.Height();
-    aTexCoord[1] = aTexCoord[7] = (rSize.Height() - rPosAry.mnSrcY - rPosAry.mnSrcHeight) / (double) rSize.Height();
+
+    if( !bInverted )
+    {
+        aTexCoord[3] = aTexCoord[5] = (rSize.Height() - rPosAry.mnSrcY) / (double) rSize.Height();
+        aTexCoord[1] = aTexCoord[7] = (rSize.Height() - rPosAry.mnSrcY - rPosAry.mnSrcHeight) / (double) rSize.Height();
+    }
+    else
+    {
+        aTexCoord[1] = aTexCoord[7] = (rSize.Height() - rPosAry.mnSrcY) / (double) rSize.Height();
+        aTexCoord[3] = aTexCoord[5] = (rSize.Height() - rPosAry.mnSrcY - rPosAry.mnSrcHeight) / (double) rSize.Height();
+    }
 
     glEnableVertexAttribArray( GL_ATTRIB_TEX );
     glVertexAttribPointer( GL_ATTRIB_TEX, 2, GL_FLOAT, GL_FALSE, 0, aTexCoord );
@@ -520,7 +529,7 @@ void OpenGLSalGraphicsImpl::DrawTextureRect( const Size& rSize, const SalTwoRect
     glDisableVertexAttribArray( GL_ATTRIB_TEX );
 }
 
-void OpenGLSalGraphicsImpl::DrawTexture( GLuint nTexture, const Size& rSize, const SalTwoRect& pPosAry )
+void OpenGLSalGraphicsImpl::DrawTexture( GLuint nTexture, const Size& rSize, const SalTwoRect& pPosAry, bool bInverted )
 {
     if( mnTextureProgram == 0 )
     {
@@ -534,7 +543,7 @@ void OpenGLSalGraphicsImpl::DrawTexture( GLuint nTexture, const Size& rSize, con
     CHECK_GL_ERROR();
     glBindTexture( GL_TEXTURE_2D, nTexture );
 
-    DrawTextureRect( rSize, pPosAry );
+    DrawTextureRect( rSize, pPosAry, bInverted );
     CHECK_GL_ERROR();
 
     glBindTexture( GL_TEXTURE_2D, 0 );
diff --git a/vcl/opengl/x11/gdiimpl.cxx b/vcl/opengl/x11/gdiimpl.cxx
index 6e803bd21acd..13b70495341a 100644
--- a/vcl/opengl/x11/gdiimpl.cxx
+++ b/vcl/opengl/x11/gdiimpl.cxx
@@ -83,9 +83,38 @@ X11Pixmap* X11OpenGLSalGraphicsImpl::GetPixmapFromScreen( const Rectangle& rRect
 {
     Display* pDisplay = mrParent.GetXDisplay();
     SalX11Screen nScreen = mrParent.GetScreenNumber();
+    XVisualInfo aVisualInfo;
+    X11Pixmap* pPixmap;
+    XImage* pImage;
+    sal_uInt8* pData;
 
     SAL_INFO( "vcl.opengl", "GetPixmapFromScreen" );
-    return new X11Pixmap( pDisplay, nScreen, rRect.GetWidth(), rRect.GetHeight(), 24 );
+    // TODO: lfrb: Use context depth
+    pPixmap = new X11Pixmap( pDisplay, nScreen, rRect.GetWidth(), rRect.GetHeight(), 24 );
+
+    if( !OpenGLHelper::GetVisualInfo( pDisplay, nScreen.getXScreen(), aVisualInfo ) )
+        return pPixmap;
+
+    // make sure everything is synced up before reading back
+    maContext.makeCurrent();
+    glXWaitX();
+
+    // TODO: lfrb: What if offscreen?
+    pData = new sal_uInt8[rRect.GetWidth() * rRect.GetHeight() * 4];
+    glPixelStorei( GL_PACK_ALIGNMENT, 1 );
+    glReadPixels( rRect.Left(), GetHeight() - rRect.Top(), rRect.GetWidth(), rRect.GetHeight(),
+                  GL_RGBA, GL_UNSIGNED_BYTE, pData );
+
+    pImage = XCreateImage( pDisplay, aVisualInfo.visual, 24, ZPixmap, 0, (char*) pData,
+                           rRect.GetWidth(), rRect.GetHeight(), 8, 0 );
+    XInitImage( pImage );
+    GC aGC = XCreateGC( pDisplay, pPixmap->GetPixmap(), 0, NULL );
+    XPutImage( pDisplay, pPixmap->GetDrawable(), aGC, pImage,
+               0, 0, 0, 0, rRect.GetWidth(), rRect.GetHeight() );
+    XFreeGC( pDisplay, aGC );
+    XDestroyImage( pImage );
+
+    return pPixmap;
 }
 
 bool X11OpenGLSalGraphicsImpl::RenderPixmapToScreen( X11Pixmap* pPixmap, int nX, int nY )
@@ -128,7 +157,7 @@ bool X11OpenGLSalGraphicsImpl::RenderPixmapToScreen( X11Pixmap* pPixmap, int nX,
     glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR );
     glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR );
 
-    DrawTexture( nTexture, pPixmap->GetSize(), aPosAry );
+    DrawTexture( nTexture, pPixmap->GetSize(), aPosAry, !bInverted );
 
     glXReleaseTexImageEXT( pDisplay, pGlxPixmap, GLX_FRONT_LEFT_EXT );
     glDeleteTextures( 1, &nTexture );