windows opengl: Proof-of-concept text rendering.

We don't have a method that would paint a texture with transparency yet.  We
also need to limit the size of the DIBSection exactly to what we are going to
paint, no point in creating a huge bitmap that is mostly empty (but the part
where is the text being drawn).

Change-Id: Ice0bf325743d08e19e636be73cef6aff3cde5704

2 files changed, 64 insertions, 15 deletions

diff --git a/vcl/win/source/gdi/salvd.cxx b/vcl/win/source/gdi/salvd.cxx
index 2269debcd1a8..2b00c0377be3 100644
--- a/vcl/win/source/gdi/salvd.cxx
+++ b/vcl/win/source/gdi/salvd.cxx
@@ -27,14 +27,14 @@
 #include <win/salgdi.h>
 #include <win/salvd.h>
 
-static HBITMAP ImplCreateVirDevBitmap( HDC hDC, long nDX, long nDY,
-                                       sal_uInt16 nBitCount )
+HBITMAP WinSalVirtualDevice::ImplCreateVirDevBitmap(HDC hDC, long nDX, long nDY, sal_uInt16 nBitCount, void **ppData)
 {
     HBITMAP hBitmap;
 
      if ( nBitCount == 1 )
      {
          hBitmap = CreateBitmap( (int)nDX, (int)nDY, 1, 1, NULL );
+         ppData = NULL;
      }
      else
      {
@@ -55,9 +55,8 @@ static HBITMAP ImplCreateVirDevBitmap( HDC hDC, long nDX, long nDY,
          aBitmapInfo.bmiHeader.biClrUsed = 0;
          aBitmapInfo.bmiHeader.biClrImportant = 0;
 
-         void* pDummy;
          hBitmap = CreateDIBSection( hDC, &aBitmapInfo,
-                                     DIB_RGB_COLORS, &pDummy, NULL,
+                                     DIB_RGB_COLORS, ppData, NULL,
                                      0 );
      }
 
@@ -87,8 +86,8 @@ SalVirtualDevice* WinSalInstance::CreateVirtualDevice( SalGraphics* pSGraphics,
         if( !hDC )
             ImplWriteLastError( GetLastError(), "CreateCompatibleDC in CreateVirtualDevice" );
 
-        hBmp    = ImplCreateVirDevBitmap( pGraphics->getHDC(),
-                                        nDX, nDY, nBitCount );
+        void *pDummy;
+        hBmp = WinSalVirtualDevice::ImplCreateVirDevBitmap(pGraphics->getHDC(), nDX, nDY, nBitCount, &pDummy);
         if( !hBmp )
             ImplWriteLastError( GetLastError(), "ImplCreateVirDevBitmap in CreateVirtualDevice" );
         // #124826# continue even if hBmp could not be created
@@ -198,8 +197,8 @@ bool WinSalVirtualDevice::SetSize( long nDX, long nDY )
         return TRUE;    // ???
     else
     {
-        HBITMAP hNewBmp = ImplCreateVirDevBitmap( getHDC(), nDX, nDY,
-                                              mnBitCount );
+        void *pDummy;
+        HBITMAP hNewBmp = ImplCreateVirDevBitmap(getHDC(), nDX, nDY, mnBitCount, &pDummy);
         if ( hNewBmp )
         {
             SelectBitmap( getHDC(), hNewBmp );
diff --git a/vcl/win/source/gdi/winlayout.cxx b/vcl/win/source/gdi/winlayout.cxx
index 4351883cd965..a5945daeb11b 100644
--- a/vcl/win/source/gdi/winlayout.cxx
+++ b/vcl/win/source/gdi/winlayout.cxx
@@ -22,10 +22,12 @@
 #include "osl/module.h"
 #include "osl/file.h"
 
+#include <opengl/texture.hxx>
+#include <opengl/win/gdiimpl.hxx>
 #include <vcl/opengl/OpenGLHelper.hxx>
-
-#include "win/salgdi.h"
-#include "win/saldata.hxx"
+#include <win/salgdi.h>
+#include <win/saldata.hxx>
+#include <win/salvd.h>
 
 #include "sft.hxx"
 #include "sallayout.hxx"
@@ -151,14 +153,62 @@ SCRIPT_CACHE& WinLayout::GetScriptCache() const
 
 void WinLayout::DrawText(SalGraphics& rGraphics) const
 {
-    if (mbUseOpenGL)
+    WinSalGraphics& rWinGraphics = static_cast<WinSalGraphics&>(rGraphics);
+    HDC hDC = rWinGraphics.getHDC();
+
+    if (!mbUseOpenGL)
     {
-        // TODO draw to a texture instead
-        DrawTextImpl(static_cast<WinSalGraphics&>(rGraphics).getHDC());
+        // no OpenGL, just classic rendering
+        DrawTextImpl(hDC);
     }
     else
     {
-        DrawTextImpl(static_cast<WinSalGraphics&>(rGraphics).getHDC());
+        // we have to render the text to a hidden texture, and draw it
+
+        // FIXME so that we don't have to use enormous bitmap, move the text
+        // to 0,0, size the width / height accordingly, and move it back via
+        // SalTwoRects later
+        const int width = 1024;
+        const int height = 1024;
+        const int bpp = 32;
+
+        HDC compatibleDC = CreateCompatibleDC(hDC);
+
+        sal_uInt8 *data;
+        HBITMAP hBitmap = WinSalVirtualDevice::ImplCreateVirDevBitmap(compatibleDC, width, height, bpp, reinterpret_cast<void **>(&data));
+        // FIXME fill transparent instead of 128
+        memset(data, 128, width*height*4);
+
+        // draw the text to the hidden DC
+        HGDIOBJ hBitmapOld = SelectObject(compatibleDC, hBitmap);
+        SelectFont(compatibleDC, mhFont);
+        DrawTextImpl(compatibleDC);
+        SelectObject(compatibleDC, hBitmapOld);
+
+        // and turn it into a texture
+        OpenGLTexture aTexture(width, height, GL_RGBA, GL_UNSIGNED_BYTE, data);
+        CHECK_GL_ERROR();
+
+        WinOpenGLSalGraphicsImpl *pImpl = dynamic_cast<WinOpenGLSalGraphicsImpl*>(rWinGraphics.mpImpl.get());
+        if (pImpl)
+        {
+            SalTwoRect aRects;
+            aRects.mnSrcX = 0;
+            aRects.mnSrcY = 0;
+            aRects.mnSrcWidth = width;
+            aRects.mnSrcHeight = height;
+            aRects.mnDestX = 0;
+            aRects.mnDestY = 0;
+            aRects.mnDestWidth = width;
+            aRects.mnDestHeight = height;
+
+            // FIXME We don't have a method that could paint a texture with
+            // transparency yet, use it when we have it
+            pImpl->DrawTexture(aTexture.Id(), Size(width, height), aRects);
+        }
+
+        DeleteObject(hBitmap);
+        DeleteDC(compatibleDC);
     }
 }