Still more hacking on OpenGL glyph caching for Windows

Show the whole height of the cache bitmap after all (when SAL_LOG
contains vcl.gdi.opengl). The interesting pieces are often at the
bottom, like the tip of the hook of the "j" glyphs that used to bleed
over into the preceding glyphs, usually "i", when they were rendered
into the same chunk.

Add more space between glyphs and at top and bottom of the bitmap, for
anti-aliasing. The glyph ABC widths don't take expansions caused by
anti-aliasing into consideration and are misleading. Hopefully
anti-aliasing can expand the (partially) painted pixels of a glyph
just one column/row in each direction, but for safety use a two-pixel
border. (Defensive programming, eek?)

Some getWidth() instead of GetWidth() etc craziness. Using
<tools/gen.hxx> types truly is programming-by-coincidence as Thorsten
says.

In a dbgutil build, setting the environment variable
VCL_GLYPH_CACHING_HACK_NO_ANTIALIAS causes the code to turn off
anti-aliasing for the fonts used. I used this to verify that it indeed
was anti-aliasing that made the ABC widths inconsistent with
reality. Not sure if it makes sense to keep this code in?

Anyway, now I don't see any leaked pixels in "i" glyphs any more,
touch wood.

Change-Id: If527343ff1dcdb1fa208cd5e7fa4d08f812d0d7b

1 files changed, 45 insertions, 10 deletions

diff --git a/vcl/win/source/gdi/winlayout.cxx b/vcl/win/source/gdi/winlayout.cxx
index 540a76bd7979..c1c2d7e65d34 100644
--- a/vcl/win/source/gdi/winlayout.cxx
+++ b/vcl/win/source/gdi/winlayout.cxx
@@ -147,7 +147,7 @@ OUString DumpGlyphBitmap(OpenGLGlyphCacheChunk& rChunk, HDC hDC)
     }
     std::cerr << std::endl;
 
-    for (long y = 0; y < std::min(20l, aBitmap.bmHeight); y++)
+    for (long y = 0; y < aBitmap.bmHeight; y++)
     {
         for (long x = 0; x < std::min(75l, aBitmap.bmWidth); x++)
             std::cerr << ColorFor(GetPixel(hDC, x, y));
@@ -279,7 +279,10 @@ bool ImplWinFontEntry::AddChunkOfGlyphs(int nGlyphIndex, const WinLayout& rLayou
         std::cerr << aABC[i].abcA << ":" << aABC[i].abcB << ":" << aABC[i].abcC << " ";
     std::cerr << std::endl;
 
-    // Avoid kerning as we want to be able to use individual rectangles for each glyph
+    // Try hard to avoid overlap as we want to be able to use
+    // individual rectangles for each glyph. The ABC widths don't
+    // take anti-alising into consideration. Let's hope that leaving
+    // four pixels of "extra" space inbetween glyphs will help.
     std::vector<int> aDX(nCount);
     int totWidth = 0;
     for (int i = 0; i < nCount; i++)
@@ -289,6 +292,7 @@ bool ImplWinFontEntry::AddChunkOfGlyphs(int nGlyphIndex, const WinLayout& rLayou
             aDX[0] += std::abs(aABC[0].abcA);
         if (i < nCount-1)
             aDX[i] += std::abs(aABC[i+1].abcA);
+        aDX[i] += 4;
         totWidth += aDX[i];
     }
 
@@ -299,9 +303,32 @@ bool ImplWinFontEntry::AddChunkOfGlyphs(int nGlyphIndex, const WinLayout& rLayou
     if (!DeleteDC(hDC))
         SAL_WARN("vcl.gdi", "DeleteDC failed: " << WindowsErrorString(GetLastError()));
 
-    OpenGLCompatibleDC aDC(rGraphics, 0, 0, totWidth, aSize.cy);
+    // Leave two pixels of extra space also at top and bottom
+    OpenGLCompatibleDC aDC(rGraphics, 0, 0, totWidth, aSize.cy + 4);
 
-    hOrigFont = SelectFont(aDC.getCompatibleHDC(), rLayout.mhFont);
+    HFONT hNonAntialiasedFont = NULL;
+
+#ifdef DBG_UTIL
+    static bool bNoAntialias = (std::getenv("VCL_GLYPH_CACHING_HACK_NO_ANTIALIAS") != NULL);
+    if (bNoAntialias)
+    {
+        LOGFONTW aLogfont;
+        if (!GetObjectW(rLayout.mhFont, sizeof(aLogfont), &aLogfont))
+        {
+            SAL_WARN("vcl.gdi", "GetObject failed: " << WindowsErrorString(GetLastError()));
+            return false;
+        }
+        aLogfont.lfQuality = NONANTIALIASED_QUALITY;
+        hNonAntialiasedFont = CreateFontIndirectW(&aLogfont);
+        if (hNonAntialiasedFont == NULL)
+        {
+            SAL_WARN("vcl.gdi", "CreateFontIndirect failed: " << WindowsErrorString(GetLastError()));
+            return false;
+        }
+    }
+#endif
+
+    hOrigFont = SelectFont(aDC.getCompatibleHDC(), hNonAntialiasedFont != NULL ? hNonAntialiasedFont : rLayout.mhFont);
     if (hOrigFont == NULL)
     {
         SAL_WARN("vcl.gdi", "SelectObject failed: " << WindowsErrorString(GetLastError()));
@@ -311,9 +338,15 @@ bool ImplWinFontEntry::AddChunkOfGlyphs(int nGlyphIndex, const WinLayout& rLayou
     SetTextColor(aDC.getCompatibleHDC(), RGB(0, 0, 0));
     SetBkColor(aDC.getCompatibleHDC(), RGB(255, 255, 255));
 
-    if (!ExtTextOutW(aDC.getCompatibleHDC(), 0, 0, ETO_GLYPH_INDEX, NULL, aGlyphIndices.data(), nCount, aDX.data()))
+    aDC.fill(MAKE_SALCOLOR(0xff, 0xff, 0xff));
+
+    // The 2,2 is for the extra space
+    if (!ExtTextOutW(aDC.getCompatibleHDC(), 2, 2, ETO_GLYPH_INDEX, NULL, aGlyphIndices.data(), nCount, aDX.data()))
     {
         SAL_WARN("vcl.gdi", "ExtTextOutW failed: " << WindowsErrorString(GetLastError()));
+        SelectFont(aDC.getCompatibleHDC(), hOrigFont);
+        if (hNonAntialiasedFont != NULL)
+            DeleteObject(hNonAntialiasedFont);
         return false;
     }
 
@@ -325,7 +358,7 @@ bool ImplWinFontEntry::AddChunkOfGlyphs(int nGlyphIndex, const WinLayout& rLayou
         aChunk.maLocation[i].Right() = nPos + aDX[i];
         nPos = aChunk.maLocation[i].Right();
         aChunk.maLocation[i].Top() = 0;
-        aChunk.maLocation[i].Bottom() = aSize.cy;
+        aChunk.maLocation[i].Bottom() = aSize.cy + 4;
     }
 
     aChunk.mpTexture = std::unique_ptr<OpenGLTexture>(aDC.getTexture());
@@ -333,6 +366,8 @@ bool ImplWinFontEntry::AddChunkOfGlyphs(int nGlyphIndex, const WinLayout& rLayou
     maOpenGLGlyphCache.insert(n, aChunk);
 
     SelectFont(aDC.getCompatibleHDC(), hOrigFont);
+    if (hNonAntialiasedFont != NULL)
+        DeleteObject(hNonAntialiasedFont);
 
     SAL_INFO("vcl.gdi.opengl", "this=" << this << " now: " << maOpenGLGlyphCache << DumpGlyphBitmap(aChunk, aDC.getCompatibleHDC()));
 
@@ -1562,7 +1597,7 @@ void UniscribeLayout::DrawTextImpl(HDC hDC) const
 
 bool UniscribeLayout::CacheGlyphs(SalGraphics& rGraphics) const
 {
-    const bool bDoGlyphCaching = (std::getenv("SAL_ENABLE_GLYPH_CACHING") != NULL);
+    static bool bDoGlyphCaching = (std::getenv("SAL_ENABLE_GLYPH_CACHING") != NULL);
 
     if (!bDoGlyphCaching)
         return false;
@@ -1639,9 +1674,9 @@ bool UniscribeLayout::DrawCachedGlyphs(SalGraphics& rGraphics) const
             const int n = mpOutGlyphs[i] - rChunk.mnFirstGlyph;
 
             SalTwoRect a2Rects(rChunk.maLocation[n].Left(), rChunk.maLocation[n].Top(),
-                               rChunk.maLocation[n].GetWidth(), rChunk.maLocation[n].GetHeight(),
-                               nAdvance + aPos.X() + mpGlyphOffsets[i].du, aPos.Y() + mpGlyphOffsets[i].dv - rChunk.maLocation[n].GetHeight(),
-                               rChunk.maLocation[n].GetWidth(), rChunk.maLocation[n].GetHeight()); // ???
+                               rChunk.maLocation[n].getWidth(), rChunk.maLocation[n].getHeight(),
+                               nAdvance + aPos.X() + mpGlyphOffsets[i].du, aPos.Y() + mpGlyphOffsets[i].dv - rChunk.maLocation[n].getHeight(),
+                               rChunk.maLocation[n].getWidth(), rChunk.maLocation[n].getHeight()); // ???
             pImpl->DrawMask(*rChunk.mpTexture, salColor, a2Rects);
             nAdvance += mpGlyphAdvances[i];
         }