TextBlob: Use deferred bounds if negative letter or word spacing exists.

Source/platform/fonts/Font.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2000 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2003, 2006, 2010, 2011 Apple Inc. All rights reserved.
  * Copyright (c) 2007, 2008, 2010 Google Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
@@ skipping 241 matching lines @@
     if (cacheEntry && (!fallbackFonts || fallbackFonts->isEmpty())) {
         cacheEntry->glyphBounds = glyphBounds;
         cacheEntry->width = result;
     }
 
     if (glyphOverflow)
         updateGlyphOverflowFromBounds(glyphBounds, fontMetrics(), glyphOverflow);
     return result;
 }
 
+static bool requiresRecomputingBounds(const Font& font)
+{
+    const FontDescription& fontDescription = font.fontDescription();
+    return fontDescription.letterSpacing() < 0 || fontDescription.wordSpacing() < 0;
+}
+
 PassTextBlobPtr Font::buildTextBlob(const GlyphBuffer& glyphBuffer, const FloatRect& bounds,
     bool couldUseLCD) const
 {
     ASSERT(RuntimeEnabledFeatures::textBlobEnabled());
 
     SkTextBlobBuilder builder;
     SkRect skBounds = bounds;
+    // FIXME: Identify these cases earlier on and avoid using bounds that are
+    // not visually correct in other places.
+    const SkRect* skBoundsPtr = requiresRecomputingBounds(*this) ? nullptr : &skBounds;
     bool hasVerticalOffsets = glyphBuffer.hasVerticalOffsets();
 
     unsigned i = 0;
     while (i < glyphBuffer.size()) {
         const SimpleFontData* fontData = glyphBuffer.fontDataAt(i);
 
         // FIXME: Handle vertical text.
         if (fontData->platformData().orientation() == Vertical)
             return nullptr;
 
         // FIXME: FontPlatformData makes some decisions on the device scale
         // factor, which is found via the GraphicsContext. This should be fixed
         // to avoid correctness problems here.
         SkPaint paint;
         fontData->platformData().setupPaint(&paint, 0, this);
         paint.setTextEncoding(SkPaint::kGlyphID_TextEncoding);
 
         // FIXME: this should go away after the big LCD cleanup.
         paint.setLCDRenderText(paint.isLCDRenderText() && couldUseLCD);
 
         unsigned start = i++;
         while (i < glyphBuffer.size() && glyphBuffer.fontDataAt(i) == fontData)
             i++;
         unsigned count = i - start;
 
         const SkTextBlobBuilder::RunBuffer& buffer = hasVerticalOffsets
-            ? builder.allocRunPos(paint, count, &skBounds)
-            : builder.allocRunPosH(paint, count, 0, &skBounds);
+            ? builder.allocRunPos(paint, count, skBoundsPtr)
+            : builder.allocRunPosH(paint, count, 0, skBoundsPtr);
 
         const uint16_t* glyphs = glyphBuffer.glyphs(start);
         const float* offsets = glyphBuffer.offsets(start);
         std::copy(glyphs, glyphs + count, buffer.glyphs);
         std::copy(offsets, offsets + (hasVerticalOffsets ? 2 * count : count), buffer.pos);
     }
 
     return adoptRef(builder.build());
 }
 
@@ skipping 667 matching lines @@
                 if (delta <= 0)
                     break;
             }
         }
     }
 
     return offset;
 }
 
 } // namespace blink