Rotate emoji with FreeType.

src/ports/SkFontHost_FreeType_common.cpp

 /*
  * Copyright 2006-2012 The Android Open Source Project
  * Copyright 2012 Mozilla Foundation
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkBitmap.h"
 #include "SkCanvas.h"
@@ skipping 316 matching lines @@
         case SkMask::kLCD16_Format:
             return kAlpha_8_SkColorType;
         case SkMask::kARGB32_Format:
             return kN32_SkColorType;
         default:
             SkDEBUGFAIL("unsupported destination SkBitmap::Config");
             return kAlpha_8_SkColorType;
     }
 }
 
-void SkScalerContext_FreeType_Base::generateGlyphImage(FT_Face face, const SkGlyph& glyph) {
+void SkScalerContext_FreeType_Base::generateGlyphImage(
+    FT_Face face,
+    const SkGlyph& glyph,
+    const SkMatrix& bitmapTransform)
+{
     const bool doBGR = SkToBool(fRec.fFlags & SkScalerContext::kLCD_BGROrder_Flag);
     const bool doVert = SkToBool(fRec.fFlags & SkScalerContext::kLCD_Vertical_Flag);
 
     switch ( face->glyph->format ) {
         case FT_GLYPH_FORMAT_OUTLINE: {
             FT_Outline* outline = &face->glyph->outline;
             FT_BBox     bbox;
             FT_Bitmap   target;
 
             int dx = 0, dy = 0;
@@ skipping 56 matching lines @@
 
             if (fRec.fFlags & SkScalerContext::kEmbolden_Flag &&
                 !(face->style_flags & FT_STYLE_FLAG_BOLD))
             {
                 FT_GlyphSlot_Own_Bitmap(face->glyph);
                 FT_Bitmap_Embolden(face->glyph->library, &face->glyph->bitmap,
                                    kBitmapEmboldenStrength, 0);
             }
 
             // If no scaling needed, directly copy glyph bitmap.
-            if (glyph.fWidth == face->glyph->bitmap.width &&
-                glyph.fHeight == face->glyph->bitmap.rows &&
-                glyph.fTop == -face->glyph->bitmap_top &&
-                glyph.fLeft == face->glyph->bitmap_left)
-            {
+            if (bitmapTransform.isIdentity()) {
                 SkMask dstMask;
                 glyph.toMask(&dstMask);
                 copyFTBitmap(face->glyph->bitmap, dstMask);
                 break;
             }
 
             // Otherwise, scale the bitmap.
 
             // Copy the FT_Bitmap into an SkBitmap (either A8 or ARGB)
             SkBitmap unscaledBitmap;
@@ skipping 23 matching lines @@
                                                 kPremul_SkAlphaType),
                               bitmapRowBytes);
             if (SkMask::kBW_Format == maskFormat || SkMask::kLCD16_Format == maskFormat) {
                 dstBitmap.allocPixels();
             } else {
                 dstBitmap.setPixels(glyph.fImage);
             }
 
             // Scale unscaledBitmap into dstBitmap.
             SkCanvas canvas(dstBitmap);
+#ifdef SK_SHOW_TEXT_BLIT_COVERAGE
+            canvas.clear(0x33FF0000);
+#else
             canvas.clear(SK_ColorTRANSPARENT);
-            canvas.scale(SkIntToScalar(glyph.fWidth) / SkIntToScalar(face->glyph->bitmap.width),
-                         SkIntToScalar(glyph.fHeight) / SkIntToScalar(face->glyph->bitmap.rows));
+#endif
+            canvas.translate(-glyph.fLeft, -glyph.fTop);
+            canvas.concat(bitmapTransform);

[bungeman-skia, 2016/07/11 22:18:42]

For the no-skew case everything is the same except right here. Now the transform
is directly computed and applied. Before the ratio of the rounded out bounds
were used to back form an approximation of a scale. This accounts for the
changes to existing gms.

+            canvas.translate(face->glyph->bitmap_left, -face->glyph->bitmap_top);
+
             SkPaint paint;
             paint.setFilterQuality(kMedium_SkFilterQuality);
             canvas.drawBitmap(unscaledBitmap, 0, 0, &paint);
 
             // If the destination is BW or LCD, convert from A8.
             if (SkMask::kBW_Format == maskFormat) {
                 // Copy the A8 dstBitmap into the A1 glyph.fImage.
                 SkMask dstMask;
                 glyph.toMask(&dstMask);
                 packA8ToA1(dstMask, dstBitmap.getAddr8(0, 0), dstBitmap.rowBytes());
@@ skipping 81 matching lines @@
 
     FT_Error err = FT_Outline_Decompose(&face->glyph->outline, &funcs, path);
 
     if (err != 0) {
         path->reset();
         return;
     }
 
     path->close();
 }