Take only the scale params into account to rasterize text

This change extracts the scale parameters of the current transform
to pass then to the font renderer. Rotation and perspective are
applied to the generated mesh inside the vertex shader. This limits
the number of glyphs we have to create in the font cache and thus
reduces memory churn.

Change-Id: Ic5b3bae2b2b0e0250a8ee723b071a1709725c749

1 files changed, 6 insertions, 25 deletions

diff --git a/libs/hwui/font/Font.cpp b/libs/hwui/font/Font.cpp
index bf522b7..9307f11 100644
--- a/libs/hwui/font/Font.cpp
+++ b/libs/hwui/font/Font.cpp
@@ -53,10 +53,8 @@ Font::FontDescription::FontDescription(const SkPaint* paint, const mat4& matrix)
     mStrokeWidth = paint->getStrokeWidth();
     mAntiAliasing = paint->isAntiAlias();
     mLookupTransform.reset();
-    mLookupTransform[SkMatrix::kMScaleX] = matrix.data[mat4::kScaleX];
-    mLookupTransform[SkMatrix::kMScaleY] = matrix.data[mat4::kScaleY];
-    mLookupTransform[SkMatrix::kMSkewX] = matrix.data[mat4::kSkewX];
-    mLookupTransform[SkMatrix::kMSkewY] = matrix.data[mat4::kSkewY];
+    mLookupTransform[SkMatrix::kMScaleX] = matrix[mat4::kScaleX];
+    mLookupTransform[SkMatrix::kMScaleY] = matrix[mat4::kScaleY];
     if (!mLookupTransform.invert(&mInverseLookupTransform)) {
         ALOGW("Could not query the inverse lookup transform for this font");
     }
@@ -81,8 +79,6 @@ hash_t Font::FontDescription::hash() const {
     hash = JenkinsHashMix(hash, int(mAntiAliasing));
     hash = JenkinsHashMix(hash, android::hash_type(mLookupTransform[SkMatrix::kMScaleX]));
     hash = JenkinsHashMix(hash, android::hash_type(mLookupTransform[SkMatrix::kMScaleY]));
-    hash = JenkinsHashMix(hash, android::hash_type(mLookupTransform[SkMatrix::kMSkewX]));
-    hash = JenkinsHashMix(hash, android::hash_type(mLookupTransform[SkMatrix::kMSkewY]));
     return JenkinsHashWhiten(hash);
 }
 
@@ -122,16 +118,6 @@ int Font::FontDescription::compare(const Font::FontDescription& lhs,
     if (lhs.mLookupTransform[SkMatrix::kMScaleY] >
             rhs.mLookupTransform[SkMatrix::kMScaleY]) return +1;
 
-    if (lhs.mLookupTransform[SkMatrix::kMSkewX] <
-            rhs.mLookupTransform[SkMatrix::kMSkewX]) return -1;
-    if (lhs.mLookupTransform[SkMatrix::kMSkewX] >
-            rhs.mLookupTransform[SkMatrix::kMSkewX]) return +1;
-
-    if (lhs.mLookupTransform[SkMatrix::kMSkewY] <
-            rhs.mLookupTransform[SkMatrix::kMSkewY]) return -1;
-    if (lhs.mLookupTransform[SkMatrix::kMSkewY] >
-            rhs.mLookupTransform[SkMatrix::kMSkewY]) return +1;
-
     return 0;
 }
 
@@ -185,7 +171,7 @@ void Font::drawCachedGlyph(CachedGlyphInfo* glyph, int x, int y,
             nPenX, nPenY - height, u1, v1, glyph->mCacheTexture);
 }
 
-void Font::drawCachedGlyphPerspective(CachedGlyphInfo* glyph, int x, int y,
+void Font::drawCachedGlyphTransformed(CachedGlyphInfo* glyph, int x, int y,
         uint8_t* bitmap, uint32_t bitmapW, uint32_t bitmapH, Rect* bounds, const float* pos) {
     SkPoint p[4];
     p[0].iset(glyph->mBitmapLeft, glyph->mBitmapTop + glyph->mBitmapHeight);
@@ -388,18 +374,17 @@ void Font::render(SkPaint* paint, const char* text, uint32_t start, uint32_t len
 
     static RenderGlyph gRenderGlyph[] = {
             &android::uirenderer::Font::drawCachedGlyph,
-            &android::uirenderer::Font::drawCachedGlyphPerspective,
+            &android::uirenderer::Font::drawCachedGlyphTransformed,
             &android::uirenderer::Font::drawCachedGlyphBitmap,
             &android::uirenderer::Font::drawCachedGlyphBitmap,
             &android::uirenderer::Font::measureCachedGlyph,
             &android::uirenderer::Font::measureCachedGlyph
     };
-    RenderGlyph render = gRenderGlyph[(mode << 1) + mTransform.isPerspective()];
+    RenderGlyph render = gRenderGlyph[(mode << 1) + !mIdentityTransform];
 
     text += start;
     int glyphsCount = 0;
 
-    const bool applyTransform = !mTransform.isIdentity() && !mTransform.isPerspective();
     const SkPaint::Align align = paint->getTextAlign();
 
     while (glyphsCount < numGlyphs) {
@@ -418,10 +403,6 @@ void Font::render(SkPaint* paint, const char* text, uint32_t start, uint32_t len
             float penX = x + positions[(glyphsCount << 1)];
             float penY = y + positions[(glyphsCount << 1) + 1];
 
-            if (applyTransform) {
-                mTransform.mapPoint(penX, penY);
-            }
-
             (*this.*render)(cachedGlyph, roundf(penX), roundf(penY),
                     bitmap, bitmapW, bitmapH, bounds, positions);
         }
@@ -495,7 +476,7 @@ Font* Font::create(FontRenderer* state, const SkPaint* paint, const mat4& matrix
         font = new Font(state, description);
         state->mActiveFonts.put(description, font);
     }
-    font->mTransform.load(matrix);
+    font->mIdentityTransform = matrix.isIdentity();
 
     return font;
 }