Various fixes for scaled emojis

Bug: skia:7562
Change-Id: I66cf290ca4541ceae7ee1009a1524046a2c5893e
Reviewed-on: https://skia-review.googlesource.com/111481
Commit-Queue: Jim Van Verth <jvanverth@google.com>
Reviewed-by: Robert Phillips <robertphillips@google.com>

3 files changed, 79 insertions, 16 deletions

diff --git a/gm/scaledemoji.cpp b/gm/scaledemoji.cpp
index c4a4c34499..ac8b3c6d51 100644
--- a/gm/scaledemoji.cpp
+++ b/gm/scaledemoji.cpp
@@ -61,11 +61,75 @@ protected:
 
     }
 
+private:
+    typedef GM INHERITED;
+};
+
+class ScaledEmojiPosGM : public GM {
+public:
+    ScaledEmojiPosGM() {}
+
+protected:
+    struct EmojiFont {
+        sk_sp<SkTypeface> fTypeface;
+        const char* fText;
+    } fEmojiFont;
+
+    void onOnceBeforeDraw() override {
+        fEmojiFont.fTypeface = sk_tool_utils::emoji_typeface();
+        fEmojiFont.fText = sk_tool_utils::emoji_sample_text();
+    }
+
+    SkString onShortName() override {
+        SkString name("scaledemojipos");
+        name.append(sk_tool_utils::platform_font_manager());
+        return name;
+    }
+
+    SkISize onISize() override { return SkISize::Make(1200, 1200); }
+
+    void onDraw(SkCanvas* canvas) override {
+
+        canvas->drawColor(sk_tool_utils::color_to_565(SK_ColorGRAY));
+
+        SkPaint paint;
+        paint.setTypeface(fEmojiFont.fTypeface);
+        const char* text = fEmojiFont.fText;
+
+        // draw text at different point sizes
+        // Testing GPU bitmap path, SDF path with no scaling,
+        // SDF path with scaling, path rendering with scaling
+        SkPaint::FontMetrics metrics;
+        SkScalar y = 0;
+        for (SkScalar textSize : { 70, 180, 270, 340 }) {
+            paint.setTextSize(textSize);
+            paint.getFontMetrics(&metrics);
+            y += -metrics.fAscent;
+
+            int len = SkToInt(strlen(text));
+            SkAutoTArray<SkPoint>  pos(len);
+            SkAutoTArray<SkScalar> widths(len);
+            paint.getTextWidths(text, len, &widths[0]);
+
+            SkScalar x = SkIntToScalar(10);
+            for (int i = 0; i < len; ++i) {
+                pos[i].set(x, y);
+                x += widths[i];
+            }
+
+            canvas->drawPosText(text, len, &pos[0], paint);
+            y += metrics.fDescent + metrics.fLeading;
+        }
+
+    }
+
+private:
     typedef GM INHERITED;
 };
 
 //////////////////////////////////////////////////////////////////////////////
 
 DEF_GM(return new ScaledEmojiGM;)
+DEF_GM(return new ScaledEmojiPosGM;)
 
 }
diff --git a/src/gpu/text/GrAtlasTextContext.cpp b/src/gpu/text/GrAtlasTextContext.cpp
index ce1b52e0cd..5ac683e6f3 100644
--- a/src/gpu/text/GrAtlasTextContext.cpp
+++ b/src/gpu/text/GrAtlasTextContext.cpp
@@ -459,9 +459,7 @@ void GrAtlasTextContext::DrawBmpTextAsPaths(GrAtlasTextBlob* blob, int runIndex,
     pathPaint.setPathEffect(nullptr);
 
     GrTextUtils::PathTextIter iter(text, byteLength, pathPaint, true);
-    FallbackTextHelper fallbackTextHelper(viewMatrix, pathPaint.getTextSize(),
-                                          glyphCache->getGlyphSizeLimit(),
-                                          iter.getPathScale());
+    FallbackTextHelper fallbackTextHelper(viewMatrix, pathPaint, glyphCache, iter.getPathScale());
 
     const SkGlyph* iterGlyph;
     const SkPath* iterPath;
@@ -499,8 +497,7 @@ void GrAtlasTextContext::DrawBmpPosTextAsPaths(GrAtlasTextBlob* blob, int runInd
     // setup our std paint, in hopes of getting hits in the cache
     SkPaint pathPaint(origPaint);
     SkScalar matrixScale = pathPaint.setupForAsPaths();
-    FallbackTextHelper fallbackTextHelper(viewMatrix, pathPaint.getTextSize(), matrixScale,
-                                          glyphCache->getGlyphSizeLimit());
+    FallbackTextHelper fallbackTextHelper(viewMatrix, origPaint, glyphCache, matrixScale);
 
     // Temporarily jam in kFill, so we only ever ask for the raw outline from the cache.
     pathPaint.setStyle(SkPaint::kFill_Style);
@@ -773,10 +770,7 @@ void GrAtlasTextContext::drawDFPosText(GrAtlasTextBlob* blob, int runIndex,
     blob->setSubRunHasDistanceFields(runIndex, paint.skPaint().isLCDRenderText(),
                                      paint.skPaint().isAntiAlias(), hasWCoord);
 
-    FallbackTextHelper fallbackTextHelper(viewMatrix,
-                                          paint.skPaint().getTextSize(),
-                                          glyphCache->getGlyphSizeLimit(),
-                                          textRatio);
+    FallbackTextHelper fallbackTextHelper(viewMatrix, paint, glyphCache, textRatio);
 
     sk_sp<GrTextStrike> currStrike;
 
@@ -867,7 +861,12 @@ void GrAtlasTextContext::FallbackTextHelper::appendText(const SkGlyph& glyph, in
 
     fFallbackTxt.append(count, text);
     if (fUseScaledFallback) {
-        SkScalar glyphTextSize = SkScalarFloorToScalar(fMaxTextSize*fTextSize / maxDim);
+        // If there's a glyph in the font that's particularly large, it's possible
+        // that fScaledFallbackTextSize may end up minimizing too much. We'd rather skip
+        // that glyph than make the others pixelated, so we set a minimum size of half the
+        // maximum text size to avoid this case.
+        SkScalar glyphTextSize = SkTMax(SkScalarFloorToScalar(fMaxTextSize*fTextSize / maxDim),
+                                        0.5f*fMaxTextSize);
         fScaledFallbackTextSize = SkTMin(glyphTextSize, fScaledFallbackTextSize);
     }
     *fFallbackPos.append() = glyphPos;
diff --git a/src/gpu/text/GrAtlasTextContext.h b/src/gpu/text/GrAtlasTextContext.h
index bcdc9fdd02..2f95d9a0c0 100644
--- a/src/gpu/text/GrAtlasTextContext.h
+++ b/src/gpu/text/GrAtlasTextContext.h
@@ -61,14 +61,14 @@ private:
     class FallbackTextHelper {
     public:
         FallbackTextHelper(const SkMatrix& viewMatrix,
-                           SkScalar textSize,
-                           SkScalar maxTextSize,
+                           const SkPaint& pathPaint,
+                           const GrGlyphCache* glyphCache,
                            SkScalar textRatio)
             : fViewMatrix(viewMatrix)
+            , fTextSize(pathPaint.getTextSize())
+            , fMaxTextSize(glyphCache->getGlyphSizeLimit())
             , fTextRatio(textRatio)
-            , fTextSize(textSize)
-            , fMaxTextSize(maxTextSize)
-            , fScaledFallbackTextSize(maxTextSize)
+            , fScaledFallbackTextSize(fMaxTextSize)
             , fUseScaledFallback(false) {
             fMaxScale = viewMatrix.getMaxScale();
         }
@@ -82,9 +82,9 @@ private:
         SkTDArray<SkPoint> fFallbackPos;
 
         const SkMatrix& fViewMatrix;
-        SkScalar fTextRatio;
         SkScalar fTextSize;
         SkScalar fMaxTextSize;
+        SkScalar fTextRatio;
         SkScalar fScaledFallbackTextSize;
         SkScalar fMaxScale;
         bool fUseScaledFallback;