[canvaskit] Add halfLeading to TextStyle and StrutStyle

- Add halfLeading (introduced in https://skia-review.googlesource.com/c/skia/+/394969) to canvaskit bindings

- Fix wrong initial value of fDescent

Change-Id: I01d522cd5a3761f32426038dce2ab82f24c9c529
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/398276
Reviewed-by: Kevin Lubick <kjlubick@google.com>
Commit-Queue: Kevin Lubick <kjlubick@google.com>

modules/canvaskit/CHANGELOG.md

@@ -13,6 +13,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
  - `CanvasKit.RuntimeEffect` now supports integer uniforms in the SkSL. These are still passed
    to `RuntimeEffect.makeShader` as floats (like all other uniforms), and will be converted to
    integers internally, to match the expectations of the shader.
+ - Add 'halfLeading' to `TextStyle` and `StrutStyle`.
 
 ### Removed
  - `Picture.saveAsFile()`, in favor of `Picture.serialize()` where clients can control how to

modules/canvaskit/npm_build/types/index.d.ts

@@ -2666,6 +2666,7 @@ export interface StrutStyle {
     fontStyle?: FontStyle;
     fontSize?: number;
     heightMultiplier?: number;
+    halfLeading?: boolean;
     leading?: number;
     forceStrutHeight?: boolean;
 }
@@ -2697,6 +2698,7 @@ export interface TextStyle {
     fontStyle?: FontStyle;
     foregroundColor?: InputColor;
     heightMultiplier?: number;
+    halfLeading?: boolean;
     letterSpacing?: number;
     locale?: string;
     shadows?: TextShadow[];

modules/canvaskit/paragraph.js

@@ -101,6 +101,7 @@
         s['fontStyle'] = fontStyle(s['fontStyle']);
         s['fontSize'] = s['fontSize'] || 0;
         s['heightMultiplier'] = s['heightMultiplier'] || 0;
+        s['halfLeading'] = s['halfLeading'] || false;
         s['leading'] = s['leading'] || 0;
         s['forceStrutHeight'] = s['forceStrutHeight'] || false;
         return s;
@@ -120,6 +121,7 @@
       s['letterSpacing'] = s['letterSpacing'] || 0;
       s['wordSpacing'] = s['wordSpacing'] || 0;
       s['heightMultiplier'] = s['heightMultiplier'] || 0;
+      s['halfLeading'] = s['halfLeading'] || false;
       if (s['locale']) {
         var str = s['locale'];
         s['_localePtr'] = cacheOrCopyString(str);

modules/canvaskit/paragraph_bindings.cpp

@@ -52,6 +52,7 @@ struct SimpleTextStyle {
     SkScalar letterSpacing;
     SkScalar wordSpacing;
     SkScalar heightMultiplier;
+    bool halfLeading;
     uintptr_t /* const char* */ localePtr;
     int localeLen;
     SimpleFontStyle fontStyle;
@@ -75,6 +76,7 @@ struct SimpleStrutStyle {
     SimpleFontStyle fontStyle;
     SkScalar fontSize;
     SkScalar heightMultiplier;
+    bool halfLeading;
     SkScalar leading;
     bool strutEnabled;
     bool forceStrutHeight;
@@ -102,6 +104,8 @@ para::StrutStyle toStrutStyle(const SimpleStrutStyle& s) {
         ss.setHeight(s.heightMultiplier);
         ss.setHeightOverride(true);
     }
+    ss.setHalfLeading(s.halfLeading);
+
     if (s.leading != 0) {
         ss.setLeading(s.leading);
     }
@@ -147,6 +151,8 @@ para::TextStyle toTextStyle(const SimpleTextStyle& s) {
         ts.setHeightOverride(true);
     }
 
+    ts.setHalfLeading(s.halfLeading);
+
     ts.setDecoration(para::TextDecoration(s.decoration));
     ts.setDecorationStyle(s.decorationStyle);
     if (s.decorationThickness != 0) {
@@ -475,6 +481,7 @@ EMSCRIPTEN_BINDINGS(Paragraph) {
         .field("fontSize",         &SimpleStrutStyle::fontSize)
         .field("fontStyle",        &SimpleStrutStyle::fontStyle)
         .field("heightMultiplier", &SimpleStrutStyle::heightMultiplier)
+        .field("halfLeading",      &SimpleStrutStyle::halfLeading)
         .field("leading",          &SimpleStrutStyle::leading)
         .field("forceStrutHeight", &SimpleStrutStyle::forceStrutHeight);
 
@@ -492,6 +499,7 @@ EMSCRIPTEN_BINDINGS(Paragraph) {
         .field("letterSpacing",         &SimpleTextStyle::letterSpacing)
         .field("wordSpacing",           &SimpleTextStyle::wordSpacing)
         .field("heightMultiplier",      &SimpleTextStyle::heightMultiplier)
+        .field("halfLeading",           &SimpleTextStyle::halfLeading)
         .field("_localePtr",            &SimpleTextStyle::localePtr)
         .field("_localeLen",            &SimpleTextStyle::localeLen)
         .field("fontStyle",             &SimpleTextStyle::fontStyle)

modules/canvaskit/tests/paragraph.spec.js

@@ -805,6 +805,47 @@ describe('Paragraph Behavior', function() {
         builder.delete();
     });
 
+    gm('paragraph_text_styles_mixed_leading_distribution', (canvas) => {
+        const fontMgr = CanvasKit.FontMgr.FromData(notoSerifFontBuffer);
+        expect(fontMgr.countFamilies()).toEqual(1);
+        expect(fontMgr.getFamilyName(0)).toEqual('Noto Serif');
+
+        const wrapTo = 200;
+
+        const paraStyle = new CanvasKit.ParagraphStyle({
+            textStyle: {
+                color: CanvasKit.BLACK,
+                backgroundColor: CanvasKit.Color(234, 208, 232), // light pink
+                fontFamilies: ['Noto Serif'],
+                fontSize: 10,
+                heightMultiplier: 10,
+            },
+        });
+
+        const builder = CanvasKit.ParagraphBuilder.Make(paraStyle, fontMgr);
+        builder.addText('Not half leading');
+
+        const halfLeadingText = new CanvasKit.TextStyle({
+            color: CanvasKit.Color(48, 37, 199),
+            backgroundColor: CanvasKit.Color(234, 208, 232), // light pink
+            fontFamilies: ['Noto Serif'],
+            fontSize: 10,
+            heightMultiplier: 10,
+            halfLeading: true,
+        });
+        builder.pushStyle(halfLeadingText);
+        builder.addText('Half Leading Text');
+        const paragraph = builder.build();
+
+        paragraph.layout(wrapTo);
+        canvas.clear(CanvasKit.WHITE);
+        canvas.drawParagraph(paragraph, 0, 0);
+
+        fontMgr.delete();
+        paragraph.delete();
+        builder.delete();
+    });
+
     it('should not crash if we omit font family on pushed textStyle', () => {
         const surface = CanvasKit.MakeCanvasSurface('test');
         expect(surface).toBeTruthy('Could not make surface');

modules/skparagraph/include/Metrics.h

@@ -70,7 +70,7 @@ public:
     // for specific runs of text can be obtained in run_metrics_map. These values
     // are the cumulative metrics for the entire line.
     double fAscent = SK_ScalarMax;
-    double fDescent = SK_ScalarMax;
+    double fDescent = SK_ScalarMin;
     double fUnscaledAscent = SK_ScalarMax;
     // Total height of the paragraph including the current line.
     //