add support for capped hairlines

gm/hairlines.cpp

Index: gm/hairlines.cpp
diff --git a/gm/hairlines.cpp b/gm/hairlines.cpp
index 9d7e36631d9ef1c83b3cd7740a2b6058e2263882..c263bfc5a37e5bd03150159d6c676e79cce4117f 100644
--- a/gm/hairlines.cpp
+++ b/gm/hairlines.cpp
@@ -218,6 +218,52 @@ private:
     typedef GM INHERITED;
 };
 
+static void draw_squarehair_tests(SkCanvas* canvas, SkScalar width, SkPaint::Cap cap, bool aa) {
+    SkPaint paint;
+    paint.setStrokeCap(cap);
+    paint.setStrokeWidth(width);
+    paint.setAntiAlias(aa);
+    paint.setStyle(SkPaint::kStroke_Style);
+    canvas->drawLine(10, 10, 20, 10, paint);
+    canvas->drawLine(30, 10, 30, 20, paint);
+    canvas->drawLine(40, 10, 50, 20, paint);
+    SkPath path;
+    path.moveTo(60, 10);
+    path.quadTo(60, 20, 70, 20);
+    path.conicTo(70, 10, 80, 10, 0.707f);
+    canvas->drawPath(path, paint);
+    path.reset();
+    path.moveTo(90, 10);
+    path.cubicTo(90, 20, 100, 20, 100, 10);
+    path.lineTo(110, 10);
+    canvas->drawPath(path, paint);
+    canvas->translate(0, 30);
+}
+
+DEF_SIMPLE_GM(squarehair, canvas, 400, 400) {
+    canvas->save();
+    draw_squarehair_tests(canvas, 0, SkPaint::kButt_Cap, false);
+    draw_squarehair_tests(canvas, 0, SkPaint::kSquare_Cap, false);

[reed1, 2015/12/04 18:01:10]

Wonder if adding 0.999 would be helpful.

[caryclark, 2015/12/04 20:55:15]

Done.

+    draw_squarehair_tests(canvas, 0, SkPaint::kRound_Cap, false);
+    draw_squarehair_tests(canvas, 1, SkPaint::kButt_Cap, false);
+    draw_squarehair_tests(canvas, 1, SkPaint::kSquare_Cap, false);
+    draw_squarehair_tests(canvas, 1, SkPaint::kRound_Cap, false);
+    draw_squarehair_tests(canvas, 1.001f, SkPaint::kButt_Cap, false);
+    draw_squarehair_tests(canvas, 1.001f, SkPaint::kSquare_Cap, false);
+    draw_squarehair_tests(canvas, 1.001f, SkPaint::kRound_Cap, false);
+    canvas->restore();
+    canvas->translate(120, 0);
+    draw_squarehair_tests(canvas, 0, SkPaint::kButt_Cap, true);
+    draw_squarehair_tests(canvas, 0, SkPaint::kSquare_Cap, true);
+    draw_squarehair_tests(canvas, 0, SkPaint::kRound_Cap, true);
+    draw_squarehair_tests(canvas, 1, SkPaint::kButt_Cap, true);
+    draw_squarehair_tests(canvas, 1, SkPaint::kSquare_Cap, true);
+    draw_squarehair_tests(canvas, 1, SkPaint::kRound_Cap, true);
+    draw_squarehair_tests(canvas, 1.001f, SkPaint::kButt_Cap, true);
+    draw_squarehair_tests(canvas, 1.001f, SkPaint::kSquare_Cap, true);
+    draw_squarehair_tests(canvas, 1.001f, SkPaint::kRound_Cap, true);
+}
+
 //////////////////////////////////////////////////////////////////////////////
 
 static GM* MyFactory(void*) { return new HairlinesGM; }