efficiently dash very large rectangles and very long lines

Speed up dashing when lines and rects are absurdly large.

Prior to this CL, only horizontal lines were detected.

The onOnceBeforeDraw changes are there to make debugging easier.

Also folded in a change to handle dashing of zero length lines.

R=reed@google.com, egdaniel@google.com
Bug: skia:7311
Change-Id: Ia16fb124c7a78a5cc639e612fae29c879a37da1a
Reviewed-on: https://skia-review.googlesource.com/84862
Commit-Queue: Cary Clark <caryclark@skia.org>
Reviewed-by: Mike Reed <reed@google.com>

1 files changed, 28 insertions, 0 deletions

diff --git a/gm/strokes.cpp b/gm/strokes.cpp
index ed13d090ff..e9faad4d6c 100644
--- a/gm/strokes.cpp
+++ b/gm/strokes.cpp
@@ -533,3 +533,31 @@ DEF_SIMPLE_GM(zerolinedash, canvas, 256, 256) {
 
     canvas->drawLine(100, 100, 100, 100, paint);
 }
+
+DEF_SIMPLE_GM(longrect_dash, canvas, 250, 250) {
+    canvas->clear(SK_ColorWHITE);
+
+    SkPaint paint;
+    paint.setColor(SkColorSetARGB(255, 0, 0, 0));
+    paint.setStrokeWidth(5);
+    paint.setStrokeCap(SkPaint::kRound_Cap);
+    paint.setStrokeJoin(SkPaint::kBevel_Join);
+    paint.setStyle(SkPaint::kStroke_Style);
+    SkScalar dash_pattern[] = {1, 5};
+    paint.setPathEffect(SkDashPathEffect::Make(dash_pattern, 2, 0));
+    // try all combinations of stretching bounds
+    for (auto left : { 20.f, -100001.f } ) {
+        for (auto top : { 20.f, -100001.f } ) {
+            for (auto right : { 40.f, 100001.f } ) {
+                for (auto bottom : { 40.f, 100001.f } ) {
+                    canvas->save();
+                    canvas->clipRect({10, 10, 50, 50});
+                    canvas->drawRect({left, top, right, bottom}, paint);
+                    canvas->restore();
+                    canvas->translate(60, 0);
+               }
+            }
+            canvas->translate(-60 * 4, 60);
+        }
+    }
+}