[skotty,sksg] Initial trim path effect
TBR=
Change-Id: I5b612c5aade23f727a3622daeff2534f68e6b66a
Reviewed-on: https://skia-review.googlesource.com/91404
Reviewed-by: Florin Malita <fmalita@chromium.org>
Commit-Queue: Florin Malita <fmalita@chromium.org>
diff --git a/experimental/sksg/geometry/SkSGTrimEffect.cpp b/experimental/sksg/geometry/SkSGTrimEffect.cpp
new file mode 100644
index 0000000..4c30389
--- /dev/null
+++ b/experimental/sksg/geometry/SkSGTrimEffect.cpp
@@ -0,0 +1,61 @@
+/*
+ * Copyright 2017 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "SkSGTrimEffect.h"
+
+#include "SkCanvas.h"
+#include "SkDashPathEffect.h"
+#include "SkPathMeasure.h"
+
+namespace sksg {
+
+TrimEffect::TrimEffect(sk_sp<GeometryNode> child)
+ : fChild(std::move(child)) {
+ fChild->addInvalReceiver(this);
+}
+
+TrimEffect::~TrimEffect() {
+ fChild->removeInvalReceiver(this);
+}
+
+// TODO
+// This is a quick hack to get something on the screen. What we really want here is to apply
+// the geometry transformation and cache the result on revalidation. Or an SkTrimPathEffect.
+void TrimEffect::onDraw(SkCanvas* canvas, const SkPaint& paint) const {
+ SkASSERT(!this->hasInval());
+
+ SkASSERT(!paint.getPathEffect());
+
+ const auto path = fChild->asPath();
+ SkScalar pathLen = 0;
+ SkPathMeasure measure(path, false);
+ do {
+ pathLen += measure.getLength();
+ } while (measure.nextContour());
+
+ const auto start = SkScalarPin(fStart , 0, 1) * pathLen,
+ end = SkScalarPin(fEnd , 0, 1) * pathLen,
+ offset = SkScalarPin(fOffset, 0, 1) * pathLen,
+ len = SkTMax<SkScalar>(end - start, 0);
+
+ const SkScalar dashes[4] = { 0, start, len, pathLen - end };
+ SkPaint dashedPaint(paint);
+ dashedPaint.setPathEffect(SkDashPathEffect::Make(dashes, 4, -offset));
+
+ canvas->drawPath(path, dashedPaint);
+}
+
+SkPath TrimEffect::onAsPath() const {
+ return fChild->asPath();
+}
+
+SkRect TrimEffect::onRevalidate(InvalidationController* ic, const SkMatrix& ctm) {
+ SkASSERT(this->hasInval());
+ return fChild->revalidate(ic, ctm);
+}
+
+} // namespace sksg