add TrimPathEffect

Bug: skia:
Change-Id: I453fb81ded4435b33567e9c8a6f3abe9535d687f
Reviewed-on: https://skia-review.googlesource.com/112820
Commit-Queue: Mike Reed <reed@google.com>
Reviewed-by: Florin Malita <fmalita@chromium.org>

1 files changed, 36 insertions, 0 deletions

diff --git a/include/effects/SkTrimPathEffect.h b/include/effects/SkTrimPathEffect.h
new file mode 100644
index 0000000000..d40c9e2bbf
--- /dev/null
+++ b/include/effects/SkTrimPathEffect.h
@@ -0,0 +1,36 @@
+/*
+ * Copyright 2018 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef SkTrimPathEffect_DEFINED
+#define SkTrimPathEffect_DEFINED
+
+#include "SkPathEffect.h"
+
+class SK_API SkTrimPathEffect {
+public:
+    /**
+     *  Take start and stop "t" values (values between 0...1), and return a path that is that
+     *  subset of the original path.
+     *
+     *  e.g.
+     *      Make(0.5, 1.0) --> return the 2nd half of the path
+     *      Make(0.33333, 0.66667) --> return the middle third of the path
+     *
+     *  The trim values apply to the entire path, so if it contains several contours, all of them
+     *  are including in the calculation.
+     *
+     *  startT and stopT must be 0..1 inclusive. If they are outside of that interval, they will
+     *  be pinned to the nearest legal value. If either is NaN, null will be returned.
+     *
+     *  Note: if startT < stopT, this will return one (logical) segment (even if it is spread
+     *        across multiple contours). If startT > stopT, then this will return 2 logical
+     *        segments: 0...stopT and startT...1
+     */
+    static sk_sp<SkPathEffect> Make(SkScalar startT, SkScalar stopT);
+};
+
+#endif