Create GrQuad

src/gpu/GrQuad.h

+/*
+ * Copyright 2015 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef GrQuad_DEFINED
+#define GrQuad_DEFINED
+
+#include "SkPoint.h"
+#include "SkMatrix.h"
+
+/**
+ * GrQuad is a collection of 4 points which can be used to represent an arbitrary quadrilateral
+ */
+class GrQuad {
+public:
+    GrQuad(const GrQuad& that) {
+        *this = that;
+    }
+
+    GrQuad(const SkRect& rect) {

[bsalomon, 2015/08/19 15:04:51]

explicit

+        this->set(rect);
+    }
+
+    void set(const SkRect& rect) {
+        fPoints->setRectFan(rect.fLeft, rect.fTop, rect.fRight, rect.fBottom);
+    }
+
+    void map(const SkMatrix& matrix) {
+        matrix.mapPoints(fPoints, kNumPoints);
+    }
+
+    void map(const SkRect& rect, const SkMatrix& matrix) {

[bsalomon, 2015/08/19 15:04:51]

The other "map" maps the existing values. This one discards them. Could we give
it a more clear name? setFromMappedRect? Don't love it... but something that
clearly distinguishes the two.

+        this->set(rect);
+        matrix.mapPoints(fPoints, kNumPoints);
+    }
+
+    const GrQuad& operator=(const GrQuad& that) {
+        memcpy(fPoints, that.fPoints, sizeof(SkPoint) * kNumPoints);
+        return *this;
+    }
+
+    SkPoint* points() {

[bsalomon, 2015/08/19 15:04:51]

const version?

+        return fPoints;
+    }
+
+private:
+    static const int kNumPoints = 4;
+    SkPoint fPoints[kNumPoints];
+};
+
+#endif