Make GPU coord transforms automatic

include/gpu/GrCoordTransform.h

Index: include/gpu/GrCoordTransform.h
diff --git a/include/gpu/GrCoordTransform.h b/include/gpu/GrCoordTransform.h
new file mode 100644
index 0000000000000000000000000000000000000000..931526092c9a68747ce9fae856626b33423cb1b3
--- /dev/null
+++ b/include/gpu/GrCoordTransform.h
@@ -0,0 +1,73 @@
+/*
+ * Copyright 2013 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef GrCoordTransform_DEFINED
+#define GrCoordTransform_DEFINED
+
+#include "GrEffect.h"
+#include "SkMatrix.h"
+#include "GrTexture.h"
+#include "GrTypes.h"
+
+/**
+ * A class representing a linear transformation from one of the built-in coordinate sets (local or
+ * position). GrEffects just define these transformations, and the framework does the rest of the
+ * work to make the transformed coordinates available in their shaders.

[bsalomon, 2013/09/27 19:23:57]

... ^fragment shaders.

[Chris Dalton, 2013/09/27 23:33:45]

Done.

+ */
+class GrCoordTransform : public SkNoncopyable {
+public:
+    GrCoordTransform() {}
+
+    GrCoordTransform(GrCoordSet sourceCoords, const GrTexture* texture) {
+        this->reset(sourceCoords, texture);
+    }
+
+    GrCoordTransform(GrCoordSet sourceCoords, const SkMatrix& m, const GrTexture* texture) {

[bsalomon, 2013/09/27 19:23:57]

Maybe some documentation that the texture is just used to possibly infer a y
reversal to account for textures that are upside down by Skia's coord
convention.

[Chris Dalton, 2013/09/27 23:33:45]

Done.

+        this->reset(sourceCoords, m, texture);
+    }
+
+    GrCoordTransform(GrCoordSet sourceCoords, const SkMatrix& m, bool reverseY = false) {

[bsalomon, 2013/09/27 19:23:57]

Is this constructor used in practice?

[Chris Dalton, 2013/09/27 23:33:45]

Removed.

+        this->reset(sourceCoords, m, reverseY);
+    }
+
+    void reset(GrCoordSet sourceCoords, const GrTexture* texture) {
+        SkASSERT(NULL != texture);
+        this->reset(sourceCoords,
+                    GrEffect::MakeDivByTextureWHMatrix(texture),
+                    kBottomLeft_GrSurfaceOrigin == texture->origin());
+    }
+
+    void reset(GrCoordSet sourceCoords, const SkMatrix& m, const GrTexture* texture) {
+        SkASSERT(NULL != texture);
+        this->reset(sourceCoords, m, kBottomLeft_GrSurfaceOrigin == texture->origin());
+    }
+
+    void reset(GrCoordSet sourceCoords, const SkMatrix& m, bool reverseY = false) {

[bsalomon, 2013/09/27 19:23:57]

If this version could be private that would seem nice.

[Chris Dalton, 2013/09/27 23:33:45]

Done.

+        fSourceCoords = sourceCoords;
+        fMatrix = m;
+        fReverseY = reverseY;
+    }
+
+    bool operator== (const GrCoordTransform& other) const {
+        return fSourceCoords == other.fSourceCoords &&
+               fMatrix.cheapEqualTo(other.fMatrix) &&
+               fReverseY == other.fReverseY;
+    }
+
+    GrCoordSet sourceCoords() const { return fSourceCoords; }
+    const SkMatrix& getMatrix() const { return fMatrix; }
+    bool reverseY() const { return fReverseY; }
+
+private:
+    GrCoordSet fSourceCoords;
+    SkMatrix   fMatrix;
+    bool       fReverseY;
+
+    typedef SkNoncopyable INHERITED;
+};
+
+#endif