Implement text rendering with NVPR

src/core/SkTextMapState.h

+/*
+ * Copyright 2014 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef SkTextMapState_DEFINED
+#define SkTextMapState_DEFINED
+
+#include "SkPoint.h"
+#include "SkMatrix.h"
+
+class SkTextMapState {
+public:
+    SkPoint fLoc;
+
+    SkTextMapState(const SkMatrix& matrix, SkScalar y)
+        : fMatrix(matrix), fProc(matrix.getMapXYProc()), fY(y) {}
+
+    typedef void (*Proc)(SkTextMapState&, const SkScalar pos[]);
+
+    Proc pickProc(int scalarsPerPosition);
+
+private:
+    const SkMatrix&     fMatrix;
+    SkMatrix::MapXYProc fProc;
+    SkScalar            fY; // ignored by MapXYProc
+    // these are only used by Only... procs
+    SkScalar            fScaleX, fTransX, fTransformedY;
+
+    static void MapXProc(SkTextMapState& state, const SkScalar pos[]) {
+        state.fProc(state.fMatrix, *pos, state.fY, &state.fLoc);
+    }
+
+    static void MapXYProc(SkTextMapState& state, const SkScalar pos[]) {
+        state.fProc(state.fMatrix, pos[0], pos[1], &state.fLoc);
+    }
+
+    static void MapOnlyScaleXProc(SkTextMapState& state,
+                                  const SkScalar pos[]) {
+        state.fLoc.set(SkScalarMul(state.fScaleX, *pos) + state.fTransX,
+                       state.fTransformedY);
+    }
+
+    static void MapOnlyTransXProc(SkTextMapState& state,
+                                  const SkScalar pos[]) {
+        state.fLoc.set(*pos + state.fTransX, state.fTransformedY);
+    }
+};
+
+inline SkTextMapState::Proc SkTextMapState::pickProc(int scalarsPerPosition) {
+    SkASSERT(1 == scalarsPerPosition || 2 == scalarsPerPosition);
+
+    if (1 == scalarsPerPosition) {
+        unsigned mtype = fMatrix.getType();
+        if (mtype & (SkMatrix::kAffine_Mask | SkMatrix::kPerspective_Mask)) {
+            return MapXProc;
+        } else {
+            fScaleX = fMatrix.getScaleX();
+            fTransX = fMatrix.getTranslateX();
+            fTransformedY = SkScalarMul(fY, fMatrix.getScaleY()) +
+                            fMatrix.getTranslateY();
+            return (mtype & SkMatrix::kScale_Mask) ?
+                        MapOnlyScaleXProc : MapOnlyTransXProc;
+        }
+    } else {
+        return MapXYProc;
+    }
+}
+
+#endif
+