1 files changed, 77 insertions, 0 deletions
diff --git a/gfx/gl/DecomposeIntoNoRepeatTriangles.h b/gfx/gl/DecomposeIntoNoRepeatTriangles.h
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index 000000000..f67d6f93e
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+++ b/gfx/gl/DecomposeIntoNoRepeatTriangles.h
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+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* vim: set ts=8 sts=4 et sw=4 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef DecomposeIntoNoRepeatTriangles_h_
+#define DecomposeIntoNoRepeatTriangles_h_
+
+#include "GLTypes.h"
+#include "nsRect.h"
+#include "nsTArray.h"
+
+namespace mozilla {
+namespace gl {
+
+/** Helper for DecomposeIntoNoRepeatTriangles
+  */
+class RectTriangles {
+public:
+    typedef struct { GLfloat x,y; } coord;
+
+    // Always pass texture coordinates upright. If you want to flip the
+    // texture coordinates emitted to the tex_coords array, set flip_y to
+    // true.
+    void addRect(GLfloat x0, GLfloat y0, GLfloat x1, GLfloat y1,
+                 GLfloat tx0, GLfloat ty0, GLfloat tx1, GLfloat ty1,
+                 bool flip_y = false);
+
+    /**
+      * these return a float pointer to the start of each array respectively.
+      * Use it for glVertexAttribPointer calls.
+      * We can return nullptr if we choose to use Vertex Buffer Objects here.
+      */
+    InfallibleTArray<coord>& vertCoords() {
+        return mVertexCoords;
+    }
+
+    InfallibleTArray<coord>& texCoords() {
+        return mTexCoords;
+    }
+
+    unsigned int elements() {
+        return mVertexCoords.Length();
+    }
+private:
+    // Reserve inline storage for one quad (2 triangles, 3 coords).
+    AutoTArray<coord, 6> mVertexCoords;
+    AutoTArray<coord, 6> mTexCoords;
+
+    static void
+    AppendRectToCoordArray(InfallibleTArray<coord>& array, GLfloat x0, GLfloat y0, GLfloat x1, GLfloat y1);
+};
+
+/**
+  * Decompose drawing the possibly-wrapped aTexCoordRect rectangle
+  * of a texture of aTexSize into one or more rectangles (represented
+  * as 2 triangles) and associated tex coordinates, such that
+  * we don't have to use the REPEAT wrap mode. If aFlipY is true, the
+  * texture coordinates will be specified vertically flipped.
+  *
+  * The resulting triangle vertex coordinates will be in the space of
+  * (0.0, 0.0) to (1.0, 1.0) -- transform the coordinates appropriately
+  * if you need a different space.
+  *
+  * The resulting vertex coordinates should be drawn using GL_TRIANGLES,
+  * and rects.numRects * 3 * 6
+  */
+void DecomposeIntoNoRepeatTriangles(const gfx::IntRect& aTexCoordRect,
+                                    const gfx::IntSize& aTexSize,
+                                    RectTriangles& aRects,
+                                    bool aFlipY = false);
+
+} // namespace gl
+} // namespace mozilla
+
+#endif // DecomposeIntoNoRepeatTriangles_h_