diff -r 000000000000 -r 6474c204b198 gfx/thebes/gfxWindowsNativeDrawing.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gfx/thebes/gfxWindowsNativeDrawing.h	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,119 @@
+/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ * 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 _GFXWINDOWSNATIVEDRAWING_H_
+#define _GFXWINDOWSNATIVEDRAWING_H_
+
+#include <windows.h>
+
+#include "gfxContext.h"
+#include "gfxWindowsSurface.h"
+
+class gfxWindowsNativeDrawing {
+public:
+
+    /* Flags for notifying this class what kind of operations the native
+     * drawing supports
+     */
+
+    enum {
+        /* Whether the native drawing can draw to a surface of content COLOR_ALPHA */
+        CAN_DRAW_TO_COLOR_ALPHA    = 1 << 0,
+        CANNOT_DRAW_TO_COLOR_ALPHA = 0 << 0,
+
+        /* Whether the native drawing can be scaled using SetWorldTransform */
+        CAN_AXIS_ALIGNED_SCALE     = 1 << 1,
+        CANNOT_AXIS_ALIGNED_SCALE  = 0 << 1,
+
+        /* Whether the native drawing can be both scaled and rotated arbitrarily using SetWorldTransform */
+        CAN_COMPLEX_TRANSFORM      = 1 << 2,
+        CANNOT_COMPLEX_TRANSFORM   = 0 << 2,
+
+        /* If we have to do transforms with cairo, should we use nearest-neighbour filtering? */
+        DO_NEAREST_NEIGHBOR_FILTERING = 1 << 3,
+        DO_BILINEAR_FILTERING         = 0 << 3
+    };
+
+    /* Create native win32 drawing for a rectangle bounded by
+     * nativeRect.
+     *
+     * Typical usage looks like:
+     *
+     *   gfxWindowsNativeDrawing nativeDraw(ctx, destGfxRect, capabilities);
+     *   do {
+     *     HDC dc = nativeDraw.BeginNativeDrawing();
+     *     if (!dc)
+     *       return NS_ERROR_FAILURE;
+     *
+     *     RECT winRect;
+     *     nativeDraw.TransformToNativeRect(rect, winRect);
+     *
+     *       ... call win32 operations on HDC to draw to winRect ...
+     *
+     *     nativeDraw.EndNativeDrawing();
+     *   } while (nativeDraw.ShouldRenderAgain());
+     *   nativeDraw.PaintToContext();
+     */
+    gfxWindowsNativeDrawing(gfxContext *ctx,
+                            const gfxRect& nativeRect,
+                            uint32_t nativeDrawFlags = CANNOT_DRAW_TO_COLOR_ALPHA |
+                                                       CANNOT_AXIS_ALIGNED_SCALE |
+                                                       CANNOT_COMPLEX_TRANSFORM |
+                                                       DO_BILINEAR_FILTERING);
+
+    /* Returns a HDC which may be used for native drawing.  This HDC is valid
+     * until EndNativeDrawing is called; if it is used for drawing after that time,
+     * the result is undefined. */
+    HDC BeginNativeDrawing();
+
+    /* Transform the native rect into something valid for rendering
+     * to the HDC.  This may or may not change RECT, depending on
+     * whether SetWorldTransform is used or not. */
+    void TransformToNativeRect(const gfxRect& r, RECT& rout);
+
+    /* Marks the end of native drawing */
+    void EndNativeDrawing();
+
+    /* Returns true if the native drawing should be executed again */
+    bool ShouldRenderAgain();
+
+    /* Returns true if double pass alpha extraction is taking place. */
+    bool IsDoublePass();
+
+    /* Places the result to the context, if necessary */
+    void PaintToContext();
+
+private:
+
+    nsRefPtr<gfxContext> mContext;
+    gfxRect mNativeRect;
+    uint32_t mNativeDrawFlags;
+
+    // what state the rendering is in
+    uint8_t mRenderState;
+
+    gfxPoint mDeviceOffset;
+    nsRefPtr<gfxPattern> mBlackPattern, mWhitePattern;
+
+    enum TransformType {
+        TRANSLATION_ONLY,
+        AXIS_ALIGNED_SCALE,
+        COMPLEX
+    };
+
+    TransformType mTransformType;
+    gfxPoint mTranslation;
+    gfxSize mScale;
+    XFORM mWorldTransform;
+
+    // saved state
+    nsRefPtr<gfxWindowsSurface> mWinSurface, mBlackSurface, mWhiteSurface;
+    HDC mDC;
+    XFORM mOldWorldTransform;
+    POINT mOrigViewportOrigin;
+    gfxIntSize mTempSurfaceSize;
+};
+
+#endif