1 files changed, 131 insertions, 0 deletions
diff --git a/gfx/2d/BorrowedContext.h b/gfx/2d/BorrowedContext.h
new file mode 100644
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+++ b/gfx/2d/BorrowedContext.h
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+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 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 _MOZILLA_GFX_BORROWED_CONTEXT_H
+#define _MOZILLA_GFX_BORROWED_CONTEXT_H
+
+#include "2D.h"
+
+#ifdef MOZ_X11
+#  include <X11/Xlib.h>
+#  include "X11UndefineNone.h"
+#endif
+
+namespace mozilla {
+
+namespace gfx {
+
+#ifdef MOZ_X11
+/* This is a helper class that let's you borrow an Xlib drawable from
+ * a DrawTarget. This is used for drawing themed widgets.
+ *
+ * Callers should check the Xlib drawable after constructing the object
+ * to see if it succeeded. The DrawTarget should not be used while
+ * the drawable is borrowed. */
+class BorrowedXlibDrawable {
+ public:
+  BorrowedXlibDrawable()
+      : mDT(nullptr),
+        mDisplay(nullptr),
+        mDrawable(X11None),
+        mScreen(nullptr),
+        mVisual(nullptr) {}
+
+  explicit BorrowedXlibDrawable(DrawTarget* aDT)
+      : mDT(nullptr),
+        mDisplay(nullptr),
+        mDrawable(X11None),
+        mScreen(nullptr),
+        mVisual(nullptr) {
+    Init(aDT);
+  }
+
+  // We can optionally Init after construction in
+  // case we don't know what the DT will be at construction
+  // time.
+  bool Init(DrawTarget* aDT);
+
+  // The caller needs to call Finish if drawable is non-zero when
+  // they are done with the context. This is currently explicit
+  // instead of happening implicitly in the destructor to make
+  // what's happening in the caller more clear. It also
+  // let's you resume using the DrawTarget in the same scope.
+  void Finish();
+
+  ~BorrowedXlibDrawable() { MOZ_ASSERT(!mDrawable); }
+
+  Display* GetDisplay() const { return mDisplay; }
+  Drawable GetDrawable() const { return mDrawable; }
+  Screen* GetScreen() const { return mScreen; }
+  Visual* GetVisual() const { return mVisual; }
+  IntSize GetSize() const { return mSize; }
+  Point GetOffset() const { return mOffset; }
+
+ private:
+  DrawTarget* mDT;
+  Display* mDisplay;
+  Drawable mDrawable;
+  Screen* mScreen;
+  Visual* mVisual;
+  IntSize mSize;
+  Point mOffset;
+};
+#endif
+
+#ifdef XP_DARWIN
+/* This is a helper class that let's you borrow a CGContextRef from a
+ * DrawTargetCG. This is used for drawing themed widgets.
+ *
+ * Callers should check the cg member after constructing the object
+ * to see if it succeeded. The DrawTarget should not be used while
+ * the context is borrowed. */
+class BorrowedCGContext {
+ public:
+  BorrowedCGContext() : cg(nullptr), mDT(nullptr) {}
+
+  explicit BorrowedCGContext(DrawTarget* aDT) : mDT(aDT) {
+    MOZ_ASSERT(aDT, "Caller should check for nullptr");
+    cg = BorrowCGContextFromDrawTarget(aDT);
+  }
+
+  // We can optionally Init after construction in
+  // case we don't know what the DT will be at construction
+  // time.
+  CGContextRef Init(DrawTarget* aDT) {
+    MOZ_ASSERT(aDT, "Caller should check for nullptr");
+    MOZ_ASSERT(!mDT, "Can't initialize twice!");
+    mDT = aDT;
+    cg = BorrowCGContextFromDrawTarget(aDT);
+    return cg;
+  }
+
+  // The caller needs to call Finish if cg is non-null when
+  // they are done with the context. This is currently explicit
+  // instead of happening implicitly in the destructor to make
+  // what's happening in the caller more clear. It also
+  // let's you resume using the DrawTarget in the same scope.
+  void Finish() {
+    if (cg) {
+      ReturnCGContextToDrawTarget(mDT, cg);
+      cg = nullptr;
+    }
+  }
+
+  ~BorrowedCGContext() { MOZ_ASSERT(!cg); }
+
+  CGContextRef cg;
+
+ private:
+  static CGContextRef BorrowCGContextFromDrawTarget(DrawTarget* aDT);
+  static void ReturnCGContextToDrawTarget(DrawTarget* aDT, CGContextRef cg);
+  DrawTarget* mDT;
+};
+#endif
+
+}  // namespace gfx
+}  // namespace mozilla
+
+#endif  // _MOZILLA_GFX_BORROWED_CONTEXT_H