Make scoped dc objects smarter.

base/win/scoped_hdc.cc

Index: base/win/scoped_hdc.cc
===================================================================
--- base/win/scoped_hdc.cc	(revision 0)
+++ base/win/scoped_hdc.cc	(revision 0)
@@ -0,0 +1,116 @@
+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "base/win/scoped_hdc.h"
+
+#include "base/logging.h"
+
+namespace base {
+namespace win {
+
+ScopedDC::ScopedDC(HDC hdc)
+    : hdc_(hdc),
+      bitmap_(0),
+      font_(0),
+      brush_(0),
+      pen_(0),
+      region_(0) {
+}
+
+ScopedDC::~ScopedDC() {}
+
+void ScopedDC::SelectBitmap(HBITMAP bitmap) {
+  Select(bitmap, &bitmap_);
+}
+
+void ScopedDC::SelectFont(HFONT font) {
+  Select(font, &font_);
+}
+
+void ScopedDC::SelectBrush(HBRUSH brush) {
+  Select(brush, &brush_);
+}
+
+void ScopedDC::SelectPen(HPEN pen) {
+  Select(pen, &pen_);
+}
+
+void ScopedDC::SelectRegion(HRGN region) {
+  Select(region, &region_);
+}
+
+void ScopedDC::Close() {
+  if (!hdc_)
+    return;
+  ResetObjects();
+  DisposeDC(hdc_);
+}
+
+void ScopedDC::Reset(HDC hdc) {
+  Close();
+  hdc_ = hdc;
+}
+
+void ScopedDC::ResetObjects() {
+  if (bitmap_) {
+    SelectObject(hdc_, bitmap_);
+    bitmap_ = 0;
+  }
+  if (font_) {
+    SelectObject(hdc_, font_);
+    font_ = 0;
+  }
+  if (brush_) {
+    SelectObject(hdc_, brush_);
+    brush_ = 0;
+  }
+  if (pen_) {
+    SelectObject(hdc_, pen_);
+    pen_ = 0;
+  }
+  if (region_) {
+    SelectObject(hdc_, region_);
+    region_ = 0;
+  }
+}
+
+void ScopedDC::Select(HGDIOBJ object, HGDIOBJ* holder) {
+  HGDIOBJ old = SelectObject(hdc_, object);
+  DCHECK(old);
+  // We only want to store the first |old| object.
+  if (!*holder)
+    *holder = old;
+}
+
+ScopedGetDC::ScopedGetDC(HWND hwnd) : ScopedDC(GetDC(hwnd)), hwnd_(hwnd) {
+}
+
+ScopedGetDC::~ScopedGetDC() {
+  Close();
+}
+
+void ScopedGetDC::DisposeDC(HDC hdc) {
+  ReleaseDC(hwnd_, hdc);
+}
+
+ScopedCreateDC::ScopedCreateDC() : ScopedDC(0) {
+}
+
+ScopedCreateDC::ScopedCreateDC(HDC hdc) : ScopedDC(hdc) {
+}
+
+ScopedCreateDC::~ScopedCreateDC() {
+  Close();
+}
+
+void ScopedCreateDC::Set(HDC hdc) {
+  Reset(hdc);
+}
+
+void ScopedCreateDC::DisposeDC(HDC hdc) {
+  DeleteDC(hdc);
+}
+
+}  // namespace win
+}  // namespace base