Always call the class methods to save/restore contexts.

If the current context was ever nil, sending a "restore" message would be a no-op and would likely leave an out-of-scope context as current.

BUG=90140
TEST=repeatedly select items in an open file dialog in column mode; no crash

Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=95611

Reverted: http://src.chromium.org/viewvc/chrome?view=rev&revision=95631

Review URL: http://codereview.chromium.org/7572031

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@95686 0039d316-1c4b-4281-b951-d872f2087c98

3 files changed, 30 insertions, 13 deletions

diff --git a/ui/base/clipboard/clipboard_mac.mm b/ui/base/clipboard/clipboard_mac.mm
index 4f6b88a..0437e6a 100644
--- a/ui/base/clipboard/clipboard_mac.mm
+++ b/ui/base/clipboard/clipboard_mac.mm
@@ -16,6 +16,7 @@
 #import "third_party/mozilla/NSPasteboard+Utils.h"
 #include "third_party/skia/include/core/SkBitmap.h"
 #include "ui/gfx/canvas_skia.h"
+#include "ui/gfx/scoped_ns_graphics_context_save_gstate_mac.h"
 #include "ui/gfx/size.h"
 
 namespace ui {
@@ -250,6 +251,7 @@ SkBitmap Clipboard::ReadImage(Buffer buffer) const {
   if (!image.get())
     return SkBitmap();
 
+  gfx::ScopedNSGraphicsContextSaveGState scoped_state;
   [image setFlipped:YES];
   int width = [image size].width;
   int height = [image size].height;
@@ -265,7 +267,6 @@ SkBitmap Clipboard::ReadImage(Buffer buffer) const {
              fromRect:NSZeroRect
             operation:NSCompositeCopy
              fraction:1.0];
-    [NSGraphicsContext restoreGraphicsState];
   }
   return canvas.ExtractBitmap();
 }
diff --git a/ui/gfx/scoped_ns_graphics_context_save_gstate_mac.h b/ui/gfx/scoped_ns_graphics_context_save_gstate_mac.h
index 05bf5f6..4826bcc 100644
--- a/ui/gfx/scoped_ns_graphics_context_save_gstate_mac.h
+++ b/ui/gfx/scoped_ns_graphics_context_save_gstate_mac.h
@@ -4,23 +4,27 @@
 
 #ifndef UI_GFX_SCOPED_NS_GRAPHICS_CONTEXT_SAVE_GSTATE_MAC_H_
 #define UI_GFX_SCOPED_NS_GRAPHICS_CONTEXT_SAVE_GSTATE_MAC_H_
+#pragma once
 
-#include "ui/ui_api.h"
 #include "base/basictypes.h"
-#include "base/memory/scoped_nsobject.h"
+#include "ui/ui_api.h"
 
+#if defined(__OBJC__)
 @class NSGraphicsContext;
+#else
+class NSGraphicsContext;
+#endif
 
 namespace gfx {
 
+// A class to save/restore the state of the current context.
 class UI_API ScopedNSGraphicsContextSaveGState {
  public:
-  // If |context| is nil, it will use the |+currentContext|.
-  explicit ScopedNSGraphicsContextSaveGState(NSGraphicsContext* context = nil);
+  ScopedNSGraphicsContextSaveGState();
   ~ScopedNSGraphicsContextSaveGState();
 
  private:
-  scoped_nsobject<NSGraphicsContext> context_;
+  NSGraphicsContext* context_;  // weak
 
   DISALLOW_COPY_AND_ASSIGN(ScopedNSGraphicsContextSaveGState);
 };
diff --git a/ui/gfx/scoped_ns_graphics_context_save_gstate_mac.mm b/ui/gfx/scoped_ns_graphics_context_save_gstate_mac.mm
index f3992ea..9dca120 100644
--- a/ui/gfx/scoped_ns_graphics_context_save_gstate_mac.mm
+++ b/ui/gfx/scoped_ns_graphics_context_save_gstate_mac.mm
@@ -4,19 +4,31 @@
 
 #include "ui/gfx/scoped_ns_graphics_context_save_gstate_mac.h"
 
-#include <AppKit/AppKit.h>
+#import <AppKit/AppKit.h>
+
+#include "base/logging.h"
+#include "base/mac/mac_util.h"
 
 namespace gfx {
 
-ScopedNSGraphicsContextSaveGState::ScopedNSGraphicsContextSaveGState(
-    NSGraphicsContext* context) : context_([context retain]) {
-  if (!context_)
-    context_.reset([[NSGraphicsContext currentContext] retain]);
-  [context_ saveGraphicsState];
+ScopedNSGraphicsContextSaveGState::ScopedNSGraphicsContextSaveGState()
+    : context_([NSGraphicsContext currentContext]) {
+  [NSGraphicsContext saveGraphicsState];
 }
 
 ScopedNSGraphicsContextSaveGState::~ScopedNSGraphicsContextSaveGState() {
-  [context_ restoreGraphicsState];
+  [NSGraphicsContext restoreGraphicsState];
+  if (!context_ && base::mac::IsOSLeopardOrEarlier()) {
+    // On 10.5 and earlier, there is a bug. If the current graphics context was
+    // nil when +[NSGraphicsContext saveGraphicsState] was called, then calling
+    // +[NSGraphicsContext restoreGraphicsState] will not restore a nil current
+    // context, but will leave the current context in place. Because allowing
+    // that stale context (which will be deallocated soon) to remain current
+    // will only lead to heartache and pain, the current context must be
+    // manually nilled out.
+    [NSGraphicsContext setCurrentContext:nil];
+  }
+  DCHECK_EQ(context_, [NSGraphicsContext currentContext]);
 }
 
 }  // namespace gfx