mac: Basic HighDPI implementation for web contents.

content/browser/renderer_host/render_widget_host_view_mac.mm

 // 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 "content/browser/renderer_host/render_widget_host_view_mac.h"
 
 #include <QuartzCore/QuartzCore.h>
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
@@ skipping 77 matching lines @@
 #endif  // 10.6
 
 // Declare things that are part of the 10.7 SDK.
 #if !defined(MAC_OS_X_VERSION_10_7) || \
     MAC_OS_X_VERSION_MAX_ALLOWED < MAC_OS_X_VERSION_10_7
 @interface NSEvent (LionAPI)
 + (id)addLocalMonitorForEventsMatchingMask:(NSEventMask)mask
                                    handler:(NSEvent* (^)(NSEvent*))block;
 + (void)removeMonitor:(id)eventMonitor;
 @end
+
+@interface NSScreen (LionAPI)
+- (CGFloat)backingScaleFactor;
+@end
+
+@interface NSWindow (LionAPI)
+- (CGFloat)backingScaleFactor;
+@end
+
 #endif  // 10.7
 
+
 static inline int ToWebKitModifiers(NSUInteger flags) {
   int modifiers = 0;
   if (flags & NSControlKeyMask) modifiers |= WebInputEvent::ControlKey;
   if (flags & NSShiftKeyMask) modifiers |= WebInputEvent::ShiftKey;
   if (flags & NSAlternateKeyMask) modifiers |= WebInputEvent::AltKey;
   if (flags & NSCommandKeyMask) modifiers |= WebInputEvent::MetaKey;
   return modifiers;
 }
 
 // Private methods:
@@ skipping 663 matching lines @@
     web_event.type = WebInputEvent::MouseLeave;
   ForwardMouseEvent(web_event);
 }
 
 bool RenderWidgetHostViewMac::IsPopup() const {
   return popup_type_ != WebKit::WebPopupTypeNone;
 }
 
 BackingStore* RenderWidgetHostViewMac::AllocBackingStore(
     const gfx::Size& size) {
-  // TODO(thakis): Pass correct scale factor.
-  return new BackingStoreMac(render_widget_host_, size, 1.0);
+  // TODO(thakis): Register for backing scale factor change events and pass
+  // that on.
+  float scale = 1;
+  if (NSWindow* window = [cocoa_view_ window]) {
+    if ([window respondsToSelector:@selector(backingScaleFactor)])
+      scale = [window backingScaleFactor];
+    else
+      scale = [window userSpaceScaleFactor];
+  } else if (NSScreen* screen = [NSScreen mainScreen]) {
+    if ([screen respondsToSelector:@selector(backingScaleFactor)])
+      scale = [screen backingScaleFactor];
+    else
+      scale = [screen userSpaceScaleFactor];
+  }
+  return new BackingStoreMac(render_widget_host_, size, scale);
 }
 
 void RenderWidgetHostViewMac::CopyFromCompositingSurface(
     const gfx::Size& size,
     skia::PlatformCanvas* output,
     base::Callback<void(bool)> callback) {
   base::ScopedClosureRunner scoped_callback_runner(base::Bind(callback, false));
   if (!compositing_iosurface_.get() ||
       !compositing_iosurface_->HasIOSurface())
     return;
@@ skipping 1146 matching lines @@
       [[NSColor clearColor] set];
       NSRectFill(dirtyRect);
     }
 
     renderWidgetHostView_->compositing_iosurface_->DrawIOSurface(self);
     renderWidgetHostView_->AckPendingSwapBuffers();
     return;
   }
 
   if (backingStore) {
+    // Note: All coordinates are in view units, not pixels.
     gfx::Rect bitmapRect(0, 0,
                          backingStore->size().width(),
                          backingStore->size().height());
 
     // Specify the proper y offset to ensure that the view is rooted to the
     // upper left corner.  This can be negative, if the window was resized
     // smaller and the renderer hasn't yet repainted.
     int yOffset = NSHeight([self bounds]) - backingStore->size().height();
 
     gfx::Rect paintRect = bitmapRect.Intersect(damagedRect);
@@ skipping 992 matching lines @@
   if (!string) return NO;
 
   // If the user is currently using an IME, confirm the IME input,
   // and then insert the text from the service, the same as TextEdit and Safari.
   [self confirmComposition];
   [self insertText:string];
   return YES;
 }
 
 @end