Make the visual feedback for taking screenshot, with fix.

chrome/browser/ui/views/aura/screenshot_taker.cc

 // 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 "chrome/browser/ui/views/aura/screenshot_taker.h"
 
 #include <string>
 
+#include "ash/shell.h"
+#include "ash/shell_window_ids.h"
 #include "base/bind.h"
 #include "base/file_path.h"
 #include "base/file_util.h"
 #include "base/logging.h"
 #include "base/memory/ref_counted_memory.h"
 #include "base/stringprintf.h"
 #include "base/time.h"
 #include "chrome/browser/download/download_util.h"
 #include "chrome/browser/ui/window_snapshot/window_snapshot.h"
 #include "content/public/browser/browser_thread.h"
@@ skipping 38 matching lines @@
           screenshot_filename);
       if (!file_util::ReplaceFile(screenshot_path, real_path)) {
         LOG(ERROR) << "Failed to rename the file to " << real_path.value();
       }
     }
   } else {
     LOG(ERROR) << "Failed to save to " << screenshot_path.value();
   }
 }
 
+// How opaque should the layer that we flash onscreen to provide visual
+// feedback after the screenshot is taken be?
+const unsigned char kVisualFeedbackLayerOpacity = 64;
+
+// How long should the visual feedback layer be displayed?
+const int64 kVisualFeedbackLayerDisplayTimeMs = 100;
+
 }  // namespace
 
 ScreenshotTaker::ScreenshotTaker() {
 }
 
+ScreenshotTaker::~ScreenshotTaker() {
+}
+
 void ScreenshotTaker::HandleTakePartialScreenshot(
     aura::Window* window, const gfx::Rect& rect) {
   DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::UI));
 
   scoped_refptr<RefCountedBytes> png_data(new RefCountedBytes);
 
   bool is_logged_in = true;
 #if defined(OS_CHROMEOS)
   is_logged_in = chromeos::UserManager::Get()->user_is_logged_in();
 #endif
 
   if (browser::GrabWindowSnapshot(window, &png_data->data(), rect)) {
+    DisplayVisualFeedback(rect);
     content::BrowserThread::PostTask(
         content::BrowserThread::FILE, FROM_HERE,
         base::Bind(&SaveScreenshot, is_logged_in, png_data));
   } else {
     LOG(ERROR) << "Failed to grab the window screenshot";
   }
 }
 
 void ScreenshotTaker::HandleTakeScreenshot(aura::Window* window) {
   HandleTakePartialScreenshot(window, window->bounds());
 }
+
+void ScreenshotTaker::CloseVisualFeedbackLayer() {
+  visual_feedback_layer_.reset();
+}
+
+void ScreenshotTaker::DisplayVisualFeedback(const gfx::Rect& rect) {
+  visual_feedback_layer_.reset(new ui::Layer(ui::Layer::LAYER_SOLID_COLOR));
+  visual_feedback_layer_->SetColor(
+      SkColorSetA(SK_ColorWHITE, kVisualFeedbackLayerOpacity));

[Daniel Erat, 2012/03/01 17:15:40]

When I was adding Layer::LAYER_SOLID_COLOR, I thought it was the case that
partially-transparent colors didn't work; they showed up as opaque instead. 
Assuming that this is still an issue, it'd be better to use an opaque color here
and call Layer::SetOpacity(0.25).

[Jun Mukai, 2012/03/02 03:41:18]

Added SetOpacity.  Just curious, is this a bug?  When it's fixed, then, the
color would be much less opaque?

+  visual_feedback_layer_->SetBounds(rect);
+
+  ui::Layer* parent = ash::Shell::GetInstance()->GetContainer(
+      ash::internal::kShellWindowId_OverlayContainer)->layer();
+  parent->Add(visual_feedback_layer_.get());
+  visual_feedback_layer_->SetVisible(true);
+
+  MessageLoopForUI::current()->PostDelayedTask(
+      FROM_HERE,
+      base::Bind(&ScreenshotTaker::CloseVisualFeedbackLayer,
+                 base::Unretained(this)),
+      base::TimeDelta::FromMilliseconds(kVisualFeedbackLayerDisplayTimeMs));
+}