Adds kind-of-live thumbnail generation for a potential tab switcher.

chrome/browser/tab_contents/thumbnail_generator_unittest.cc

Index: chrome/browser/tab_contents/thumbnail_generator_unittest.cc
diff --git a/chrome/browser/tab_contents/thumbnail_generator_unittest.cc b/chrome/browser/tab_contents/thumbnail_generator_unittest.cc
new file mode 100755
index 0000000000000000000000000000000000000000..53a17fcff0557486663763d423257e409d960656
--- /dev/null
+++ b/chrome/browser/tab_contents/thumbnail_generator_unittest.cc
@@ -0,0 +1,179 @@
+// Copyright (c) 2009 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/basictypes.h"
+#include "chrome/browser/renderer_host/backing_store_manager.h"
+#include "chrome/browser/renderer_host/mock_render_process_host.h"
+#include "chrome/browser/renderer_host/test_render_view_host.h"
+#include "chrome/browser/tab_contents/thumbnail_generator.h"
+#include "chrome/common/notification_service.h"
+#include "chrome/common/render_messages.h"
+#include "chrome/common/transport_dib.h"
+#include "chrome/test/testing_profile.h"
+#include "testing/gtest/include/gtest/gtest.h"
+#include "skia/ext/platform_canvas.h"
+#include "third_party/skia/include/core/SkColorPriv.h"
+
+static const int kBitmapWidth = 100;
+static const int kBitmapHeight = 100;
+
+// TODO(brettw) enable this when GetThumbnailForBackingStore is implemented
+// for other platforms in thumbnail_generator.cc
+//#if defined(OS_WIN)
+// TODO(brettw) enable this on Windows after we clobber a build to see if the
+// failures of this on the buildbot can be resolved.
+#if 0
+
+class ThumbnailGeneratorTest : public testing::Test {
+ public:
+  ThumbnailGeneratorTest()
+      : profile_(),
+        process_(new MockRenderProcessHost(&profile_)),
+        widget_(process_, 1),
+        view_(&widget_) {
+    // Paiting will be skipped if there's no view.
+    widget_.set_view(&view_);
+
+    // Need to send out a create notification for the RWH to get hooked. This is
+    // a little scary in that we don't have a RenderView, but the only listener
+    // will want a RenderWidget, so it works out OK.
+    NotificationService::current()->Notify(
+        NotificationType::RENDER_VIEW_HOST_CREATED_FOR_TAB,
+        Source<RenderViewHostManager>(NULL),
+        Details<RenderViewHost>(reinterpret_cast<RenderViewHost*>(&widget_)));
+
+    transport_dib_.reset(TransportDIB::Create(kBitmapWidth * kBitmapHeight * 4,
+                                              1));
+
+    // We don't want to be sensitive to timing.
+    generator_.set_no_timeout(true);
+  }
+
+ protected:
+  // Indicates what bitmap should be sent with the paint message. _OTHER will
+  // only be retrned by CheckFirstPixel if the pixel is none of the others.
+  enum TransportType { TRANSPORT_BLACK, TRANSPORT_WHITE, TRANSPORT_OTHER };
+
+  void SendPaint(TransportType type) {
+    ViewHostMsg_PaintRect_Params params;
+    params.bitmap_rect = gfx::Rect(0, 0, kBitmapWidth, kBitmapHeight);
+    params.view_size = params.bitmap_rect.size();
+    params.flags = 0;
+
+    scoped_ptr<skia::PlatformCanvas> canvas(
+        transport_dib_->GetPlatformCanvas(kBitmapWidth, kBitmapHeight));
+    switch (type) {
+      case TRANSPORT_BLACK:
+        canvas->getTopPlatformDevice().accessBitmap(true).eraseARGB(
+            0xFF, 0, 0, 0);
+        break;
+      case TRANSPORT_WHITE:
+        canvas->getTopPlatformDevice().accessBitmap(true).eraseARGB(
+            0xFF, 0xFF, 0xFF, 0xFF);
+        break;
+      case TRANSPORT_OTHER:
+      default:
+        NOTREACHED();
+        break;
+    }
+
+    params.bitmap = transport_dib_->id();
+
+    ViewHostMsg_PaintRect msg(1, params);
+    widget_.OnMessageReceived(msg);
+  }
+
+  TransportType ClassifyFirstPixel(const SkBitmap& bitmap) {
+    // Returns the color of the first pixel of the bitmap. The bitmap must be
+    // non-empty.
+    SkAutoLockPixels lock(bitmap);
+    uint32 pixel = *bitmap.getAddr32(0, 0);
+
+    if (SkGetPackedA32(pixel) != 0xFF)
+      return TRANSPORT_OTHER;  // All values expect an opqaue alpha channel
+
+    if (SkGetPackedR32(pixel) == 0 &&
+        SkGetPackedG32(pixel) == 0 &&
+        SkGetPackedB32(pixel) == 0)
+      return TRANSPORT_BLACK;
+
+    if (SkGetPackedR32(pixel) == 0xFF &&
+        SkGetPackedG32(pixel) == 0xFF &&
+        SkGetPackedB32(pixel) == 0xFF)
+      return TRANSPORT_WHITE;
+
+    EXPECT_TRUE(false) << "Got weird color: " << pixel;
+    return TRANSPORT_OTHER;
+  }
+
+  MessageLoopForUI message_loop_;
+
+  TestingProfile profile_;
+
+  // This will get deleted when the last RHWH associated with it is destroyed.
+  MockRenderProcessHost* process_;
+
+  RenderWidgetHost widget_;
+  TestRenderWidgetHostView view_;
+  ThumbnailGenerator generator_;
+
+  scoped_ptr<TransportDIB> transport_dib_;
+
+ private:
+  // testing::Test implementation.
+  void SetUp() {
+  }
+  void TearDown() {
+  }
+};
+
+TEST_F(ThumbnailGeneratorTest, NoThumbnail) {
+  // This is the case where there is no thumbnail available on the tab and
+  // there is no backing store. There should be no image returned.
+  SkBitmap result = generator_.GetThumbnailForRenderer(&widget_);
+  EXPECT_TRUE(result.isNull());
+}
+
+// Tests basic thumbnail generation when a backing store is discarded.
+TEST_F(ThumbnailGeneratorTest, DiscardBackingStore) {
+  // First set up a backing store and then discard it.
+  SendPaint(TRANSPORT_BLACK);
+  widget_.WasHidden();
+  ASSERT_TRUE(BackingStoreManager::ExpireBackingStoreForTest(&widget_));
+  ASSERT_FALSE(widget_.GetBackingStore(false));
+
+  // The thumbnail generator should have stashed a thumbnail of the page.
+  SkBitmap result = generator_.GetThumbnailForRenderer(&widget_);
+  ASSERT_FALSE(result.isNull());
+  EXPECT_EQ(TRANSPORT_BLACK, ClassifyFirstPixel(result));
+}
+
+TEST_F(ThumbnailGeneratorTest, QuickShow) {
+  // Set up a hidden widget with a black cached thumbnail and an expired
+  // backing store.
+  SendPaint(TRANSPORT_BLACK);
+  widget_.WasHidden();
+  ASSERT_TRUE(BackingStoreManager::ExpireBackingStoreForTest(&widget_));
+  ASSERT_FALSE(widget_.GetBackingStore(false));
+
+  // Now show the widget and paint white.
+  widget_.WasRestored();
+  SendPaint(TRANSPORT_WHITE);
+
+  // The black thumbnail should still be cached because it hasn't processed the
+  // timer message yet.
+  SkBitmap result = generator_.GetThumbnailForRenderer(&widget_);
+  ASSERT_FALSE(result.isNull());
+  EXPECT_EQ(TRANSPORT_BLACK, ClassifyFirstPixel(result));
+
+  // Running the message loop will process the timer, which should expire the
+  // cached thumbnail. Asking again should give us a new one computed from the
+  // backing store.
+  message_loop_.RunAllPending();
+  result = generator_.GetThumbnailForRenderer(&widget_);
+  ASSERT_FALSE(result.isNull());
+  EXPECT_EQ(TRANSPORT_WHITE, ClassifyFirstPixel(result));
+}
+
+#endif