Implement PrintPageAsJPEG feature for Print Preview

src/chrome/renderer/print_web_view_helper.cc

 // 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 "chrome/renderer/print_web_view_helper.h"
 
 #include "app/l10n_util.h"
+#include "base/gfx/jpeg_codec.h"
 #include "base/logging.h"
 #include "chrome/common/render_messages.h"
 #include "chrome/renderer/render_view.h"
 #include "grit/generated_resources.h"
 #include "printing/units.h"
 #include "webkit/api/public/WebFrame.h"
 #include "webkit/api/public/WebRect.h"
 #include "webkit/api/public/WebScreenInfo.h"
 #include "webkit/api/public/WebSize.h"
 #include "webkit/api/public/WebURLRequest.h"
@@ skipping 114 matching lines @@
       }
     } else {
       for (size_t i = 0; i < params.pages.size(); ++i) {
         page_params.page_number = params.pages[i];
         PrintPage(page_params, prep_frame_view.GetPrintCanvasSize(), frame);
       }
     }
   }
 }
 
+void PrintWebViewHelper::PrintPageAsJPEG(
+    const ViewMsg_PrintPage_Params& params,
+    WebFrame* frame,
+    float zoom_factor,
+    std::vector<unsigned char>* image_data) {
+  PrepareFrameAndViewForPrint prep_frame_view(params.params,
+                                              frame,
+                                              frame->view());
+  const gfx::Size& canvas_size(prep_frame_view.GetPrintCanvasSize());
+
+  // Since WebKit extends the page width depending on the magical shrink
+  // factor we make sure the canvas covers the worst case scenario
+  // (x2.0 currently).  PrintContext will then set the correct clipping region.
+  int size_x = static_cast<int>(canvas_size.width() * params.params.max_shrink);
+  int size_y = static_cast<int>(canvas_size.height() *
+      params.params.max_shrink);
+
+  // Access the bitmap from the canvas device.
+  skia::PlatformCanvas canvas(size_x, size_y, true);
+  frame->printPage(params.page_number, &canvas);
+  const SkBitmap& bitmap = canvas.getDevice()->accessBitmap(false);
+
+  // Encode the SkBitmap to jpeg.
+  SkAutoLockPixels image_lock(bitmap);
+  bool encoded = JPEGCodec::Encode(
+      reinterpret_cast<unsigned char*>(bitmap.getAddr32(0, 0)),
+      JPEGCodec::FORMAT_BGRA,
+      static_cast<int>(bitmap.width() * zoom_factor),
+      static_cast<int>(bitmap.height() * zoom_factor),
+      static_cast<int>(bitmap.rowBytes()),
+      90,
+      image_data);
+  DCHECK(encoded);
+}
+
 bool PrintWebViewHelper::Send(IPC::Message* msg) {
   return render_view_->Send(msg);
 }
 
 int32 PrintWebViewHelper::routing_id() {
   return render_view_->routing_id();
 }
 
 WebRect PrintWebViewHelper::windowRect() {
   NOTREACHED();
@@ skipping 13 matching lines @@
 WebScreenInfo PrintWebViewHelper::screenInfo() {
   NOTREACHED();
   return WebScreenInfo();
 }
 
 void PrintWebViewHelper::DidStopLoading(WebView* webview) {
   DCHECK(print_pages_params_.get() != NULL);
   DCHECK_EQ(webview, print_web_view_.get());
   PrintPages(*print_pages_params_.get(), print_web_view_->GetMainFrame());
 }