Refactor win printing workflow to support print preview.

chrome/renderer/print_web_view_helper_win.cc

 // Copyright (c) 2011 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 "base/logging.h"
 #include "base/process_util.h"
 #include "chrome/common/render_messages.h"
 #include "chrome/common/render_messages_params.h"
@@ skipping 57 matching lines @@
                                    WebFrame* frame) {
   // Generate a memory-based metafile. It will use the current screen's DPI.
   // Each metafile contains a single page.
   scoped_ptr<printing::NativeMetafile> metafile(new printing::NativeMetafile);
   metafile->CreateDc(NULL, NULL);
   DCHECK(metafile->hdc());
   skia::PlatformDevice::InitializeDC(metafile->hdc());
 
   int page_number = params.page_number;
 
-  double content_width_in_points;
-  double content_height_in_points;
-  GetPageSizeAndMarginsInPoints(frame, page_number, params.params,
-      &content_width_in_points, &content_height_in_points, NULL, NULL, NULL,
-      NULL);
-
   // Calculate the dpi adjustment.
   float scale_factor = static_cast<float>(params.params.desired_dpi /
                                           params.params.dpi);
 
-  // Since WebKit extends the page width depending on the magical |scale_factor|
-  // we make sure the canvas covers the worst case scenario (x2.0 currently).
-  // PrintContext will then set the correct clipping region.
-  gfx::Size page_size(
-      static_cast<int>(content_width_in_points * params.params.max_shrink),
-      static_cast<int>(content_height_in_points * params.params.max_shrink));
-
   // Render page for printing.
-  RenderPage(page_size, &scale_factor, page_number, frame, &metafile,
-      params.params.supports_alpha_blend);
+  RenderPage(params.params, &scale_factor, page_number, frame, &metafile);
 
   // Close the device context to retrieve the compiled metafile.
   if (!metafile->CloseDc())
     NOTREACHED();
 
   // Get the size of the compiled metafile.
   uint32 buf_size = metafile->GetDataSize();
   DCHECK_GT(buf_size, 128u);
 
   ViewHostMsg_DidPrintPage_Params page_params;
@@ skipping 14 matching lines @@
   }
   metafile->CloseEmf();
   if (Send(new ViewHostMsg_DuplicateSection(
           routing_id(),
           page_params.metafile_data_handle,
           &page_params.metafile_data_handle))) {
     Send(new ViewHostMsg_DidPrintPage(routing_id(), page_params));
   }
 }
 
+void PrintWebViewHelper::CreatePreviewDocument(
+    const ViewMsg_PrintPages_Params& params, WebFrame* frame,
+    ViewHostMsg_DidPreviewDocument_Params* preview_params) {
+  int page_count = 0;
+  ViewMsg_Print_Params printParams = params.params;

[Lei Zhang, 2011/01/26 19:45:26]

Now that you've renamed print_params to preview_params, can you change
printParams to print_params to be consistent with all the other variables?

[kmadhusu, 2011/01/26 20:00:51]

Done.

+  UpdatePrintableSizeInPrintParameters(frame, NULL, &printParams);
+  PrepareFrameAndViewForPrint prep_frame_view(printParams, frame, NULL,
+                                              frame->view());
+  page_count = prep_frame_view.GetExpectedPageCount();
+  if (!page_count)
+    return;
+
+  // NOTE: This is an enhanced-format metafile(EMF) which has an appearance of
+  // single page metafile. For print preview, we need a metafile with multiple
+  // pages.
+  // TODO(kmadhusu): Use a PDF metafile to support multiple pages. After "Skia
+  // PDF backend" work is completed for windows, make changes to replace this
+  // EMF with PDF metafile.
+  // http://code.google.com/p/chromium/issues/detail?id=62889
+  scoped_ptr<printing::NativeMetafile> metafile(new printing::NativeMetafile);
+  metafile->CreateDc(NULL, NULL);
+  DCHECK(metafile->hdc());
+  skia::PlatformDevice::InitializeDC(metafile->hdc());
+
+  // Calculate the dpi adjustment.
+  float shrink = static_cast<float>(params.params.desired_dpi /
+                                    params.params.dpi);
+
+  if (params.pages.empty()) {
+    for (int i = 0; i < page_count; ++i) {
+      float scale_factor = shrink;
+      RenderPage(params.params, &scale_factor, i, frame, &metafile);
+    }
+  } else {
+    for (size_t i = 0; i < params.pages.size(); ++i) {
+      if (params.pages[i] >= page_count)
+        break;
+      float scale_factor = shrink;
+      RenderPage(params.params, &scale_factor,
+          static_cast<int>(params.pages[i]), frame, &metafile);
+    }
+  }
+
+  // Close the device context to retrieve the compiled metafile.
+  if (!metafile->CloseDc())
+    NOTREACHED();
+
+  // Get the size of the compiled metafile.
+  uint32 buf_size = metafile->GetDataSize();
+  DCHECK_GT(buf_size, 128u);
+
+  preview_params->document_cookie = params.params.document_cookie;
+  preview_params->data_size = 0;
+  preview_params->metafile_data_handle = NULL;
+
+  if (CopyMetafileDataToSharedMem(metafile.get(),
+          &(preview_params->metafile_data_handle))) {
+    preview_params->data_size = buf_size;
+  }
+  metafile->CloseEmf();
+  if (!Send(new ViewHostMsg_DuplicateSection(
+          routing_id(),
+          preview_params->metafile_data_handle,
+          &preview_params->metafile_data_handle))) {
+    NOTREACHED() << "Send message failed.";
+  }
+}
+
 void PrintWebViewHelper::RenderPage(
-    const gfx::Size& page_size, float* scale_factor, int page_number,
-    WebFrame* frame, scoped_ptr<printing::NativeMetafile>* metafile,
-    bool supports_alpha_blend) {
+    const ViewMsg_Print_Params& params, float* scale_factor, int page_number,
+    WebFrame* frame, scoped_ptr<printing::NativeMetafile>* metafile) {
   HDC hdc = (*metafile)->hdc();
   DCHECK(hdc);
 
-  int width = page_size.width();
-  int height = page_size.height();
+  double content_width_in_points;
+  double content_height_in_points;
+  GetPageSizeAndMarginsInPoints(frame, page_number, params,
+      &content_width_in_points, &content_height_in_points, NULL, NULL, NULL,
+      NULL);
+
+  // Since WebKit extends the page width depending on the magical scale factor
+  // we make sure the canvas covers the worst case scenario (x2.0 currently).
+  // PrintContext will then set the correct clipping region.
+  int width = static_cast<int>(content_width_in_points * params.max_shrink);
+  int height = static_cast<int>(content_height_in_points * params.max_shrink);
+
 #if 0
   // TODO(maruel): This code is kept for testing until the 100% GDI drawing
   // code is stable. maruels use this code's output as a reference when the
   // GDI drawing code fails.
 
   // Mix of Skia and GDI based.
   skia::PlatformCanvas canvas(width, height, true);
   canvas.drawARGB(255, 255, 255, 255, SkXfermode::kSrc_Mode);
   float webkit_scale_factor = frame->printPage(page_number, &canvas);
   if (*scale_factor <= 0 || webkit_scale_factor <= 0) {
@@ skipping 28 matching lines @@
     NOTREACHED() << "Printing page " << page_number << " failed.";
   } else {
     // Update the dpi adjustment with the "page |scale_factor|" calculated in
     // webkit.
     *scale_factor /= webkit_scale_factor;
   }
 #endif
 
   skia::VectorPlatformDevice* platform_device =
       static_cast<skia::VectorPlatformDevice*>(canvas.getDevice());
-  if (platform_device->alpha_blend_used() && !supports_alpha_blend) {
+  if (platform_device->alpha_blend_used() && !params.supports_alpha_blend) {
     // Close the device context to retrieve the compiled metafile.
     if (!(*metafile)->CloseDc())
       NOTREACHED();
 
     scoped_ptr<printing::NativeMetafile> metafile2(
         new printing::NativeMetafile);
     // Page used alpha blend, but printer doesn't support it.  Rewrite the
     // metafile and flatten out the transparency.
     HDC bitmap_dc = CreateCompatibleDC(GetDC(NULL));
     if (!bitmap_dc) {
@@ skipping 57 matching lines @@
   // Copy the bits into shared memory.
   if (!metafile->GetData(shared_buf.memory(), buf_size)) {
     NOTREACHED() << "GetData() failed";
     shared_buf.Unmap();
     return false;
   }
   shared_buf.GiveToProcess(base::GetCurrentProcessHandle(), shared_mem_handle);
   shared_buf.Unmap();
   return true;
 }