Refactor win printing workflow to support print preview.

chrome/renderer/print_web_view_helper_win.cc

Index: chrome/renderer/print_web_view_helper_win.cc
diff --git a/chrome/renderer/print_web_view_helper_win.cc b/chrome/renderer/print_web_view_helper_win.cc
index 94b622ff96eaa848ecfb147e0514ea92e5ef3e72..7e6e53dec76c312e1d40192c0c2b605a0f1210ea 100644
--- a/chrome/renderer/print_web_view_helper_win.cc
+++ b/chrome/renderer/print_web_view_helper_win.cc
@@ -75,26 +75,12 @@ void PrintWebViewHelper::PrintPage(const ViewMsg_PrintPage_Params& params,
 
   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())
@@ -129,15 +115,92 @@ void PrintWebViewHelper::PrintPage(const ViewMsg_PrintPage_Params& params,
   }
 }
 
+void PrintWebViewHelper::CreatePreviewDocument(

[vandebo (ex-Chrome), 2011/01/26 23:38:54]

nit: It'd be good to document the parameters to this method in the header.
Specifically because most methods tend to take one params struct so pointing out
what they are in this case would be useful.

[kmadhusu, 2011/01/27 00:13:54]

Done.

+    const ViewMsg_PrintPages_Params& params, WebFrame* frame,
+    ViewHostMsg_DidPreviewDocument_Params* preview_params) {
+  int page_count = 0;
+  ViewMsg_Print_Params print_params = params.params;
+  UpdatePrintableSizeInPrintParameters(frame, NULL, &print_params);
+  PrepareFrameAndViewForPrint prep_frame_view(print_params, 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
@@ -186,7 +249,7 @@ void PrintWebViewHelper::RenderPage(
 
   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();