text: // 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/renderer/printing/print_web_view_helper.h"
  
  #include "base/logging.h"
  #include "base/memory/scoped_ptr.h"
  #include "base/metrics/histogram.h"
  #include "base/process_util.h"
  #include "base/win/scoped_gdi_object.h"
  #include "base/win/scoped_hdc.h"
  #include "base/win/scoped_select_object.h"
  #include "chrome/common/print_messages.h"
  #include "printing/metafile.h"
  #include "printing/metafile_impl.h"
  #include "printing/metafile_skia_wrapper.h"
  #include "printing/page_size_margins.h"
  #include "printing/units.h"
  #include "skia/ext/platform_device.h"
  #include "skia/ext/refptr.h"
  #include "skia/ext/vector_canvas.h"
  #include "third_party/WebKit/public/web/WebFrame.h"
  #include "ui/gfx/gdi_util.h"
  #include "ui/gfx/point.h"
  #include "ui/gfx/rect.h"
  #include "ui/gfx/size.h"
  
  namespace printing {
  
  using WebKit::WebFrame;
  
  void PrintWebViewHelper::PrintPageInternal(
      const PrintMsg_PrintPage_Params& params,
      const gfx::Size& canvas_size,
      WebFrame* frame) {
    // Generate a memory-based metafile. It will use the current screen's DPI.
    // Each metafile contains a single page.
    scoped_ptr<NativeMetafile> metafile(new NativeMetafile);
    metafile->Init();
    DCHECK(metafile->context());
    skia::InitializeDC(metafile->context());
  
    int page_number = params.page_number;
  
    // Calculate the dpi adjustment.
    // Browser will render context using desired_dpi, so we need to calculate
    // adjustment factor to play content on the printer DC later during the
    // actual printing.
    double actual_shrink = static_cast<float>(params.params.desired_dpi /
                                              params.params.dpi);
    gfx::Size page_size_in_dpi;
    gfx::Rect content_area_in_dpi;
  
    // Render page for printing.
    RenderPage(params.params, page_number, frame, false, metafile.get(),
               &actual_shrink, &page_size_in_dpi, &content_area_in_dpi);
  
    // Close the device context to retrieve the compiled metafile.
    if (!metafile->FinishDocument())
      NOTREACHED();
  
    if (!params.params.supports_alpha_blend && metafile->IsAlphaBlendUsed()) {
      scoped_ptr<NativeMetafile> raster_metafile(
          metafile->RasterizeAlphaBlend());
      if (raster_metafile.get())
        metafile.swap(raster_metafile);
    }
  
    // Get the size of the compiled metafile.
    uint32 buf_size = metafile->GetDataSize();
    DCHECK_GT(buf_size, 128u);
  
    PrintHostMsg_DidPrintPage_Params page_params;
    page_params.data_size = buf_size;
    page_params.metafile_data_handle = NULL;
    page_params.page_number = page_number;
    page_params.document_cookie = params.params.document_cookie;
    page_params.actual_shrink = actual_shrink;
    page_params.page_size = page_size_in_dpi;
    page_params.content_area = content_area_in_dpi;
  
    if (!CopyMetafileDataToSharedMem(metafile.get(),
                                     &(page_params.metafile_data_handle))) {
      page_params.data_size = 0;
    }
  
    Send(new PrintHostMsg_DidPrintPage(routing_id(), page_params));
  }
  
  bool PrintWebViewHelper::RenderPreviewPage(
      int page_number,
      const PrintMsg_Print_Params& print_params) {
    // Calculate the dpi adjustment.
    double actual_shrink = static_cast<float>(print_params.desired_dpi /
                                              print_params.dpi);
    scoped_ptr<Metafile> draft_metafile;
    Metafile* initial_render_metafile = print_preview_context_.metafile();
  
    if (print_preview_context_.IsModifiable() && is_print_ready_metafile_sent_) {
      draft_metafile.reset(new PreviewMetafile);
      initial_render_metafile = draft_metafile.get();
    }
  
    base::TimeTicks begin_time = base::TimeTicks::Now();
    RenderPage(print_params, page_number, print_preview_context_.prepared_frame(),
               true, initial_render_metafile, &actual_shrink, NULL, NULL);
    print_preview_context_.RenderedPreviewPage(
        base::TimeTicks::Now() - begin_time);
  
    if (draft_metafile.get()) {
      draft_metafile->FinishDocument();
    } else if (print_preview_context_.IsModifiable() &&
               print_preview_context_.generate_draft_pages()) {
      DCHECK(!draft_metafile.get());
      draft_metafile.reset(
          print_preview_context_.metafile()->GetMetafileForCurrentPage());
    }
    return PreviewPageRendered(page_number, draft_metafile.get());
  }
  
  void PrintWebViewHelper::RenderPage(
      const PrintMsg_Print_Params& params, int page_number, WebFrame* frame,
      bool is_preview, Metafile* metafile, double* actual_shrink,
      gfx::Size* page_size_in_dpi, gfx::Rect* content_area_in_dpi) {
    PageSizeMargins page_layout_in_points;
    double css_scale_factor = 1.0f;
    ComputePageLayoutInPointsForCss(frame, page_number, params,
                                    ignore_css_margins_, &css_scale_factor,
                                    &page_layout_in_points);
    gfx::Size page_size;
    gfx::Rect content_area;
    GetPageSizeAndContentAreaFromPageLayout(page_layout_in_points, &page_size,
                                            &content_area);
    int dpi = static_cast<int>(params.dpi);
    // Calculate the actual page size and content area in dpi.
    if (page_size_in_dpi) {
      *page_size_in_dpi = gfx::Size(
          static_cast<int>(ConvertUnitDouble(page_size.width(), kPointsPerInch,
                                             dpi)),
          static_cast<int>(ConvertUnitDouble(page_size.height(), kPointsPerInch,
                                             dpi)));
    }
  
    if (content_area_in_dpi) {
      *content_area_in_dpi = gfx::Rect(
          static_cast<int>(ConvertUnitDouble(content_area.x(), kPointsPerInch,
                                             dpi)),
          static_cast<int>(ConvertUnitDouble(content_area.y(), kPointsPerInch,
                                             dpi)),
          static_cast<int>(ConvertUnitDouble(content_area.width(), kPointsPerInch,
                                             dpi)),
          static_cast<int>(ConvertUnitDouble(content_area.height(),
                                             kPointsPerInch, dpi)));
    }
  
    if (!is_preview) {
      // 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.
      page_size = gfx::Size(
          static_cast<int>(page_layout_in_points.content_width *
                           params.max_shrink),
          static_cast<int>(page_layout_in_points.content_height *
                           params.max_shrink));
    }
  
    float webkit_page_shrink_factor = frame->getPrintPageShrink(page_number);
    float scale_factor = css_scale_factor * webkit_page_shrink_factor;
  
    gfx::Rect canvas_area =
        params.display_header_footer ? gfx::Rect(page_size) : content_area;
  
    SkDevice* device = metafile->StartPageForVectorCanvas(
        page_size, canvas_area, scale_factor);
    DCHECK(device);
    // The printPage method may take a reference to the canvas we pass down, so it
    // can't be a stack object.
    skia::RefPtr<skia::VectorCanvas> canvas =
        skia::AdoptRef(new skia::VectorCanvas(device));
  
    if (is_preview) {
      MetafileSkiaWrapper::SetMetafileOnCanvas(*canvas, metafile);
      skia::SetIsDraftMode(*canvas, is_print_ready_metafile_sent_);
      skia::SetIsPreviewMetafile(*canvas, is_preview);
    }
  
    if (params.display_header_footer) {
      // |page_number| is 0-based, so 1 is added.
      PrintHeaderAndFooter(canvas.get(), page_number + 1,
          print_preview_context_.total_page_count(), scale_factor,
          page_layout_in_points, *header_footer_info_, params);
    }
  
    float webkit_scale_factor = RenderPageContent(frame, page_number, canvas_area,
                                                  content_area, scale_factor,
                                                  canvas.get());
  
    if (*actual_shrink <= 0 || webkit_scale_factor <= 0) {
      NOTREACHED() << "Printing page " << page_number << " failed.";
    } else {
      // While rendering certain plugins (PDF) to metafile, we might need to
      // set custom scale factor. Update |actual_shrink| with custom scale
      // if it is set on canvas.
      // TODO(gene): We should revisit this solution for the next versions.
      // Consider creating metafile of the right size (or resizable)
      // https://code.google.com/p/chromium/issues/detail?id=126037
      if (!MetafileSkiaWrapper::GetCustomScaleOnCanvas(
              *canvas, actual_shrink)) {
        // Update the dpi adjustment with the "page |actual_shrink|" calculated in
        // webkit.
        *actual_shrink /= (webkit_scale_factor * css_scale_factor);
      }
    }
  
    bool result = metafile->FinishPage();
    DCHECK(result);
  }
  
  bool PrintWebViewHelper::CopyMetafileDataToSharedMem(
      Metafile* metafile, base::SharedMemoryHandle* shared_mem_handle) {
    uint32 buf_size = metafile->GetDataSize();
    base::SharedMemory shared_buf;
    if (buf_size >= kMetafileMaxSize) {
      NOTREACHED() << "Buffer too large: " << buf_size;
      return false;
    }
  
    // Allocate a shared memory buffer to hold the generated metafile data.
    if (!shared_buf.CreateAndMapAnonymous(buf_size)) {
      NOTREACHED() << "Buffer allocation failed";
      return false;
    }
  
    // 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();
  
    Send(new PrintHostMsg_DuplicateSection(routing_id(), *shared_mem_handle,
                                           shared_mem_handle));
    return true;
  }
  
  }  // namespace printing
  