Implement native metafile for printing on Linux.

printing/pdf_ps_metafile_linux.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 "printing/pdf_ps_metafile_linux.h"
+
+#include <stdio.h>
+
+#include <cairo-pdf.h>
+#include <cairo-ps.h>
+
+#include "base/file_util.h"
+#include "base/logging.h"
+
+namespace printing {
+
+PdfPsMetafile::PdfPsMetafile(const FileFormat& format)
+    : format_(format),
+      surface_(NULL), context_(NULL),
+      page_surface_(NULL), page_context_(NULL) {
+
+  // Create an 1 by 1 Cairo surface for entire PDF/PS file.
+  // The size for each page will be overwritten later in StartPage().
+  switch (format_) {
+    case PDF: {
+      surface_ = cairo_pdf_surface_create_for_stream(WriteCairoStream,
+                                                     &all_pages_, 1, 1);
+    }
+    break;
+
+    case PS: {
+      surface_ = cairo_ps_surface_create_for_stream(WriteCairoStream,
+                                                    &all_pages_, 1, 1);
+    }
+    break;
+
+    default:
+      NOTREACHED();
+      return;
+  }
+
+  // Cairo always returns a valid pointer.
+  // Hence, we have to check if it points to a "nil" object.
+  if (!IsSurfaceValid(surface_)) {
+    DLOG(ERROR) << "Cannot create Cairo surface for PdfPsMetafile!";
+    cairo_surface_destroy(surface_);
+    return;
+  }
+
+  // Create a context.
+  context_ = cairo_create(surface_);
+  if (!IsContextValid(context_)) {
+    DLOG(ERROR) << "Cannot create Cairo context for PdfPsMetafile!";
+    cairo_destroy(context_);
+    cairo_surface_destroy(surface_);
+    return;
+  }
+
+  // Since |context_| will keep a reference of |surface_|, we can decreace
+  // surface's reference count by one safely.
+  cairo_surface_destroy(surface_);
+}
+
+PdfPsMetafile::PdfPsMetafile(const FileFormat& format,
+                             const void* src_buffer,
+                             size_t src_buffer_size)
+    : format_(format),
+      surface_(NULL), context_(NULL),
+      page_surface_(NULL), page_context_(NULL) {
+
+  all_pages_ = std::string(reinterpret_cast<const char*>(src_buffer),
+                           src_buffer_size);
+}
+
+PdfPsMetafile::~PdfPsMetafile() {
+  // Releases resources if we forgot to do so.
+  Close();
+}
+
+bool PdfPsMetafile::StartPage(double width_in_points, double height_in_points) {
+  DCHECK(IsSurfaceValid(surface_));
+  DCHECK(IsContextValid(context_));
+  DCHECK(!page_surface_ && !page_context_);
+  DCHECK_GT(width_in_points, 0.);
+  DCHECK_GT(height_in_points, 0.);
+
+  // Create a target surface for the new page.
+  // Cairo 1.6.0 does NOT allow the first argument be NULL,
+  // but some newer versions do support NULL pointer.
+  switch (format_) {
+    case PDF: {
+      page_surface_ = cairo_pdf_surface_create_for_stream(WriteCairoStream,
+                                                          &current_page_,
+                                                          width_in_points,
+                                                          height_in_points);
+    }
+    break;
+
+    case PS: {
+      page_surface_ = cairo_ps_surface_create_for_stream(WriteCairoStream,
+                                                         &current_page_,
+                                                         width_in_points,
+                                                         height_in_points);
+    }
+    break;
+
+    default:
+      NOTREACHED();
+      return false;
+  }
+
+  // Cairo always returns a valid pointer.
+  // Hence, we have to check if it points to a "nil" object.
+  if (!IsSurfaceValid(page_surface_)) {
+    DLOG(ERROR) << "Cannot create Cairo surface for PdfPsMetafile!";
+    cairo_surface_destroy(page_surface_);
+    return false;
+  }
+
+  // Create a context.
+  page_context_ = cairo_create(page_surface_);
+  if (!IsContextValid(page_context_)) {
+    DLOG(ERROR) << "Cannot create Cairo context for PdfPsMetafile!";
+    cairo_destroy(page_context_);
+    cairo_surface_destroy(page_surface_);
+    return false;
+  }
+
+  // Since |page_context_| will keep a reference of |page_surface_|, we can
+  // decreace surface's reference count by one safely.
+  cairo_surface_destroy(page_surface_);
+
+  return true;
+}
+
+void PdfPsMetafile::FinishPage(float shrink) {
+  DCHECK(IsSurfaceValid(surface_));
+  DCHECK(IsContextValid(context_));
+  DCHECK(IsSurfaceValid(page_surface_));
+  DCHECK(IsContextValid(page_context_));
+
+  // Flush all rendering for current page.
+  cairo_surface_flush(page_surface_);
+
+  // TODO(myhuang): Use real page settings.
+  // We hard-coded page settings here for testing purpose.
+  // The paper size is US Letter (8.5 in. by 11 in.).
+  // The default margins are:
+  //   Left = 0.25 in.
+  //   Right = 0.25 in.
+  //   Top = 0.25 in.
+  //   Bottom = 0.56 in.
+  const double kDPI = 72.0;  // Dots (points) per inch.
+  const double kWidthInInch = 8.5;
+  const double kHeightInInch = 11.0;
+  const double kWidthInPoint = kWidthInInch * kDPI;
+  const double kHeightInPoint = kHeightInInch * kDPI;
+  switch (format_) {
+    case PDF: {
+      cairo_pdf_surface_set_size(surface_, kWidthInPoint, kHeightInPoint);
+    }
+    break;
+
+    case PS: {
+      cairo_ps_surface_set_size(surface_, kWidthInPoint, kHeightInPoint);
+    }
+    break;
+
+    default:
+      NOTREACHED();
+      return;
+  }
+
+  // Save context's states.
+  cairo_save(context_);
+  // Copy current page onto the surface of final result.
+  // Margins are done by coordinates transformation.
+  // Please NOTE that we have to call cairo_scale() before we call
+  // cairo_set_source_surface().
+  const double scale_factor = 1. / shrink;
+  cairo_scale(context_, scale_factor, scale_factor);
+  const double kLeftMarginInInch = 0.25;
+  const double kTopMarginInInch = 0.25;
+  const double kLeftMarginInPoint = kLeftMarginInInch * kDPI;
+  const double kTopMarginInPoint = kTopMarginInInch * kDPI;
+  const double kScaledLeftMarginInPoint = kLeftMarginInPoint * shrink;
+  const double kScaledTopMarginInPoint = kTopMarginInPoint * shrink;
+  cairo_set_source_surface(context_,
+                           page_surface_,
+                           kScaledLeftMarginInPoint,
+                           kScaledTopMarginInPoint);
+  // In Cairo 1.6.0, if we use the following API, either the renderer will
+  // crash, or we will get an empty page. This might be a bug in Cairo.
+  // cairo_set_operator(context_, CAIRO_OPERATOR_SOURCE);
+  const double kRightMarginInInch = 0.25;
+  const double kBottomMarginInInch = 0.56;
+  const double kPrintableWidthInInch =
+      kWidthInInch - kLeftMarginInInch - kRightMarginInInch;
+  const double kPrintableHeightInInch =
+      kHeightInInch - kTopMarginInInch - kBottomMarginInInch;
+  const double kScaledPrintableWidthInPoint =
+      kPrintableWidthInInch * kDPI * shrink;
+  const double kScaledPrintableHeightInPoint =
+      kPrintableHeightInInch * kDPI * shrink;
+  cairo_rectangle(context_,
+                  kScaledLeftMarginInPoint,
+                  kScaledTopMarginInPoint,
+                  kScaledPrintableWidthInPoint,
+                  kScaledPrintableHeightInPoint);
+  cairo_fill(context_);
+
+  // Finishing the duplication of current page.
+  cairo_show_page(context_);
+  cairo_surface_flush(surface_);
+
+  // Destroy resoreces for current page.
+  cairo_destroy(page_context_);
+  page_context_ = NULL;
+  page_surface_ = NULL;
+  current_page_.clear();
+
+  // Restore context's states.
+  cairo_restore(context_);
+}
+
+void PdfPsMetafile::Close() {
+  if (surface_ != NULL && IsSurfaceValid(surface_)) {
+    cairo_surface_finish(surface_);
+    surface_ = NULL;
+  }
+  if (context_ != NULL && IsContextValid(context_)) {
+    cairo_destroy(context_);
+    context_ = NULL;
+  }
+}
+
+unsigned int PdfPsMetafile::GetDataSize() const {
+  DCHECK(!surface_ && !context_);
+
+  return all_pages_.size();
+}
+
+void PdfPsMetafile::GetData(void* dst_buffer, size_t dst_buffer_size) const {
+  DCHECK(!surface_ && !context_);
+  DCHECK(dst_buffer);
+
+  size_t data_size = GetDataSize();
+  if (data_size < dst_buffer_size)
+    dst_buffer_size = data_size;
+  memcpy(dst_buffer, all_pages_.data(), dst_buffer_size);
+}
+
+bool PdfPsMetafile::SaveTo(const FilePath& filename) const {
+  DCHECK(!surface_ && !context_);
+
+  const unsigned int data_size = GetDataSize();
+  const unsigned int bytes_written =
+      file_util::WriteFile(filename, all_pages_.data(), data_size);
+  if (bytes_written != data_size) {
+    DLOG(ERROR) << "Failed to save file: " << filename.value();
+    return false;
+  }
+
+  return true;
+}
+
+cairo_status_t PdfPsMetafile::WriteCairoStream(void* dst_buffer,
+                                               const unsigned char* src_data,
+                                               unsigned int src_data_length) {
+  DCHECK(dst_buffer);
+  DCHECK(src_data);
+
+  std::string* buffer = reinterpret_cast<std::string* >(dst_buffer);
+  buffer->append(reinterpret_cast<const char*>(src_data), src_data_length);
+
+  return CAIRO_STATUS_SUCCESS;
+}
+
+bool PdfPsMetafile::IsSurfaceValid(cairo_surface_t* surface) const {
+  return cairo_surface_status(surface) == CAIRO_STATUS_SUCCESS;
+}
+
+bool PdfPsMetafile::IsContextValid(cairo_t* context) const {
+  return cairo_status(context) == CAIRO_STATUS_SUCCESS;
+}
+
+}  // namespace printing
+