Printing: Load the source PDF only once.

pdf/pdf.h

 // Copyright (c) 2010 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.
 
 #ifndef PDF_PDF_H_
 #define PDF_PDF_H_
 
 #include "ppapi/c/ppb.h"
 #include "ppapi/cpp/module.h"
 
@@ skipping 18 matching lines @@
   bool Init() override;
   pp::Instance* CreateInstance(PP_Instance instance) override;
 };
 
 int PPP_InitializeModule(PP_Module module_id,
                          PPB_GetInterface get_browser_interface);
 void PPP_ShutdownModule();
 const void* PPP_GetInterface(const char* interface_name);
 
 #if defined(OS_WIN)
-// |pdf_buffer| is the buffer that contains the entire PDF document to be
-//     rendered.
-// |buffer_size| is the size of |pdf_buffer| in bytes.
+// |pdf_handle| is the handle to the PDF document.
 // |page_number| is the 0-based index of the page to be rendered.
 // |dc| is the device context to render into.
 // |dpi| and |dpi_y| is the resolution. If the value is -1, the dpi from the DC
 //     will be used.
 // |bounds_origin_x|, |bounds_origin_y|, |bounds_width| and |bounds_height|
 //     specify a bounds rectangle within the DC in which to render the PDF
 //     page.
 // |fit_to_bounds| specifies whether the output should be shrunk to fit the
 //     supplied bounds if the page size is larger than the bounds in any
 //     dimension. If this is false, parts of the PDF page that lie outside
 //     the bounds will be clipped.
 // |stretch_to_bounds| specifies whether the output should be stretched to fit
 //     the supplied bounds if the page size is smaller than the bounds in any
 //     dimension.
 // If both |fit_to_bounds| and |stretch_to_bounds| are true, then
 //     |fit_to_bounds| is honored first.
 // |keep_aspect_ratio| If any scaling is to be done is true, this flag
 //     specifies whether the original aspect ratio of the page should be
 //     preserved while scaling.
 // |center_in_bounds| specifies whether the final image (after any scaling is
 //     done) should be centered within the given bounds.
 // |autorotate| specifies whether the final image should be rotated to match
 //     the output bound.
 // Returns false if the document or the page number are not valid.
-bool RenderPDFPageToDC(const void* pdf_buffer,
-                       int buffer_size,
+bool RenderPDFPageToDC(void* pdf_handle,
                        int page_number,
                        HDC dc,
                        int dpi,
                        int bounds_origin_x,
                        int bounds_origin_y,
                        int bounds_width,
                        int bounds_height,
                        bool fit_to_bounds,
                        bool stretch_to_bounds,
                        bool keep_aspect_ratio,
                        bool center_in_bounds,
                        bool autorotate);
 
 void SetPDFEnsureTypefaceCharactersAccessible(
     PDFEnsureTypefaceCharactersAccessible func);
 
 void SetPDFUseGDIPrinting(bool enable);
 #endif  // defined(OS_WIN)
 
-// |page_count| and |max_page_width| are optional and can be NULL.
+// All the out parameters are optional and can be NULL.
 // Returns false if the document is not valid.
+// Returns true on success. In which case, if |pdf_handle| is not NULL, then
+// the handle is guaranteed to be valid and not NULL. The caller takes
+// ownership of |pdf_handle| and must call ReleasePDFHandle() on it when done.
 bool GetPDFDocInfo(const void* pdf_buffer,
-                   int buffer_size, int* page_count,
-                   double* max_page_width);
+                   int buffer_size,
+                   int* page_count,
+                   double* max_page_width,
+                   void** pdf_handle);
+
+// Releases the handle received from GetPDFDocInfo().
+// |pdf_handle| can be NULL.
+void ReleasePDFHandle(void* pdf_handle);
 
 // Gets the dimensions of a specific page in a document.
-// |pdf_buffer| is the buffer that contains the entire PDF document to be
-//     rendered.
-// |pdf_buffer_size| is the size of |pdf_buffer| in bytes.
+// |pdf_handle| is the handle to the PDF document.
 // |page_number| is the page number that the function will get the dimensions
 //     of.
 // |width| is the output for the width of the page in points.
 // |height| is the output for the height of the page in points.
 // Returns false if the document or the page number are not valid.
-bool GetPDFPageSizeByIndex(const void* pdf_buffer,
-                           int pdf_buffer_size, int page_number,
-                           double* width, double* height);
+bool GetPDFPageSizeByIndex(void* pdf_handle,
+                           int page_number,
+                           double* width,
+                           double* height);
 
 // Renders PDF page into 4-byte per pixel BGRA color bitmap.
-// |pdf_buffer| is the buffer that contains the entire PDF document to be
-//     rendered.
-// |pdf_buffer_size| is the size of |pdf_buffer| in bytes.
+// |pdf_handle| is the handle to the PDF document.
 // |page_number| is the 0-based index of the page to be rendered.
 // |bitmap_buffer| is the output buffer for bitmap.
 // |bitmap_width| is the width of the output bitmap.
 // |bitmap_height| is the height of the output bitmap.
 // |dpi| is the resolutions.
 // |autorotate| specifies whether the final image should be rotated to match
 //     the output bound.
 // Returns false if the document or the page number are not valid.
-bool RenderPDFPageToBitmap(const void* pdf_buffer,
-                           int pdf_buffer_size,
+bool RenderPDFPageToBitmap(void* pdf_handle,
                            int page_number,
                            void* bitmap_buffer,
                            int bitmap_width,
                            int bitmap_height,
                            int dpi,
                            bool autorotate);
 
 }  // namespace chrome_pdf
 
 #endif  // PDF_PDF_H_