Implement --svg-embed-bitmap: saving bitmaps in svg as external files.

3rdparty/poppler/git/CairoOutputDev.h

@@ -272,7 +272,7 @@ protected:
   cairo_filter_t getFilterForSurface(cairo_surface_t *image,
 				     GBool interpolate);
   GBool getStreamData (Stream *str, char **buffer, int *length);
-  void setMimeData(Stream *str, Object *ref, cairo_surface_t *image);
+  virtual void setMimeData(Stream *str, Object *ref, cairo_surface_t *image);
   void fillToStrokePathClip(GfxState *state);
   void alignStrokeCoords(GfxSubpath *subpath, int i, double *x, double *y);
 

src/BackgroundRenderer/CairoBackgroundRenderer.cc

@@ -19,8 +19,7 @@
 
 namespace pdf2htmlEX {
 
-using std::string;
+using namespace std;
-using std::ifstream;
 
 CairoBackgroundRenderer::CairoBackgroundRenderer(HTMLRenderer * html_renderer, const Param & param)
     : CairoOutputDev()
@@ -29,6 +28,15 @@ CairoBackgroundRenderer::CairoBackgroundRenderer(HTMLRenderer * html_renderer, c
     , surface(nullptr)
 { }
 
+CairoBackgroundRenderer::~CairoBackgroundRenderer()
+{
+    for(auto i = bitmaps_ref_count.begin(); i != bitmaps_ref_count.end(); ++i)
+    {
+        if (i->second == 0)
+            html_renderer->tmp_files.add(this->get_bitmap_path(i->first));
+    }
+}
+
 void CairoBackgroundRenderer::drawChar(GfxState *state, double x, double y,
         double dx, double dy,
         double originX, double originY,
@@ -86,6 +94,8 @@ bool CairoBackgroundRenderer::render_page(PDFDoc * doc, int pageno)
     cairo_t * cr = cairo_create(surface);
     setCairo(cr);
 
+    bitmaps_in_current_page.resize(0);
+
     bool process_annotation = param.process_annotation;
     doc->displayPage(this, pageno, param.h_dpi, param.v_dpi,
             0, 
@@ -131,6 +141,10 @@ bool CairoBackgroundRenderer::render_page(PDFDoc * doc, int pageno)
         }
     }
 
+    // the svg file is actually used, so add its bitmaps' ref count.
+    for (auto i = bitmaps_in_current_page.begin(); i != bitmaps_in_current_page.end(); i++)
+        ++bitmaps_ref_count[*i];
+
     return true;
 }
 
@@ -138,7 +152,19 @@ void CairoBackgroundRenderer::embed_image(int pageno)
 {
     auto & f_page = *(html_renderer->f_curpage);
     
-    f_page << "<img class=\"" << CSS::FULL_BACKGROUND_IMAGE_CN 
+    // SVGs introduced by <img> or background-image can't have external resources;
+    // SVGs introduced by <embed> and <object> can, but they are more expensive for browsers.
+    // So we use <img> if the SVG contains no external bitmaps, and use <embed> otherwise.
+    // See also:
+    //   https://developer.mozilla.org/en-US/docs/Web/SVG/SVG_as_an_Image
+    //   http://stackoverflow.com/questions/4476526/do-i-use-img-object-or-embed-for-svg-files
+
+    if (param.svg_embed_bitmap || bitmaps_in_current_page.empty())
+        f_page << "<img";
+    else
+        f_page << "<embed";
+
+    f_page << " class=\"" << CSS::FULL_BACKGROUND_IMAGE_CN
         << "\" alt=\"\" src=\"";
 
     if(param.embed_image)
@@ -156,6 +182,56 @@ void CairoBackgroundRenderer::embed_image(int pageno)
     f_page << "\"/>";
 }
 
+// use object number as bitmap file name, without pageno prefix,
+// because a bitmap may be shared by multiple pages.
+const char* CairoBackgroundRenderer::get_bitmap_path(int id)
+{
+    return html_renderer->str_fmt("%s/%d.jpg", param.dest_dir.c_str(), id);
+}
+// Override CairoOutputDev::setMimeData() and dump bitmaps in SVG to external files.
+void CairoBackgroundRenderer::setMimeData(Stream *str, Object *ref, cairo_surface_t *image)
+{
+    if (param.svg_embed_bitmap)
+    {
+        CairoOutputDev::setMimeData(str, ref, image);
+        return;
+    }
+
+    // TODO dump bitmaps in other formats.
+    if (str->getKind() != strDCT)
+        return;
+
+    // TODO inline image?
+    if (ref == nullptr || !ref->isRef())
+        return;
+
+    int imgId = ref->getRef().num;
+    auto uri = strdup((char*) html_renderer->str_fmt("%d.jpg", imgId));
+    auto st = cairo_surface_set_mime_data(image, CAIRO_MIME_TYPE_URI,
+        (unsigned char*) uri, strlen(uri), gfree, uri);
+    if (st)
+    {
+        gfree(uri);
+        return;
+    }
+    bitmaps_in_current_page.push_back(imgId);
+
+    if(bitmaps_ref_count.find(imgId) != bitmaps_ref_count.end())
+        return;
+
+    bitmaps_ref_count[imgId] = 0;
+
+    char *strBuffer;
+    int len;
+    if (getStreamData(str->getNextStream(), &strBuffer, &len))
+    {
+        string path = get_bitmap_path(imgId);
+        ofstream imgfile(path, ofstream::binary);
+        imgfile.write(strBuffer, len);
+        gfree(strBuffer);
+    }
+}
+
 } // namespace pdf2htmlEX
 
 #endif // ENABLE_SVG

src/BackgroundRenderer/CairoBackgroundRenderer.h

@@ -12,6 +12,8 @@
 #include <CairoOutputDev.h>
 #include <cairo.h>
 #include <cairo-svg.h>
+#include <map>
+#include <vector>
 
 #include "pdf2htmlEX-config.h"
 
@@ -26,7 +28,7 @@ class CairoBackgroundRenderer : public BackgroundRenderer, CairoOutputDev
 public:
   CairoBackgroundRenderer(HTMLRenderer * html_renderer, const Param & param);
 
-  virtual ~CairoBackgroundRenderer() { }
+  virtual ~CairoBackgroundRenderer();
 
   virtual void init(PDFDoc * doc);
   virtual bool render_page(PDFDoc * doc, int pageno);
@@ -41,10 +43,23 @@ public:
       double originX, double originY,
       CharCode code, int nBytes, Unicode *u, int uLen);
 
+protected:
+  virtual void setMimeData(Stream *str, Object *ref, cairo_surface_t *image);
+
 protected:
   HTMLRenderer * html_renderer;
   const Param & param;
   cairo_surface_t * surface;
+
+private:
+  // convert bitmap stream id to bitmap file name. No pageno prefix,
+  // because a bitmap may be shared by multiple pages.
+  const char* get_bitmap_path(int id);
+  // map<id_of_bitmap_stream, usage_count_in_all_svgs>
+  // note: if a svg bg fallbacks to bitmap bg, its bitmaps are not taken into account.
+  std::map<int, int> bitmaps_ref_count;
+  // id of bitmaps' stream used by current page
+  std::vector<int> bitmaps_in_current_page;
 };
 
 }

src/Param.h

@@ -64,6 +64,7 @@ struct Param
     // background image
     std::string bg_format;
     int svg_nodes_limit;
+    int svg_embed_bitmap;
 
     // encryption
     std::string owner_password, user_password;

src/pdf2htmlEX.cc

@@ -192,6 +192,9 @@ void parse_options (int argc, char **argv)
         .add("bg-format", &param.bg_format, "png", "specify background image format")
         .add("svg-nodes-limit", &param.svg_nodes_limit, 0, "if node count in a svg background image exceeds this limit,"
                 " fall back to bitmap background. 0 or negative means no limit.")
+        .add("svg-embed-bitmap", &param.svg_embed_bitmap, 1, "embed bitmaps in svg files or save them as external files"
+                " (even if 0 is specified, some bitmaps may still be embedded)")
+
         // encryption
         .add("owner-password,o", &param.owner_password, "", "owner password (for encrypted files)", true)
         .add("user-password,u", &param.user_password, "", "user password (for encrypted files)", true)