using_skia_and_harfbuzz: use default typeface

tools/using_skia_and_harfbuzz.cpp

 /*
  * Copyright 2016 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 // This sample progam demonstrates how to use Skia and HarfBuzz to
 // produce a PDF file from UTF-8 text in stdin.
 
@@ skipping 68 matching lines @@
 };
 
 struct Config {
   DoubleOption *page_width = new DoubleOption("-w", "Page width", 600.0f);
   DoubleOption *page_height = new DoubleOption("-h", "Page height", 800.0f);
   SkStringOption *title = new SkStringOption("-t", "PDF title", SkString("---"));
   SkStringOption *author = new SkStringOption("-a", "PDF author", SkString("---"));
   SkStringOption *subject = new SkStringOption("-k", "PDF subject", SkString("---"));
   SkStringOption *keywords = new SkStringOption("-c", "PDF keywords", SkString("---"));
   SkStringOption *creator = new SkStringOption("-t", "PDF creator", SkString("---"));
-  StdStringOption *font_file = new StdStringOption("-f", ".ttf font file", "fonts/DejaVuSans.ttf");
+  StdStringOption *font_file = new StdStringOption("-f", ".ttf font file", "");
   DoubleOption *font_size = new DoubleOption("-z", "Font size", 8.0f);
   DoubleOption *left_margin = new DoubleOption("-m", "Left margin", 20.0f);
   DoubleOption *line_spacing_ratio = new DoubleOption("-h", "Line spacing ratio", 1.5f);
   StdStringOption *output_file_name = new StdStringOption("-o", ".pdf output file name", "out-skiahf.pdf");
 
   std::map<std::string, BaseOption*> options = {
     { page_width->selector, page_width },
     { page_height->selector, page_height },
     { title->selector, title },
     { author->selector, author },
@@ skipping 34 matching lines @@
   } // end of Config::Config
 };
 
 const double FONT_SIZE_SCALE = 64.0f;
 
 struct Face {
   struct HBFDel { void operator()(hb_face_t* f) { hb_face_destroy(f); } };
   std::unique_ptr<hb_face_t, HBFDel> fHarfBuzzFace;
   sk_sp<SkTypeface> fSkiaTypeface;
 
+  Face(sk_sp<SkTypeface> skiaTypeface) : fSkiaTypeface(std::move(skiaTypeface)) {
+    int index;
+    std::unique_ptr<SkStreamAsset> asset(fSkiaTypeface->openStream(&index));
+    size_t size = asset->getLength();
+    // TODO(halcanary): avoid this malloc and copy.
+    char* buffer = (char*)malloc(size);
+    asset->read(buffer, size);
+    hb_blob_t* blob = hb_blob_create(buffer,
+                                     size,
+                                     HB_MEMORY_MODE_READONLY,
+                                     nullptr,
+                                     free);
+    assert(blob);
+    hb_blob_make_immutable(blob);
+    hb_face_t* face = hb_face_create(blob, (unsigned)index);
+    hb_blob_destroy(blob);
+    assert(face);
+    if (!face) {
+        fSkiaTypeface.reset();
+        return;
+    }
+    hb_face_set_index(face, (unsigned)index);
+    hb_face_set_upem(face, fSkiaTypeface->getUnitsPerEm());
+    fHarfBuzzFace.reset(face);
+  }
   Face(const char* path, int index) {
     // fairly portable mmap impl
     auto data = SkData::MakeFromFileName(path);
     assert(data);
     if (!data) { return; }
     fSkiaTypeface = SkTypeface::MakeFromStream(new SkMemoryStream(data), index);
     assert(fSkiaTypeface);
     if (!fSkiaTypeface) { return; }
     auto destroy = [](void *d) { static_cast<SkData*>(d)->unref(); };
     const char* bytes = (const char*)data->data();
@@ skipping 14 matching lines @@
     }
     hb_face_set_index(face, (unsigned)index);
     hb_face_set_upem(face, fSkiaTypeface->getUnitsPerEm());
     fHarfBuzzFace.reset(face);
   }
 };
 
 class Placement {
  public:
   Placement(Config &_config, SkWStream* outputStream) : config(_config) {
-    face = new Face(config.font_file->value.c_str(), 0 /* index */);
+    const std::string& font_file = config.font_file->value;
+    if (font_file.size() > 0) {
+      face = new Face(font_file.c_str(), 0 /* index */);
+    } else {
+      face = new Face(SkTypeface::MakeDefault());
+    }
     hb_font = hb_font_create(face->fHarfBuzzFace.get());
 
     hb_font_set_scale(hb_font,
         FONT_SIZE_SCALE * config.font_size->value,
         FONT_SIZE_SCALE * config.font_size->value);
     hb_ot_font_set_funcs(hb_font);
 
     SkDocument::PDFMetadata pdf_info;
     pdf_info.fTitle = config.title->value;
     pdf_info.fAuthor = config.author->value;
@@ skipping 110 matching lines @@
     Config config(argc, argv);
 
     Placement placement(config, new SkFILEWStream(config.output_file_name->value.c_str()));
     for (std::string line; std::getline(std::cin, line);) {
       placement.WriteLine(line.c_str());
     }
     placement.Close();
 
     return 0;
 }