[boost] boost::freetype - extension for boost::gil

From: Tom Brinkman (reportbase_at_[hidden])
Date: 2007-04-12 23:17:42

I've written a few freetype wrappers over the years.  I've since converted
it to use boost::gil and
will be submiting it to GIL graphics library developers as an extension.
The source code
is now available  for the asking.

Yes, it supports "cleartype" and "kerning" so it will produce fonts are
equivalent to Microsoft's and
Apples.  I've also added extras such as "word-wrapping" and "clipping".

Heres a complete working example of its usage.  It shows all the steps
necessary, including
initializing the "freetype" font engine, creating the boost::gil image and
saving it as a "png" file.

//Step 1.  Initialize the freetype library
FT_Library library;
FT_Face face;
FT_Init_FreeType(&library);
FT_New_Face(library,"c:/fonts/mini/ARGOW___.TTF",0,&face);
FT_Set_Pixel_Sizes(face,0,12);

//Step 2.  Create a gil image
gil::rgba8_image_t img(200,30);
gil::fill_pixels(gil::view(img),gil::rgba8_pixel_t(255,210,200,255));

//Step 3. Initialize Variables
std::string str = "A1234567890";
boost::freetype::glyph glyphs;
gil::rgba8_pixel_t black(0,0,0,255);
typdef freetype::make_glyphs<gil::rgba8_pixel_t> make_glyphs_t;
boost::gil::subimage_view view(view,0,0,width,height);

//Step 4. Transform the string into a freetype::glyphs vector
std::transform(str.begin(), str.end(),
    std::back_inserter(glyphs), make_glyphs_t(face,black));

//Step 5: Create kerning vector
std::vector<int> kernings;
std::transform(glyphs.begin(),glyphs.end(),
    std::back_inserter(kernings), make_kerning());

//Step 6. Draw the freetype::glyphs vector onto the gil image
std::for_each(glyphs.begin(), units.end(), kernings.begin(),
    boost::freetype::draw_glyphs<>(view));

//Step 7. output the image
png_write_view("c:/out/example_1.png", gil::view(img));