ofxMsdfgen/src/ofxMsdfgen.cpp

#include "ofxMsdfgen.h"
#include "BitmapRef.hpp"
#include "ofGraphicsConstants.h"
#include "ofPixels.h"

bool ofxMsdfgen::generateAtlas(const char * fontFilename){
    bool success = false;
    // Initialize instance of FreeType library
    if(msdfgen::FreetypeHandle * ft = msdfgen::initializeFreetype()){
        // Load font file
        if(msdfgen::FontHandle * font = msdfgen::loadFont(ft, fontFilename)){
            // Storage for glyph geometry and their coordinates in the atlas
            std::vector <msdf_atlas::GlyphGeometry> glyphs;
            // FontGeometry is a helper class that loads a set of glyphs from a single font.
            // It can also be used to get additional font metrics, kerning information, etc.
            msdf_atlas::FontGeometry fontGeometry(&glyphs);
            // Load a set of character glyphs:
            // The second argument can be ignored unless you mix different font sizes in one atlas.
            // In the last argument, you can specify a charset other than ASCII.
            // To load specific glyph indices, use loadGlyphs instead.
            fontGeometry.loadCharset(font, 1.0, msdf_atlas::Charset::ASCII);
            // Apply MSDF edge coloring. See edge-coloring.h for other coloring strategies.
            const double maxCornerAngle = 3.0;
            for(msdf_atlas::GlyphGeometry & glyph : glyphs){
                glyph.edgeColoring(&msdfgen::edgeColoringInkTrap, maxCornerAngle, 0);
            }
            // TightAtlasPacker class computes the layout of the atlas.
            msdf_atlas::TightAtlasPacker packer;
            // Set atlas parameters:
            // setDimensions or setDimensionsConstraint to find the best value
            packer.setDimensionsConstraint(msdf_atlas::TightAtlasPacker::DimensionsConstraint::SQUARE);
            // setScale for a fixed size or setMinimumScale to use the largest that fits
            packer.setMinimumScale(24.0);
            // setPixelRange or setUnitRange
            packer.setPixelRange(2.0);
            packer.setMiterLimit(1.0);
            // Compute atlas layout - pack glyphs
            packer.pack(glyphs.data(), glyphs.size());
            // Get final atlas dimensions
            int width = 0, height = 0;
            packer.getDimensions(width, height);
            // The ImmediateAtlasGenerator class facilitates the generation of the atlas bitmap.
            msdf_atlas::ImmediateAtlasGenerator <
                float, // pixel type of buffer for individual glyphs depends on generator function
                3, // number of atlas color channels
                & msdf_atlas::msdfGenerator, // function to generate bitmaps for individual glyphs
                msdf_atlas::BitmapAtlasStorage <float, 3> // class that stores the atlas bitmap
                // For example, a custom atlas storage class that stores it in VRAM can be used.
                > generator(width, height);
            // GeneratorAttributes can be modified to change the generator's default settings.
            msdf_atlas::GeneratorAttributes attributes;
            generator.setAttributes(attributes);
            generator.setThreadCount(12);
            // Generate atlas bitmap
            generator.generate(glyphs.data(), glyphs.size());
            // The atlas bitmap can now be retrieved via atlasStorage as a BitmapConstRef.
            // The glyphs array (or fontGeometry) contains positioning data for typesetting text.
            success = submitAtlasBitmapAndLayout((msdfgen::BitmapConstRef <float, 3>)generator.atlasStorage(),
                                                 glyphs,
                                                 width,
                                                 height);
            // Cleanup
            msdfgen::destroyFont(font);
        }
        msdfgen::deinitializeFreetype(ft);
    }
    return success;
}

bool ofxMsdfgen::submitAtlasBitmapAndLayout(const msdfgen::BitmapConstRef <float, 3> & storage,
                                            const std::vector <msdf_atlas::GlyphGeometry> & glyphs,
                                            const int & width,
                                            const int & height){
    const msdfgen::Bitmap <float, 3> bitmap(storage);
    ofImage image;
    toOfImage(bitmap, image);
    image.save("atlas.png");

    return true;
}