canvas_ity VS nanovgXC

I have a small TTF implementation that's in the neighborhood of that size and is open source. It's part of my canvas_ity single-header library [0] that's around 2300 LOC / 36 KB object size and implements a C++ version of most of the 2D HTML5 canvas spec [1].

The core implementation of the TTF parsing and drawing is in L1526-L1846 with another small bit at L3205-L3274 of src/canvas_ity.hpp.

It's something of a toy implementation that only supports western left-to-right text, and doesn't do any hinting at all, nor kerning, nor shaping. But it's enough to draw a basic "Hello world!" using any typical TTF file.

The test suite in test/test.cpp L84-304 embeds a few custom Base64-encoded TTF files. They're small and only have a few glyphs but they do exercise a number of interesting edge cases in the OpenType TTF spec [2]. Have a look at the HTML5 port of the test suite at test/test.html in different browsers to see how their canvas implementations render those fonts.

[0] https://github.com/a-e-k/canvas_ity

[1] https://www.w3.org/TR/2015/REC-2dcontext-20151119/

[2] https://standards.iso.org/ittf/PubliclyAvailableStandards/c0...

Agreed, that sort of documentation is pure gold when done well.

It's something I always try to pay forward by doing in my own code. For example, one of my own solo projects was an STB-style single-header -like rasterizer library for C++. I started the implementation half of the library with a short outline of the rendering pipeline's dataflow and the top-level functions responsible for each stage:

https://github.com/a-e-k/canvas_ity/blob/f32fbb37e2fe7c0fcae...

https://github.com/a-e-k/canvas_ity

This is an STB-style single-header C++ library with no dependencies beyond the standard C++ library. In about 2300 lines of 78-column code (not counting blanks or comments), or 1300 semicolons, it implements an API based on the basic W3C specification to draw 2D vector graphics into an image buffer:

- Strokes and fills (with antialiasing and gamma-correct blending)

- Linear and radial gradients

- Patterns (with repeat modes and bi-cubic resampling)

- Line caps and line joins (handling high curvature)

- Dash patterns and dash offsets

- Transforms

- Lines, quadratic and cubic Beziers, arcs, and rectangles

- Text (very basic, but does its own TTF font file parsing!)

- Raster images (i.e., sprites)

- Clipping (via masking)

- Compositing modes (Porter-Duff)

- Drop shadows with Gaussian blurs

I also uncovered a number of interesting browser quirks along the way with the HTML5 port of my testing suite.

Repository: https://github.com/a-e-k/canvas_ity

Nice work. Any plan to add GPU (opengl) support? CPU rendering is OK but the performance using the GPU is likely order of magnitudes better. Here is a library that uses the same antialiasing technique https://github.com/styluslabs/nanovgXC using OpenGL (based on NanoVG).

GPU vector graphics library I released a few years ago: https://github.com/styluslabs/nanovgXC - basically a new backend for nanovg that supports arbitrary paths. Coverage calculation (for analytic antialiasing) is explained a bit here: https://github.com/styluslabs/nanovgXC/blob/master/src/nanov...

Getting sufficient antialiasing quality for 2D graphics is difficult on GPUs. https://github.com/memononen/nanovg accomplishes this with GL2/GLES2 level hardware for most of the stuff one would want to render as part of a GUI. My project https://github.com/styluslabs/nanovgXC supports rendering arbitrary paths with exact coverage antialiasing, but requires GLES3.1 or GL4 level hardware for reasonable performance.