★ Roadmap

[tdewolff]

This is a roadmap of future plans with canvas, the intention is to finish all these matters, but not necessarily in a timely matter. Please see this list as possible plans. Features will be implemented in the develop branch and merged when deemed mature. Also see https://github.com/tdewolff/canvas/wiki/Planning.

• Parse SFNT (TTF and OTF) fonts with tables cmap, head, hhea, hmtx, maxp, name, OS/2, post, glyf, loca, kern, vhea, vmtx, CFF
• Generate subset font by defining the glyph IDs that are used (reduces font file size greatly for embedding)
• Text shaping using HarfBuzz (https://harfbuzz.github.io/ch01s03.html) to properly display Arabic, Devanagari, etc.
• Text directionality using FriBidi (https://github.com/fribidi/fribidi) in order to mix e.g. Arabic and English in one sentence
• Vertical text such as Chinese and Japanese
• Text justification algorithm from Donald Knuth (http://www.eprg.org/G53DOC/pdfs/knuth-plass-breaking.pdf) as used in TeX
• Text itemization using a rich text implementation to allow different font faces and decoration to occur in one paragraph
• Support adding paths and images to rich text implementation for e.g. emoticons
• Support PDF text copying
• Support fill patterns (from paths?) and gradients (linear, radial)
• Support path intersection to allow path merging (AND, OR, XOR)
• Set Z-index for draw order for Canvas
• SetView should also change coordinate position
• Path transformation (SetView) should transform stroke as well (works only for raster, PDF, SVG)
• Dashed stroke at start/corners is not always equivalent between renderers
• EPS stroking support
• PostScript target
• Optimize stroke first point
• Support native LaTeX formulas using https://github.com/go-latex/latex, see More frontends/backends #48 (comment)
• Improve examples
• Improve readme
• Use https://github.com/benoitkugler/textlayout/tree/main/harfbuzz as a default
• Use gamma corrected blending (incl. for fonts), see https://www.puredevsoftware.com/blog/2019/01/22/sub-pixel-gamma-correct-font-rendering/, http://nothings.org/gamedev/rasterize/, https://github.com/chmike/gofontrender
• Add text attribute spans to RichText in order to properly track underlining for text ending in spaces (?)
• Support Chinese text H/V alignment and position/line-height (text-orientation)
• Self intersecting paths for boolean operations
• Increase test coverage
• Add CI and GitHub actions integration, see CI and github actions #88
• Support path tessellation
• Support OpenGL rendering using Blinn and Loop algorithm or something similar (see https://lambdacube3d.wordpress.com/2014/11/12/playing-around-with-font-rendering/ as well), also see this rust library: https://raphlinus.github.io/rust/graphics/gpu/2020/06/13/fast-2d-rendering.html
• Make PDFs linearized (see Annex F) if possible
• Add support for PDF external/internal links, see Supporting External/Internal links in PDF #114
• Support target formats: PGF, JPEG2000, WEBP, CCITT, CDR (CorelDRAW), DWG (AutoCAD Drawing)
• Font features and variants to enable swash or stylistic ligatures, and to change the font weight variably
• Add Liang's hyphenation algorithm
• Use ligatures to improve line breaking, see e.g. Arabic justification rules https://www.tug.org/tugboat/tb27-2/tb87benatia.pdf
• Support vertical hinting/instructing of fonts
• Text on a path support
• Support Porter-Duffman Src blending mode for all renderers, see Implement option to use Porter-Duffman src operator #193
• Support ColorSpace and LCD-subpixel rasterization natively in rasterizer
• Add path approximator, based on a max error will linearize and simplify parts (implemented with Path.SimplifyVisvalingamWhyatt)
• Add path patterns and wall tiling support
• Optimize memory layout: combine path commands in one float64 and include command count