aljaz/njump
1
0
Fork 0
mirror of https://github.com/aljazceru/njump.git synced 2025-12-17 06:14:22 +01:00
Code Issues Packages Projects Releases Wiki Activity

document the mess we made with the font rendering stuff.

Browse Source
This commit is contained in:
fiatjaf
2023-12-26 22:16:31 -03:00
parent 1022fb76fa
commit 9f30fbeac9
2 changed files with 26 additions and 7 deletions
Download Patch File Download Diff File Expand all files Collapse all files

31
image_utils.go
View File

@@ -345,6 +345,13 @@ func shortenURLs(text string) string {
})
}
// beware: this is all very hacky and I don't know what I am doing!
// this function is copied from go-text/typesetting/shaping's HarfbuzzShaper and adapted to not require a "class",
// to rely on our dirty globals like fontCache, shaperLock and shaperBuffer; it also uses a custom function to
// determine language, script, direction and font face internally instead of taking a shaping.Input argument --
// but also, the most important change was to make it "shape" the same text, twice, with the default font and with
// the emoji font, then build an output of glyphs containing normal glyphs for when the referenced rune is not an
// emoji and an emoji glyph for when it is.
func shapeText(rawText []rune, fontSize int) (shaping.Output, []bool) {
lang, script, dir, face := getLanguageAndScriptAndDirectionAndFont(rawText)
@@ -458,8 +465,7 @@ func shapeText(rawText []rune, fontSize int) (shaping.Output, []bool) {
return out, emojiMask
}
// countClusters tallies the number of runes and glyphs in each cluster
// and updates the relevant fields on the provided glyph slice.
// this function is copied from go-text/typesetting/shaping because shapeText needs it
func countClusters(glyphs []shaping.Glyph, textLen int, dir di.Progression) {
currentCluster := -1
runesInCluster := 0
@@ -499,7 +505,20 @@ func countClusters(glyphs []shaping.Glyph, textLen int, dir di.Progression) {
}
}
func drawShapedRunAt(fontSize int, clr color.Color, out shaping.Output, emojiMask []bool, img draw.Image, startX, startY int) int {
// this function is copied from go-text/render, but adapted to not require a "class" to be instantiated and also,
// more importantly, to take an emojiMask parameter, with the same length as out.Glyphs, to determine when a
// glyph should be rendered with the emoji font instead of with the default font
func drawShapedRunAt(
fontSize int,
clr color.Color,
out shaping.Output,
emojiMask []bool,
img draw.Image,
startX,
startY int,
) int {
scale := float32(fontSize) / float32(out.Face.Upem())
b := img.Bounds()
scanner := rasterx.NewScannerGV(b.Dx(), b.Dy(), img, b)
f := rasterx.NewFiller(b.Dx(), b.Dy(), scanner)
@@ -511,15 +530,16 @@ func drawShapedRunAt(fontSize int, clr color.Color, out shaping.Output, emojiMas
yPos := y - fixed266ToFloat(g.YOffset)
face := out.Face
currentScale := scale
if emojiMask[i] {
face = emojiFace
currentScale = float32(fontSize) / float32(face.Upem())
}
data := face.GlyphData(g.GlyphID)
switch format := data.(type) {
case api.GlyphOutline:
scale := float32(fontSize) / float32(face.Upem())
drawOutline(g, format, f, scale, xPos, yPos)
drawOutline(g, format, f, currentScale, xPos, yPos)
default:
panic("format not supported for glyph")
}
@@ -530,6 +550,7 @@ func drawShapedRunAt(fontSize int, clr color.Color, out shaping.Output, emojiMas
return int(math.Ceil(float64(x)))
}
// this draws a font glyph (i.e. a letter) according to instructions and scale and whatever
func drawOutline(g shaping.Glyph, bitmap api.GlyphOutline, f *rasterx.Filler, scale float32, x, y float32) {
for _, s := range bitmap.Segments {
switch s.Op {