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New line height in atlas based on character lengths

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This commit is contained in:
bloeys
2022-07-10 21:49:33 +04:00
parent f21e1ec201
commit dec853adca
2 changed files with 19 additions and 9 deletions
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26
glyphs/font_atlas.go
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@ -67,6 +67,7 @@ func calcNeededAtlasSize(glyphs []rune, face font.Face, charPaddingXFixed, charP
//Calculate needed atlas size
atlasSizeX = 512
atlasSizeY = 512
largestLineDescent := fixed.I(0)
lineHeight := face.Metrics().Height
foundAtlasSize := false
for !foundAtlasSize {
@ -83,7 +84,11 @@ func calcNeededAtlasSize(glyphs []rune, face font.Face, charPaddingXFixed, charP
gBounds, _, _ := face.GlyphBounds(g)
bearingXFixed := gBounds.Min.X
gWidthFixed := gBounds.Max.X - gBounds.Min.X
// descent := gBounds.Max.Y
descent := gBounds.Max.Y
if descent > largestLineDescent {
largestLineDescent = descent
}
// Calculate distance dot will move after drawing. Advance normally if line has space,
// otherwise go to next line and reset X position.
@ -99,7 +104,8 @@ func calcNeededAtlasSize(glyphs []rune, face font.Face, charPaddingXFixed, charP
if dotX+distToMoveX >= atlasSizeXFixed {
dotX = distToMoveX
dotY += lineHeight + charPaddingYFixed
dotY += lineHeight + fixed.I(largestLineDescent.Ceil()) + charPaddingYFixed
largestLineDescent = 0
//If we have only one more empty line then resize to be safe against descents being clipped
if dotY+lineHeight >= atlasSizeYFixed {
@ -125,11 +131,9 @@ func calcNeededAtlasSize(glyphs []rune, face font.Face, charPaddingXFixed, charP
//Only monospaced fonts are supported.
func NewFontAtlasFromFont(f *truetype.Font, face font.Face, pointSize uint) (*FontAtlas, error) {
// Vertical padding must be a bit larger because low descent on one line
// and high ascent on the next might cause overlapping chars
const maxAtlasSize = 8192
const charPaddingXFixed = 4 << 6
const charPaddingYFixed = 4 << 6
const maxAtlasSize = 8192
glyphs := getGlyphsFromRuneRanges(getGlyphRangesFromFont(f))
assert.T(len(glyphs) > 0, "no glyphs")
@ -166,6 +170,7 @@ func NewFontAtlasFromFont(f *truetype.Font, face font.Face, pointSize uint) (*Fo
drawer.Dot.Y = lineHeight
const drawBoundingBoxes bool = false
largestLineDescent := fixed.I(0)
atlasSizeXFixed := fixed.I(atlasSizeX)
atlasSizeYFixed := fixed.I(atlasSizeY)
for _, g := range glyphs {
@ -177,6 +182,10 @@ func NewFontAtlasFromFont(f *truetype.Font, face font.Face, pointSize uint) (*Fo
descentAbsFixed := absI26_6(gBounds.Max.Y)
gWidthFixed := gBounds.Max.X - gBounds.Min.X
if descentAbsFixed > largestLineDescent {
largestLineDescent = descentAbsFixed
}
//If bearing is negative this char might overlap with the previous one.
//So we need to move the dot so the drawer won't overlap even after a negative offset
if bearingXFixed < 0 {
@ -188,17 +197,18 @@ func NewFontAtlasFromFont(f *truetype.Font, face font.Face, pointSize uint) (*Fo
nextDotPosDeltaX := bearingXFixed + gWidthFixed + charPaddingXFixed
if drawer.Dot.X+nextDotPosDeltaX >= atlasSizeXFixed {
assert.T(drawer.Dot.Y+lineHeight < atlasSizeYFixed, "Failed to create atlas because it did not fit")
assert.T(drawer.Dot.Y+lineHeight < atlasSizeYFixed, "Failed to create atlas because it did not fit all glyphs. Is calcNeededAtlasSize wrong?")
drawer.Dot.X = charPaddingXFixed
if bearingXFixed < 0 {
drawer.Dot.X += absI26_6(bearingXFixed)
}
drawer.Dot.Y += lineHeight + charPaddingYFixed
drawer.Dot.Y += lineHeight + fixed.I(largestLineDescent.Ceil()) + charPaddingYFixed
largestLineDescent = 0
}
drawer.Dot = fixed.P(drawer.Dot.X.Round(), drawer.Dot.Y.Round())
drawer.Dot = fixed.P(drawer.Dot.X.Floor(), drawer.Dot.Y.Floor())
//Build and insert glyph struct
gTopLeft := image.Point{

2
main.go
View File

@ -94,7 +94,7 @@ func (p *program) Init() {
fmt.Printf("DPI: %f, font size: %d\n", dpi, p.FontSize)
w, h := p.win.SDLWin.GetSize()
p.GlyphRend, err = glyphs.NewGlyphRend("./res/fonts/arabtype-variable.ttf", &truetype.Options{Size: float64(p.FontSize), DPI: p.Dpi, SubPixelsX: subPixelX, SubPixelsY: subPixelY, Hinting: hinting}, w, h)
p.GlyphRend, err = glyphs.NewGlyphRend("./res/fonts/alm-fixed.ttf", &truetype.Options{Size: float64(p.FontSize), DPI: p.Dpi, SubPixelsX: subPixelX, SubPixelsY: subPixelY, Hinting: hinting}, w, h)
if err != nil {
panic("Failed to create atlas from font file. Err: " + err.Error())
}