much improved text scaling
This commit is contained in:
Thomas Friedel
parent
978852494a
commit
d3cc20f911
1 changed files with 101 additions and 58 deletions
159
text.go
159
text.go
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@ -6,6 +6,7 @@ import (
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"image"
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"image/draw"
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"io/ioutil"
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"math"
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"os"
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"time"
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@ -116,16 +117,17 @@ func (cv *Canvas) FillText(str string, x, y float64) {
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return
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}
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frc := cv.getFRContext(cv.state.font, cv.state.fontSize)
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scaleX := vec{cv.state.transform[0], cv.state.transform[1]}.len()
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scaleY := vec{cv.state.transform[2], cv.state.transform[3]}.len()
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scale := (scaleX + scaleY) * 0.5
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fontSize := fixed.Int26_6(math.Round(float64(cv.state.fontSize) * scale))
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frc := cv.getFRContext(cv.state.font, fontSize)
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fnt := cv.state.font.font
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curX := x
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// measure rendered text size
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var p fixed.Point26_6
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prev, hasPrev := truetype.Index(0), false
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strFrom, strTo := 0, len(str)
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curInside := false
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var textOffset image.Point
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var strWidth, strMaxY int
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for i, rn := range str {
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@ -137,33 +139,12 @@ func (cv *Canvas) FillText(str string, x, y float64) {
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if err != nil {
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continue
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}
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var kern fixed.Int26_6
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if hasPrev {
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kern := fnt.Kern(frc.fontSize, prev, idx)
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kern = fnt.Kern(fontSize, prev, idx)
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if frc.hinting != font.HintingNone {
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kern = (kern + 32) &^ 63
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}
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curX += float64(kern) / 64
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}
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w, h := cv.b.Size()
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fw, fh := float64(w), float64(h)
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p0 := cv.tf(vec{float64(bounds.Min.X) + curX, float64(bounds.Min.Y) + y})
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p1 := cv.tf(vec{float64(bounds.Min.X) + curX, float64(bounds.Max.Y) + y})
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p2 := cv.tf(vec{float64(bounds.Max.X) + curX, float64(bounds.Max.Y) + y})
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p3 := cv.tf(vec{float64(bounds.Max.X) + curX, float64(bounds.Min.Y) + y})
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inside := (p0[0] >= 0 || p1[0] >= 0 || p2[0] >= 0 || p3[0] >= 0) &&
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(p0[1] >= 0 || p1[1] >= 0 || p2[1] >= 0 || p3[1] >= 0) &&
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(p0[0] < fw || p1[0] < fw || p2[0] < fw || p3[0] < fw) &&
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(p0[1] < fh || p1[1] < fh || p2[1] < fh || p3[1] < fh)
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if !curInside && inside {
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curInside = true
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strFrom = i
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x = curX
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} else if curInside && !inside {
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strTo = i
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break
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}
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if i == 0 {
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@ -175,16 +156,93 @@ func (cv *Canvas) FillText(str string, x, y float64) {
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if bounds.Max.Y > strMaxY {
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strMaxY = bounds.Max.Y
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}
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p.X += advance
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curX += float64(advance) / 64
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p.X += advance + kern
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}
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strWidth = p.X.Ceil() - textOffset.X
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strHeight := strMaxY - textOffset.Y
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if strFrom == strTo || strWidth == 0 || strHeight == 0 {
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if strWidth <= 0 || strHeight <= 0 {
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return
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}
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fstrWidth := float64(strWidth) / scale
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fstrHeight := float64(strHeight) / scale
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// calculate offsets
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if cv.state.textAlign == Center {
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x -= float64(fstrWidth) * 0.5
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} else if cv.state.textAlign == Right || cv.state.textAlign == End {
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x -= float64(fstrWidth)
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}
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metrics := cv.state.fontMetrics
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switch cv.state.textBaseline {
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case Alphabetic:
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case Middle:
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y += (-float64(metrics.Descent)/64 + float64(metrics.Height)*0.5/64) / scale
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case Top, Hanging:
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y += (-float64(metrics.Descent)/64 + float64(metrics.Height)/64) / scale
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case Bottom, Ideographic:
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y += -float64(metrics.Descent) / 64 / scale
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}
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// find out which characters are inside the visible area
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p = fixed.Point26_6{}
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prev, hasPrev = truetype.Index(0), false
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var insideCount int
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strFrom, strTo := 0, len(str)
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curInside := false
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curX := x
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for i, rn := range str {
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idx := fnt.Index(rn)
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if idx == 0 {
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idx = fnt.Index(' ')
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}
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advance, bounds, err := frc.glyphMeasure(idx, p)
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if err != nil {
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continue
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}
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var kern fixed.Int26_6
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if hasPrev {
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kern = fnt.Kern(fontSize, prev, idx)
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if frc.hinting != font.HintingNone {
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kern = (kern + 32) &^ 63
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}
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curX += float64(kern) / 64 / scale
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}
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w, h := cv.b.Size()
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fw, fh := float64(w), float64(h)
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p0 := cv.tf(vec{float64(bounds.Min.X)/scale + curX, float64(bounds.Min.Y)/scale + y})
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p1 := cv.tf(vec{float64(bounds.Min.X)/scale + curX, float64(bounds.Max.Y)/scale + y})
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p2 := cv.tf(vec{float64(bounds.Max.X)/scale + curX, float64(bounds.Max.Y)/scale + y})
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p3 := cv.tf(vec{float64(bounds.Max.X)/scale + curX, float64(bounds.Min.Y)/scale + y})
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inside := (p0[0] >= 0 || p1[0] >= 0 || p2[0] >= 0 || p3[0] >= 0) &&
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(p0[1] >= 0 || p1[1] >= 0 || p2[1] >= 0 || p3[1] >= 0) &&
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(p0[0] < fw || p1[0] < fw || p2[0] < fw || p3[0] < fw) &&
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(p0[1] < fh || p1[1] < fh || p2[1] < fh || p3[1] < fh)
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if inside {
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insideCount++
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}
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if !curInside && inside {
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curInside = true
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strFrom = i
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x = curX
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} else if curInside && !inside {
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strTo = i
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break
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}
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p.X += advance + kern
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curX += float64(advance) / 64 / scale
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}
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if strFrom == strTo || insideCount == 0 {
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return
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}
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// make sure textImage is large enough for the rendered string
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if textImage == nil || textImage.Bounds().Dx() < strWidth || textImage.Bounds().Dy() < strHeight {
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var size int
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for size = 2; size < alphaTexSize; size *= 2 {
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@ -201,6 +259,7 @@ func (cv *Canvas) FillText(str string, x, y float64) {
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curX = x
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p = fixed.Point26_6{}
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// clear the render region in textImage
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for y := 0; y < strHeight; y++ {
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off := textImage.PixOffset(0, y)
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line := textImage.Pix[off : off+strWidth]
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@ -209,6 +268,7 @@ func (cv *Canvas) FillText(str string, x, y float64) {
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}
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}
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// render the string into textImage
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prev, hasPrev = truetype.Index(0), false
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for _, rn := range str[strFrom:strTo] {
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idx := fnt.Index(rn)
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@ -218,7 +278,7 @@ func (cv *Canvas) FillText(str string, x, y float64) {
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continue
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}
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if hasPrev {
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kern := fnt.Kern(frc.fontSize, prev, idx)
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kern := fnt.Kern(fontSize, prev, idx)
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if frc.hinting != font.HintingNone {
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kern = (kern + 32) &^ 63
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}
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@ -237,30 +297,12 @@ func (cv *Canvas) FillText(str string, x, y float64) {
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curX += float64(advance) / 64
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}
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if cv.state.textAlign == Center {
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x -= float64(strWidth) * 0.5
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} else if cv.state.textAlign == Right || cv.state.textAlign == End {
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x -= float64(strWidth)
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}
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var yOff float64
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metrics := cv.state.fontMetrics
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switch cv.state.textBaseline {
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case Alphabetic:
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yOff = 0
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case Middle:
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yOff = -float64(metrics.Descent)/64 + float64(metrics.Height)*0.5/64
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case Top, Hanging:
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yOff = -float64(metrics.Descent)/64 + float64(metrics.Height)/64
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case Bottom, Ideographic:
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yOff = -float64(metrics.Descent) / 64
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}
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// render textImage to the screen
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var pts [4][2]float64
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pts[0] = cv.tf(vec{float64(textOffset.X) + x, float64(textOffset.Y) + y + yOff})
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pts[1] = cv.tf(vec{float64(textOffset.X) + x, float64(textOffset.Y+strHeight) + y + yOff})
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pts[2] = cv.tf(vec{float64(textOffset.X+strWidth) + x, float64(textOffset.Y+strHeight) + y + yOff})
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pts[3] = cv.tf(vec{float64(textOffset.X+strWidth) + x, float64(textOffset.Y) + y + yOff})
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pts[0] = cv.tf(vec{float64(textOffset.X)/scale + x, float64(textOffset.Y)/scale + y})
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pts[1] = cv.tf(vec{float64(textOffset.X)/scale + x, float64(textOffset.Y)/scale + fstrHeight + y})
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pts[2] = cv.tf(vec{float64(textOffset.X)/scale + fstrWidth + x, float64(textOffset.Y)/scale + fstrHeight + y})
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pts[3] = cv.tf(vec{float64(textOffset.X)/scale + fstrWidth + x, float64(textOffset.Y)/scale + y})
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mask := textImage.SubImage(image.Rect(0, 0, strWidth, strHeight)).(*image.Alpha)
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@ -400,8 +442,9 @@ func (cv *Canvas) MeasureText(str string) TextMetrics {
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hasPrev = false
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continue
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}
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var kern fixed.Int26_6
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if hasPrev {
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kern := fnt.Kern(frc.fontSize, prev, idx)
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kern = fnt.Kern(frc.fontSize, prev, idx)
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if frc.hinting != font.HintingNone {
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kern = (kern + 32) &^ 63
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}
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@ -421,7 +464,7 @@ func (cv *Canvas) MeasureText(str string) TextMetrics {
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maxY = glyphMaxY
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}
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x += float64(advance) / 64
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p.X += advance
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p.X += advance + kern
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}
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return TextMetrics{
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