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label-tool: respect font ascent and descent 

Also try to load the values from the BDF font file.
This commit is contained in:
Přemysl Eric Janouch 2019-04-26 11:40:43 +02:00
parent e56482d73f
commit 696ea89530
Signed by: p
GPG Key ID: A0420B94F92B9493
2 changed files with 44 additions and 24 deletions
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28
bdf/bdf.go
View File

@ -49,6 +49,8 @@ func (g *glyph) At(x, y int) color.Color {
// Font represents a particular bitmap font.
type Font struct {
Name string
Ascent int // needn't be present in the font
Descent int // needn't be present in the font
glyphs map[rune]glyph
fallback glyph
}
@ -192,17 +194,23 @@ func (p *bdfParser) readLine() bool {
return true
}
func (p *bdfParser) readCharEncoding() int {
func (p *bdfParser) readIntegerArgument() int {
if len(p.tokens) < 2 {
panic("insufficient arguments")
}
if i, err := strconv.Atoi(p.tokens[1]); err != nil {
panic(err)
} else {
return i // Some fonts even use -1 for things outside the encoding.
return i
}
}
// Some fonts even use -1 for things outside the encoding.
func (p *bdfParser) readCharEncoding() int { return p.readIntegerArgument() }
// XXX: Ignoring vertical advance since we only expect purely horizontal fonts.
func (p *bdfParser) readDwidth() int { return p.readIntegerArgument() }
func (p *bdfParser) parseProperties() {
// The wording in the specification suggests that the argument
// with the number of properties to follow isn't reliable.
@ -210,22 +218,14 @@ func (p *bdfParser) parseProperties() {
switch p.tokens[0] {
case "DEFAULT_CHAR":
p.defaultChar = p.readCharEncoding()
case "FONT_ASCENT":
p.font.Ascent = p.readIntegerArgument()
case "FONT_DESCENT":
p.font.Descent = p.readIntegerArgument()
}
}
}
// XXX: Ignoring vertical advance since we only expect purely horizontal fonts.
func (p *bdfParser) readDwidth() int {
if len(p.tokens) < 2 {
panic("insufficient arguments")
}
if i, err := strconv.Atoi(p.tokens[1]); err != nil {
panic(err)
} else {
return i
}
}
func (p *bdfParser) readBBX() image.Rectangle {
if len(p.tokens) < 5 {
panic("insufficient arguments")

40
label/label.go
View File

@ -51,6 +51,13 @@ func GenLabelForHeight(font *bdf.Font,
return combinedImg
}
func max(a, b int) int {
if a > b {
return a
}
return b
}
func GenLabelForWidth(font *bdf.Font,
text string, width, scale int) image.Image {
var lines []string
@ -58,30 +65,43 @@ func GenLabelForWidth(font *bdf.Font,
lines = append(lines, strings.TrimSuffix(line, "\r"))
}
height := 0
var rects []image.Rectangle
for _, line := range lines {
// Respect font ascent and descent so that there are gaps between lines.
rects := make([]image.Rectangle, len(lines))
jumps := make([]int, len(lines))
for i, line := range lines {
r, _ := font.BoundString(line)
rects = append(rects, r)
height += r.Dy() * scale
rects[i] = r
if i > 0 {
deficitD := font.Descent - rects[i-1].Max.Y
jumps[i] += max(0, deficitD)
deficitA := font.Ascent - (-r.Min.Y)
jumps[i] += max(0, deficitA)
}
}
imgRect := image.Rect(0, 0, width, height)
height := 0
for i := range lines {
height += jumps[i] + rects[i].Dy()
}
imgRect := image.Rect(0, 0, width, height*scale)
img := image.NewRGBA(imgRect)
draw.Draw(img, imgRect, image.White, image.ZP, draw.Src)
y := 0
for i := 0; i < len(lines); i++ {
for i, line := range lines {
textImg := image.NewRGBA(rects[i])
draw.Draw(textImg, rects[i], image.White, image.ZP, draw.Src)
font.DrawString(textImg, image.ZP, lines[i])
font.DrawString(textImg, image.ZP, line)
scaledImg := imgutil.Scale{Image: textImg, Scale: scale}
scaledRect := scaledImg.Bounds()
target := image.Rect(0, y, imgRect.Max.X, imgRect.Max.Y)
y += jumps[i]
target := image.Rect(0, y*scale, imgRect.Max.X, imgRect.Max.Y)
draw.Draw(img, target, &scaledImg, scaledRect.Min, draw.Src)
y += scaledRect.Dy()
y += rects[i].Dy()
}
return img
}