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authorPřemysl Janouch <p@janouch.name>2019-04-26 11:40:43 +0200
committerPřemysl Janouch <p@janouch.name>2019-04-26 11:40:43 +0200
commit696ea8953089c3872bca22ec24ca28139ef46cd3 (patch)
treeafc3837e77f57461d13a6b95d7304c292d41d1df
parente56482d73f6d8f8f46096ca980ac9e6dcd7b8300 (diff)
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label-tool: respect font ascent and descent
Also try to load the values from the BDF font file.
-rw-r--r--bdf/bdf.go28
-rw-r--r--label/label.go40
2 files changed, 44 insertions, 24 deletions
diff --git a/bdf/bdf.go b/bdf/bdf.go
index c02e31e..5ff8f30 100644
--- a/bdf/bdf.go
+++ b/bdf/bdf.go
@@ -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")
diff --git a/label/label.go b/label/label.go
index 062b072..63c600e 100644
--- a/label/label.go
+++ b/label/label.go
@@ -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)
+ }
+ }
+
+ height := 0
+ for i := range lines {
+ height += jumps[i] + rects[i].Dy()
}
- imgRect := image.Rect(0, 0, width, height)
+ 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
}