new file structure

inc/ui.text.go

@@ -0,0 +1,125 @@
+package inc
+
+// The HUD's coloured text rendering.
+//
+// inkwell's drawText (asset.text.go) discards its colour argument (`_ = c`) and
+// always renders white through the ebitenutil debug font. The two-channel
+// colour rule — "if something is amber, a tape said it" — cannot work through
+// it, so the custom widgets do not call Game.DrawText: they render glyphs onto
+// a scratch image and blit it tinted with ColorScale. The built-in widgets
+// (StatusLine, DialogBox, TopBar) still render white. See README, "Engine
+// workarounds".
+
+import (
+	"image"
+	"image/color"
+	"unicode/utf8"
+
+	"github.com/hajimehoshi/ebiten/v2"
+	"github.com/hajimehoshi/ebiten/v2/ebitenutil"
+)
+
+// glyphW and glyphH are the ebitenutil debug font's cell. The engine's own
+// textWidth uses the same 6px but counts bytes, which mismeasures any
+// non-ASCII text; we count runes.
+const (
+	glyphW = 6
+	glyphH = 16
+)
+
+var scratch *ebiten.Image
+
+// textW is the pixel width of a string, counted in runes.
+func textW(s string) int { return utf8.RuneCountInString(s) * glyphW }
+
+// drawTextC draws one line in colour c, with the same origin as DebugPrintAt.
+func drawTextC(dst *ebiten.Image, s string, x, y int, c color.Color) {
+	if s == "" {
+		return
+	}
+	w, h := textW(s)+glyphW, glyphH
+	if scratch == nil || scratch.Bounds().Dx() < w || scratch.Bounds().Dy() < h {
+		nw, nh := w, h
+		if nw < 320 {
+			nw = 320
+		}
+		scratch = ebiten.NewImage(nw, nh)
+	}
+	scratch.Clear()
+	ebitenutil.DebugPrintAt(scratch, s, 0, 0)
+
+	if c == nil {
+		c = color.White
+	}
+	r, g, b, a := c.RGBA()
+	op := &ebiten.DrawImageOptions{}
+	op.GeoM.Translate(float64(x), float64(y))
+	op.ColorScale.Scale(
+		float32(r)/0xffff, float32(g)/0xffff, float32(b)/0xffff, float32(a)/0xffff,
+	)
+	dst.DrawImage(scratch.SubImage(image.Rect(0, 0, w, h)).(*ebiten.Image), op)
+}
+
+// wrap breaks s at word boundaries into lines no wider than maxPx. The engine's
+// wrapText is unexported and byte-based, hence our own.
+func wrap(s string, maxPx int) []string {
+	if maxPx <= glyphW || textW(s) <= maxPx {
+		return []string{s}
+	}
+	var out []string
+	line, word := "", ""
+	flush := func() {
+		if line != "" {
+			out = append(out, line)
+			line = ""
+		}
+	}
+	emit := func() {
+		if word == "" {
+			return
+		}
+		switch {
+		case line == "":
+			line = word
+		case textW(line+" "+word) <= maxPx:
+			line += " " + word
+		default:
+			flush()
+			line = word
+		}
+		word = ""
+	}
+	for _, r := range s {
+		switch r {
+		case ' ':
+			emit()
+		case '\n':
+			emit()
+			flush()
+		default:
+			word += string(r)
+		}
+	}
+	emit()
+	flush()
+	if len(out) == 0 {
+		return []string{s}
+	}
+	return out
+}
+
+// clip truncates a string so it fits into maxPx.
+func clip(s string, maxPx int) string {
+	r := []rune(s)
+	max := maxPx / glyphW
+	switch {
+	case max <= 0:
+		return ""
+	case len(r) <= max:
+		return s
+	case max == 1:
+		return string(r[:1])
+	default:
+		return string(r[:max-1]) + "…"
+	}
+}