78 lines
1.8 KiB
Go
78 lines
1.8 KiB
Go
// alphaprobe：打印一张图若干采样点的 RGBA，并统计 alpha 分布。
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//
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// 用来诊断「缩放后图标看起来全透明」这类问题 ——
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// 光看缩略图分不清是图像真透明，还是预览器把透明当白底。
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//
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// 用法：go run ./tools/alphaprobe <img.png> [更多.png...]
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package main
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import (
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"fmt"
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"image"
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"image/png"
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"os"
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)
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func main() {
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if len(os.Args) < 2 {
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fmt.Fprintln(os.Stderr, "用法: go run ./tools/alphaprobe <img>...")
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os.Exit(1)
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}
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for _, p := range os.Args[1:] {
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probe(p)
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fmt.Println()
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}
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}
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func probe(path string) {
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f, err := os.Open(path)
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if err != nil {
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fmt.Printf("%s: %v\n", path, err)
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return
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}
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defer f.Close()
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im, err := png.Decode(f)
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if err != nil {
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fmt.Printf("%s: 解不开: %v\n", path, err)
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return
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}
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b := im.Bounds()
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fmt.Printf("%s bounds=%v\n", path, b)
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pts := []struct {
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name string
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x, y int
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}{
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{"左上角", b.Min.X, b.Min.Y},
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{"中心", b.Min.X + b.Dx()/2, b.Min.Y + b.Dy()/2},
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{"上边中", b.Min.X + b.Dx()/2, b.Min.Y},
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{"左边中", b.Min.X, b.Min.Y + b.Dy()/2},
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{"右下角", b.Max.X - 1, b.Max.Y - 1},
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}
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for _, p := range pts {
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r, g, bl, a := im.At(p.x, p.y).RGBA()
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fmt.Printf(" %-8s (%3d,%3d) R=%3d G=%3d B=%3d A=%3d\n",
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p.name, p.x, p.y, r>>8, g>>8, bl>>8, a>>8)
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}
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var opaque, semi, clear int
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for y := b.Min.Y; y < b.Max.Y; y++ {
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for x := b.Min.X; x < b.Max.X; x++ {
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if _, _, _, a := im.At(x, y).RGBA(); a>>8 > 240 {
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opaque++
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} else if a>>8 > 10 {
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semi++
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} else {
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clear++
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}
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}
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}
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total := b.Dx() * b.Dy()
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fmt.Printf(" alpha: 不透明 %d (%.1f%%) · 半透明 %d (%.1f%%) · 透明 %d (%.1f%%)\n",
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opaque, 100*float64(opaque)/float64(total),
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semi, 100*float64(semi)/float64(total),
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clear, 100*float64(clear)/float64(total))
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_ = image.Rect
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}
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