76 lines
1.5 KiB
Go
76 lines
1.5 KiB
Go
package doodle
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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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"math"
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"os"
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"time"
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)
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// Screenshot saves the level canvas to disk as a PNG image.
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func (d *Doodle) Screenshot() {
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screenshot := image.NewRGBA(image.Rect(0, 0, int(d.width), int(d.height)))
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// White-out the image.
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for x := 0; x < int(d.width); x++ {
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for y := 0; y < int(d.height); y++ {
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screenshot.Set(x, y, image.White)
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}
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}
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// Fill in the dots we drew.
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for pixel := range d.canvas {
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// A line or a dot?
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if pixel.x == pixel.dx && pixel.y == pixel.dy {
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screenshot.Set(int(pixel.x), int(pixel.y), image.Black)
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} else {
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// Draw a line. TODO: get this into its own function!
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// https://en.wikipedia.org/wiki/Digital_differential_analyzer_(graphics_algorithm)
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var (
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x1 = pixel.x
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x2 = pixel.dx
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y1 = pixel.y
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y2 = pixel.dy
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)
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var (
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dx = float64(x2 - x1)
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dy = float64(y2 - y1)
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)
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var step float64
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if math.Abs(dx) >= math.Abs(dy) {
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step = math.Abs(dx)
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} else {
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step = math.Abs(dy)
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}
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dx = dx / step
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dy = dy / step
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x := float64(x1)
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y := float64(y1)
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for i := 0; i <= int(step); i++ {
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screenshot.Set(int(x), int(y), image.Black)
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x += dx
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y += dy
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}
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}
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}
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filename := fmt.Sprintf("screenshot-%s.png",
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time.Now().Format("2006-01-02T15-04-05"),
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)
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fh, err := os.Create(filename)
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if err != nil {
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log.Error(err.Error())
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return
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}
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defer fh.Close()
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if err := png.Encode(fh, screenshot); err != nil {
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log.Error(err.Error())
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return
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}
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}
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