Hochwasser/pixelflut/commands.go

77 lines
1.9 KiB
Go

package pixelflut
import (
"fmt"
"image"
"image/color"
"math/rand"
)
// Commands represent a list of messages to be sent to a pixelflut server.
type commands [][]byte
// Chunk splits commands into equally sized chunks, while flattening each chunk
// so that all commands are concatenated as a single `[]byte`.
func (c commands) Chunk(numChunks int) [][]byte {
chunks := make([][]byte, numChunks)
chunkLength := len(c) / numChunks
for i := 0; i < numChunks; i++ {
cmdOffset := i * chunkLength
for j := 0; j < chunkLength; j++ {
chunks[i] = append(chunks[i], c[cmdOffset+j]...)
}
}
return chunks
}
// Shuffle reorders commands randomly, in place.
func (c commands) Shuffle() {
for i := range c {
j := rand.Intn(i + 1)
c[i], c[j] = c[j], c[i]
}
}
// CommandsFromImage converts an image to the respective pixelflut commands
func commandsFromImage(img *image.NRGBA, offset image.Point) (cmds commands) {
b := img.Bounds()
cmds = make([][]byte, b.Size().X*b.Size().Y)
numCmds := 0
for x := b.Min.X; x < b.Max.X; x++ {
for y := b.Min.Y; y < b.Max.Y; y++ {
c := img.At(x, y).(color.NRGBA)
// ignore transparent pixels
if c.A == 0 {
continue
}
var cmd string
if c.A != 255 {
cmd = fmt.Sprintf("PX %d %d %.2x%.2x%.2x%.2x\n",
x+offset.X, y+offset.Y, c.R, c.G, c.B, c.A)
} else {
// @speed: this sprintf call is quite slow..
cmd = fmt.Sprintf("PX %d %d %.2x%.2x%.2x\n",
x+offset.X, y+offset.Y, c.R, c.G, c.B)
}
cmds[numCmds] = []byte(cmd)
numCmds++
}
}
return cmds[:numCmds]
}
func cmdsFetchImage(bounds image.Rectangle) (cmds commands) {
cmds = make([][]byte, bounds.Size().X*bounds.Size().Y)
numCmds := 0
for x := bounds.Min.X; x < bounds.Max.X; x++ {
for y := bounds.Min.Y; y < bounds.Max.Y; y++ {
cmd := fmt.Sprintf("PX %d %d\n", x, y)
cmds[numCmds] = []byte(cmd)
numCmds++
}
}
return cmds
}