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hochwasser/render/image.go

92 lines
2.0 KiB
Go

package render
import (
"image"
"image/color"
_ "image/gif" // register gif, jpeg, png format handlers
_ "image/jpeg"
"image/png"
"math"
"os"
"golang.org/x/image/draw"
)
func ReadImage(path string) (*image.NRGBA, error) {
reader, err := os.Open(path)
if err != nil {
return nil, err
}
img, _, err := image.Decode(reader)
if err != nil {
return nil, err
}
return imgToNRGBA(img), nil
}
func WriteImage(path string, img image.Image) error {
f, err := os.Create(path)
if err != nil {
return err
}
if err := png.Encode(f, img); err != nil {
f.Close()
return err
}
return nil
}
func imgToNRGBA(img image.Image) *image.NRGBA {
b := img.Bounds()
r := image.NewNRGBA(b)
for x := b.Min.X; x < b.Max.X; x++ {
for y := b.Min.Y; y < b.Max.Y; y++ {
r.Set(x, y, img.At(x, y))
}
}
return r
}
// ImgColorFilter replaces `from` with `to` in `img`, and sets all other pixels
// to color.Transparent
func ImgColorFilter(img *image.NRGBA, from, to color.NRGBA) *image.NRGBA {
b := img.Bounds()
r := image.NewNRGBA(b)
for x := b.Min.X; x < b.Max.X; x++ {
for y := b.Min.Y; y < b.Max.Y; y++ {
if img.At(x, y) == from {
r.SetNRGBA(x, y, to)
} else {
r.Set(x, y, color.Transparent)
}
}
}
return r
}
func ScaleImage(img image.Image, factorX, factorY float64, highQuality bool) (scaled *image.NRGBA) {
b := img.Bounds()
newX := int(math.Ceil(factorX * float64(b.Max.X)))
newY := int(math.Ceil(factorY * float64(b.Max.Y)))
scaledBounds := image.Rect(0, 0, newX, newY)
scaledImg := image.NewNRGBA(scaledBounds)
scaler := draw.NearestNeighbor
if highQuality {
scaler = draw.CatmullRom
}
scaler.Scale(scaledImg, scaledBounds, img, b, draw.Src, nil)
return scaledImg
}
func RotateImage90(img *image.NRGBA) (rotated *image.NRGBA) {
b := img.Bounds()
rotated = image.NewNRGBA(image.Rect(0, 0, b.Max.Y, b.Max.X))
for x := b.Min.X; x < b.Max.X; x++ {
for y := b.Min.Y; y < b.Max.Y; y++ {
col := img.NRGBAAt(x, y)
rotated.SetNRGBA(b.Max.Y-y, x, col)
}
}
return
}