/
image.go
87 lines (77 loc) · 1.72 KB
/
image.go
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package main
import (
"fmt"
"image"
"image/draw"
"image/jpeg"
"math"
"os"
"strings"
"time"
)
func concatenateFiles(files []string) (string, error) {
if len(files) == 1 {
return files[0], nil
}
images := make([]image.Image, len(files))
verboseLog("concatenate %d files", len(files))
for i, f := range files {
img, err := openImage(f)
if err != nil {
return "", err
}
images[i] = img
}
res := drawImages(images)
filename := createTempFilename()
if err := writeImage(res, filename); err != nil {
return "", err
}
return filename, nil
}
func openImage(path string) (image.Image, error) {
r, err := os.Open(path)
if err != nil {
return image.Opaque, err
}
i, _, err := image.Decode(r)
if err != nil {
return image.Opaque, err
}
return i, nil
}
func drawImages(images []image.Image) image.Image {
if len(images) == 1 {
return images[0]
}
width := 640 * 2
height := 480 + 480*int(math.Floor(float64((len(images)-1)/2)))
rect := image.Rect(0, 0, width, height)
dst := image.NewRGBA(rect)
var r image.Rectangle
for i, src := range images {
x := (i % 2) * 640
y := int(math.Floor(float64(i/2))) * 480
r = image.Rect(x, y, x+640, y+480)
draw.Draw(dst, r, src, image.ZP, draw.Over)
}
return dst
}
func createTempFilename() string {
t := os.TempDir()
if !strings.HasSuffix(t, "/") {
t = t + "/"
}
return t + "cam_composite_" + time.Now().Format(time.RFC3339) + ".jpg"
}
func writeImage(img image.Image, filename string) error {
f, err := os.Create(filename)
if err != nil {
return fmt.Errorf("failed to create temp file %s", err)
}
opts := jpeg.Options{Quality: 80}
if err = jpeg.Encode(f, img, &opts); err != nil {
return fmt.Errorf("failed to encode image: %v", err)
}
return nil
}