/
imageslicer.go
245 lines (178 loc) · 4.57 KB
/
imageslicer.go
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package imageslicer
import (
"bytes"
"encoding/base64"
"fmt"
"image"
"image/draw"
"image/jpeg"
"image/png"
"log"
"math"
"net/http"
"os"
"path"
"strings"
)
/*type Grid struct {
Rows int
Columns int
}*/
type Grid [2]uint
func Slice(img image.Image, grid Grid) (tiles []image.Image) {
tiles = make([]image.Image, 0, grid[0]*grid[1])
if cap(tiles) == 0 {
return
}
shape := img.Bounds()
fheight := float64(shape.Max.Y / int(grid[0]))
fwidth := float64(shape.Max.X / int(grid[1]))
height := int(math.Ceil(fheight))
width := int(math.Ceil(fwidth))
//fmt.Printf("h%dw%d\n", height, width)
for y := shape.Min.Y; y+height <= shape.Max.Y; y += height {
for x := shape.Min.X; x+width <= shape.Max.X; x += width {
tile := img.(interface {
SubImage(r image.Rectangle) image.Image
}).SubImage(image.Rect(x, y, x+width, y+height))
tiles = append(tiles, tile)
}
}
/* if int(grid[0]*grid[1]) != len(tiles) {
log.Fatalf("expected %v got %d", grid[0]*grid[1], len(tiles))
}*/
return
}
func Join(tiles []image.Image, grid Grid) (img image.Image, err error) {
if err = CheckSlice(tiles, grid); err != nil {
return
}
i := 0
shape := tiles[0].Bounds()
height := shape.Max.Y * int(grid[0])
width := shape.Max.X * int(grid[1])
shapeOrig := image.Rect(shape.Min.X, shape.Min.Y, width, height)
srcImage := image.NewRGBA(shapeOrig)
for y, minY := 0, shapeOrig.Min.Y; y < int(grid[0]); y++ {
for x, minX := 0, shapeOrig.Min.X; x < int(grid[1]); x++ {
tile := tiles[i]
shape := tile.Bounds()
draw.Draw(srcImage, shape, tile, shape.Min, draw.Src)
i += 1
minX += shape.Min.X //not required really
}
minY += shape.Min.Y
}
img = srcImage
return
}
func GetBytes(i image.Image) (b []byte) {
var outWriter bytes.Buffer
err := jpeg.Encode(&outWriter, i, nil)
if err != nil {
fmt.Println(err)
}
b = outWriter.Bytes()
return
}
func GetImageFromUrl(imgUrl string) (img image.Image) { //FIXME add error return and remove log
res, err := http.Get(imgUrl)
if err != nil {
//log.Printf("http-res %d %s\n", res.StatusCode, res.Status)
log.Println("err", err)
return
}
defer res.Body.Close()
img, _, err = image.Decode(res.Body)
if err != nil {
log.Println("err", err)
return
}
return
}
func GetImageFromBase64(base64Img string) (img image.Image, err error) {
mimeTypeIndex := strings.Index(base64Img, ";base64,")
imageType := ""
if mimeTypeIndex != -1 {
mimeType := base64Img[:mimeTypeIndex]
base64Img = strings.TrimPrefix(base64Img, mimeType+";base64,")
imageType = strings.TrimPrefix(mimeType, "data:image/")
}
reader := base64.NewDecoder(base64.StdEncoding, strings.NewReader(base64Img))
switch imageType {
case "jpeg", "jpg":
img, err = jpeg.Decode(reader)
case "png":
img, err = png.Decode(reader)
default:
img, _, err = image.Decode(reader)
}
if err != nil {
err = fmt.Errorf("unable to decode the img due to %s", err)
return
}
return
}
func GetImageFromPath(imgPath string) (img image.Image, err error) {
f1, err := os.Open(imgPath)
if err != nil {
err = fmt.Errorf("failed to open image due to %s", err)
return
}
defer f1.Close()
imgType := path.Ext(imgPath)
imgType = strings.TrimPrefix(imgType, ".")
switch imgType {
case "jpeg", "jpg":
img, err = jpeg.Decode(f1)
case "png":
img, err = png.Decode(f1)
default:
log.Printf("img type-%s may not be supported", imgType) //TODO bring in the logger
img, _, err = image.Decode(f1)
}
if err != nil {
err = fmt.Errorf("failed to decode image due to %s", err)
return
}
return
}
func CheckSlice(tiles []image.Image, grid Grid) (err error) {
expectedNoOfTiles := int(grid[0] * grid[1])
if len(tiles) < expectedNoOfTiles { //I am using ceil
err = fmt.Errorf("expected-%d got-%d", expectedNoOfTiles, len(tiles))
return
}
return
}
// by default img is saved as jpeg explicilty specify the format otherwise
func Save(img image.Image, imgName string) (err error) {
imgType := path.Ext(imgName)
imgType = strings.TrimPrefix(imgType, ".")
if imgType == "" {
imgType = "jpeg"
imgName = fmt.Sprintf("%s.%s", imgName, imgType)
}
f1, err := os.Create(imgName)
if err != nil {
return fmt.Errorf("failed to create file: %v", err)
}
defer f1.Close()
switch imgType {
case "png":
if err = png.Encode(f1, img); err != nil {
err = fmt.Errorf("failed to encode: %v", err)
}
default:
if err = jpeg.Encode(f1, img, nil); err != nil {
err = fmt.Errorf("failed to encode: %v", err)
}
}
if err != nil {
return
}
return
}
func SaveTile(tile image.Image, tileName string) (err error) {
return Save(tile, tileName)
}