buildFull.go

func (b *MosaicBuilder) Build() error {
   b.logger.Println("Load parts paths ...")
   partsPaths, err := b.getPartsPaths()
   if err != nil {
      return err
   }

   b.logger.Println("Load parts map ...")
   partsMap, err := b.getPartsMap(partsPaths)
   if err != nil {
      return err
   }

   b.logger.Println("Open source image ...")
   img, err := os.Open("img.jpg")
   defer func(img *os.File) { _ = img.Close() }(img)

   if err != nil {
      return err
   }

   src, err := jpeg.Decode(img)
   if err != nil {
      return err
   }

   b.logger.Println("calculate ...")
   imgSize := src.Bounds().Size()

   if imgSize.X > 300 {
      src = resize.Resize(300, 0, src, resize.Lanczos3)
   }
   if imgSize.Y > 300 {
      src = resize.Resize(0, 300, src, resize.Lanczos3)
   }

   imgSize = src.Bounds().Size()
   
   partSize := int(b.partSize)
   resImg := image.NewRGBA(
      image.Rectangle{
         Min: image.Point{},
         Max: image.Point{X: imgSize.X * partSize, Y: imgSize.Y * partSize},
      },
   )

   for x := 0; x < imgSize.X; x++ {
      for y := 0; y < imgSize.Y; y++ {
         bcolor := src.At(x, y)
         part := getClosestPart(&partsMap, bcolor)

         for px := 0; px < partSize; px++ {
            for py := 0; py < partSize; py++ {

               partPixel := color.RGBAModel.Convert(part.At(px, py)).(color.RGBA)
               resImg.Set(partSize*x+px, partSize*y+py, partPixel)
            }
         }
      }
   }

   b.logger.Println("save res ...")
   f, err := os.Create("res.png")
   if err != nil {
      return err
   }

   if err := png.Encode(f, resImg); err != nil {
      return err
   }

   b.logger.Println("done!")

   return nil
}