limage - xcf/image_encode.go

  package xcf
  
  import (
  	"image"
  	"image/color"
  
  	"vimagination.zapto.org/limage/lcolor"
  )
  
  func (e *encoder) WriteImage(im image.Image, colourFunc colourBufFunc, colourChannels uint8) {
  	bounds := im.Bounds()
  
  	dx := int64(bounds.Dx())
  	dy := int64(bounds.Dy())
  
  	// Hierarchy
  
  	e.WriteUint32(uint32(dx))
  	e.WriteUint32(uint32(dy))
  	e.WriteUint32(uint32(colourChannels))
  
  	e.WriteUint32(uint32(e.pos) + 8) // currPos + this pointer (4) + zero pointer (4)
  	e.WriteUint32(0)
  
  	// Level
  
  	e.WriteUint32(uint32(dx))
  	e.WriteUint32(uint32(dy))
  
  	nx := dx >> 6 // each tile is 64 wide
  	ny := dy >> 6 // each tile is 64 high
  
  	if dx&63 > 0 { // last tile not as wide
  		nx++
  	}
  	if dy&63 > 0 { // last tile not as high
  		ny++
  	}
  
  	w := e.ReservePointerList(uint32(nx * ny))
  
  	// Tiles
  
  	for y := bounds.Min.Y; y < bounds.Max.Y; y += 64 {
  		for x := bounds.Min.X; x < bounds.Max.X; x += 64 {
  			l := uint16(0)
  			for j := y; j < y+64 && j < bounds.Max.Y; j++ {
  				for i := x; i < x+64 && i < bounds.Max.X; i++ {
  					colourFunc(e, im.At(i, j))
  					for n := uint8(0); n < colourChannels; n++ {
  						e.channelBuf[n][l] = e.colourBuf[n]
  					}
  					l++
  				}
  			}
  			w.WritePointer(uint32(e.pos))
  			for n := uint8(0); n < colourChannels; n++ {
  				e.WriteRLE(e.channelBuf[n][:l])
  			}
  		}
  	}
  }
  
  func (e *encoder) rgbAlphaToBuf(c color.Color) {
  	rgba := color.NRGBAModel.Convert(c).(color.NRGBA)
  	e.colourBuf[0] = rgba.R
  	e.colourBuf[1] = rgba.G
  	e.colourBuf[2] = rgba.B
  	e.colourBuf[3] = rgba.A
  }
  
  func (e *encoder) grayAlphaToBuf(c color.Color) {
  	ga := lcolor.GrayAlphaModel.Convert(c).(lcolor.GrayAlpha)
  	e.colourBuf[0] = ga.Y
  	e.colourBuf[1] = ga.A
  }
  
  func (e *encoder) grayToBuf(c color.Color) {
  	e.colourBuf[0] = color.GrayModel.Convert(c).(color.Gray).Y
  }
  
  func (e *encoder) paletteAlphaToBuf(c color.Color) {
  	r, g, b, a := c.RGBA()
  	i := e.colourPalette.Index(lcolor.RGB{R: uint8(r), G: uint8(g), B: uint8(b)})
  	e.colourBuf[0] = uint8(i)
  	e.colourBuf[1] = uint8(a)
  }