Function cropParams

transform.go:174–219

cropParams calculates crop rectangle parameters to keep it in image bounds

(m image.Image, opt Options)

// cropParams calculates crop rectangle parameters to keep it in image bounds
func cropParams(m image.Image, opt Options) image.Rectangle {
	if !opt.SmartCrop && opt.CropX == 0 && opt.CropY == 0 && opt.CropWidth == 0 && opt.CropHeight == 0 {
		return m.Bounds()
	}

	// width and height of image
	imgW := m.Bounds().Dx()
	imgH := m.Bounds().Dy()

	if opt.SmartCrop {
		w := evaluateFloat(opt.Width, imgW)
		h := evaluateFloat(opt.Height, imgH)
		r, err := smartcropAnalyzer.FindBestCrop(m, w, h)
		if err != nil {
			log.Printf("smartcrop error finding best crop: %v", err)
		} else {
			return r
		}
	}

	// top left coordinate of crop
	x0 := evaluateFloat(math.Abs(opt.CropX), imgW)
	if opt.CropX < 0 {
		x0 = imgW - x0 // measure from right
	}
	y0 := evaluateFloat(math.Abs(opt.CropY), imgH)
	if opt.CropY < 0 {
		y0 = imgH - y0 // measure from bottom
	}

	// width and height of crop
	w := evaluateFloat(opt.CropWidth, imgW)
	if w == 0 {
		w = imgW
	}
	h := evaluateFloat(opt.CropHeight, imgH)
	if h == 0 {
		h = imgH
	}

	// bottom right coordinate of crop
	x1 := min(x0+w, imgW)
	y1 := min(y0+h, imgH)

	return image.Rect(x0, y0, x1, y1)
}

// read EXIF orientation tag from r and adjust opt to orient image correctly.
func exifOrientation(r io.Reader) (opt Options) {