tools/util/image/scale.go

package image

type Scale struct {
	Width  uint
	Height uint
	Scale  float64
}

func NewScale(width uint, height uint, scale float64) *Scale {
	return &Scale{width, height, scale}
}

// MinRatio 获取缩放比例，等比缩放，以短边为准
func (s Scale) MinRatio(width, height uint) Scale {
	scale := 1.0
	if s.Width/s.Height > width/height {
		if s.Height > height {
			scale = CustomScale(height, s.Height)
		}
	} else {
		if s.Width > width {
			scale = CustomScale(width, s.Width)
		}
	}
	width = uint(scale * float64(s.Width))
	height = uint(scale * float64(s.Height))

	return Scale{Width: width, Height: height, Scale: scale}
}

// MaxRatio 裁切，以长边为准
func (s Scale) MaxRatio(width, height uint) Scale {
	scale := 1.0
	if s.Width/s.Height > width/height {
		scale = CustomScale(height, s.Height)
	} else {
		scale = CustomScale(width, s.Width)
	}

	width = uint(scale * float64(s.Width))
	height = uint(scale * float64(s.Height))

	return Scale{Width: width, Height: height, Scale: scale}
}