Method limitScale

processing/prepare.go:223–265

(widthToScale, heightToScale int, po ProcessingOptions)

}

func (c *Context) limitScale(widthToScale, heightToScale int, po ProcessingOptions) {
	maxresultDim := c.PO.MaxResultDimension()

	if maxresultDim <= 0 {
		return
	}

	outWidth := imath.MinNonZero(c.ScaledWidth, c.ResultCropWidth)
	outHeight := imath.MinNonZero(c.ScaledHeight, c.ResultCropHeight)

	if po.ExtendEnabled() {
		outWidth = max(outWidth, c.TargetWidth)
		outHeight = max(outHeight, c.TargetHeight)
	} else if po.ExtendAspectRatioEnabled() {
		outWidth = max(outWidth, c.ExtendAspectRatioWidth)
		outHeight = max(outHeight, c.ExtendAspectRatioHeight)
	}

	outWidth += imath.ScaleToEven(po.PaddingLeft(), c.DprScale)
	outWidth += imath.ScaleToEven(po.PaddingRight(), c.DprScale)
	outHeight += imath.ScaleToEven(po.PaddingTop(), c.DprScale)
	outHeight += imath.ScaleToEven(po.PaddingBottom(), c.DprScale)

	if maxresultDim > 0 && (outWidth > maxresultDim || outHeight > maxresultDim) {
		downScale := float64(maxresultDim) / float64(max(outWidth, outHeight))

		c.WScale *= downScale
		c.HScale *= downScale

		// Prevent scaling below 1px
		if minWScale := 1.0 / float64(widthToScale); c.WScale < minWScale {
			c.WScale = minWScale
		}
		if minHScale := 1.0 / float64(heightToScale); c.HScale < minHScale {
			c.HScale = minHScale
		}

		c.DprScale *= downScale

		// Recalculate the sizes after changing the scales
		c.calcSizes(widthToScale, heightToScale, po)
	}
}

// CalcParams calculates context image parameters based on the current image size.
// Some steps (like trim) must call this function when finished.