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refactor(resize)
This commit is contained in:
Tomas Aparicio
parent
cdade0c27f
commit
40dd19fa6a
8 changed files with 207 additions and 141 deletions
179
resize.go
179
resize.go
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@ -11,14 +11,6 @@ import (
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"math"
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)
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const (
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CENTRE Gravity = iota
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NORTH
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EAST
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SOUTH
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WEST
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)
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func Resize(buf []byte, o Options) ([]byte, error) {
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defer C.vips_thread_shutdown()
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@ -46,37 +38,8 @@ func Resize(buf []byte, o Options) ([]byte, error) {
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inWidth := int(image.Xsize)
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inHeight := int(image.Ysize)
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// prepare for factor
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factor := 0.0
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// image calculations
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switch {
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// Fixed width and height
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case o.Width > 0 && o.Height > 0:
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xf := float64(inWidth) / float64(o.Width)
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yf := float64(inHeight) / float64(o.Height)
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if o.Crop {
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factor = math.Min(xf, yf)
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} else {
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factor = math.Max(xf, yf)
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}
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// Fixed width, auto height
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case o.Width > 0:
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factor = float64(inWidth) / float64(o.Width)
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o.Height = int(math.Floor(float64(inHeight) / factor))
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// Fixed height, auto width
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case o.Height > 0:
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factor = float64(inHeight) / float64(o.Height)
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o.Width = int(math.Floor(float64(inWidth) / factor))
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// Identity transform
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default:
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factor = 1
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o.Width = inWidth
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o.Height = inHeight
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}
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debug("transform from %dx%d to %dx%d", inWidth, inHeight, o.Width, o.Height)
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factor := imageCalculations(o, inWidth, inHeight)
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shrink := int(math.Max(math.Floor(factor), 1))
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residual := float64(shrink) / factor
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@ -91,12 +54,10 @@ func Resize(buf []byte, o Options) ([]byte, error) {
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}
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}
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debug("factor: %v, shrink: %v, residual: %v", factor, shrink, residual)
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// Try to use libjpeg shrink-on-load
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if imageType == JPEG && shrink >= 2 {
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// Recalculate integral shrink and double residual
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tmpImage, factor, err := shrinkJpeg(buf, factor, shrink)
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tmpImage, factor, err := shrinkJpegImage(buf, factor, shrink)
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if err != nil {
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return nil, err
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}
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@ -108,58 +69,35 @@ func Resize(buf []byte, o Options) ([]byte, error) {
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}
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}
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// Calculate integral box shrink
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windowSize := vipsWindowSize(o.Interpolator.String())
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if factor >= 2 && windowSize > 3 {
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// Shrink less, affine more with interpolators that use at least 4x4 pixel window, e.g. bicubic
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shrink = int(math.Max(float64(math.Floor(factor*3.0/windowSize)), 1))
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}
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// Use vips_shrink with the integral reduction
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if shrink > 1 {
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debug("shrink %d", shrink)
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// Use vips_shrink with the integral reduction
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image, err = vipsShrink(image, shrink)
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image, residual, err = shrinkImage(image, o, residual, shrink)
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if err != nil {
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return nil, err
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}
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// Recalculate residual float based on dimensions of required vs shrunk images
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shrunkWidth := int(image.Xsize)
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shrunkHeight := int(image.Ysize)
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residualx := float64(o.Width) / float64(shrunkWidth)
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residualy := float64(o.Height) / float64(shrunkHeight)
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if o.Crop {
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residual = math.Max(residualx, residualy)
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} else {
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residual = math.Min(residualx, residualy)
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}
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}
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// Use vips_affine with the remaining float part
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if residual != 0 {
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debug("residual %.2f", residual)
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image, err = vipsAffine(image, residual, o.Interpolator)
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if err != nil {
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return nil, err
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}
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}
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// Crop/embed
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affinedWidth := int(image.Xsize)
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affinedHeight := int(image.Ysize)
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debug("factor: %v, shrink: %v, residual: %v", factor, shrink, residual)
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if affinedWidth != o.Width || affinedHeight != o.Height {
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if o.Crop {
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left, top := calculateCrop(affinedWidth, affinedHeight, o.Width, o.Height, o.Gravity)
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o.Width = int(math.Min(float64(inWidth), float64(o.Width)))
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o.Height = int(math.Min(float64(inHeight), float64(o.Height)))
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debug("crop image to %dx%d to %dx%d", left, top, o.Width, o.Height)
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image, err = vipsExtract(image, left, top, o.Width, o.Height)
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if err != nil {
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return nil, err
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}
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} else if o.Embed {
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left := (o.Width - affinedWidth) / 2
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top := (o.Height - affinedHeight) / 2
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image, err = vipsEmbed(image, left, top, o.Width, o.Height, o.Extend)
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if err != nil {
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return nil, err
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}
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}
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// Extract image
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image, err = extractImage(image, o)
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if err != nil {
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return nil, err
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}
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rotation, flip := calculateRotationAndFlip(image, o.Rotate)
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@ -171,8 +109,7 @@ func Resize(buf []byte, o Options) ([]byte, error) {
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}
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if o.Rotate > 0 {
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rotation := calculateRotation(o.Rotate)
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image, err = vipsRotate(image, rotation)
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image, err = vipsRotate(image, getAngle(o.Rotate))
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if err != nil {
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return nil, err
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}
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@ -195,11 +132,67 @@ func Resize(buf []byte, o Options) ([]byte, error) {
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if err != nil {
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return nil, err
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}
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C.vips_error_clear()
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return buf, nil
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}
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func extractImage(image *C.struct__VipsImage, o Options) (*C.struct__VipsImage, error) {
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var err error = nil
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affinedWidth := int(image.Xsize)
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affinedHeight := int(image.Ysize)
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if affinedWidth != o.Width || affinedHeight != o.Height {
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width := int(math.Min(float64(affinedWidth), float64(o.Width)))
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height := int(math.Min(float64(affinedHeight), float64(o.Height)))
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switch {
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case o.Crop:
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left, top := calculateCrop(affinedWidth, affinedHeight, o.Width, o.Height, o.Gravity)
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image, err = vipsExtract(image, left, top, width, height)
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break
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case o.Embed:
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left, top := (o.Width-affinedWidth)/2, (o.Height-affinedHeight)/2
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image, err = vipsEmbed(image, left, top, o.Width, o.Height, o.Extend)
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break
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case o.Top > 0 && o.Left > 0:
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image, err = vipsExtract(image, o.Left, o.Top, width, height)
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break
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}
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}
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return image, err
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}
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func imageCalculations(o Options, inWidth, inHeight int) float64 {
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factor := 1.0
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switch {
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// Fixed width and height
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case o.Width > 0 && o.Height > 0:
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xf := float64(inWidth) / float64(o.Width)
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yf := float64(inHeight) / float64(o.Height)
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if o.Crop {
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factor = math.Min(xf, yf)
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} else {
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factor = math.Max(xf, yf)
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}
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// Fixed width, auto height
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case o.Width > 0:
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factor = float64(inWidth) / float64(o.Width)
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o.Height = int(math.Floor(float64(inHeight) / factor))
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// Fixed height, auto width
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case o.Height > 0:
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factor = float64(inHeight) / float64(o.Height)
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o.Width = int(math.Floor(float64(inWidth) / factor))
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// Identity transform
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default:
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o.Width = inWidth
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o.Height = inHeight
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}
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return factor
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}
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func calculateCrop(inWidth, inHeight, outWidth, outHeight int, gravity Gravity) (int, int) {
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left, top := 0, 0
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@ -266,7 +259,27 @@ func calculateRotationAndFlip(image *C.struct__VipsImage, angle Angle) (Angle, b
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return rotate, flip
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}
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func shrinkJpeg(buf []byte, factor float64, shrink int) (*C.struct__VipsImage, float64, error) {
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func shrinkImage(image *C.struct__VipsImage, o Options, residual float64, shrink int) (*C.struct__VipsImage, float64, error) {
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// Use vips_shrink with the integral reduction
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image, err := vipsShrink(image, shrink)
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if err != nil {
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return nil, 0, err
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}
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// Recalculate residual float based on dimensions of required vs shrunk images
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residualx := float64(o.Width) / float64(image.Xsize)
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residualy := float64(o.Height) / float64(image.Ysize)
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if o.Crop {
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residual = math.Max(residualx, residualy)
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} else {
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residual = math.Min(residualx, residualy)
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}
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return image, residual, nil
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}
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func shrinkJpegImage(buf []byte, factor float64, shrink int) (*C.struct__VipsImage, float64, error) {
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shrinkOnLoad := 1
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switch {
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@ -293,7 +306,7 @@ func shrinkJpeg(buf []byte, factor float64, shrink int) (*C.struct__VipsImage, f
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return nil, factor, nil
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}
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func calculateRotation(angle Angle) Angle {
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func getAngle(angle Angle) Angle {
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divisor := angle % 90
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if divisor != 0 {
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angle = angle - divisor
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