mirror of
https://github.com/willnorris/imageproxy.git
synced 2024-12-16 21:56:43 -05:00
110 lines
2.3 KiB
Go
110 lines
2.3 KiB
Go
// Copyright 2013 Google Inc. All rights reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package imageproxy
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import (
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"bytes"
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"image"
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"image/gif"
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"image/jpeg"
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"image/png"
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"reflect"
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"github.com/disintegration/imaging"
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)
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// compression quality of resized jpegs
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const jpegQuality = 95
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// Transform the provided image.
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func Transform(img []byte, opt *Options) ([]byte, error) {
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if opt == nil || reflect.DeepEqual(opt, emptyOptions) {
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// bail if no transformation was requested
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return img, nil
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}
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// decode image
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m, format, err := image.Decode(bytes.NewReader(img))
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if err != nil {
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return nil, err
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}
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// convert percentage width and height values to absolute values
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imgW := m.Bounds().Max.X - m.Bounds().Min.X
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imgH := m.Bounds().Max.Y - m.Bounds().Min.Y
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var h, w int
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if opt.Width > 0 && opt.Width < 1 {
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w = int(float64(imgW) * opt.Width)
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} else {
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w = int(opt.Width)
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}
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if opt.Height > 0 && opt.Height < 1 {
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h = int(float64(imgH) * opt.Height)
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} else {
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h = int(opt.Height)
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}
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// never resize larger than the original image
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if w > imgW {
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w = imgW
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}
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if h > imgH {
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h = imgH
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}
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// resize
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if w != 0 || h != 0 {
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if opt.Fit {
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m = imaging.Fit(m, w, h, imaging.Lanczos)
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} else {
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if w == 0 || h == 0 {
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m = imaging.Resize(m, w, h, imaging.Lanczos)
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} else {
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m = imaging.Thumbnail(m, w, h, imaging.Lanczos)
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}
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}
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}
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// flip
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if opt.FlipVertical {
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m = imaging.FlipV(m)
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}
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if opt.FlipHorizontal {
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m = imaging.FlipH(m)
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}
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// rotate
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switch opt.Rotate {
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case 90:
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m = imaging.Rotate90(m)
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case 180:
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m = imaging.Rotate180(m)
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case 270:
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m = imaging.Rotate270(m)
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}
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// encode image
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buf := new(bytes.Buffer)
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switch format {
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case "gif":
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gif.Encode(buf, m, nil)
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case "jpeg":
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jpeg.Encode(buf, m, &jpeg.Options{Quality: jpegQuality})
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case "png":
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png.Encode(buf, m)
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}
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return buf.Bytes(), nil
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}
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