mirror of
https://github.com/opencloud-eu/opencloud.git
synced 2026-01-06 05:01:10 -05:00
100 lines
2.7 KiB
Go
100 lines
2.7 KiB
Go
package thumbnail
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import (
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"image"
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"image/color"
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"image/draw"
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"image/gif"
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"strings"
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"github.com/kovidgoyal/imaging"
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"github.com/opencloud-eu/opencloud/services/thumbnails/pkg/errors"
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)
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// Generator generates a web friendly file version.
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type Generator interface {
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Generate(size image.Rectangle, img interface{}) (interface{}, error)
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Dimensions(img interface{}) (image.Rectangle, error)
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ProcessorID() string
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}
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// GifGenerator is used to create a web friendly version of the provided gif image.
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type GifGenerator struct {
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processor Processor
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}
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func NewGifGenerator(filetype, process string) (GifGenerator, error) {
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processor, err := ProcessorFor(process, filetype)
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if err != nil {
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return GifGenerator{}, err
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}
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return GifGenerator{processor: processor}, nil
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}
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// ProcessorID returns the processor identification.
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func (g GifGenerator) ProcessorID() string {
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return g.processor.ID()
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}
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// Generate generates a alternative gif version.
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func (g GifGenerator) Generate(size image.Rectangle, img interface{}) (interface{}, error) {
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// Code inspired by https://github.com/willnorris/gifresize/blob/db93a7e1dcb1c279f7eeb99cc6d90b9e2e23e871/gifresize.go
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m, ok := img.(*gif.GIF)
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if !ok {
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return nil, errors.ErrInvalidType
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}
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// Create a new RGBA image to hold the incremental frames.
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srcX, srcY := m.Config.Width, m.Config.Height
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b := image.Rect(0, 0, srcX, srcY)
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tmp := image.NewRGBA(b)
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for i, frame := range m.Image {
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bounds := frame.Bounds()
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prev := tmp
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draw.Draw(tmp, bounds, frame, bounds.Min, draw.Over)
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processed := g.processor.Process(tmp, size.Dx(), size.Dy(), imaging.Lanczos)
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m.Image[i] = g.imageToPaletted(processed, frame.Palette)
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switch m.Disposal[i] {
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case gif.DisposalBackground:
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tmp = image.NewRGBA(b)
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case gif.DisposalPrevious:
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tmp = prev
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}
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}
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m.Config.Width = size.Dx()
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m.Config.Height = size.Dy()
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return m, nil
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}
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func (g GifGenerator) Dimensions(img interface{}) (image.Rectangle, error) {
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m, ok := img.(*gif.GIF)
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if !ok {
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return image.Rectangle{}, errors.ErrInvalidType
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}
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return m.Image[0].Bounds(), nil
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}
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func (g GifGenerator) imageToPaletted(img image.Image, p color.Palette) *image.Paletted {
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b := img.Bounds()
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pm := image.NewPaletted(b, p)
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draw.FloydSteinberg.Draw(pm, b, img, image.Point{})
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return pm
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}
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// GeneratorFor returns the generator for a given file type
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// or nil if the type is not supported.
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func GeneratorFor(fileType, processorID string) (Generator, error) {
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switch strings.ToLower(fileType) {
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case typePng, typeJpg, typeJpeg, typeGgs, typeGgp:
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return NewSimpleGenerator(fileType, processorID)
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case typeGif:
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return NewGifGenerator(fileType, processorID)
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default:
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return nil, errors.ErrNoGeneratorForType
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}
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}
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