136 lines
2.9 KiB
Go
136 lines
2.9 KiB
Go
package bucket
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import (
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"errors"
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"fmt"
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"mime"
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"net/url"
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"sort"
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"strings"
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)
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type Preview string
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const previewPrefix = "preview/"
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var ErrorInvalidPreview = errors.New("invalid preview")
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func (p Preview) Validate() error {
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if !strings.HasPrefix(string(p), previewPrefix) {
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return fmt.Errorf("%w: %v", ErrorInvalidPreview, p)
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}
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return nil
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}
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func (p Preview) String() string {
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return string(p)
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}
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func (p Preview) Path() string {
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u := url.URL{
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Path: string(p),
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}
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return u.String()
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}
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func (p Preview) Format() PhotoFormat {
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extIndex := strings.LastIndex(string(p), ".")
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return PhotoFormat(mime.TypeByExtension(string(p)[extIndex:]))
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}
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type PreviewOption struct {
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Height int
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//Width int
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Format PhotoFormat
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Quality int
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}
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type PhotoFormat string
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const (
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PhotoFormatJPEG PhotoFormat = "image/jpeg"
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PhotoFormatWEBP PhotoFormat = "image/webp"
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PhotoFormatHEIF PhotoFormat = "image/heif"
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PhotoFormatPNG PhotoFormat = "image/png"
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PhotoFormatGIF PhotoFormat = "image/gif"
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PhotoFormatTIFF PhotoFormat = "image/tiff"
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)
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func (f PhotoFormat) ContentType() string {
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return string(f)
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}
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var SupportedFormats = []PhotoFormat{
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PhotoFormatJPEG,
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PhotoFormatWEBP,
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PhotoFormatHEIF,
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PhotoFormatPNG,
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PhotoFormatGIF,
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PhotoFormatTIFF,
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}
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type PhotoQualityLevel int
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const (
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PhotoQualityLevelThumbnail PhotoQualityLevel = 0
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PhotoQualityLevelBasic PhotoQualityLevel = 1
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PhotoQualityLevelNormal PhotoQualityLevel = 2
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PhotoQualityLevelExtreme PhotoQualityLevel = 3
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)
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func (f PhotoFormat) Quality(level PhotoQualityLevel) int {
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if f == PhotoFormatJPEG || f == PhotoFormatWEBP {
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return 34 + int(level)*18
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}
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if f == PhotoFormatHEIF {
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return 10 + int(level)*10
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}
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return 0
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}
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func (p Photo) GetPreview(option PreviewOption) Preview {
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objectBase := strings.Replace(string(p), photoPrefix, previewPrefix, 1)
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extIndex := strings.LastIndex(objectBase, ".")
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base := objectBase[:extIndex]
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res := fmt.Sprintf("_h%dq%d", option.Height, option.Quality)
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exts, err := mime.ExtensionsByType(option.Format.ContentType())
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if err != nil {
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panic(err)
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}
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sort.Strings(exts)
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if len(exts) < 1 {
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panic("missing MIME type to extension mapping, please configure within your operating system")
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}
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return Preview(base + res + exts[len(exts)-1])
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}
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var defaultSizes = []int{640, 320, 160, 80}
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var defaultSizesThumb = []int{60, 30}
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var defaultFormats = []PhotoFormat{
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PhotoFormatWEBP,
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PhotoFormatJPEG,
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}
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func DefaultPreviewOptions() []PreviewOption {
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options := make([]PreviewOption, 0)
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for _, size := range defaultSizes {
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for _, format := range defaultFormats {
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options = append(options, PreviewOption{
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Height: size,
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Format: format,
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Quality: format.Quality(PhotoQualityLevelNormal),
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})
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}
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}
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for _, size := range defaultSizesThumb {
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for _, format := range defaultFormats {
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options = append(options, PreviewOption{
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Height: size,
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Format: format,
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Quality: format.Quality(PhotoQualityLevelThumbnail),
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})
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}
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}
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return options
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}
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