mirror of https://mirror.trustie.net/root/bimg.git
179 lines
4.5 KiB
Go
179 lines
4.5 KiB
Go
package bimg
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import (
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"regexp"
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"sync"
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"unicode/utf8"
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)
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// ImageType represents an image type value.
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type ImageType int
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const (
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// UNKNOWN represents an unknow image type value.
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UNKNOWN ImageType = iota
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// JPEG represents the JPEG image type.
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JPEG
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// WEBP represents the WEBP image type.
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WEBP
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// PNG represents the PNG image type.
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PNG
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// TIFF represents the TIFF image type.
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TIFF
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// GIF represents the GIF image type.
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GIF
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// PDF represents the PDF type.
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PDF
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// SVG represents the SVG image type.
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SVG
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// MAGICK represents the libmagick compatible genetic image type.
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MAGICK
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// HEIF represents the HEIC/HEIF/HVEC image type
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HEIF
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// AVIF represents the AVIF image type.
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AVIF
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)
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var (
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htmlCommentRegex = regexp.MustCompile("(?i)<!--([\\s\\S]*?)-->")
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svgRegex = regexp.MustCompile(`(?i)^\s*(?:<\?xml[^>]*>\s*)?(?:<!doctype svg[^>]*>\s*)?<svg[^>]*>[^*]*<\/svg>\s*$`)
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)
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// ImageTypes stores as pairs of image types supported and its alias names.
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var ImageTypes = map[ImageType]string{
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JPEG: "jpeg",
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PNG: "png",
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WEBP: "webp",
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TIFF: "tiff",
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GIF: "gif",
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PDF: "pdf",
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SVG: "svg",
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MAGICK: "magick",
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HEIF: "heif",
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AVIF: "avif",
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}
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// imageMutex is used to provide thread-safe synchronization
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// for SupportedImageTypes map.
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var imageMutex = &sync.RWMutex{}
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// SupportedImageType represents whether a type can be loaded and/or saved by
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// the current libvips compilation.
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type SupportedImageType struct {
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Load bool
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Save bool
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}
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// SupportedImageTypes stores the optional image type supported
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// by the current libvips compilation.
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// Note: lazy evaluation as demand is required due
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// to bootstrap runtime limitation with C/libvips world.
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var SupportedImageTypes = map[ImageType]SupportedImageType{}
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// discoverSupportedImageTypes is used to fill SupportedImageTypes map.
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func discoverSupportedImageTypes() {
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imageMutex.Lock()
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for imageType := range ImageTypes {
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SupportedImageTypes[imageType] = SupportedImageType{
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Load: VipsIsTypeSupported(imageType),
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Save: VipsIsTypeSupportedSave(imageType),
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}
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}
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imageMutex.Unlock()
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}
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// isBinary checks if the given buffer is a binary file.
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func isBinary(buf []byte) bool {
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if len(buf) < 24 {
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return false
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}
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for i := 0; i < 24; i++ {
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charCode, _ := utf8.DecodeRuneInString(string(buf[i]))
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if charCode == 65533 || charCode <= 8 {
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return true
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}
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}
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return false
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}
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// IsSVGImage returns true if the given buffer is a valid SVG image.
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func IsSVGImage(buf []byte) bool {
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return !isBinary(buf) && svgRegex.Match(htmlCommentRegex.ReplaceAll(buf, []byte{}))
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}
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// DetermineImageType determines the image type format (jpeg, png, webp or tiff)
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func DetermineImageType(buf []byte) ImageType {
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return vipsImageType(buf)
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}
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// DetermineImageTypeName determines the image type format by name (jpeg, png, webp or tiff)
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func DetermineImageTypeName(buf []byte) string {
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return ImageTypeName(vipsImageType(buf))
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}
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// IsImageTypeSupportedByVips returns true if the given image type
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// is supported by current libvips compilation.
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func IsImageTypeSupportedByVips(t ImageType) SupportedImageType {
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imageMutex.RLock()
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// Discover supported image types and cache the result
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itShouldDiscover := len(SupportedImageTypes) == 0
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if itShouldDiscover {
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imageMutex.RUnlock()
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discoverSupportedImageTypes()
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}
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// Check if image type is actually supported
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supported, ok := SupportedImageTypes[t]
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if !itShouldDiscover {
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imageMutex.RUnlock()
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}
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if ok {
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return supported
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}
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return SupportedImageType{Load: false, Save: false}
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}
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// IsTypeSupported checks if a given image type is supported
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func IsTypeSupported(t ImageType) bool {
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_, ok := ImageTypes[t]
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return ok && IsImageTypeSupportedByVips(t).Load
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}
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// IsTypeNameSupported checks if a given image type name is supported
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func IsTypeNameSupported(t string) bool {
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for imageType, name := range ImageTypes {
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if name == t {
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return IsImageTypeSupportedByVips(imageType).Load
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}
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}
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return false
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}
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// IsTypeSupportedSave checks if a given image type is support for saving
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func IsTypeSupportedSave(t ImageType) bool {
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_, ok := ImageTypes[t]
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return ok && IsImageTypeSupportedByVips(t).Save
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}
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// IsTypeNameSupportedSave checks if a given image type name is supported for
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// saving
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func IsTypeNameSupportedSave(t string) bool {
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for imageType, name := range ImageTypes {
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if name == t {
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return IsImageTypeSupportedByVips(imageType).Save
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}
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}
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return false
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}
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// ImageTypeName is used to get the human friendly name of an image format.
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func ImageTypeName(t ImageType) string {
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imageType := ImageTypes[t]
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if imageType == "" {
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return "unknown"
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}
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return imageType
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}
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