forked from pierrre/imageserver
/
handler.go
57 lines (53 loc) · 1.38 KB
/
handler.go
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package image
import (
"github.com/cognusion/imageserver"
)
// Handler is a imageserver.Handler implementation that uses Go "image" package.
//
// It supports format conversion and processing.
// It uses the "format" param to determine which Encoder is used.
//
// If there is nothing to do, Handler does not decode the Image or call the Processor.
type Handler struct {
Processor Processor // Optional Processor
}
// Handle implements imageserver.Handler.
func (hdr *Handler) Handle(im *imageserver.Image, params imageserver.Params) (*imageserver.Image, error) {
enc, format, err := getEncoderFormat(im.Format, params)
if err != nil {
if _, ok := err.(*imageserver.ParamError); !ok {
err = &imageserver.ImageError{Message: err.Error()}
}
return nil, err
}
if !hdr.change(im, format, enc, params) {
return im, nil
}
nim, err := Decode(im)
if err != nil {
return nil, err
}
if hdr.Processor != nil {
nim, err = hdr.Processor.Process(nim, params)
if err != nil {
return nil, err
}
}
im, err = encode(nim, format, enc, params)
if err != nil {
return nil, err
}
return im, nil
}
func (hdr *Handler) change(im *imageserver.Image, format string, enc Encoder, params imageserver.Params) bool {
if format != im.Format {
return true
}
if hdr.Processor != nil && hdr.Processor.Change(params) {
return true
}
if enc.Change(params) {
return true
}
return false
}