I'm writing a small image processing tool, given an image content, it only
does two things:
1. compressing the image content
2. generating a thumbnail (by resizing and then compressing it)
I want to model the compressing(the same goes for resizing) after the
compress stdlib: you create a compressor that accepts an io.Writer, and
then write to the compressor.
The problem comes when I want to join resizing and compressing. They're
Resizer and Compressor respectively, and they conforms to io.WriteCloser.
Compressor is nested inside Resizer. When Resizer is closed, I want
Compressor to be automatically closed. But I don't know how to do it in a
general way. For example
type Thumbnail struct {
w io.Writer
ContentType string
generator io.WriteCloser
}
func NewThumbnail(w io.Writer, contentType string) *Thumbnail {
c = &Content{w, contentType, nil}
switch contentType {
case "image/jpeg":
compressor := jpeg.NewCompressor(w)
resizer := jpeg.Resizer(compressor)
c.generator = jpeg.NewCompressor(w)
}
return c
}
func (c *Thumbnail) Close() error {
return generator.Close()
}
Right now, closing generator won't close compressor.
I don't want to explicitly store compressor and resizer in Thumbnail and
close them manually, because I want to support different image types, which
might involve different steps to generate the thumbnail.
In this case, should I make Compressor and Resizer accept io.WriteCloser
instead? I'm not sure because
1. why the compress stdlib doesn't accept io.WriteCloser?
2. I will need to give io.Write to Compressor eventually, in which case I
need to wrap it in a ioutil.NopCloser, which is only for io.Reader. Maybe
there is a reason it only wraps io.Reader?
Regards,
Glen
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