66 lines
1.7 KiB
Go
66 lines
1.7 KiB
Go
package util
|
|
|
|
import (
|
|
"context"
|
|
"image"
|
|
"log"
|
|
|
|
"fyne.io/fyne/v2"
|
|
)
|
|
|
|
// ThumbnailLoader is a utility type that exposes a single API to load
|
|
// a cover thumbnail by ID. If the image is immediately available in
|
|
// the cache, OnLoaded will be called immediately. If it is not,
|
|
// OnBeforeLoad will be called first, then OnLoaded will be called async
|
|
// once the image is available.
|
|
// Any subsequent calls to Load will cancel the previous load if not yet completed.
|
|
type ThumbnailLoader struct {
|
|
prevLoadCancel context.CancelFunc
|
|
im ImageFetcher
|
|
|
|
OnBeforeLoad func()
|
|
OnLoaded func(image.Image)
|
|
}
|
|
|
|
// Image backend interface for the ThumbnailLoader
|
|
// impl: backend.ImageManager
|
|
type ImageFetcher interface {
|
|
GetCoverThumbnailFromCache(string) (image.Image, bool)
|
|
GetCoverThumbnailAsync(string, func(image.Image, error)) context.CancelFunc
|
|
}
|
|
|
|
func NewThumbnailLoader(im ImageFetcher, onLoaded func(image.Image)) ThumbnailLoader {
|
|
return ThumbnailLoader{im: im, OnLoaded: onLoaded}
|
|
}
|
|
|
|
func (i *ThumbnailLoader) Load(coverID string) {
|
|
if i.prevLoadCancel != nil {
|
|
i.prevLoadCancel()
|
|
}
|
|
if coverID == "" {
|
|
i.callOnLoaded(nil)
|
|
return
|
|
}
|
|
if img, ok := i.im.GetCoverThumbnailFromCache(coverID); ok {
|
|
i.callOnLoaded(img)
|
|
return
|
|
}
|
|
if i.OnBeforeLoad != nil {
|
|
i.OnBeforeLoad()
|
|
}
|
|
i.prevLoadCancel = i.im.GetCoverThumbnailAsync(coverID, func(img image.Image, err error) {
|
|
if err != nil {
|
|
log.Printf("Error loading cover image: %s", err.Error())
|
|
} else {
|
|
fyne.Do(func() { i.callOnLoaded(img) })
|
|
}
|
|
i.prevLoadCancel() // Done. Release resources associated with un-cancelled ctx
|
|
})
|
|
}
|
|
|
|
func (i *ThumbnailLoader) callOnLoaded(im image.Image) {
|
|
if i.OnLoaded != nil {
|
|
i.OnLoaded(im)
|
|
}
|
|
}
|