func (r *FilesResource) getImageReader(registry kit.Registry, tmpDir string, file kit.File, width, height int64, filters []string, ip string) (reader kit.ReadSeekerCloser, size int64, err apperror.Error) {
if width == 0 && height == 0 && len(filters) == 0 {
reader, err = file.Reader()
return
}
// Dimensions specified.
// Check if the thumbnail was already created.
// If so, serve it. Otherwise, create it first.
if (width == 0 || height == 0) && (file.GetWidth() == 0 || file.GetHeight() == 0) {
err = &apperror.Err{
Code: "image_dimensions_not_determined",
Message: fmt.Sprintf("The file with id %v does not have width/height", file.GetId()),
}
return
}
if width < 0 || height < 0 {
err = apperror.New("invalid_dimensions")
return
}
// If either height or width is 0, determine proper values to presserve aspect ratio.
if width == 0 {
ratio := float64(file.GetWidth()) / float64(file.GetHeight())
width = int64(float64(height) * ratio)
} else if height == 0 {
ratio := float64(file.GetHeight()) / float64(file.GetWidth())
height = int64(float64(width) * ratio)
}
maxWidth := registry.Config().UInt("files.thumbGenerator.maxWidth", 2000)
maxHeight := registry.Config().UInt("files.thumbGenerator.maxHeight", 2000)
if width > int64(maxWidth) || height > int64(maxHeight) {
err = &apperror.Err{
Code: "dimensions_exceed_maximum_limits",
Message: "The specified dimensions exceed the maximum limits",
}
return
}
thumbId := fmt.Sprintf("%v_%v_%v_%v_%v_%v.%v",
file.GetId(),
file.GetBucket(),
file.GetName(),
strconv.FormatInt(width, 10),
strconv.FormatInt(height, 10),
strings.Replace(strings.Join(filters, "_"), ":", "_", -1),
"jpeg")
if ok, _ := file.GetBackend().HasFileById("thumbs", thumbId); !ok {
var channel chan bool
channel, err = r.thumbnailRateLimiter.Start(ip)
if err != nil {
return
}
if channel != nil {
<-channel
}
// Thumb does not exist yet, so create it.
reader, err = file.Reader()
if err != nil {
return
}
defer reader.Close()
img, _, err2 := image.Decode(reader)
if err2 != nil {
err = apperror.Wrap(err2, "image_decode_error")
return
}
var giftFilters []gift.Filter
if !(height == 0 && width == 0) {
giftFilters = append(giftFilters, gift.ResizeToFill(int(width), int(height), gift.LanczosResampling, gift.CenterAnchor))
}
for _, filter := range filters {
if filter == "" {
continue
}
parts := strings.Split(filter, ":")
if len(parts) > 1 {
filter = parts[0]
}
switch filter {
case "sepia":
n := float32(100)
if len(parts) == 2 {
x, err2 := strconv.ParseFloat(parts[1], 64)
if err2 == nil {
n = float32(x)
} else {
err = apperror.New("invalid_sepia_filter_value", true)
return
}
}
giftFilters = append(giftFilters, gift.Sepia(n))
case "grayscale":
giftFilters = append(giftFilters, gift.Grayscale())
case "brightness":
n := float32(0)
if len(parts) == 2 {
x, err2 := strconv.ParseFloat(parts[1], 64)
if err2 == nil {
n = float32(x)
} else {
err = apperror.New("invalid_brightness_filter_value", true)
return
}
}
giftFilters = append(giftFilters, gift.Brightness(n))
default:
err = apperror.New("unknown_filter", fmt.Sprintf("Unknown filter: %v", filter), true)
return
}
}
gift := gift.New(giftFilters...)
thumb := image.NewRGBA(gift.Bounds(img.Bounds()))
gift.Draw(thumb, img)
var writer io.WriteCloser
_, writer, err = file.GetBackend().WriterById("thumbs", thumbId, true)
if err != nil {
return
}
defer writer.Close()
jpeg.Encode(writer, thumb, &jpeg.Options{Quality: 90})
r.thumbnailRateLimiter.Finish()
}
backend := file.GetBackend()
size, err = backend.FileSizeById("thumbs", thumbId)
if err != nil {
return
}
reader, err = file.GetBackend().ReaderById("thumbs", thumbId)
return
}