// GenerateThumbnail assumes that the images have already been saved to storage,
// and that one or more image is contained within imagesValue. Returns the
// resulting filename of the generated thumbnail if successful, or an error
// otherwise.
func (imagesValue *ImagesValue) GenerateThumbnail() (string, error) {
if !imagesValue.IsComplete() {
return "", errors.New("No images to generate thumbnail for.")
}
filename := MediaDir + ThumbnailDir + uuid.NewUUID().String() + ThumbnailType
mw := imagick.NewMagickWand()
defer mw.Destroy()
err := mw.ReadImage(fieldsConfig.Website.Directory + (*imagesValue)[0])
if err != nil {
return "", err
}
err = mw.ThumbnailImage(ThumbnailMaxWidth, ThumbnailMaxHeight)
if err != nil {
return "", err
}
err = mw.SetImageCompressionQuality(ThumbnailQuality)
if err != nil {
return "", err
}
err = mw.WriteImage(fieldsConfig.Website.Directory + filename)
if err != nil {
return "", err
}
return filename, nil
}
// SaveImage converts the given base64 string into an image, saves it to the
// file system, and returns its filename. If it is unsuccessful, an error is
// returned.
func SaveImage(base64str string) (string, error) {
// removes header information
strs := strings.Split(base64str, ",")
str := strs[len(strs)-1]
blob, err := base64.StdEncoding.DecodeString(str)
if err != nil {
return "", err
}
filename := MediaDir + ImageDir + uuid.NewUUID().String() + ImageType
mw := imagick.NewMagickWand()
defer mw.Destroy()
err = mw.ReadImageBlob(blob)
if err != nil {
return "", err
}
width := mw.GetImageWidth()
newWidth := width
height := mw.GetImageHeight()
newHeight := height
if width > ImageMaxWidth {
newWidth = ImageMaxWidth
newHeight = uint(float64(height) / float64(width/ImageMaxWidth))
}
if newHeight > ImageMaxHeight {
newHeight = ImageMaxHeight
newWidth = uint(float64(width) / float64(height/ImageMaxHeight))
}
// Resize the image using the Lanczos filter
// The blur factor is a float, where > 1 is blurry, < 1 is sharp
err = mw.ResizeImage(newWidth, newHeight, imagick.FILTER_LANCZOS, 1)
if err != nil {
return "", err
}
err = mw.SetImageCompressionQuality(ImageQuality)
if err != nil {
return "", err
}
err = mw.WriteImage(fieldsConfig.Website.Directory + filename)
if err != nil {
return "", err
}
return filename, nil
}
