Add image thumbnail previews to the uploads page.

imageprocess/imageprocess.go

@@ -0,0 +1,4 @@
+package imageprocess
+
+type Processor struct {
+}

imageprocess/thumb.go

@@ -0,0 +1,47 @@
+package imageprocess
+
+import (
+	"fmt"
+	"image"
+	"image/png"
+	"io"
+	"os"
+
+	"github.com/tardisx/discord-auto-upload/upload"
+	"golang.org/x/image/draw"
+)
+
+const (
+	thumbnailMaxX = 128
+	thumbnailMaxY = 128
+)
+
+func (ip *Processor) ThumbPNG(ul *upload.Upload, w io.Writer) error {
+	file, err := os.Open(ul.OriginalFilename)
+	if err != nil {
+		return fmt.Errorf("could not open file: %s", err)
+	}
+	defer file.Close()
+	im, _, err := image.Decode(file)
+	if err != nil {
+		return fmt.Errorf("could not decode file: %s", err)
+	}
+
+	newXY := image.Point{}
+	// test width
+	if im.Bounds().Max.X/thumbnailMaxX > im.Bounds().Max.Y/thumbnailMaxY {
+		newXY.X = thumbnailMaxX
+		newXY.Y = im.Bounds().Max.Y / (im.Bounds().Max.X / thumbnailMaxX)
+	} else {
+		newXY.Y = thumbnailMaxY
+		newXY.X = im.Bounds().Max.X / (im.Bounds().Max.Y / thumbnailMaxY)
+	}
+
+	dst := image.NewRGBA(image.Rect(0, 0, newXY.X, newXY.Y))
+	draw.BiLinear.Scale(dst, dst.Rect, im, im.Bounds(), draw.Over, nil)
+
+	png.Encode(w, dst)
+
+	return nil
+
+}