chore: custom error

internal/components/images/scaling.go

@@ -0,0 +1,55 @@
+package images
+
+import (
+	"image"
+	"math"
+
+	"golang.org/x/image/draw"
+)
+
+func scale(src image.Image, options Options) image.Image {
+	// Set the expected size that you want:
+	dst := image.NewRGBA(
+		calculateFit(src.Bounds(), options),
+	)
+
+	// Resize:
+	draw.BiLinear.Scale(dst, dst.Rect, src, src.Bounds(), draw.Over, nil)
+
+	// Encode to `output`:
+	return dst
+}
+
+// calculateFit returns the new dimensions (width, height) that fit within the
+// provided Options without upscaling and while maintaining the aspect ratio.
+func calculateFit(bounds image.Rectangle, opt Options) image.Rectangle {
+	// If no limits are set, or the image is already smaller than the limits,
+	// return original dimensions (No Upscaling).
+	if (opt.Width == 0 || bounds.Max.X <= opt.Width) && (opt.Height == 0 || bounds.Max.Y <= opt.Height) {
+		return bounds
+	}
+
+	// Calculate ratios for width and height
+	ratioW := float64(opt.Width) / float64(bounds.Max.X)
+	ratioH := float64(opt.Height) / float64(bounds.Max.Y)
+
+	// Determine the scale factor
+	var scale float64
+	if opt.Width > 0 && opt.Height > 0 {
+		// Use the smaller ratio to ensure it fits in both bounds
+		scale = math.Min(ratioW, ratioH)
+	} else if opt.Width > 0 {
+		scale = ratioW
+	} else if opt.Height > 0 {
+		scale = ratioH
+	} else {
+		return bounds
+	}
+
+	return image.Rect(
+		0,
+		0,
+		int(math.Round(float64(bounds.Max.X)*scale)),
+		int(math.Round(float64(bounds.Max.Y)*scale)),
+	)
+}