Add 'thumbnails/' from commit '2ebf7b2f23af96b3b499c401fe5498a9349403d8'

git-subtree-dir: thumbnails
git-subtree-mainline: ccc651a11e
git-subtree-split: 2ebf7b2f23

thumbnails/pkg/thumbnail/resolution/resolutions.go

@@ -0,0 +1,74 @@
+package resolution
+
+import (
+	"fmt"
+	"math"
+	"sort"
+)
+
+// New creates an instance of Resolutions from resolution strings.
+func New(rStrs []string) (Resolutions, error) {
+	var rs Resolutions
+	for _, rStr := range rStrs {
+		r, err := Parse(rStr)
+		if err != nil {
+			return nil, fmt.Errorf("failed to initialize resolutions: %s", err.Error())
+		}
+		rs = append(rs, r)
+	}
+	sort.Slice(rs, func(i, j int) bool {
+		left := rs[i]
+		right := rs[j]
+
+		leftSize := left.Width * left.Height
+		rightSize := right.Width * right.Height
+
+		return leftSize < rightSize
+	})
+
+	return rs, nil
+}
+
+// Resolutions represents the available thumbnail resolutions.
+type Resolutions []Resolution
+
+// ClosestMatch returns the resolution which is closest to the provided resolution.
+// If there is no exact match the resolution will be the next higher one.
+// If the given resolution is bigger than all available resolutions the biggest available one is used.
+func (r Resolutions) ClosestMatch(width, height int) Resolution {
+	if len(r) == 0 {
+		return Resolution{Width: width, Height: height}
+	}
+
+	isLandscape := width > height
+	givenLen := int(math.Max(float64(width), float64(height)))
+
+	// Initialize with the first resolution
+	var match Resolution
+	minDiff := math.MaxInt32
+
+	for _, current := range r {
+		len := dimensionLength(current, isLandscape)
+		diff := givenLen - len
+		if diff > 0 {
+			continue
+		}
+		absDiff := int(math.Abs(float64(diff)))
+		if absDiff < minDiff {
+			minDiff = absDiff
+			match = current
+		}
+	}
+
+	if match == (Resolution{}) {
+		match = r[len(r)-1]
+	}
+	return match
+}
+
+func dimensionLength(r Resolution, landscape bool) int {
+	if landscape {
+		return r.Width
+	}
+	return r.Height
+}