Initial QSfera import

Server/vendor/github.com/kovidgoyal/imaging/prism/meta/gifmeta/gifmeta.go

@@ -0,0 +1,50 @@
+package gifmeta
+
+import (
+	"fmt"
+	"image/gif"
+	"io"
+	"strings"
+	"time"
+
+	"github.com/kovidgoyal/imaging/prism/meta"
+	"github.com/kovidgoyal/imaging/types"
+)
+
+var _ = fmt.Print
+
+func ExtractMetadata(r io.Reader) (md *meta.Data, err error) {
+	c, err := gif.DecodeConfig(r)
+	if err != nil {
+		if strings.Contains(err.Error(), "gif: can't recognize format") {
+			err = nil
+		}
+		return nil, err
+	}
+	md = &meta.Data{
+		Format: types.GIF, PixelWidth: uint32(c.Width), PixelHeight: uint32(c.Height),
+		BitsPerComponent: 8, HasFrames: true,
+	}
+	return md, nil
+}
+
+func CalcMinimumGap(gaps []int) (min_gap int) {
+	// Some broken GIF images have all zero gaps, browsers with their usual
+	// idiot ideas render these with a default 100ms gap https://bugzilla.mozilla.org/show_bug.cgi?id=125137
+	// Browsers actually force a 100ms gap at any zero gap frame, but that
+	// just means it is impossible to deliberately use zero gap frames for
+	// sophisticated blending, so we dont do that.
+	max_gap := 0
+	for _, g := range gaps {
+		max_gap = max(max_gap, g)
+	}
+	if max_gap <= 0 {
+		min_gap = 10
+	}
+	return min_gap
+}
+
+func CalculateFrameDelay(delay, min_gap int) time.Duration {
+	delay_ms := max(min_gap, delay)
+	return time.Duration(delay_ms) * 10 * time.Millisecond
+}