feat: automatic load pages in animated images (#231)

* feat: automatic load pages in animated images

Signed-off-by: STRRL <im@strrl.dev>

* chore: remove destination file during test

Signed-off-by: STRRL <im@strrl.dev>

* chore: change import param code style

Signed-off-by: STRRL <im@strrl.dev>

---------

Signed-off-by: STRRL <im@strrl.dev>

encoder.go

@@ -165,8 +165,11 @@ func webpEncoder(p1, p2 string, quality int, extraParams ExtraParams) error {
 	var buf []byte
 	var boolFalse vips.BoolParameter
 	boolFalse.Set(false)
+	var intMinusOne vips.IntParameter
+	intMinusOne.Set(-1)
 	img, err := vips.LoadImageFromFile(p1, &vips.ImportParams{
 		FailOnError: boolFalse,
+		NumPages:    intMinusOne,
 	})
 	if err != nil {
 		return err

encoder_test.go

@@ -96,6 +96,11 @@ func TestWebPEncoder(t *testing.T) {
 	_ = os.Remove(dest)
 }
 
+func TestAnimatedGIFWithWebPEncoder(t *testing.T) {
+	runEncoder(t, "./pics/gif-animated.gif", dest)
+	_ = os.Remove(dest)
+}
+
 func TestAvifEncoder(t *testing.T) {
 	// Only one file: img_over_16383px.jpg might cause memory issues on CI environment
 	assert.Nil(t, avifEncoder("./pics/big.jpg", dest, 80, ExtraParams{Width: 0, Height: 0}))