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Check for the full GIF header including version. #564

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Merged
colinrtwhite merged 1 commit into from
Oct 26, 2020
Merged

Check for the full GIF header including version. #564

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7 changes: 4 additions & 3 deletions coil-base/src/main/java/coil/decode/DecodeUtils.kt
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Original file line number Diff line number Diff line change
Expand Up @@ -16,8 +16,9 @@ import kotlin.math.roundToInt
/** A collection of useful utility methods for decoding images. */
object DecodeUtils {

// https://www.onicos.com/staff/iz/formats/gif.html
private val GIF_HEADER = "GIF".encodeUtf8()
// https://www.matthewflickinger.com/lab/whatsinagif/bits_and_bytes.asp
private val GIF_HEADER_87A = "GIF87a".encodeUtf8()
private val GIF_HEADER_89A = "GIF89a".encodeUtf8()

// https://developers.google.com/speed/webp/docs/riff_container
private val WEBP_HEADER_RIFF = "RIFF".encodeUtf8()
Expand All @@ -33,7 +34,7 @@ object DecodeUtils {
/** Return true if the [source] contains a GIF image. The [source] is not consumed. */
@JvmStatic
fun isGif(source: BufferedSource): Boolean {
return source.rangeEquals(0, GIF_HEADER)
return source.rangeEquals(0, GIF_HEADER_89A) || source.rangeEquals(0, GIF_HEADER_87A)
}

/** Return true if the [source] contains a WebP image. The [source] is not consumed. */
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