Avoid unnecessary overhead

app/src/main/cpp/CMakeLists.txt

@@ -45,6 +45,6 @@ SET(LIBARCHIVE_CUSTOM_LIBS "liblzma" "nettle")
 add_subdirectory(libarchive)
 
 # Build and link our app's native lib
-add_library(${PROJECT_NAME} SHARED archive.c fdutils.c)
+add_library(${PROJECT_NAME} SHARED archive.c fdutils.c gifUtils.c)
 target_include_directories(${PROJECT_NAME} PUBLIC libarchive/libarchive)
 target_link_libraries(${PROJECT_NAME} archive_static log -Wl,--gc-sections)

app/src/main/cpp/gifUtils.c

@@ -0,0 +1,11 @@
+#include <string.h>
+#include <jni.h>
+
+#define GIF_HEADER_87A "GIF87a"
+#define GIF_HEADER_89A "GIF89a"
+
+JNIEXPORT jboolean JNICALL
+Java_com_hippo_Native_isGif(JNIEnv *env, jobject thiz, jobject buffer) {
+    void *addr = (*env)->GetDirectBufferAddress(env, buffer);
+    return !memcmp(addr, GIF_HEADER_87A, 6) || !memcmp(addr, GIF_HEADER_89A, 6);
+}

app/src/main/java/coil/decode/DecodeUtils.kt

@@ -1,66 +0,0 @@
-@file:JvmName("GifDecodeUtils")
-
-package coil.decode
-
-import okio.BufferedSource
-import okio.ByteString.Companion.encodeUtf8
-import kotlin.experimental.and
-
-// 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()
-private val WEBP_HEADER_WEBP = "WEBP".encodeUtf8()
-private val WEBP_HEADER_VPX8 = "VP8X".encodeUtf8()
-
-// https://nokiatech.github.io/heif/technical.html
-private val HEIF_HEADER_FTYP = "ftyp".encodeUtf8()
-private val HEIF_HEADER_MSF1 = "msf1".encodeUtf8()
-private val HEIF_HEADER_HEVC = "hevc".encodeUtf8()
-private val HEIF_HEADER_HEVX = "hevx".encodeUtf8()
-
-/**
- * Return 'true' if the [source] contains a GIF image. The [source] is not consumed.
- */
-fun DecodeUtils.isGif(source: BufferedSource): Boolean {
-    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.
- */
-fun DecodeUtils.isWebP(source: BufferedSource): Boolean {
-    return source.rangeEquals(0, WEBP_HEADER_RIFF) &&
-        source.rangeEquals(8, WEBP_HEADER_WEBP)
-}
-
-/**
- * Return 'true' if the [source] contains an animated WebP image. The [source] is not consumed.
- */
-fun DecodeUtils.isAnimatedWebP(source: BufferedSource): Boolean {
-    return isWebP(source) &&
-        source.rangeEquals(12, WEBP_HEADER_VPX8) &&
-        source.request(17) &&
-        (source.buffer[16] and 0b00000010) > 0
-}
-
-/**
- * Return 'true' if the [source] contains an HEIF image. The [source] is not consumed.
- */
-fun DecodeUtils.isHeif(source: BufferedSource): Boolean {
-    return source.rangeEquals(4, HEIF_HEADER_FTYP)
-}
-
-/**
- * Return 'true' if the [source] contains an animated HEIF image sequence. The [source] is not
- * consumed.
- */
-fun DecodeUtils.isAnimatedHeif(source: BufferedSource): Boolean {
-    return isHeif(source) &&
-        (source.rangeEquals(8, HEIF_HEADER_MSF1) ||
-            source.rangeEquals(8, HEIF_HEADER_HEVC) ||
-            source.rangeEquals(8, HEIF_HEADER_HEVX))
-}

app/src/main/java/com/hippo/Native.kt

@@ -18,6 +18,7 @@
 package com.hippo
 
 import java.io.FileDescriptor
+import java.nio.ByteBuffer
 
 object Native {
     fun initialize() {
@@ -26,4 +27,6 @@ object Native {
 
     @JvmStatic
     external fun getFd(fd: FileDescriptor?): Int
+
+    external fun isGif(buffer: ByteBuffer): Boolean
 }

app/src/main/java/com/hippo/image/Image.kt

@@ -25,9 +25,8 @@ import android.graphics.ImageDecoder.Source
 import android.graphics.drawable.Animatable
 import android.graphics.drawable.BitmapDrawable
 import android.graphics.drawable.Drawable
-import coil.decode.DecodeUtils
 import coil.decode.FrameDelayRewritingSource
-import coil.decode.isGif
+import com.hippo.Native
 import com.hippo.UriArchiveAccessor
 import com.hippo.ehviewer.EhApplication
 import okio.Buffer
@@ -87,35 +86,41 @@ class Image private constructor(source: Source, private val byteBuffer: ByteBuff
         @Throws(DecodeException::class)
         @JvmStatic
         fun decode(stream: FileInputStream): Image {
-            val source = stream.source().buffer()
-            val buffer = if (DecodeUtils.isGif(source)) {
-                rewriteSource(source)
+            val buffer = stream.channel.map(
+                FileChannel.MapMode.READ_ONLY, 0,
+                stream.available().toLong()
+            )
+            val source = if (checkIsGif(buffer)) {
+                rewriteSource(stream.source().buffer())
             } else {
-                stream.channel.map(
-                    FileChannel.MapMode.READ_ONLY, 0,
-                    stream.available().toLong()
-                )
+                buffer
             }
-            val src = ImageDecoder.createSource(buffer)
+            val src = ImageDecoder.createSource(source)
             return Image(src)
         }
 
         @Throws(DecodeException::class)
         @JvmStatic
         fun decode(buffer: ByteBuffer): Image {
-            val source = Buffer().apply { write(buffer) }
-            val byteBuffer = if (DecodeUtils.isGif(source)) {
-                rewriteSource(source)
+            return if (checkIsGif(buffer)) {
+                val rewritten = rewriteSource(Buffer().apply {
+                    write(buffer)
+                    UriArchiveAccessor.releaseByteBuffer(buffer)
+                })
+                Image(ImageDecoder.createSource(rewritten))
             } else {
-                buffer.position(0) as ByteBuffer
+                Image(ImageDecoder.createSource(buffer), buffer)
             }
-            val src = ImageDecoder.createSource(byteBuffer)
-            return Image(src, buffer)
         }
 
         private fun rewriteSource(source: BufferedSource): ByteBuffer {
             val bufferedSource = FrameDelayRewritingSource(source).buffer()
             return ByteBuffer.wrap(bufferedSource.use { it.readByteArray() })
         }
+
+        private fun checkIsGif(buffer: ByteBuffer): Boolean {
+            check(buffer.isDirect)
+            return Native.isGif(buffer)
+        }
     }
 }