feat(Twitter - Unlock downloads): Unlock GIF downloads

src/main/kotlin/app/revanced/patches/twitter/interaction/downloads/UnlockDownloadsPatch.kt

@@ -2,27 +2,36 @@ package app.revanced.patches.twitter.interaction.downloads
 
 import app.revanced.patcher.data.BytecodeContext
 import app.revanced.patcher.extensions.InstructionExtensions.addInstruction
+import app.revanced.patcher.extensions.InstructionExtensions.addInstructionsWithLabels
 import app.revanced.patcher.extensions.InstructionExtensions.getInstruction
 import app.revanced.patcher.extensions.InstructionExtensions.getInstructions
+import app.revanced.patcher.extensions.InstructionExtensions.removeInstruction
 import app.revanced.patcher.fingerprint.MethodFingerprint
 import app.revanced.patcher.fingerprint.MethodFingerprintResult
 import app.revanced.patcher.patch.BytecodePatch
 import app.revanced.patcher.patch.annotation.CompatiblePackage
 import app.revanced.patcher.patch.annotation.Patch
+import app.revanced.patcher.util.smali.ExternalLabel
+import app.revanced.patches.twitter.interaction.downloads.fingerprints.BuildMediaOptionsSheetFingerprint
 import app.revanced.patches.twitter.interaction.downloads.fingerprints.ConstructMediaOptionsSheetFingerprint
 import app.revanced.patches.twitter.interaction.downloads.fingerprints.ShowDownloadVideoUpsellBottomSheetFingerprint
 import app.revanced.util.exception
+import com.android.tools.smali.dexlib2.Opcode
 import com.android.tools.smali.dexlib2.iface.instruction.OneRegisterInstruction
 import com.android.tools.smali.dexlib2.iface.instruction.TwoRegisterInstruction
 
 @Patch(
     name = "Unlock downloads",
-    description = "Unlocks the ability to download any video.",
+    description = "Unlocks the ability to download any video. GIFs can be downloaded via the menu on long press.",
-    compatiblePackages = [CompatiblePackage("com.twitter.android")]
+    compatiblePackages = [CompatiblePackage("com.twitter.android")],
 )
 @Suppress("unused")
 object UnlockDownloadsPatch : BytecodePatch(
-    setOf(ConstructMediaOptionsSheetFingerprint, ShowDownloadVideoUpsellBottomSheetFingerprint)
+    setOf(
+        ConstructMediaOptionsSheetFingerprint,
+        ShowDownloadVideoUpsellBottomSheetFingerprint,
+        BuildMediaOptionsSheetFingerprint,
+    ),
 ) {
     override fun execute(context: BytecodeContext) {
         fun MethodFingerprint.patch(getRegisterAndIndex: MethodFingerprintResult.() -> Pair<Int, Int>) = result?.let {
@@ -46,5 +55,29 @@ object UnlockDownloadsPatch : BytecodePatch(
 
             showDownloadButtonIndex to register
         }
+
+        // Make GIFs downloadable.
+        BuildMediaOptionsSheetFingerprint.result?.let {
+            val scanResult = it.scanResult.patternScanResult!!
+            it.mutableMethod.apply {
+                val checkMediaTypeIndex = scanResult.startIndex
+                val checkMediaTypeInstruction = getInstruction<TwoRegisterInstruction>(checkMediaTypeIndex)
+
+                // Treat GIFs as videos.
+                addInstructionsWithLabels(
+                    checkMediaTypeIndex + 1,
+                    """
+                        const/4 v${checkMediaTypeInstruction.registerB}, 0x2 # GIF
+                        if-eq v${checkMediaTypeInstruction.registerA}, v${checkMediaTypeInstruction.registerB}, :video
+                    """,
+                    ExternalLabel("video", getInstruction(scanResult.endIndex)),
+                )
+
+                // Remove media.isDownloadable check.
+                removeInstruction(
+                    getInstructions().first { insn -> insn.opcode == Opcode.IGET_BOOLEAN }.location.index + 1,
+                )
+            }
+        } ?: throw BuildMediaOptionsSheetFingerprint.exception
     }
 }

src/main/kotlin/app/revanced/patches/twitter/interaction/downloads/fingerprints/BuildMediaOptionsSheetFingerprint.kt

@@ -0,0 +1,14 @@
+package app.revanced.patches.twitter.interaction.downloads.fingerprints
+
+import app.revanced.patcher.fingerprint.MethodFingerprint
+import com.android.tools.smali.dexlib2.Opcode
+
+internal object BuildMediaOptionsSheetFingerprint : MethodFingerprint(
+    opcodes = listOf(
+        Opcode.IF_EQ,
+        Opcode.SGET_OBJECT,
+        Opcode.GOTO_16,
+        Opcode.NEW_INSTANCE,
+    ),
+    strings = listOf("resources.getString(R.string.post_video)"),
+)