1 files changed, 84 insertions, 0 deletions
diff --git a/ui/src/main/java/com/wireguard/android/util/QrCodeFromFileScanner.kt b/ui/src/main/java/com/wireguard/android/util/QrCodeFromFileScanner.kt
new file mode 100644
index 00000000..4ea2dc7a
--- /dev/null
+++ b/ui/src/main/java/com/wireguard/android/util/QrCodeFromFileScanner.kt
@@ -0,0 +1,84 @@
+/*
+ * Copyright © 2017-2025 WireGuard LLC. All Rights Reserved.
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package com.wireguard.android.util
+
+import android.content.ContentResolver
+import android.graphics.Bitmap
+import android.graphics.BitmapFactory
+import android.net.Uri
+import android.util.Log
+import com.google.zxing.BinaryBitmap
+import com.google.zxing.DecodeHintType
+import com.google.zxing.NotFoundException
+import com.google.zxing.RGBLuminanceSource
+import com.google.zxing.Reader
+import com.google.zxing.Result
+import com.google.zxing.common.HybridBinarizer
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.withContext
+
+/**
+ * Encapsulates the logic of scanning a barcode from a file,
+ * @property contentResolver - Resolver to read the incoming data
+ * @property reader - An instance of zxing's [Reader] class to parse the image
+ */
+class QrCodeFromFileScanner(
+    private val contentResolver: ContentResolver,
+    private val reader: Reader,
+) {
+    private fun scanBitmapForResult(source: Bitmap): Result {
+        val width = source.width
+        val height = source.height
+        val pixels = IntArray(width * height)
+        source.getPixels(pixels, 0, width, 0, 0, width, height)
+
+        val bBitmap = BinaryBitmap(HybridBinarizer(RGBLuminanceSource(width, height, pixels)))
+        return reader.decode(bBitmap, mapOf(DecodeHintType.TRY_HARDER to true))
+    }
+
+    private fun doScan(data: Uri): Result {
+        Log.d(TAG, "Starting to scan an image: $data")
+        contentResolver.openInputStream(data).use { inputStream ->
+            var bitmap: Bitmap? = null
+            var firstException: Throwable? = null
+            for (i in arrayOf(1, 2, 4, 8, 16, 32, 64, 128)) {
+                try {
+                    val options = BitmapFactory.Options()
+                    options.inSampleSize = i
+                    bitmap = BitmapFactory.decodeStream(inputStream, null, options)
+                        ?: throw IllegalArgumentException("Can't decode stream for bitmap")
+                    return scanBitmapForResult(bitmap)
+                } catch (e: Throwable) {
+                    bitmap?.recycle()
+                    System.gc()
+                    Log.e(TAG, "Original image scan at scale factor $i finished with error: $e")
+                    if (firstException == null)
+                        firstException = e
+                }
+            }
+            throw Exception(firstException)
+        }
+    }
+
+    /**
+     * Attempts to parse incoming data
+     * @return result of the decoding operation
+     * @throws NotFoundException when parser didn't find QR code in the image
+     */
+    suspend fun scan(data: Uri) = withContext(Dispatchers.Default) { doScan(data) }
+
+    companion object {
+        private const val TAG = "QrCodeFromFileScanner"
+
+        /**
+         * Given a reference to a file, check if this file could be parsed by this class
+         * @return true if the file can be parsed, false if not
+         */
+        fun validContentType(contentResolver: ContentResolver, data: Uri): Boolean {
+            return contentResolver.getType(data)?.startsWith("image/") == true
+        }
+    }
+}