feat(desktop): add QR code scanning for bunker login

Adds a QR scan button to the login card that decodes QR codes from
clipboard images or image files using ZXing. Useful for scanning
bunker:// URIs from Amber's QR display.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

desktopApp/build.gradle.kts

@@ -46,6 +46,10 @@ dependencies {
     // JSON
     implementation(libs.jackson.module.kotlin)
 
+    // QR code decoding from images
+    implementation(libs.zxing)
+    implementation(libs.zxing.javase)
+
     // Collections
     implementation(libs.kotlinx.collections.immutable)
 

desktopApp/src/jvmMain/kotlin/com/vitorpamplona/amethyst/desktop/ui/auth/LoginCard.kt

@@ -30,10 +30,14 @@ import androidx.compose.foundation.layout.height
 import androidx.compose.foundation.layout.padding
 import androidx.compose.foundation.layout.size
 import androidx.compose.foundation.layout.width
+import androidx.compose.material.icons.Icons
+import androidx.compose.material.icons.filled.QrCodeScanner
 import androidx.compose.material3.Button
 import androidx.compose.material3.Card
 import androidx.compose.material3.CardDefaults
 import androidx.compose.material3.CircularProgressIndicator
+import androidx.compose.material3.Icon
+import androidx.compose.material3.IconButton
 import androidx.compose.material3.MaterialTheme
 import androidx.compose.material3.OutlinedButton
 import androidx.compose.material3.Text
@@ -56,6 +60,8 @@ import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.launch
 import kotlinx.coroutines.withContext
 import org.jetbrains.compose.resources.stringResource
+import javax.swing.JFileChooser
+import javax.swing.filechooser.FileNameExtensionFilter
 
 private val HEX_64_REGEX = Regex("^[0-9a-fA-F]{64}$")
 
@@ -113,14 +119,62 @@ fun LoginCard(
 
             Spacer(Modifier.height(16.dp))
 
-            KeyInputField(
+            Row(
-                value = keyInput,
+                modifier = Modifier.fillMaxWidth(),
-                onValueChange = {
+                verticalAlignment = Alignment.CenterVertically,
-                    keyInput = it
+                horizontalArrangement = Arrangement.spacedBy(4.dp),
-                    errorMessage = null
+            ) {
-                },
+                KeyInputField(
-                errorMessage = errorMessage,
+                    value = keyInput,
-            )
+                    onValueChange = {
+                        keyInput = it
+                        errorMessage = null
+                    },
+                    errorMessage = errorMessage,
+                    modifier = Modifier.weight(1f),
+                )
+
+                IconButton(
+                    onClick = {
+                        // Try clipboard first, then file picker
+                        val clipboardResult = decodeQrFromClipboard()
+                        if (clipboardResult != null) {
+                            keyInput = clipboardResult
+                            errorMessage = null
+                        } else {
+                            val chooser =
+                                JFileChooser().apply {
+                                    fileFilter =
+                                        FileNameExtensionFilter(
+                                            "Images",
+                                            "png",
+                                            "jpg",
+                                            "jpeg",
+                                            "gif",
+                                            "bmp",
+                                            "webp",
+                                        )
+                                    dialogTitle = "Select QR code image"
+                                }
+                            if (chooser.showOpenDialog(null) == JFileChooser.APPROVE_OPTION) {
+                                val decoded = decodeQrFromFile(chooser.selectedFile)
+                                if (decoded != null) {
+                                    keyInput = decoded
+                                    errorMessage = null
+                                } else {
+                                    errorMessage = "No QR code found in image"
+                                }
+                            }
+                        }
+                    },
+                ) {
+                    Icon(
+                        Icons.Default.QrCodeScanner,
+                        contentDescription = "Scan QR code",
+                        tint = MaterialTheme.colorScheme.primary,
+                    )
+                }
+            }
 
             Spacer(Modifier.height(8.dp))
 

desktopApp/src/jvmMain/kotlin/com/vitorpamplona/amethyst/desktop/ui/auth/QrCodeDecoder.kt

@@ -0,0 +1,63 @@
+/*
+ * Copyright (c) 2025 Vitor Pamplona
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the
+ * Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+ * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+ * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
+ * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+package com.vitorpamplona.amethyst.desktop.ui.auth
+
+import com.google.zxing.BinaryBitmap
+import com.google.zxing.MultiFormatReader
+import com.google.zxing.NotFoundException
+import com.google.zxing.client.j2se.BufferedImageLuminanceSource
+import com.google.zxing.common.HybridBinarizer
+import java.awt.Image
+import java.awt.Toolkit
+import java.awt.datatransfer.DataFlavor
+import java.awt.image.BufferedImage
+import java.io.File
+import javax.imageio.ImageIO
+
+fun decodeQrFromFile(file: File): String? {
+    val image = ImageIO.read(file) ?: return null
+    return decodeQrFromImage(image)
+}
+
+fun decodeQrFromClipboard(): String? {
+    val clipboard = Toolkit.getDefaultToolkit().systemClipboard
+    if (!clipboard.isDataFlavorAvailable(DataFlavor.imageFlavor)) return null
+    val image = clipboard.getData(DataFlavor.imageFlavor) as? Image ?: return null
+    return decodeQrFromImage(image.toBufferedImage())
+}
+
+private fun decodeQrFromImage(image: BufferedImage): String? =
+    try {
+        val source = BufferedImageLuminanceSource(image)
+        val bitmap = BinaryBitmap(HybridBinarizer(source))
+        MultiFormatReader().decode(bitmap).text
+    } catch (_: NotFoundException) {
+        null
+    }
+
+private fun Image.toBufferedImage(): BufferedImage {
+    if (this is BufferedImage) return this
+    val buffered = BufferedImage(getWidth(null), getHeight(null), BufferedImage.TYPE_INT_ARGB)
+    val g = buffered.createGraphics()
+    g.drawImage(this, 0, 0, null)
+    g.dispose()
+    return buffered
+}

gradle/libs.versions.toml

@@ -160,6 +160,7 @@ vico-charts-views = { group = "com.patrykandpatrick.vico", name = "views", versi
 zelory-image-compressor = { group = "id.zelory", name = "compressor", version.ref = "zelory" }
 zoomable = { group = "net.engawapg.lib", name = "zoomable", version.ref = "zoomable" }
 zxing = { group = "com.google.zxing", name = "core", version.ref = "zxing" }
+zxing-javase = { group = "com.google.zxing", name = "javase", version.ref = "zxing" }
 zxing-embedded = { group = "com.journeyapps", name = "zxing-android-embedded", version.ref = "zxingAndroidEmbedded" }
 androidx-window-core-android = { group = "androidx.window", name = "window-core-android", version.ref = "windowCoreAndroid" }
 kotlin-stdlib = { group = "org.jetbrains.kotlin", name = "kotlin-stdlib", version.ref = "kotlin" }