feat: 添加照片发送确认对话框，优化相机捕获功能

android/app/src/main/kotlin/io/openim/flutter/openim/MainActivity.kt

@@ -1,7 +1,8 @@
 package io.openim.flutter.openim
 
-import android.content.Intent
 import android.app.Activity
+import android.app.AlertDialog
+import android.content.Intent
 import android.content.pm.PackageInfo
 import android.content.pm.PackageManager
 import android.graphics.Bitmap
@@ -15,6 +16,8 @@ import android.util.Base64
 import android.util.Log
 import android.view.View
 import android.view.ViewGroup
+import android.widget.FrameLayout
+import android.widget.ImageView
 import androidx.core.content.FileProvider
 import io.flutter.embedding.android.FlutterActivity
 import org.conscrypt.Conscrypt
@@ -33,6 +36,7 @@ class MainActivity : FlutterActivity() {
     private val FILE_PICKER_REQUEST_CODE = 4201
     private var pendingFilePickerResult: MethodChannel.Result? = null
     private var pendingCameraCaptureUri: Uri? = null
+    private var pendingCaptureConfirmationDialog: AlertDialog? = null
 
     override fun onCreate(savedInstanceState: android.os.Bundle?) {
         // 华为/荣耀/OPPO 等国产设备：在任意网络请求之前同步安装 Conscrypt，修复 SSL 握手失败（无 GMS 时系统 SSL 实现不完整）
@@ -51,6 +55,12 @@ class MainActivity : FlutterActivity() {
         disableAutofillForCurrentWindow()
     }
 
+    override fun onDestroy() {
+        pendingCaptureConfirmationDialog?.dismiss()
+        pendingCaptureConfirmationDialog = null
+        super.onDestroy()
+    }
+
     override fun configureFlutterEngine(flutterEngine: FlutterEngine) {
         super.configureFlutterEngine(flutterEngine)
         MethodChannel(flutterEngine.dartExecutor.binaryMessenger, CHANNEL).setMethodCallHandler { call, result ->
@@ -153,8 +163,7 @@ class MainActivity : FlutterActivity() {
 
             pendingCameraCaptureUri?.let { uri ->
                 pendingCameraCaptureUri = null
-                grantPickedFileReadPermission(uri)
+                showCaptureConfirmation(uri, result)
-                result.success(listOf(uri.toString()))
                 return
             }
 
@@ -191,7 +200,7 @@ class MainActivity : FlutterActivity() {
         capture: Boolean,
         result: MethodChannel.Result
     ) {
-        if (pendingFilePickerResult != null) {
+        if (pendingFilePickerResult != null || pendingCaptureConfirmationDialog != null) {
             result.error("FILE_PICKER_BUSY", "A file picker request is already active", null)
             return
         }
@@ -258,6 +267,95 @@ class MainActivity : FlutterActivity() {
         }
     }
 
+    private fun showCaptureConfirmation(uri: Uri, result: MethodChannel.Result) {
+        if (isFinishing ||
+            (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN_MR1 && isDestroyed)
+        ) {
+            deleteCaptureUri(uri)
+            result.success(emptyList<String>())
+            return
+        }
+
+        val preview = ImageView(this).apply {
+            setImageURI(uri)
+            adjustViewBounds = true
+            scaleType = ImageView.ScaleType.FIT_CENTER
+            setBackgroundColor(0xFFF2F5F8.toInt())
+            layoutParams = FrameLayout.LayoutParams(
+                ViewGroup.LayoutParams.MATCH_PARENT,
+                dp(360)
+            )
+        }
+        val previewContainer = FrameLayout(this).apply {
+            setPadding(dp(20), dp(12), dp(20), 0)
+            addView(preview)
+        }
+
+        var completed = false
+        fun complete(uris: List<String>) {
+            if (completed) {
+                return
+            }
+            completed = true
+            if (uris.isEmpty()) {
+                deleteCaptureUri(uri)
+            }
+            result.success(uris)
+        }
+
+        val dialog = AlertDialog.Builder(this)
+            .setTitle("确认发送照片")
+            .setMessage("确认后才会发送给好友。")
+            .setView(previewContainer)
+            .setNegativeButton("取消") { _, _ -> }
+            .setPositiveButton("发送") { _, _ -> }
+            .create()
+
+        dialog.setOnCancelListener {
+            complete(emptyList())
+        }
+        dialog.setOnDismissListener {
+            if (pendingCaptureConfirmationDialog == dialog) {
+                pendingCaptureConfirmationDialog = null
+            }
+            complete(emptyList())
+        }
+        dialog.setOnShowListener {
+            val sendButton = dialog.getButton(AlertDialog.BUTTON_POSITIVE)
+            val cancelButton = dialog.getButton(AlertDialog.BUTTON_NEGATIVE)
+            sendButton.setOnClickListener {
+                sendButton.isEnabled = false
+                cancelButton.isEnabled = false
+                grantPickedFileReadPermission(uri)
+                complete(listOf(uri.toString()))
+                dialog.dismiss()
+            }
+            cancelButton.setOnClickListener {
+                complete(emptyList())
+                dialog.dismiss()
+            }
+        }
+
+        pendingCaptureConfirmationDialog = dialog
+        try {
+            dialog.show()
+        } catch (e: Exception) {
+            pendingCaptureConfirmationDialog = null
+            complete(emptyList())
+        }
+    }
+
+    private fun dp(value: Int): Int {
+        return (value * resources.displayMetrics.density).toInt()
+    }
+
+    private fun deleteCaptureUri(uri: Uri) {
+        try {
+            contentResolver.delete(uri, null, null)
+        } catch (_: Exception) {
+        }
+    }
+
     private fun createCameraCaptureUri(extension: String): Uri {
         val directory = externalCacheDir ?: cacheDir
         val file = File.createTempFile(