feat: 大图查看支持左右滑动切换图片

- 传入所有图片 URL 列表和起始索引
- 左滑下一张，右滑上一张
- 底部显示页码指示 1/3
- 单击关闭

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

app/src/main/java/com/xiaoqu/watch/ui/task/TaskListFragment.kt

@@ -437,18 +437,20 @@ class TaskListFragment : BaseFragment<FragmentTaskListBinding>() {
                 isFocusable = true
             }
             loadImage(imageView, pic.url)
-            // 点击放大全屏查看
-            val picUrl = pic.url
-            imageView.setOnClickListener { showFullImage(picUrl) }
+            // 点击放大全屏查看（传入所有图片和当前索引）
+            val idx = index
+            val allUrls = pics.map { it.url }
+            imageView.setOnClickListener { showFullImage(allUrls, idx) }
             binding.picContainer.addView(imageView)
         }
     }
 
-    /** 全屏显示大图（覆盖在 Activity 窗口顶层，点击关闭） */
-    private fun showFullImage(url: String) {
-        Timber.d("查看大图: $url")
-        // 使用 Activity 的 decorView 确保在最顶层
+    /** 全屏查看大图（左右滑切换，点击关闭） */
+    private fun showFullImage(urls: List<String>, startIndex: Int) {
+        Timber.d("查看大图: index=$startIndex, total=${urls.size}")
         val rootView = requireActivity().window.decorView as ViewGroup
+        var currentIndex = startIndex
+
         val overlay = FrameLayout(requireContext()).apply {
             layoutParams = ViewGroup.LayoutParams(
                 ViewGroup.LayoutParams.MATCH_PARENT,
@@ -458,6 +460,7 @@ class TaskListFragment : BaseFragment<FragmentTaskListBinding>() {
             isClickable = true
             isFocusable = true
         }
+
         val imageView = android.widget.ImageView(requireContext()).apply {
             layoutParams = FrameLayout.LayoutParams(
                 FrameLayout.LayoutParams.MATCH_PARENT,
@@ -465,13 +468,54 @@ class TaskListFragment : BaseFragment<FragmentTaskListBinding>() {
             )
             scaleType = android.widget.ImageView.ScaleType.FIT_CENTER
         }
+
+        // 页码指示（多张图片时显示）
+        val tvIndicator = android.widget.TextView(requireContext()).apply {
+            layoutParams = FrameLayout.LayoutParams(
+                FrameLayout.LayoutParams.WRAP_CONTENT,
+                FrameLayout.LayoutParams.WRAP_CONTENT
+            ).apply {
+                gravity = android.view.Gravity.BOTTOM or android.view.Gravity.CENTER_HORIZONTAL
+                bottomMargin = (20 * resources.displayMetrics.density).toInt()
+            }
+            setTextColor(0xCCFFFFFF.toInt())
+            textSize = 18f
+            visibility = if (urls.size > 1) View.VISIBLE else View.GONE
+        }
+
         overlay.addView(imageView)
+        overlay.addView(tvIndicator)
         rootView.addView(overlay)
-        // 点击任意位置关闭
-        overlay.setOnClickListener { rootView.removeView(overlay) }
-        imageView.setOnClickListener { rootView.removeView(overlay) }
-        // 加载大图
-        loadImage(imageView, url)
+
+        // 显示当前图片
+        fun showAt(index: Int) {
+            currentIndex = index
+            tvIndicator.text = "${index + 1}/${urls.size}"
+            loadImage(imageView, urls[index])
+        }
+        showAt(startIndex)
+
+        // 手势：左右滑切换，点击关闭
+        val detector = GestureDetector(requireContext(), object : GestureDetector.SimpleOnGestureListener() {
+            override fun onSingleTapConfirmed(e: MotionEvent): Boolean {
+                rootView.removeView(overlay)
+                return true
+            }
+            override fun onFling(e1: MotionEvent?, e2: MotionEvent, velocityX: Float, velocityY: Float): Boolean {
+                if (e1 == null) return false
+                val dx = e2.x - e1.x
+                if (kotlin.math.abs(dx) > 50) {
+                    if (dx < 0 && currentIndex < urls.size - 1) {
+                        showAt(currentIndex + 1)  // 左滑下一张
+                    } else if (dx > 0 && currentIndex > 0) {
+                        showAt(currentIndex - 1)  // 右滑上一张
+                    }
+                    return true
+                }
+                return false
+            }
+        })
+        overlay.setOnTouchListener { _, event -> detector.onTouchEvent(event); true }
     }
 
     /** 异步加载图片到 ImageView（使用系统 HttpURLConnection） */