增加双击放大图片功能

android/app/src/main/java/com/memory/app/ui/components/PostCard.kt

@@ -42,6 +42,7 @@ import androidx.compose.animation.core.tween
 import androidx.compose.animation.core.LinearEasing
 import androidx.compose.material3.*
 import androidx.compose.runtime.*
+import androidx.compose.runtime.mutableLongStateOf
 import androidx.compose.runtime.snapshots.SnapshotStateMap
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
@@ -1018,6 +1019,9 @@ private fun ZoomableImage(
     var offsetX by remember { mutableFloatStateOf(0f) }
     var offsetY by remember { mutableFloatStateOf(0f) }
     
+    // 双击检测
+    var lastTapTime by remember { mutableLongStateOf(0L) }
+    
     // 通知父组件缩放状态变化
     LaunchedEffect(scale) {
         onScaleChanged(scale)
@@ -1030,6 +1034,8 @@ private fun ZoomableImage(
                 awaitEachGesture {
                     // 等待第一个手指按下
                     val firstDown = awaitFirstDown(requireUnconsumed = false)
+                    val downTime = System.currentTimeMillis()
+                    val downPosition = firstDown.position
                     
                     var pointerId = firstDown.id
                     var isTap = true
@@ -1053,48 +1059,78 @@ private fun ZoomableImage(
                             }
                         }
                         
+                        // 缩放状态下的单指拖动
+                        if (changes.size == 1 && scale > 1f) {
+                            val change = changes.first()
+                            val dragAmount = change.position - change.previousPosition
+                            if (dragAmount.getDistance() > 2f) {
+                                isTap = false
+                                offsetX += dragAmount.x
+                                offsetY += dragAmount.y
+                                // 限制拖动范围
+                                val maxOffsetX = (scale - 1f) * size.width / 2
+                                val maxOffsetY = (scale - 1f) * size.height / 2
+                                offsetX = offsetX.coerceIn(-maxOffsetX, maxOffsetX)
+                                offsetY = offsetY.coerceIn(-maxOffsetY, maxOffsetY)
+                                change.consume()
+                            }
+                        }
+                        
                         // 检查是否所有手指都抬起
                         if (changes.all { !it.pressed }) {
                             // 单指点击且没有移动太多
                             if (isTap && !isMultiTouch) {
-                                if (scale > 1f) {
-                                    scale = 1f
-                                    offsetX = 0f
-                                    offsetY = 0f
+                                val currentTime = System.currentTimeMillis()
+                                val timeSinceLastTap = currentTime - lastTapTime
+                                
+                                if (timeSinceLastTap < 300) {
+                                    // 双击 - 切换缩放
+                                    if (scale > 1f) {
+                                        scale = 1f
+                                        offsetX = 0f
+                                        offsetY = 0f
+                                    } else {
+                                        scale = 2.5f
+                                    }
+                                    lastTapTime = 0L
                                 } else {
-                                    onTap()
+                                    // 可能是单击，记录时间等待判断
+                                    lastTapTime = currentTime
                                 }
                             }
                             break
                         }
                         
                         // 单指移动时检查是否移动太多（判断是否为点击）
-                        if (changes.size == 1 && !isMultiTouch) {
+                        if (changes.size == 1 && !isMultiTouch && scale <= 1f) {
                             val change = changes.first()
                             val moved = (change.position - change.previousPosition).getDistance()
                             if (moved > 10f) {
                                 isTap = false
-                                // 单指滑动不消费事件，让 Pager 处理
                             }
                         }
                     }
                 }
-            }
-            .pointerInput(Unit) {
-                detectTapGestures(
-                    onDoubleTap = {
-                        if (scale > 1f) {
-                            scale = 1f
-                            offsetX = 0f
-                            offsetY = 0f
-                        } else {
-                            scale = 2.5f
-                        }
-                    }
-                )
             },
         contentAlignment = Alignment.Center
     ) {
+        // 延迟处理单击关闭
+        LaunchedEffect(lastTapTime) {
+            if (lastTapTime > 0) {
+                kotlinx.coroutines.delay(300)
+                if (System.currentTimeMillis() - lastTapTime >= 300) {
+                    if (scale > 1f) {
+                        scale = 1f
+                        offsetX = 0f
+                        offsetY = 0f
+                    } else {
+                        onTap()
+                    }
+                    lastTapTime = 0L
+                }
+            }
+        }
+        
         AsyncImage(
             model = imageUrl,
             contentDescription = null,