Merge EhPreviewItem and its placeholder

app/src/main/java/com/hippo/ehviewer/ui/main/GalleryPreview.kt

@@ -87,22 +87,7 @@ fun EhAsyncPreview(
 
 @Composable
 fun EhPreviewItem(
-    galleryPreview: GalleryPreview,
-    onClick: () -> Unit,
-) = Column(horizontalAlignment = Alignment.CenterHorizontally) {
-    Box(contentAlignment = Alignment.Center) {
-        CrystalCard(
-            onClick = onClick,
-            modifier = Modifier.fillMaxWidth().aspectRatio(0.6666667F),
-        ) {
-            EhAsyncPreview(model = galleryPreview, modifier = Modifier.fillMaxSize())
-        }
-    }
-    Text((galleryPreview.position + 1).toString())
-}
-
-@Composable
-fun EhPreviewItemPlaceholder(
+    galleryPreview: GalleryPreview?,
     position: Int,
     onClick: () -> Unit,
 ) = Column(horizontalAlignment = Alignment.CenterHorizontally) {
@@ -111,6 +96,7 @@ fun EhPreviewItemPlaceholder(
             onClick = onClick,
             modifier = Modifier.fillMaxWidth().aspectRatio(0.6666667F),
         ) {
+            if (galleryPreview != null) EhAsyncPreview(model = galleryPreview, modifier = Modifier.fillMaxSize())
         }
     }
     Text((position + 1).toString())

app/src/main/java/com/hippo/ehviewer/ui/scene/GalleryDetailScene.kt

@@ -636,6 +636,7 @@ class GalleryDetailScene : BaseScene() {
         items(previewList) {
             EhPreviewItem(
                 galleryPreview = it,
+                position = it.position,
                 onClick = { context?.navToReader(gd, it.position) },
             )
         }

app/src/main/java/com/hippo/ehviewer/ui/scene/GalleryPreviewScreen.kt

@@ -57,7 +57,6 @@ import com.hippo.ehviewer.coil.imageRequest
 import com.hippo.ehviewer.coil.justDownload
 import com.hippo.ehviewer.ui.legacy.calculateSuitableSpanCount
 import com.hippo.ehviewer.ui.main.EhPreviewItem
-import com.hippo.ehviewer.ui.main.EhPreviewItemPlaceholder
 import com.hippo.ehviewer.ui.navToReader
 import com.hippo.ehviewer.ui.setMD3Content
 import com.hippo.ehviewer.ui.tools.rememberDialogState
@@ -154,14 +153,8 @@ class GalleryPreviewScreen : Fragment() {
                             contentType = data.itemContentType(),
                         ) { index ->
                             val item = data[index]
-                            if (item != null) {
-                                EhPreviewItem(item) {
-                                    onPreviewCLick(item.position)
-                                }
-                            } else {
-                                EhPreviewItemPlaceholder(index) {
-                                    onPreviewCLick(index)
-                                }
+                            EhPreviewItem(item, index) {
+                                onPreviewCLick(index)
                             }
                         }
                     }