updated

Author: flocked

Sources/AdvancedCollectionTableView/DiffableDataSource/NSOutlineView/OutlineViewDiffableDataSource.swift

@@ -498,7 +498,7 @@ public class OutlineViewDiffableDataSource<ItemIdentifierType: Hashable>: NSObje
         return nil
     }
 
-    /// Returns a preview image of the table row for the specified item.
+    /// Returns a preview image of the table row for the specified items.
     public func previewImage(for item: ItemIdentifierType) -> NSImage? {
         let columns = outlineView.tableColumns
         guard !columns.isEmpty else { return nil }

Sources/AdvancedCollectionTableView/Extensions/NSCollectionView/NSCollectionViewDiffableDataSource+.swift

@@ -0,0 +1,50 @@
+//
+//  NSCollectionViewDiffableDataSource+.swift
+//
+//
+//  Created by Florian Zand on 16.03.25.
+//
+
+import AppKit
+import FZSwiftUtils
+
+extension NSCollectionViewDiffableDataSource {
+    /// The item provider of the datasource.
+    public var itemProvider: ItemProvider {
+        typealias itemProviderBlock = @convention(block) (NSCollectionView, IndexPath, Any) -> NSCollectionViewItem?
+        guard let object: NSObject = getIvarValue(for: "_impl"), let cellProvider: itemProviderBlock = object.getIvarValue(for: "_collectionViewItemProvider") else { return { _,_,_ in return nil } }
+        return cellProvider
+    }
+    
+    /// Creates a new collection view item for the specified item identifier using the item provider.
+    public func createItem(for itemIdentifier: ItemIdentifierType) -> NSCollectionViewItem? {
+        itemProvider(collectionView, IndexPath(item: 0, section: 0), itemIdentifier)
+    }
+    
+    /// Returns a preview image of the collection view item for the specified element.
+    public func previewImage(for item: ItemIdentifierType) -> NSImage? {
+        _previewImage(for: item, size: nil)
+    }
+    
+    /// Returns a preview image of the collection view item for the specified element and item size.
+    public func previewImage(for item: ItemIdentifierType, size: CGSize) -> NSImage? {
+        _previewImage(for: item, size: size)
+    }
+    
+    private func _previewImage(for item: ItemIdentifierType, size: CGSize? = nil, width: CGFloat? = nil, height: CGFloat? = nil) -> NSImage? {
+        guard let item = createItem(for: item) else { return nil }
+        if width != nil || height != nil {
+            item.view.frame.size = item.view.systemLayoutSizeFitting(width: width, height: height)
+            item.view.frame.size.width = width ?? item.view.frame.size.width
+            item.view.frame.size.height = height ?? item.view.frame.size.height
+        } else {
+            item.view.frame.size = size ?? collectionView.frameForItem(at: IndexPath(item: 0, section: 0))?.size ?? CGSize(512, 512)
+        }
+        return item.view.renderedImage
+    }
+    
+    private var collectionView: NSCollectionView {
+        guard let object: NSObject = getIvarValue(for: "_impl"), let collectionView: NSCollectionView =  object.getIvarValue(for: "_nsCollectionView") else { return NSCollectionView() }
+        return collectionView
+    }
+}

Sources/AdvancedCollectionTableView/Extensions/NSTableView/NSTableViewDiffableDataSource+.swift

@@ -75,21 +75,35 @@ public extension NSTableViewDiffableDataSource {
     }
 
     /// The cell provider of the datasource.
-    private var cellProvider: ((NSTableView, NSTableColumn, Int, ItemIdentifierType)->(Any)) {
-        guard let cellProvider: ((NSTableView, NSTableColumn, Int, ItemIdentifierType)->(NSView?)) = getIvarValue(for: "cellProvider") else { return { _,_,_,_ in return NSTableCellView() } }
+    public var cellProvider: ((NSTableView, NSTableColumn, Int, ItemIdentifierType)->(NSView)) {
+        typealias CellProviderBlock = @convention(block) (_ tableView: NSTableView, _ tableColumn: NSTableColumn, _ row: Int, _ identifier: Any) -> NSView
+        guard let cellProvider: CellProviderBlock = getIvarValue(for: "_cellProvider") else { return { _,_,_,_ in return NSTableCellView() } }
         return cellProvider
     }
 
-    private func previewImage(for item: ItemIdentifierType, tableView: NSTableView) -> NSImage? {
+    /// Creates a new table cell view for the specified item using the cell provider.
+    public func createCellView(for item: ItemIdentifierType, tableColumn: NSTableColumn? = nil, tableView: NSTableView) -> NSView? {
+        guard let tableColumn = tableColumn ?? tableView.tableColumns.first, tableView.tableColumns.contains(tableColumn) else { return nil }
+        return cellProvider(tableView, tableColumn, 0, item)
+    }
+        
+    /// Returns a preview image of the table cell for the specified item and table column.
+    public func previewImage(for item: ItemIdentifierType, tableView: NSTableView) -> NSImage? {
         let columns = tableView.tableColumns
         guard !columns.isEmpty else { return nil }
         return NSImage(combineHorizontal: columns.compactMap({ _previewImage(for: item, tableColumn: $0, tableView: tableView, useColumnWidth: $0 !== columns.last!) }), alignment: .top)
     }
 
-    private func previewImage(for item: ItemIdentifierType, tableColumn: NSTableColumn, tableView: NSTableView) -> NSImage? {
+    /// Returns a preview image of the table row for the specified item.
+    public func previewImage(for item: ItemIdentifierType, tableColumn: NSTableColumn, tableView: NSTableView) -> NSImage? {
         _previewImage(for: item, tableColumn: tableColumn, tableView: tableView)
     }
 
+    /// Returns a preview image of the table rows for the specified items.
+    public func previewImage(for items: [ItemIdentifierType], tableView: NSTableView) -> NSImage? {
+        return NSImage(combineVertical: items.compactMap({ previewImage(for: $0, tableView: tableView)}).reversed(), alignment: .left)
+    }
+    
     private func _previewImage(for item: ItemIdentifierType, tableColumn: NSTableColumn, tableView: NSTableView, useColumnWidth: Bool = true) -> NSImage? {
         guard let index = tableView.tableColumns.firstIndex(of: tableColumn) else { return nil }
         let view: NSView