Delphi TreeView Drag and Drop でノードを移動

 Delphi の TreeView(TTreeView) ノードをドラッグ・アンド・ドロップで移動させるコード

TreeView の DragMode プロパティを dmAutomatic にしておく

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1. // TreeView1.DragMode := dmAutomatic;  
2.   
3. procedure TForm1.TreeView1DragDrop(Sender, Source: TObject; X, Y: Integer);  
4. var  
5.     SourceNode, TargetNode: TTreeNode;  
6. begin  
7.     SourceNode := TreeView1.Selected;  
8.     TargetNode := TreeView1.GetNodeAt(X, Y);  
9.   
10.     if Assigned(SourceNode) and Assigned(TargetNode) then begin  
11.         SourceNode.MoveTo(TargetNode, naInsert);  
12.     end;  
13. end;  
14.   
15. procedure TForm1.TreeView1DragOver(Sender, Source: TObject; X, Y: Integer; State: TDragState; var Accept: Boolean);  
16. var  
17.     SourceNode, TargetNode: TTreeNode;  
18. begin  
19.     SourceNode := TreeView1.Selected;  
20.     TargetNode := TreeView1.GetNodeAt(X, Y);  
21.       
22.     Accept := Assigned(SourceNode) and Assigned(TargetNode) and (TargetNode <> SourceNode);  
23. end;  

// TreeView1.DragMode := dmAutomatic;

procedure TForm1.TreeView1DragDrop(Sender, Source: TObject; X, Y: Integer);
var
    SourceNode, TargetNode: TTreeNode;
begin
    SourceNode := TreeView1.Selected;
    TargetNode := TreeView1.GetNodeAt(X, Y);

    if Assigned(SourceNode) and Assigned(TargetNode) then begin
        SourceNode.MoveTo(TargetNode, naInsert);
    end;
end;

procedure TForm1.TreeView1DragOver(Sender, Source: TObject; X, Y: Integer; State: TDragState; var Accept: Boolean);
var
    SourceNode, TargetNode: TTreeNode;
begin
    SourceNode := TreeView1.Selected;
    TargetNode := TreeView1.GetNodeAt(X, Y);
    
    Accept := Assigned(SourceNode) and Assigned(TargetNode) and (TargetNode <> SourceNode);
end;

OnDragOver でドロップしてよい場所を判定、OnDragDrop で TargetNode 位置へ、SourceNode(ドラッグしたノード)をインサート