我想改变现有虚拟(根)节点的单元格文本。我可以改变数据,但必须刷新整个TreeView,以便再次触发GetText。是否有更简单的方法或可能仅刷新一个根节点而不是整个树的方法?
感谢您的帮助。
我想改变现有虚拟(根)节点的单元格文本。我可以改变数据,但必须刷新整个TreeView,以便再次触发GetText。是否有更简单的方法或可能仅刷新一个根节点而不是整个树的方法?
感谢您的帮助。
Button1Click
表示。如果您单击按钮,则数据记录中的值将增加,并且节点将被强制重新绘制(这将触发OnGetText
事件,在该事件中,您将准备好获取该记录中的新增值)。在您的实际代码中,您需要执行以下操作:
TopNode
:-) Count
值递增)InvalidateNode
(这将触发某些事件的虚拟事件链,但其中包括OnGetText
)type
PTreeData = ^TTreeData;
TTreeData = record
Title: string;
Count: Integer;
end;
procedure TForm1.FormCreate(Sender: TObject);
var
TreeData: PTreeData;
TreeNode: PVirtualNode;
begin
// this is just for memory leaks report
ReportMemoryLeaksOnShutdown := True;
// initialize data size for our data record
VirtualTree.NodeDataSize := SizeOf(TTreeData);
// add one node and store it to the TreeNode variable
TreeNode := VirtualTree.AddChild(nil);
// get the pointer to just created node data record
TreeData := VirtualTree.GetNodeData(TreeNode);
// and assign some values to that data record
TreeData.Title := 'Count: ';
TreeData.Count := 0;
end;
procedure TForm1.Button1Click(Sender: TObject);
var
TreeData: PTreeData;
TreeNode: PVirtualNode;
begin
// now I take the the top node just as an example
TreeNode := VirtualTree.TopNode;
// get the pointer to its data record
TreeData := VirtualTree.GetNodeData(TreeNode);
// increase the value in data record for this node
TreeData.Count := TreeData.Count + 1;
// and force the node to repaint, what will except
// other events trigger also the OnGetText one
VirtualTree.InvalidateNode(TreeNode);
end;
procedure TForm1.VirtualTreeGetText(Sender: TBaseVirtualTree;
Node: PVirtualNode; Column: TColumnIndex; TextType: TVSTTextType;
var CellText: string);
var
TreeData: PTreeData;
begin
// here I'll get the pointer to data of the currently refreshed cell's node
TreeData := VirtualTree.GetNodeData(Node);
// and return the caption of the cell
CellText := TreeData.Title + IntToStr(TreeData.Count);
end;
procedure TForm1.VirtualTreeFreeNode(Sender: TBaseVirtualTree;
Node: PVirtualNode);
var
TreeData: PTreeData;
begin
// this is here because of VT memory leaks, so get the pointer to data
TreeData := Sender.GetNodeData(Node);
// and finalize them
Finalize(TreeData^);
end;
procedure Form1.btnEditTextClick(Sender: TObject);
var
Data: PTreeData;
begin
Data := VST.GetNodeData(VST.FocusedNode);
Data.Title := Edit2.Text;
VST.InvalidateNode(VST.FocusedNode);
end;