本文介绍了如何将对象添加到virtualtreeview的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!
问题描述
简而言之,我试图将对象添加到VirtualTreeView中,但总是在CellText上出现错误EAccessViolation
,我想知道我尽力而为却没有结果的错误原因...
In short, I'm trying to add Object into VirtualTreeView but am always getting error EAccessViolation
at CellText I'm wondering about the reason for the error i tried to do my best but without result...
这是我的尝试
TForm1 = class(TForm)
private
public
end;
TPerson = class;
PPersonNode = ^TPersonNode;
TPersonNode = record
PersonObj: TPerson;
end;
TPerson = class(TObject)
private
FName: string;
public
property Name: string read FName write FName;
end;
procedure TForm1.Button1Click(Sender: TObject);
var
PersonRec: PPersonNode;
begin
PersonRec := VirtualStringTree1.GetNodeData(VirtualStringTree1.AddChild(nil));
PersonRec.PersonObj := TPerson.Create;
PersonRec.PersonObj.Name := 'aaa';
end;
procedure TForm1.VirtualStringTree1GetNodeDataSize(Sender: TBaseVirtualTree;
var NodeDataSize: Integer);
begin
NodeDataSize := SizeOf(TPersonNode);
end;
procedure TForm1.VirtualStringTree1GetText(Sender: TBaseVirtualTree;
Node: PVirtualNode; Column: TColumnIndex; TextType: TVSTTextType;
var CellText: string);
var
PersonRec: PPersonNode;
begin
PersonRec := Sender.GetNodeData(Node);
CellText := PersonRec.PersonObj.Name;
end;
推荐答案
在创建TPerson对象之前,似乎正在触发 OnGetText 事件.尝试先检查对象是否为零:
It looks like the OnGetText event is being fired before the TPerson object has been created. Try checking that the object isn't nil first:
procedure TForm1.VirtualStringTree1GetText(Sender: TBaseVirtualTree;
Node: PVirtualNode; Column: TColumnIndex; TextType: TVSTTextType;
var CellText: string);
var
PersonRec: PPersonNode;
begin
PersonRec := Sender.GetNodeData(Node);
if PersonRec <> nil then // <- check that the object has been created
CellText := PersonRec.PersonObj.Name;
end;
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