Delphi TStringEditLink被破坏后的访问冲突(TVirtualStringTree)-Lazarus示例
我试图实现一个基于Lazarius的VirtualStringTree编辑器 你能告诉我为什么在Delphi TStringEditLink被破坏后的访问冲突(TVirtualStringTree)-Lazarus示例,delphi,virtualtreeview,tvirtualstringtree,Delphi,Virtualtreeview,Tvirtualstringtree,我试图实现一个基于Lazarius的VirtualStringTree编辑器 你能告诉我为什么在TStringEditLink被销毁后我会遇到访问冲突吗 很奇怪,只有按ESCAPE或ENTER键时才会出现错误。如果我从一个单元格单击到另一个单元格,则没有错误 像观察一样,我知道如果我从析构函数TStringEditLink.Destroy中删除FEdit.Free代码,错误就会消失 你有解决这个问题的办法吗 下面是完整的代码: unit Unit2; interface uses Win
TStringEditLink
被销毁后我会遇到访问冲突吗
很奇怪,只有按ESCAPE或ENTER键时才会出现错误。如果我从一个单元格单击到另一个单元格,则没有错误
像观察一样,我知道如果我从析构函数TStringEditLink.Destroy中删除FEdit.Free
代码,错误就会消失
你有解决这个问题的办法吗
下面是完整的代码:
unit Unit2;
interface
uses
Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
Vcl.Controls, Vcl.Forms, Vcl.Dialogs, VirtualTrees, EditorLink, Vcl.StdCtrls,
Vcl.ExtCtrls, Vcl.Imaging.jpeg;
type
TTreeData = record
Fields: array of String;
end;
PTreeData = ^TTreeData;
const
SizeVirtualTree = SizeOf(TTreeData);
type
TForm2 = class(TForm)
VirtualTree: TVirtualStringTree;
procedure FormCreate(Sender: TObject);
procedure VirtualTreeClick(Sender: TObject);
procedure VirtualTreeCreateEditor(Sender: TBaseVirtualTree;
Node: PVirtualNode; Column: TColumnIndex; out EditLink: IVTEditLink);
procedure VirtualTreeEditing(Sender: TBaseVirtualTree; Node: PVirtualNode;
Column: TColumnIndex; var Allowed: Boolean);
procedure VirtualTreeFreeNode(Sender: TBaseVirtualTree; Node: PVirtualNode);
procedure VirtualTreeGetNodeDataSize(Sender: TBaseVirtualTree;
var NodeDataSize: Integer);
procedure VirtualTreeGetText(Sender: TBaseVirtualTree; Node: PVirtualNode;
Column: TColumnIndex; TextType: TVSTTextType; var CellText: string);
procedure VirtualTreeNewText(Sender: TBaseVirtualTree; Node: PVirtualNode;
Column: TColumnIndex; NewText: string);
private
{ Private declarations }
public
{ Public declarations }
end;
var
Form2: TForm2;
implementation
{$R *.dfm}
procedure TForm2.FormCreate(Sender: TObject);
var
Node: PVirtualNode;
LTreeData: PTreeData;
begin
VirtualTree.Clear;
VirtualTree.BeginUpdate;
//node 1
Node:= VirtualTree.AddChild(nil,nil);
VirtualTree.ValidateNode(Node,False);
LTreeData:= VirtualTree.GetNodeData(Node);
SetLength(LTreeData^.Fields,3);
LTreeData^.Fields[0]:= 'John';
LTreeData^.Fields[1]:= '2500';
LTreeData^.Fields[2]:= 'Production';
//node 2
Node:= VirtualTree.AddChild(nil,nil);
VirtualTree.ValidateNode(Node,False);
LTreeData:= VirtualTree.GetNodeData(Node);
SetLength(LTreeData^.Fields,3);
LTreeData^.Fields[0]:= 'Mary';
LTreeData^.Fields[1]:= '2100';
LTreeData^.Fields[2]:= 'HR';
VirtualTree.EndUpdate;
end;
procedure TForm2.VirtualTreeClick(Sender: TObject);
var
VT: TVirtualStringTree;
Click: THitInfo;
begin
VT:= Sender as TVirtualStringTree;
VT.GetHitTestInfoAt(Mouse.CursorPos.X-VT.ClientOrigin.X, Mouse.CursorPos.Y-VT.ClientOrigin.Y, True, Click);
VT.EditNode(Click.HitNode,Click.HitColumn);
end;
procedure TForm2.VirtualTreeCreateEditor(Sender: TBaseVirtualTree;
Node: PVirtualNode; Column: TColumnIndex; out EditLink: IVTEditLink);
begin
EditLink := TStringEditLink.Create;
end;
procedure TForm2.VirtualTreeEditing(Sender: TBaseVirtualTree;
Node: PVirtualNode; Column: TColumnIndex; var Allowed: Boolean);
begin
Allowed:= True;
end;
procedure TForm2.VirtualTreeFreeNode(Sender: TBaseVirtualTree;
Node: PVirtualNode);
var
LTreeData: PTreeData;
begin
LTreeData:= Sender.GetNodeData(Node);
Finalize(LTreeData^);
end;
procedure TForm2.VirtualTreeGetNodeDataSize(Sender: TBaseVirtualTree;
var NodeDataSize: Integer);
begin
NodeDataSize:= SizeVirtualTree;
end;
procedure TForm2.VirtualTreeGetText(Sender: TBaseVirtualTree;
Node: PVirtualNode; Column: TColumnIndex; TextType: TVSTTextType;
var CellText: string);
var
LTreeData: PTreeData;
begin
if Assigned(Node) and (Column > NoColumn) then
begin
LTreeData:= Sender.GetNodeData(Node);
CellText:= LTreeData^.Fields[Column];
end;
end;
procedure TForm2.VirtualTreeNewText(Sender: TBaseVirtualTree;
Node: PVirtualNode; Column: TColumnIndex; NewText: string);
var
LTreeData: PTreeData;
begin
LTreeData:= Sender.GetNodeData(Node);
LTreeData^.Fields[Column]:= NewText;
end;
end.
以及EditorLink
单元
unit EditorLink;
interface
uses
Classes, SysUtils, Forms, Controls, Graphics, Dialogs,
VirtualTrees, Messages, Windows, StdCtrls, Vcl.ExtCtrls;
type
TStringEditLink = class(TInterfacedObject, IVTEditLink)
private
FEdit: TWinControl;
FTree: TVirtualStringTree;
FNode: PVirtualNode;
FColumn: Integer;
FStopping: Boolean;
protected
procedure EditKeyDown(Sender: TObject; var Key: Word; Shift: TShiftState);
public
destructor Destroy; override;
function BeginEdit: Boolean; stdcall;
function CancelEdit: Boolean; stdcall;
function EndEdit: Boolean; stdcall;
function GetBounds: TRect; stdcall;
function PrepareEdit(Tree: TBaseVirtualTree; Node: PVirtualNode; Column: TColumnIndex): Boolean; stdcall;
procedure ProcessMessage(var Message: TMessage); stdcall;
procedure SetBounds(R: TRect); stdcall;
end;
implementation
uses unit2;
destructor TStringEditLink.Destroy;
begin
FEdit.Free; //--> seems that due to this I get the access violation
inherited;
end;
procedure TStringEditLink.EditKeyDown(Sender: TObject; var Key: Word; Shift: TShiftState);
begin
case Key of
VK_ESCAPE:
begin
FTree.CancelEditNode;
Key := 0;
FTree.setfocus;
end;
VK_RETURN:
begin
PostMessage(FTree.Handle, WM_KEYDOWN, VK_DOWN, 0);
Key := 0;
FTree.EndEditNode;
FTree.setfocus;
end;
end; //case
end;
function TStringEditLink.BeginEdit: Boolean;
begin
Result := not FStopping;
if Result then
begin
FEdit.Show;
FEdit.SetFocus;
end;
end;
function TStringEditLink.CancelEdit: Boolean;
begin
Result := True;
FEdit.Hide;
end;
function TStringEditLink.EndEdit: Boolean;
var
s: String;
begin
Result := True;
s := TComboBox(FEdit).Text;
FTree.Text[FNode, FColumn] := s;
FTree.InvalidateNode(FNode);
FEdit.Hide;
FTree.SetFocus;
end;
function TStringEditLink.GetBounds: TRect;
begin
Result := FEdit.BoundsRect;
end;
function TStringEditLink.PrepareEdit(Tree: TBaseVirtualTree; Node: PVirtualNode; Column: TColumnIndex): Boolean;
var
FCellText: String;
FCellTextBounds: TRect;
FCellFont: TFont;
begin
Result := True;
FTree := Tree as TVirtualStringTree;
FNode := Node;
FColumn := Column;
FCellFont:= TFont.Create;
FTree.GetTextInfo(FNode, FColumn, FCellFont, FCellTextBounds, FCellText);
FEdit := TComboBox.Create(nil);
with FEdit as TComboBox do
begin
Visible := False;
Parent := Tree;
Items.Add('Google');
Items.Add('Yahoo');
Items.Add('Altavista');
OnKeyDown := EditKeyDown;
Text:= FCellText;
end;
end;
procedure TStringEditLink.ProcessMessage(var Message: TMessage);
begin
FEdit.WindowProc(Message);
end;
procedure TStringEditLink.SetBounds(R: TRect);
var
Dummy: Integer;
begin
FTree.Header.Columns.GetColumnBounds(FColumn, Dummy, R.Right);
FEdit.BoundsRect := R;
end;
end.
我没有Lazarus,但它在XE4上的表现似乎相同
在我的VST安装中,位于/VirtualTreeviewV5.3.0/Demos/Advanced
中有一个Editors.pas
文件,我在其中找到了下面的析构函数。注意注释原因问题357
:
destructor TPropertyEditLink.Destroy;
begin
//FEdit.Free; casues issue #357. Fix:
if FEdit.HandleAllocated then
PostMessage(FEdit.Handle, CM_RELEASE, 0, 0);
inherited;
end;
此外,FEdit.Free
在新创建之前在PrepareEdit
方法中执行:
function TStringEditLink.PrepareEdit(Tree: TBaseVirtualTree; Node: PVirtualNode; Column: TColumnIndex): Boolean;
var
FCellText: String;
FCellTextBounds: TRect;
FCellFont: TFont;
begin
Result := True;
FTree := Tree as TVirtualStringTree;
FNode := Node;
FColumn := Column;
FEdit.Free;
FEdit := nil;
FCellFont:= TFont.Create;
FTree.GetTextInfo(FNode, FColumn, FCellFont, FCellTextBounds, FCellText);
FEdit := TComboBox.Create(nil);
with FEdit as TComboBox do
. . .
这解决了XE4和XE7安装中的VK_ESC
和VK_返回问题
问题似乎尚未解决:请参阅。我没有发现#361补丁的证据
在编辑操作后单击未分配的节点时,我会遇到另一个问题。
在开始编辑之前,检查单击.HitNode
是否不是nil
,可以解决上述问题
procedure TForm2.VirtualTreeClick(Sender: TObject);
var
VT: TVirtualStringTree;
Click: THitInfo;
begin
VT:= Sender as TVirtualStringTree;
VT.GetHitTestInfoAt(Mouse.CursorPos.X-VT.ClientOrigin.X, Mouse.CursorPos.Y-VT.ClientOrigin.Y, True, Click);
if Assigned(Click.HitNode) then
VT.EditNode(Click.HitNode,Click.HitColumn);
end;
请注意,EditorLink
单元中还有一个循环引用:
uses Unit2;
我没有Lazarus,但它在XE4上的表现似乎相同
在我的VST安装中,位于/VirtualTreeviewV5.3.0/Demos/Advanced
中有一个Editors.pas
文件,我在其中找到了下面的析构函数。注意注释原因问题357
:
destructor TPropertyEditLink.Destroy;
begin
//FEdit.Free; casues issue #357. Fix:
if FEdit.HandleAllocated then
PostMessage(FEdit.Handle, CM_RELEASE, 0, 0);
inherited;
end;
此外,FEdit.Free
在新创建之前在PrepareEdit
方法中执行:
function TStringEditLink.PrepareEdit(Tree: TBaseVirtualTree; Node: PVirtualNode; Column: TColumnIndex): Boolean;
var
FCellText: String;
FCellTextBounds: TRect;
FCellFont: TFont;
begin
Result := True;
FTree := Tree as TVirtualStringTree;
FNode := Node;
FColumn := Column;
FEdit.Free;
FEdit := nil;
FCellFont:= TFont.Create;
FTree.GetTextInfo(FNode, FColumn, FCellFont, FCellTextBounds, FCellText);
FEdit := TComboBox.Create(nil);
with FEdit as TComboBox do
. . .
这解决了XE4和XE7安装中的VK_ESC
和VK_返回问题
问题似乎尚未解决:请参阅。我没有发现#361补丁的证据
在编辑操作后单击未分配的节点时,我会遇到另一个问题。
在开始编辑之前,检查单击.HitNode
是否不是nil
,可以解决上述问题
procedure TForm2.VirtualTreeClick(Sender: TObject);
var
VT: TVirtualStringTree;
Click: THitInfo;
begin
VT:= Sender as TVirtualStringTree;
VT.GetHitTestInfoAt(Mouse.CursorPos.X-VT.ClientOrigin.X, Mouse.CursorPos.Y-VT.ClientOrigin.Y, True, Click);
if Assigned(Click.HitNode) then
VT.EditNode(Click.HitNode,Click.HitColumn);
end;
请注意,EditorLink
单元中还有一个循环引用:
uses Unit2;
代码的伪堆栈跟踪说明了问题:
FEdit.EditKeyDown()
-- calls --
FTree.EndEditNode() { or FTree.CancelEditNode }
-- which calls --
TStringEditLink.Destroy()
-- which calls --
FEdit.Free()
FEdit.EditKeyDown()的事件处理程序中的代码在向下键事件处理程序代码完成运行之前释放FEdit
。因此,访问冲突是错误的
我们通过设置一个信号机制来处理这个问题,这样TStringEditLink
可以在完成时向主窗体发出信号,主窗体可以运行代码来销毁TStringEditLink
(因为它首先创建了TStringEditLink
)。我们在主窗体中添加了一个TTimer
,以及一个接收信号的属性。TTimer
监视属性。TStringEditLink
组件有一个指向表单的指针,因此它可以设置属性
单元1;
接口
使用
Winapi.Windows、Winapi.Messages、System.SysUtils、System.Variants、System.Classes、Vcl.Graphics、,
控件、窗体、对话框、文本、虚拟树;
类型
TEditorAction=(eaCancel、eaAccept、eaNotSet);
TForm1=类(TForm)
vstTree:TVirtualStringTree;
过程vstTreeCreateEditor(发送方:TBaseVirtualTree;节点:PVirtualNode;列:TColumnIndex;输出编辑链接:IVTEditLink);
程序DoWatchTreeEditorTimer(发送方:TObject);
过程表单创建(发送方:ToObject);
销毁程序表(发送方:TObject);
私有的
定时器:TTimer;
FEditorAction:TEditorAction;
过程SetEditorAction(常量值:TEditorAction);
公众的
属性EditorAction:TEditorAction read FEditorAction write SetEditorAction;
结束;
TPropertyEdit=class(TInterfacedObject,IVTEditLink)
程序EditKeyDown(发送方:ToObject;变量关键字:Word;Shift:TShiftState);
私有的
FEdit:双控制;
FTree:TVirtualStringTree;
FNode:PVirtualNode;
FColumn:整数;
公众的
FForm:TForm1;
毁灭者毁灭;推翻
函数BeginEdit:Boolean;stdcall;
函数取消编辑:布尔;stdcall;
函数EndEdit:布尔型;stdcall;
函数GetBounds:TRect;stdcall;
函数PrepareEdit(树:TBaseVirtualTree;节点:PVirtualNode;列:TColumnIndex):布尔;stdcall;
过程ProcessMessage(var消息:TMessage);stdcall;
程序设定点(R:TRCT);stdcall;
结束;
变量
表1:TForm1;
实施
{$R*.dfm}
{TForm1}
过程TForm1.FormCreate(发送方:TObject);
开始
FEndEditTimer:=TTimer.Create(无);
FEndEditTimer.Enabled:=False;
时间间隔:=100;
FEndEditTimer.OnTimer:=DoWatchTreeEditorTimer;
结束;
程序TForm1.FormDestroy(发送方:ToObject);
开始
FreeAndNil(FEndEditTimer);
结束;
过程TForm1.vstTreeCreateEditor(发送方:TBaseVirtualTree;节点:PVirtualNode;列:TColumnIndex;输出编辑链接:IVTEditLink);
开始
EditLink:=TPropertyEdit.Create;
TPropertyEdit(EditLink).FForm:=Self;{让我们在需要销毁编辑器时发出窗体信号}
FEditorAction:=eaNotSet;
结束;
过程TForm1.SetEditorAction(常量值:TEditorAction);
开始
如果是FEditorAction值,则
开始
FEditorAction:=值;
FEndEditTimer.Enabled:=真;
结束;
结束;
程序TForm1.DoWatchTreeEditorTimer(发送方:TObject);
开始
FEndEditTimer.Enabled:=False;
Application.ProcessMessages;
案例二
eaCancel:
开始
vstTree.CancelEditNode;
vstTree.SetFocu