Question

我正在尝试使用TButton创建节点。我创建节点和链接到节点的按钮。在事件TVirtualStringTree.AfterCellPaint上，我初始化按钮上的BoundsRect。但按钮始终显示在第一个节点中。

您对这个问题有所了解吗？

type
  TNodeData = record
    TextValue: string;
    Button: TButton;
  end;
  PNodeData = ^TNodeData;

procedure TForm1.FormCreate(Sender: TObject);

  procedure AddButton(__Node: PVirtualNode);
  var
    NodeData: PNodeData;
  begin
    NodeData := VirtualStringTree1.GetNodeData(__Node);
    NodeData.Button := TButton.Create(nil);
    with NodeData.Button do
    begin
      Parent := VirtualStringTree1;
      Height := VirtualStringTree1.DefaultNodeHeight;
      Caption := '+';
      Visible := false;
    end;
  end;

  procedure InitializeNodeData(__Node: PVirtualNode; __Text: string);
  var
    NodeData: PNodeData;
  begin
    NodeData := VirtualStringTree1.GetNodeData(__Node);
    NodeData.TextValue := __Text;
  end;

var
  Node: PVirtualNode;
begin
  VirtualStringTree1.NodeDataSize := SizeOf(TNodeData);

  Node := VirtualStringTree1.AddChild(nil);
  InitializeNodeData(Node, 'a');      
  Node := VirtualStringTree1.AddChild(Node);
  InitializeNodeData(Node, 'a.1');

  Node := VirtualStringTree1.AddChild(nil);
  InitializeNodeData(Node, 'b');
  Node := VirtualStringTree1.AddChild(Node);
  InitializeNodeData(Node, 'Here the button');
  AddButton(Node);
end;

procedure TForm1.VirtualStringTree1AfterCellPaint(Sender: TBaseVirtualTree;
  TargetCanvas: TCanvas; Node: PVirtualNode; Column: TColumnIndex; CellRect: TRect);
var
 NodeData: PNodeData;
begin
  if (Column = 0) then
    Exit;

  NodeData := VirtualStringTree1.GetNodeData(Node);
  if (Assigned(NodeData)) and (Assigned(NodeData.Button)) then
  begin
    with NodeData.Button Do
    begin
      Visible := (vsVisible in Node.States)
                 and ((Node.Parent = VirtualStringTree1.RootNode) or   (vsExpanded in Node.Parent.States));
      BoundsRect := CellRect;
    end;
  end;
end;

Answer 1

我写了一个小程序来为节点创建任何控件。我发现设置节点的最佳位置控制OnAfterPaint事件中的可见性。滚动按预期工作，几乎没有闪烁。

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, VirtualTrees, StdCtrls, Buttons, ExtCtrls;

type
  TForm1 = class(TForm)
    VirtualStringTree1: TVirtualStringTree;
    procedure FormCreate(Sender: TObject);            
    procedure VirtualStringTree1GetText(Sender: TBaseVirtualTree;
      Node: PVirtualNode; Column: TColumnIndex; TextType: TVSTTextType;
      var CellText: WideString);
    procedure VirtualStringTree1AfterPaint(Sender: TBaseVirtualTree;
      TargetCanvas: TCanvas);
    procedure VirtualStringTree1MeasureItem(Sender: TBaseVirtualTree;
      TargetCanvas: TCanvas; Node: PVirtualNode; var NodeHeight: Integer);  
  private
    procedure SetNodesControlVisibleProc(Sender: TBaseVirtualTree; Node: PVirtualNode; Data: Pointer; var Abort: Boolean);
    procedure SetNodeControlVisible(Tree: TBaseVirtualTree; Node: PVirtualNode; Column: TColumnIndex = NoColumn);
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

type
  TNodeData = record
    Text: WideString;
    Control: TControl;
  end;
  PNodeData = ^TNodeData;

{ Utility }
function IsNodeVisibleInClientRect(Tree: TBaseVirtualTree; Node: PVirtualNode;
  Column: TColumnIndex = NoColumn): Boolean;
var
  OutRect: TRect;
begin
  Result := Tree.IsVisible[Node] and
    Windows.IntersectRect(OutRect, Tree.GetDisplayRect(Node, Column, False), Tree.ClientRect);
end;

type
  TControlClass = class of TControl;

  TMyPanel = class(TPanel)
  public
    CheckBox: TCheckBox;
  end;

{ TForm1 }
procedure TForm1.FormCreate(Sender: TObject);

  function CreateNodeControl(Tree: TVirtualStringTree; Node: PVirtualNode; ControlClass: TControlClass): TControl;
  var
    NodeData: PNodeData;
  begin
    NodeData := Tree.GetNodeData(Node);
    NodeData.Control := ControlClass.Create(nil);
    with NodeData.Control do
    begin
      Parent := Tree; // Parent will destroy the control
      Height := Tree.DefaultNodeHeight;
      Visible := False;
    end;
    Tree.IsDisabled[Node] := True;
    Result := NodeData.Control;
  end;

  procedure InitializeNodeData(Node: PVirtualNode; const Text: WideString);
  var
    NodeData: PNodeData;
  begin
    NodeData := VirtualStringTree1.GetNodeData(Node);
    Initialize(NodeData^);
    NodeData.Text := Text;
  end;

var
  Node: PVirtualNode;
  MyPanel: TMyPanel;
  I: integer;
begin
  VirtualStringTree1.NodeDataSize := SizeOf(TNodeData);
  // trigger MeasureItem
  VirtualStringTree1.TreeOptions.MiscOptions := VirtualStringTree1.TreeOptions.MiscOptions + [toVariableNodeHeight]; 

  // Populate some nodes    
  for I := 1 to 5 do begin
    Node := VirtualStringTree1.AddChild(nil);
    InitializeNodeData(Node, Format('%d', [I]));
    Node := VirtualStringTree1.AddChild(Node);
    InitializeNodeData(Node, Format('%d.1', [I]));
  end;

  Node := VirtualStringTree1.AddChild(nil);
  InitializeNodeData(Node, '[TSpeedButton Parent]');
  Node := VirtualStringTree1.AddChild(Node);
  InitializeNodeData(Node, 'TSpeedButton');
  TSpeedButton(CreateNodeControl(VirtualStringTree1, Node, TSpeedButton)).Caption := '+';

  Node := VirtualStringTree1.AddChild(nil);
  InitializeNodeData(Node, '[TEdit Parent]');
  Node := VirtualStringTree1.AddChild(Node);
  InitializeNodeData(Node, 'TEdit');
  TEdit(CreateNodeControl(VirtualStringTree1, Node, TEdit)).Text := 'Hello';

  Node := VirtualStringTree1.AddChild(nil);
  InitializeNodeData(Node, '[TMyPanel Parent]');
  Node := VirtualStringTree1.AddChild(Node);
  InitializeNodeData(Node, 'TMyPanel');
  MyPanel := TMyPanel(CreateNodeControl(VirtualStringTree1, Node, TMyPanel));
  with MyPanel do
  begin
    Caption := 'TMyPanel';
    ParentBackground := False;
    CheckBox := TCheckBox.Create(nil);
    CheckBox.Caption := 'CheckBox';
    CheckBox.Left := 10;
    CheckBox.Top := 10;
    CheckBox.Parent := MyPanel;
  end;

  for I := 6 to 10 do begin
    Node := VirtualStringTree1.AddChild(nil);
    InitializeNodeData(Node, Format('%d', [I]));
    Node := VirtualStringTree1.AddChild(Node);
    InitializeNodeData(Node, Format('%d.1', [I]));
  end;
end;

procedure TForm1.VirtualStringTree1GetText(Sender: TBaseVirtualTree;
  Node: PVirtualNode; Column: TColumnIndex; TextType: TVSTTextType;
  var CellText: WideString);
var
  NodeData: PNodeData;
begin
  NodeData := Sender.GetNodeData(Node);
  if Assigned(NodeData) then
    CellText := NodeData.Text;
end;

procedure TForm1.SetNodeControlVisible(Tree: TBaseVirtualTree; Node: PVirtualNode; Column: TColumnIndex = NoColumn);
var
  NodeData: PNodeData;
  R: TRect;
begin
  NodeData := Tree.GetNodeData(Node);
  if Assigned(NodeData) and Assigned(NodeData.Control) then
  begin
    with NodeData.Control do
    begin
      Visible := IsNodeVisibleInClientRect(Tree, Node, Column)
                 and ((Node.Parent = Tree.RootNode) or (vsExpanded in Node.Parent.States));
      R := Tree.GetDisplayRect(Node, Column, False);
      BoundsRect := R;
    end;
  end;
end;

procedure TForm1.SetNodesControlVisibleProc(Sender: TBaseVirtualTree; Node: PVirtualNode; Data: Pointer; var Abort: Boolean);
begin
  SetNodeControlVisible(Sender, Node);
end;

procedure TForm1.VirtualStringTree1AfterPaint(Sender: TBaseVirtualTree;
  TargetCanvas: TCanvas);
begin
  // Iterate all Tree nodes and set visibility
  Sender.IterateSubtree(nil, SetNodesControlVisibleProc, nil);
end;

procedure TForm1.VirtualStringTree1MeasureItem(Sender: TBaseVirtualTree;
  TargetCanvas: TCanvas; Node: PVirtualNode; var NodeHeight: Integer);
var
  NodeData: PNodeData;
begin
  NodeData := Sender.GetNodeData(Node);
  if Assigned(NodeData) and Assigned(NodeData.Control) then
  // set node special height if control is TMyPanel
    if NodeData.Control is TMyPanel then
      NodeHeight := 50;
end;

end.

<强> DFM：

object Form1: TForm1
  Left = 192
  Top = 124
  Width = 782
  Height = 365
  Caption = 'Form1'
  Color = clBtnFace
  Font.Charset = DEFAULT_CHARSET
  Font.Color = clWindowText
  Font.Height = -11
  Font.Style = []
  OldCreateOrder = False
  OnCreate = FormCreate
  DesignSize = (
    766
    327)
  PixelsPerInch = 96
  TextHeight = 13
  object VirtualStringTree1: TVirtualStringTree
    Left = 8
    Top = 8
    Width = 450
    Height = 277
    Anchors = [akLeft, akTop, akRight, akBottom]
    Header.AutoSizeIndex = 0
    Header.Font.Charset = DEFAULT_CHARSET
    Header.Font.Color = clWindowText
    Header.Font.Height = -11
    Header.Font.Name = 'MS Sans Serif'
    Header.Font.Style = []
    Header.MainColumn = -1
    TabOrder = 0
    OnAfterPaint = VirtualStringTree1AfterPaint
    OnGetText = VirtualStringTree1GetText
    OnMeasureItem = VirtualStringTree1MeasureItem
    Columns = <>
  end
end

<强> 输出：

使用Delphi 7，VT版本5.3.0，Windows 7进行测试

Answer 2

所以iamjoosy的答案问题是 - 即使它有效 - 只要你用绘制的按钮/ images /滚动滚动这个树，那些应该再次离开树的那个仍然是现有的，被绘制在你离开它们的最低/最高位置。根据您刚刚滚动的数量，它会在该列中留下更小或更大的按钮杂乱。 AfterCellPaint不再移动它们，因为现在隐藏在底部/顶部上方的隐藏节点的单元格不再被绘制。

你可以做的是遍历所有树节点（如果有很多节点，可能非常昂贵）并检查它们是否实际位于树的可见区域并隐藏面板（您可能需要在面板内部按钮）相应地用你的按钮/ whatevers画在树顶而不是后面：

procedure TMyTree.MyTreeAfterCellPaint(Sender: TBaseVirtualTree;
  TargetCanvas: TCanvas; Node: PVirtualNode; Column: TColumnIndex;
  CellRect: TRect);
var
  InitialIndex: Integer;
// onInitNode I AddOrSetValue a "DataIndexList" TDictionary<PVirtualNode, LongInt>
// to preserve an original index "InitialIndex" (violating the virtual paradigm),
// because I need it for something else anyways
  Data: PMyData;
  ANode: PVirtualNode;
begin
  if Node <> nil then
  begin
    if Column = 2 then
    begin
      ANode := MyTree.GetFirst;
      while Assigned(ANode) do
      begin
        DataIndexList.TryGetValue(ANode, InitialIndex);
        if not ( CheckVisibility(Sender.GetDisplayRect(ANode, Column, False)) ) then
        begin
          MyBtnArray[InitialIndex].Visible := False;
          MyPanelArray[InitialIndex].Visible := False;
        end
        else
        begin
          MyBtnArray[InitialIndex].Visible := True;
          MyPanelArray[InitialIndex].Visible := True;
        end;
        ANode := MyTree.GetNext(ANode);
      end;
      DataIndexList.TryGetValue(Node, InitialIndex);
      Data := MyTree.GetNodeData(Node);
      MyPanelArray[InitialIndex].BoundsRect := Sender.GetDisplayRect(Node, Column, False);
    end;
  end;
end;

function TMyTree.CheckVisibility(R: TRect): Boolean;
begin
// in my case these checks are the way to go, because
// MyTree is touching the top border of the TForm.  You will have
// to adjust accordingly if your placement is different
  if (R.Bottom < MyTree.Top) or (R.Bottom > MyTree.Top + MyTree.Height) then
    Result := False
  else
    Result := True;
end;

毋庸置疑，您可以成功地在其他许多OnEvents中使用visibilityCheck进行遍历。它不一定要在AfterCellPaint中;也许另一个事件可能是更好的表现明智。

要创建一个原始Panel + Button的RunTime副本，放置在ButtonArray或您正在使用的任何结构中，您还必须复制他们的RTTI。此过程取自http://www.blong.com/Conferences/BorConUK98/DelphiRTTI/CB140.zip（http://www.blong.com/Conferences/BorConUK98/DelphiRTTI/CB140.htm处的进一步RTTI信息）和＆＃34;使用TypInfo＆＃34;：

procedure CopyObject(ObjFrom, ObjTo: TObject);
var
  PropInfos: PPropList;
  PropInfo: PPropInfo;
  Count, Loop: Integer;
  OrdVal: Longint;
  StrVal: String;
  FloatVal: Extended;
  MethodVal: TMethod;
begin
  { Iterate thru all published fields and properties of source }
  { copying them to target }

  { Find out how many properties we'll be considering }
  Count := GetPropList(ObjFrom.ClassInfo, tkAny, nil);
  { Allocate memory to hold their RTTI data }
  GetMem(PropInfos, Count * SizeOf(PPropInfo));
  try
    { Get hold of the property list in our new buffer }
    GetPropList(ObjFrom.ClassInfo, tkAny, PropInfos);
    { Loop through all the selected properties }
    for Loop := 0 to Count - 1 do
    begin
      PropInfo := GetPropInfo(ObjTo.ClassInfo, PropInfos^[Loop]^.Name);
      { Check the general type of the property }
      { and read/write it in an appropriate way }
      case PropInfos^[Loop]^.PropType^.Kind of
        tkInteger, tkChar, tkEnumeration,
        tkSet, tkClass{$ifdef Win32}, tkWChar{$endif}:
        begin
          OrdVal := GetOrdProp(ObjFrom, PropInfos^[Loop]);
          if Assigned(PropInfo) then
            SetOrdProp(ObjTo, PropInfo, OrdVal);
        end;
        tkFloat:
        begin
          FloatVal := GetFloatProp(ObjFrom, PropInfos^[Loop]);
          if Assigned(PropInfo) then
            SetFloatProp(ObjTo, PropInfo, FloatVal);
        end;
        {$ifndef DelphiLessThan3}
        tkWString,
        {$endif}
        {$ifdef Win32}
        tkLString,
        {$endif}
        tkString:
        begin
          { Avoid copying 'Name' - components must have unique names }
          if UpperCase(PropInfos^[Loop]^.Name) = 'NAME' then
            Continue;
          StrVal := GetStrProp(ObjFrom, PropInfos^[Loop]);
          if Assigned(PropInfo) then
            SetStrProp(ObjTo, PropInfo, StrVal);
        end;
        tkMethod:
        begin
          MethodVal := GetMethodProp(ObjFrom, PropInfos^[Loop]);
          if Assigned(PropInfo) then
            SetMethodProp(ObjTo, PropInfo, MethodVal);
        end
      end
    end
  finally
    FreeMem(PropInfos, Count * SizeOf(PPropInfo));
  end;
end;

稍后看到我的这个旧答案，我现在有一个不同的解决方案运行VisibilityCheck，这更可靠，更容易：

function TFoo.IsNodeVisibleInClientRect(Node: PVirtualNode; Column: TColumnIndex = NoColumn): Boolean;
begin
  Result := VST.IsVisible[Node] and
    VST.GetDisplayRect(Node, Column, False).IntersectsWith(VST.ClientRect);
end;

Answer 3

OnAfterCellPaint事件处理程序中CellRect参数的坐标是相对于绘制的节点。你需要的是树窗口中节点的absoulte位置。您可以通过调用树的GetDisplayRect来获取它。所以改变你的代码：

procedure TForm1.VirtualStringTree1AfterCellPaint(Sender: TBaseVirtualTree; TargetCanvas: TCanvas; Node: PVirtualNode; Column: TColumnIndex; CellRect: TRect);
var
  NodeData: PNodeData;
  R: TRect;
begin
  if (Column = 0) then
    Exit;
  NodeData := VirtualStringTree1.GetNodeData(Node);
  if (Assigned(NodeData)) and (Assigned(NodeData.Button)) then
  begin
    with NodeData.Button Do
    begin
      Visible := (vsVisible in Node.States)
                 and ((Node.Parent = VirtualStringTree1.RootNode) or (vsExpanded in Node.Parent.States));
      R := Sender.GetDisplayRect(Node, Column, False);
      BoundsRect := R;
    end;
  end;
end;

单元格中的VirtualTreeView嵌入按钮

3 个答案: