delphi - 是否可以使用 VirtualStringTree 作为主细节 GridView ？

Question

好吧，我这里遇到了一些非常棘手的事情......我想将 header 绘制/使用到子节点。我认为这个想法是合理的，因为在子节点中包含标题看起来会很神奇，因此可以在表中指定子节点。VST 有什么功能或者根本不可能吗？

感谢您的帮助。

Answer 1

1。有没有办法将 VirtualTreeView 用于主/详细 GridView ？

不，目前没有这样的功能，恕我直言，也不会，因为这将涉及对现有代码的很大的干预。

2。如何为子节点详细信息 GridView 创建功能齐全的标题？

考虑到几种方法，如何模拟子节点的标题外观和行为，我发现使用嵌套 TreeView 作为详细 GridView 很有用。这为您带来了详细数据的分离性，并允许您最小化将嵌套 TreeView 定位到子节点矩形中的整个模拟。

2.1。启动项目

在下面的项目中，我试图展示实现如此简单的任务(例如在子节点内定位控件)可能有多复杂(不涉及原始 VirtualTree 代码)。仅将其视为启动项目，而不是最终解决方案。

2.2。已知问题和限制:

• 此项目的编写和测试是为了每个根节点仅使用一个子节点，因此当您超过此限制时，请不要对这种行为感到惊讶，因为这不是设计的，甚至没有经过测试
• 当双击主树的列大小调整动画列大小调整时，当 ScrollDC 函数滚动 Canvas 时，嵌套 TreeView 会被线条 overdraw
• 为了保留 VirtualTree 代码而不更改，我重写了滚动条更新的方法。它用于在需要更新滚动条时更新嵌套 TreeView 边界
• 当前的OnExpanded实现在范围和滚动位置固定之前触发事件，这使得代码更加复杂并且有一个很大的弱点 - 详细 TreeView 的边界在树被更新后更新显示，有时可以看到

2.3。项目代码

它是在 Delphi 2009 中编写并测试的，可在 Delphi 7 中使用。对于下一个代码的注释版本 follow this link :

Unit1.pas

unit Unit1;

interface

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

type
  TVTScrollBarsUpdateEvent = procedure(Sender: TBaseVirtualTree; DoRepaint: Boolean) of object;
  TVirtualStringTree = class(VirtualTrees.TVirtualStringTree)
  private
    FOnUpdateScrollBars: TVTScrollBarsUpdateEvent;
  public
    procedure UpdateScrollBars(DoRepaint: Boolean); override;
  published
    property OnUpdateScrollBars: TVTScrollBarsUpdateEvent read FOnUpdateScrollBars write FOnUpdateScrollBars;
  end;

type
  PNodeSubTree = ^TNodeSubTree;
  TNodeSubTree = class
    FChildTree: TVirtualStringTree;
  end;

type
  TForm1 = class(TForm)
    Button1: TButton;
    VirtualStringTree1: TVirtualStringTree;
    procedure FormCreate(Sender: TObject);
    procedure Button1Click(Sender: TObject);
    procedure VirtualStringTree1AfterAutoFitColumns(Sender: TVTHeader);
    procedure VirtualStringTree1BeforeDrawTreeLine(Sender: TBaseVirtualTree;
      Node: PVirtualNode; Level: Integer; var PosX: Integer);
    procedure VirtualStringTree1Collapsed(Sender: TBaseVirtualTree;
      Node: PVirtualNode);
    procedure VirtualStringTree1ColumnResize(Sender: TVTHeader;
      Column: TColumnIndex);
    procedure VirtualStringTree1Expanded(Sender: TBaseVirtualTree;
      Node: PVirtualNode);
    procedure VirtualStringTree1FocusChanging(Sender: TBaseVirtualTree; OldNode,
      NewNode: PVirtualNode; OldColumn, NewColumn: TColumnIndex;
      var Allowed: Boolean);
    procedure VirtualStringTree1FreeNode(Sender: TBaseVirtualTree;
      Node: PVirtualNode);
    procedure VirtualStringTree1MeasureItem(Sender: TBaseVirtualTree;
      TargetCanvas: TCanvas; Node: PVirtualNode; var NodeHeight: Integer);
  private
    procedure InvalidateSubTrees(Tree: TBaseVirtualTree);
    procedure ResizeSubTrees(Tree: TBaseVirtualTree);
    procedure UpdateSubTreeBounds(Tree: TBaseVirtualTree; Node: PVirtualNode);
    procedure OnUpdateScrollBars(Sender: TBaseVirtualTree; DoRepaint: Boolean);
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

{ TVirtualStringTree }

procedure TVirtualStringTree.UpdateScrollBars(DoRepaint: Boolean);
begin
  inherited;
  if HandleAllocated and Assigned(FOnUpdateScrollBars) then
    FOnUpdateScrollBars(Self, DoRepaint);
end;

{ TForm1 }

procedure TForm1.FormCreate(Sender: TObject);
begin
  ReportMemoryLeaksOnShutdown := True;
  VirtualStringTree1.NodeDataSize := SizeOf(TNodeSubTree);
  VirtualStringTree1.OnUpdateScrollBars := OnUpdateScrollBars;
end;

procedure TForm1.Button1Click(Sender: TObject);
var
  Data: PNodeSubTree;
  Node: PVirtualNode;
begin
  Node := VirtualStringTree1.AddChild(nil);
  Node := VirtualStringTree1.AddChild(Node);
  VirtualStringTree1.InitNode(Node);
  Data := VirtualStringTree1.GetNodeData(Node);
  Data^ := TNodeSubTree.Create;
  Data^.FChildTree := TVirtualStringTree.Create(nil);
  with Data.FChildTree do
  begin
    Visible := False;
    Parent := VirtualStringTree1;
    Height := 150;
    DefaultNodeHeight := 21;
    Header.AutoSizeIndex := 0;
    Header.Font.Charset := DEFAULT_CHARSET;
    Header.Font.Color := clWindowText;
    Header.Font.Height := -11;
    Header.Font.Name := 'Tahoma';
    Header.Font.Style := [];
    Header.Height := 21;
    Header.Options := [hoColumnResize, hoDrag, hoShowSortGlyphs, hoVisible];
    TabStop := False;
    with Header.Columns.Add do
    begin
      Width := 100;
      Text := 'Header item 1';
    end;
    with Header.Columns.Add do
    begin
      Width := 100;
      Text := 'Header item 2';
    end;
  end;
end;

procedure TForm1.VirtualStringTree1AfterAutoFitColumns(Sender: TVTHeader);
begin
  InvalidateSubTrees(Sender.Treeview);
end;

procedure TForm1.VirtualStringTree1BeforeDrawTreeLine(Sender: TBaseVirtualTree;
  Node: PVirtualNode; Level: Integer; var PosX: Integer);
begin
  if Level = 1 then
    PosX := 0;
end;

procedure TForm1.VirtualStringTree1Collapsed(Sender: TBaseVirtualTree;
  Node: PVirtualNode);
var
  Data: PNodeSubTree;
begin
  Data := VirtualStringTree1.GetNodeData(Node.FirstChild);
  if Assigned(Data^) and Assigned(Data^.FChildTree) then
    Data^.FChildTree.Visible := False;
end;

procedure TForm1.VirtualStringTree1ColumnResize(Sender: TVTHeader;
  Column: TColumnIndex);
begin
  ResizeSubTrees(Sender.Treeview);
end;

procedure TForm1.VirtualStringTree1Expanded(Sender: TBaseVirtualTree;
  Node: PVirtualNode);
var
  Data: PNodeSubTree;
begin
  Data := VirtualStringTree1.GetNodeData(Node.FirstChild);
  if Assigned(Data^) and Assigned(Data^.FChildTree) then
    Data^.FChildTree.Visible := True;
end;

procedure TForm1.VirtualStringTree1FocusChanging(Sender: TBaseVirtualTree;
  OldNode, NewNode: PVirtualNode; OldColumn, NewColumn: TColumnIndex;
  var Allowed: Boolean);
begin
  if Sender.GetNodeLevel(NewNode) = 1 then
  begin
    Allowed := False;
    if Sender.AbsoluteIndex(OldNode) > Sender.AbsoluteIndex(NewNode) then
      Sender.FocusedNode := Sender.GetPreviousSibling(OldNode)
    else
    if OldNode <> Sender.GetLastChild(nil) then
      Sender.FocusedNode := Sender.GetNextSibling(OldNode)
    else
      Sender.FocusedNode := OldNode;
  end;
end;

procedure TForm1.VirtualStringTree1FreeNode(Sender: TBaseVirtualTree;
  Node: PVirtualNode);
var
  Data: PNodeSubTree;
begin
  Data := VirtualStringTree1.GetNodeData(Node);
  if Assigned(Data^) then
  begin
    if Assigned(Data^.FChildTree) then
      Data^.FChildTree.Free;
    Data^.Free;
  end;
end;

procedure TForm1.VirtualStringTree1MeasureItem(Sender: TBaseVirtualTree;
  TargetCanvas: TCanvas; Node: PVirtualNode; var NodeHeight: Integer);
var
  Data: PNodeSubTree;
begin
  if VirtualStringTree1.GetNodeLevel(Node) = 1 then
  begin
    Data := VirtualStringTree1.GetNodeData(Node);
    if Assigned(Data^) and Assigned(Data^.FChildTree) then
      NodeHeight := Data^.FChildTree.Height + 8;
  end;
end;

procedure TForm1.InvalidateSubTrees(Tree: TBaseVirtualTree);
var
  Data: PNodeSubTree;
  Node: PVirtualNode;
begin
  Node := Tree.GetFirst;
  while Assigned(Node) do
  begin
    if Tree.HasChildren[Node] then
    begin
      Data := Tree.GetNodeData(Node.FirstChild);
      if Assigned(Data^) and Assigned(Data^.FChildTree) then
      begin
        Data^.FChildTree.Header.Invalidate(nil);
        Data^.FChildTree.Invalidate;
      end;
    end;
    Node := Tree.GetNextSibling(Node);
  end;
end;

procedure TForm1.ResizeSubTrees(Tree: TBaseVirtualTree);
var
  Node: PVirtualNode;
begin
  Node := Tree.GetFirst;
  while Assigned(Node) do
  begin
    if Tree.HasChildren[Node] then
      UpdateSubTreeBounds(Tree, Node.FirstChild);
    Node := Tree.GetNextSibling(Node);
  end;
end;

procedure TForm1.UpdateSubTreeBounds(Tree: TBaseVirtualTree; Node: PVirtualNode);
var
  R: TRect;
  Data: PNodeSubTree;
begin
  if Assigned(Node) then
  begin
    Data := Tree.GetNodeData(Node);
    if Assigned(Data^) and Assigned(Data^.FChildTree) and
      Data^.FChildTree.Visible then
    begin
      R := Tree.GetDisplayRect(Node, -1, False, True);
      R.Left := R.Left + (Tree as TVirtualStringTree).Indent;
      R.Top := R.Top + 4;
      R.Right := R.Right - 8;
      R.Bottom := R.Bottom - 4;
      Data^.FChildTree.BoundsRect := R;
    end;
  end;
end;

procedure TForm1.OnUpdateScrollBars(Sender: TBaseVirtualTree; DoRepaint: Boolean);
begin
  ResizeSubTrees(Sender);
end;

end.

Unit1.dfm

object Form1: TForm1
  Left = 0
  Top = 0
  Caption = 'Form1'
  ClientHeight = 282
  ClientWidth = 468
  Color = clBtnFace
  Font.Charset = DEFAULT_CHARSET
  Font.Color = clWindowText
  Font.Height = -11
  Font.Name = 'Tahoma'
  Font.Style = []
  OldCreateOrder = False
  OnCreate = FormCreate
  DesignSize = (
    468
    282)
  PixelsPerInch = 96
  TextHeight = 13
  object VirtualStringTree1: TVirtualStringTree
    Left = 8
    Top = 8
    Width = 371
    Height = 266
    Anchors = [akLeft, akTop, akRight, akBottom]
    Header.AutoSizeIndex = 0
    Header.Font.Charset = DEFAULT_CHARSET
    Header.Font.Color = clWindowText
    Header.Font.Height = -11
    Header.Font.Name = 'Tahoma'
    Header.Font.Style = []
    Header.Height = 21
    Header.Options = [hoColumnResize, hoDblClickResize, hoDrag, hoShowSortGlyphs, hoVisible]
    TabOrder = 0
    TreeOptions.MiscOptions = [toVariableNodeHeight]
    OnAfterAutoFitColumns = VirtualStringTree1AfterAutoFitColumns
    OnBeforeDrawTreeLine = VirtualStringTree1BeforeDrawTreeLine
    OnCollapsed = VirtualStringTree1Collapsed
    OnColumnResize = VirtualStringTree1ColumnResize
    OnExpanded = VirtualStringTree1Expanded
    OnFocusChanging = VirtualStringTree1FocusChanging
    OnFreeNode = VirtualStringTree1FreeNode
    OnMeasureItem = VirtualStringTree1MeasureItem
    ExplicitWidth = 581
    ExplicitHeight = 326
    Columns = <
      item
        Position = 0
        Width = 75
        WideText = 'Column 1'
      end
      item
        Position = 1
        Width = 75
        WideText = 'Column 2'
      end
      item
        Position = 2
        Width = 75
        WideText = 'Column 3'
      end>
  end
  object Button1: TButton
    Left = 385
    Top = 8
    Width = 75
    Height = 25
    Anchors = [akTop, akRight]
    Caption = 'Button1'
    TabOrder = 1
    OnClick = Button1Click
    ExplicitLeft = 595
  end
end

2.4。截图