好吧,我在这里遇到了一些非常棘手的事情......我想将标题绘制/使用到 ChildNode。我认为这个想法是合理的,因为在子节点中有标题看起来很神奇,因此可以在表中指定子节点。VST 是否具有或根本不可能的功能?
谢谢你的帮助。
好吧,我在这里遇到了一些非常棘手的事情......我想将标题绘制/使用到 ChildNode。我认为这个想法是合理的,因为在子节点中有标题看起来很神奇,因此可以在表中指定子节点。VST 是否具有或根本不可能的功能?
谢谢你的帮助。
1. 有没有办法将 VirtualTreeView 用于主/详细网格视图?
不,目前没有这样的功能可用,恕我直言,因为这将涉及对现有代码的非常大的干预。
2.如何为子节点详细网格视图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将嵌套树视图用于详细网格视图很有用。这为您带来了详细数据的分离性,并允许您将整个模拟最小化到将嵌套树视图定位到子节点的矩形中。
2.1。启动项目
在下面的项目中,我试图展示实现这样一个简单的任务是多么复杂,比如在子节点内定位控件可能是(不涉及原始的 VirtualTree 代码)。把它当作一个启动项目,而不是最终的解决方案。
2.2. 已知问题和限制:
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 - 详细树视图的边界在树显示后更新,有时可以看到2.3. 项目代码
它是在 Delphi 2009 中针对在 Delphi 7 中使用而编写和测试的。对于下一个代码的注释版本follow this link
:
单元1.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.
单元1.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. 截屏