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unit VisibilityDemo;
{$MODE Delphi}
{$H+}
// Virtual Treeview sample form demonstrating following features:
// - Hiding nodes.
// - Synchronization between 2 trees (expand, scroll, selection).
// - Wheel scrolling and panning.
// Written by Mike Lischke.
interface
uses
LCLIntf, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
StdCtrls, Laz.VirtualTrees, ExtCtrls, LResources;
type
TVisibilityForm = class(TForm)
Label17: TLabel;
RadioGroup1: TRadioGroup;
VST2: TLazVirtualStringTree;
VST1: TLazVirtualStringTree;
VST3: TLazVirtualStringTree;
Splitter2: TSplitter;
Panel2: TPanel;
Label1: TLabel;
Label2: TLabel;
Label3: TLabel;
Label4: TLabel;
procedure VST1InitChildren(Sender: TBaseVirtualTree; Node: PVirtualNode; var ChildCount: Cardinal);
procedure VST1InitNode(Sender: TBaseVirtualTree; ParentNode, Node: PVirtualNode;
var InitialStates: TVirtualNodeInitStates);
procedure FormCreate(Sender: TObject);
procedure RadioGroup1Click(Sender: TObject);
procedure VST2GetText(Sender: TBaseVirtualTree; Node: PVirtualNode; Column: TColumnIndex; TextType: TVSTTextType;
var CellText: String);
procedure VST3Scroll(Sender: TBaseVirtualTree; DeltaX, DeltaY: Integer);
procedure VST2InitChildren(Sender: TBaseVirtualTree; Node: PVirtualNode; var ChildCount: Cardinal);
procedure VST2Scroll(Sender: TBaseVirtualTree; DeltaX, DeltaY: Integer);
procedure VSTCollapsedExpanded(Sender: TBaseVirtualTree; Node: PVirtualNode);
procedure VST2Change(Sender: TBaseVirtualTree; Node: PVirtualNode);
procedure Splitter2CanResize(Sender: TObject; var NewSize: Integer;
var Accept: Boolean);
procedure Splitter2Paint(Sender: TObject);
procedure VST1GetText(Sender: TBaseVirtualTree; Node: PVirtualNode; Column: TColumnIndex; TextType: TVSTTextType;
var CellText: String);
procedure FormShow(Sender: TObject);
procedure FormHide(Sender: TObject);
private
FChanging: Boolean;
procedure HideNodes(Sender: TBaseVirtualTree; Node: PVirtualNode; Data: Pointer; var Abort: Boolean);
end;
var
VisibilityForm: TVisibilityForm;
//----------------------------------------------------------------------------------------------------------------------
implementation
{$R *.lfm}
uses States;
type
PLinkData = ^TLinkData;
TLinkData = record
Caption: String;
OtherNode: PVirtualNode;
end;
//----------------------------------------------------------------------------------------------------------------------
procedure TVisibilityForm.VST1InitNode(Sender: TBaseVirtualTree; ParentNode, Node: PVirtualNode;
var InitialStates: TVirtualNodeInitStates);
var
Level: Integer;
begin
Level := Sender.GetNodeLevel(Node);
if Level < 4 then
Include(InitialStates, ivsHasChildren);
if Level > 0 then
Node.CheckType := TCheckType(Level)
else
Node.CheckType := ctTriStateCheckBox;
end;
//----------------------------------------------------------------------------------------------------------------------
procedure TVisibilityForm.VST1InitChildren(Sender: TBaseVirtualTree; Node: PVirtualNode; var ChildCount: Cardinal);
begin
ChildCount := Random(5);
end;
//----------------------------------------------------------------------------------------------------------------------
procedure TVisibilityForm.FormCreate(Sender: TObject);
var
Run1, Run2: PVirtualNode;
Data1, Data2: PLinkData;
begin
Randomize;
VST1.RootNodeCount := 5;
// The base idea behind linking two (or more) trees together is that one has access to the nodes of the others.
// This can be reached in several ways. I use here the simplest approach by validating both trees fully and creating
// cross references for all nodes. Another one would be to create a common data base and link all trees to this.
VST2.NodeDataSize := SizeOf(TLinkData);
VST2.RootNodeCount := 5;
VST3.NodeDataSize := SizeOf(TLinkData);
VST3.RootNodeCount := 5;
VST3.BackgroundOffsetX := Splitter2.Left + Splitter2.Width;
// Create cross references. This will validate all nodes.
Run1 := VST2.GetFirst;
Run2 := VST3.GetFirst;
while Assigned(Run1) do
begin
Data1 := VST2.GetNodeData(Run1);
Data1.OtherNode := Run2;
Data2 := VST3.GetNodeData(Run2);
Data2.OtherNode := Run1;
Run1 := VST2.GetNext(Run1);
Run2 := VST3.GetNext(Run2);
end;
end;
//----------------------------------------------------------------------------------------------------------------------
procedure TVisibilityForm.HideNodes(Sender: TBaseVirtualTree; Node: PVirtualNode; Data: Pointer; var Abort: Boolean);
begin
case PtrUInt(Data) of
0: // show all nodes
Sender.IsVisible[Node] := True;
1: // hide every second
Sender.IsVisible[Node] := not Odd(Node.Index);
2: // hide nodes with child nodes only
Sender.IsVisible[Node] := not Sender.HasChildren[Node];
3: // hide all
Sender.IsVisible[Node] := False;
end;
end;
//----------------------------------------------------------------------------------------------------------------------
procedure TVisibilityForm.RadioGroup1Click(Sender: TObject);
begin
with Sender as TRadioGroup do
begin
VST1.BeginUpdate;
try
VST1.IterateSubtree(nil, HideNodes, Pointer(ItemIndex), [], True);
finally
VST1.EndUpdate;
end;
end;
end;
//----------------------------------------------------------------------------------------------------------------------
procedure TVisibilityForm.VST2GetText(Sender: TBaseVirtualTree; Node: PVirtualNode; Column: TColumnIndex;
TextType: TVSTTextType; var CellText: String);
var
Data: PLinkData;
begin
Data := Sender.GetNodeData(Node);
if Length(Data.Caption) = 0 then
Data.Caption := 'Node ' + IntToStr(Sender.AbsoluteIndex(Node));
CellText := Data.Caption;
end;
//----------------------------------------------------------------------------------------------------------------------
procedure TVisibilityForm.VST3Scroll(Sender: TBaseVirtualTree; DeltaX, DeltaY: Integer);
// Synchronizes scroll offsets of VST2 and VST3.
begin
if not FChanging then
begin
FChanging := True;
try
VST3.Update;
VST2.OffsetY := VST3.OffsetY;
VST2.Update;
finally
FChanging := False;
end;
end;
end;
//----------------------------------------------------------------------------------------------------------------------
procedure TVisibilityForm.VST2Scroll(Sender: TBaseVirtualTree; DeltaX, DeltaY: Integer);
// Synchronizes scroll offsets of VST2 and VST3.
begin
if not FChanging then
begin
FChanging := True;
try
VST2.Update;
VST3.OffsetY := VST2.OffsetY;
VST3.Update;
finally
FChanging := False;
end;
end;
end;
//----------------------------------------------------------------------------------------------------------------------
procedure TVisibilityForm.VST2InitChildren(Sender: TBaseVirtualTree; Node: PVirtualNode; var ChildCount: Cardinal);
begin
ChildCount := Sender.GetNodeLevel(Node) + 2;
end;
//----------------------------------------------------------------------------------------------------------------------
procedure TVisibilityForm.VSTCollapsedExpanded(Sender: TBaseVirtualTree; Node: PVirtualNode);
// Collapse/Expand state synchronization.
var
OtherTree: TBaseVirtualTree;
Data: PLinkData;
begin
// Avoid recursive calls.
if not FChanging then
begin
FChanging := True;
try
if Sender = VST2 then
OtherTree := VST3
else
OtherTree := VST2;
Data := Sender.GetNodeData(Node);
OtherTree.ToggleNode(Data.OtherNode);
finally
FChanging := False;
end;
end;
end;
//----------------------------------------------------------------------------------------------------------------------
procedure TVisibilityForm.VST2Change(Sender: TBaseVirtualTree; Node: PVirtualNode);
// Keep selected nodes in sync.
var
Data: PLinkData;
OtherTree: TBaseVirtualTree;
begin
if not FChanging and Assigned(Node) then
begin
FChanging := True;
try
Data := Sender.GetNodeData(Node);
if Sender = VST2 then
OtherTree := VST3
else
OtherTree := VST2;
OtherTree.Selected[Data.OtherNode] := True;
OtherTree.FocusedNode := Data.OtherNode;
finally
FChanging := False;
end;
end;
end;
//----------------------------------------------------------------------------------------------------------------------
procedure TVisibilityForm.Splitter2CanResize(Sender: TObject; var NewSize: Integer; var Accept: Boolean);
// This method is called just before resizing is done. This is a good opportunity to adjust the background image
// offset.
begin
VST3.BackgroundOffsetX := NewSize + Splitter2.Width;
end;
//----------------------------------------------------------------------------------------------------------------------
procedure TVisibilityForm.Splitter2Paint(Sender: TObject);
begin
with Splitter2, Canvas do
begin
Brush.Color := clBtnFace;
FillRect(Rect(0, 0, Width, VST2.Header.Height));
Brush.Color := clWindow;
FillRect(Rect(0, VST2.Header.Height, Width, Height));
end;
end;
//----------------------------------------------------------------------------------------------------------------------
procedure TVisibilityForm.VST1GetText(Sender: TBaseVirtualTree; Node: PVirtualNode; Column: TColumnIndex;
TextType: TVSTTextType; var CellText: String);
begin
CellText := Format('Node Level %d, Index %d', [Sender.GetNodeLevel(Node), Node.Index]);
end;
//----------------------------------------------------------------------------------------------------------------------
procedure TVisibilityForm.FormShow(Sender: TObject);
begin
StateForm.Hide;
end;
//----------------------------------------------------------------------------------------------------------------------
procedure TVisibilityForm.FormHide(Sender: TObject);
begin
StateForm.Show;
end;
//----------------------------------------------------------------------------------------------------------------------
end.
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