Delphi类和组件 - TreeView 智能拖拽

属性：
TreeView：需要实现拖拽功能的 TreeView，当把一个 TreeView
指定给该属性后，这个 TreeView 的节点就具有智能拖拽功能了。
DragMode = dmHotKeyDrag // 通过快捷键才能拖拽
HotKeyMoveNode = hkCtrl; // 拖拽节点： Ctrl
HotKeyCopyNode = hkShift; // 拖拽并复制节点：Shift
HotKeyChildNode = hkAlt; // 拖拽到子节点：Alt
EnableRButtonDrag = True; // 允许右键拖拽，会弹出菜单

Public 方法：
AddNode：添加节点，根据 AddMode 决定添加的位置
DeleteNode：删除节点，返回被删除节点临近的节点
MoveNode：移动或复制节点，根据 MoveMode 决定移动方式

******************************************************* }

unit TreeViewManage;

interface

uses
SysUtils, Windows, Classes, Controls, ComCtrls, Menus;

type
TAttachMode = (amLast, amFirst, amChildLast, amChildFirst, amPrev,
amNext, amAuto);

{ 控制拖拽方式的热键：禁止，Ctrl，Shift，Alt }
THotKey = (hkNone, hkCtrl, hkShift, hkAlt);

{ 节点拖动方式：自动拖拽，热键拖拽，禁止拖拽 }
TDragMode = (dmAutoDrag, dmHotKeyDrag, dmDisableDrag);

TTreeViewDrager = class(TComponent)
private
    FTreeView: TTreeView;
    FOldOnMouseDown: TMouseEvent;
    FOldOnMouseUp: TMouseEvent;
    FOldOnDragOver: TDragOverEvent;
    FOldOnDragDrop: TDragDropEvent;

    FDragMode: TDragMode; { 节点拖动方式 }
    FDragButton: TMouseButton; { 拖动节点的按钮 }
    FDropMenu: TPopupMenu; { 右键拖拽后的弹出菜单 }
    FMoveSourceNode: TTreeNode; { 移动的源节点 }
    FMoveTargetNode: TTreeNode; { 移动的目标节点 }
    FHotKeyMoveNode: Integer; { 拖动节点的热键 }
    FHotKeyCopyNode: Integer; { 复制节点的热键 }
    FHotKeyChildNode: Integer; { 拖动到子节点的热键 }
    FEnableRButtonDrag: Boolean; { 是否允许右键拖拽，右键拖拽会弹出菜单 }

    function GetTreeView: TCustomTreeView;
    procedure SetTreeView(Value: TCustomTreeView);
    function GetHotKeyMoveNode: THotKey;
    procedure SetHotKeyMoveNode(Key: THotKey);
    function GetHotKeyCopyNode: THotKey;
    procedure SetHotKeyCopyNode(Key: THotKey);
    function GetHotKeyChildNode: THotKey;
    procedure SetHotKeyChildNode(Key: THotKey);

    procedure MouseDown(Sender: TObject; Button: TMouseButton;
      Shift: TShiftState; X, Y: Integer);
    procedure MouseUp(Sender: TObject; Button: TMouseButton; Shift: TShiftState;
      X, Y: Integer);
    procedure DragOver(Sender, Source: TObject; X, Y: Integer;
      State: TDragState; var Accept: Boolean);
    procedure DragDrop(Sender, Source: TObject; X, Y: Integer);
protected
    function CreateDropMenu: TPopupMenu; virtual;
    procedure DragMenuEvent(Sender: TObject); virtual;
    function GetNewNode(RelativeNode: TTreeNode = nil; NodeName: string = '';
      AddMode: TAttachMode = amAuto): TTreeNode;
    function CloneNode(FromNode, ToNode: TTreeNode;
      MoveMode: TAttachMode = amAuto): TTreeNode;
    procedure CopyChildNodes(FromNode, ToNode: TTreeNode); virtual;
public
    constructor Create(AOwner: TComponent); override;
    destructor Destroy; override;

    function AddNode(RelativeNode: TTreeNode = nil; NodeName: string = '';
      AddMode: TAttachMode = amAuto): TTreeNode; virtual;
    function DeleteNode(RelativeNode: TTreeNode): TTreeNode; virtual;
    function MoveNode(FromNode, ToNode: TTreeNode;
      MoveMode: TAttachMode = amAuto; bCopy: Boolean = False)
      : TTreeNode; virtual;
published
    property TreeView: TCustomTreeView read GetTreeView Write SetTreeView;
    property DragMode: TDragMode read FDragMode Write FDragMode
      default dmHotKeyDrag;
    property HotKeyMoveNode: THotKey read GetHotKeyMoveNode
      write SetHotKeyMoveNode default hkCtrl;
    property HotKeyCopyNode: THotKey read GetHotKeyCopyNode
      write SetHotKeyCopyNode default hkShift;
    property HotKeyChildNode: THotKey read GetHotKeyChildNode
      write SetHotKeyChildNode default hkAlt;
    property EnableRButtonDrag: Boolean read FEnableRButtonDrag
      write FEnableRButtonDrag default True;
end;

const
{ 由于 Delphi 的 TreeView 所能管理的最大节点数为 65535，所以这里给出范围限制 }
MaxNodeCount = 65535;

resourcestring
Error_NodeOutOfRange = '警告：TreeView 节点数达到最大限制：%d，无法继续添加节点';

procedure Register;

implementation

procedure Register;
begin
RegisterComponents('Samples', [TTreeViewDrager]);
end;

{ 判断按键是否被按下 }
function IsKeyDown(VK: Integer): Boolean;
begin
Result := GetKeyState(VK) < 0;
end;

constructor TTreeViewDrager.Create(AOwner: TComponent);
begin
inherited;
FDragMode := dmHotKeyDrag;
HotKeyMoveNode := hkCtrl;
HotKeyCopyNode := hkShift;
HotKeyChildNode := hkAlt;
FDropMenu := CreateDropMenu;
FEnableRButtonDrag := True;
end;

destructor TTreeViewDrager.Destroy;
begin
FDropMenu.Free;
inherited;
end;

{ ------------------------------------------------------------ }
{ 拖放后的弹出菜单 }
{ ------------------------------------------------------------ }

function TTreeViewDrager.CreateDropMenu: TPopupMenu;
const
DropMenuName: array [1 .. 9] of PChar = ('移动到之前(&1)', '移动到之后(&2)',
'移动到子节点最前(&5)', '移动到子节点最后(&6)', '-', '复制到之前(&A)', '复制到之后(&B)',
'复制到子节点最前(&E)', '复制到子节点最后(&F)');
var
I: Integer;
NewItem: TMenuItem;
begin
Result := TPopupMenu.Create(FTreeView);

for I := Low(DropMenuName) to High(DropMenuName) do
begin
    NewItem := TMenuItem.Create(FTreeView);
    NewItem.Tag := I;
    NewItem.OnClick := DragMenuEvent;
    NewItem.Caption := DropMenuName[I];
    Result.Items.Add(NewItem);
end;
end;

procedure TTreeViewDrager.DragMenuEvent(Sender: TObject);
const
MoveMode: array [1 .. 4] of TAttachMode = (amPrev, amNext, amChildFirst,
amChildLast);
var
bCopy: Boolean;
Inde

补充：软件开发 , Delphi ,