诚心请教这个单元在树中起到什么作用呢?

[DFans]

{================ Free TIBXTreeView component for IBX =======================
 Igor Ilyinsky, 2001, www.sinn.ru/~mapnn  ([e-mail])
 ==============================================================================
 }
unit IBXtrees;

interface

uses ComCtrls, DB, Classes, SysUtils, IBDatabase, IBSQL;

type

  PItemRec = ^ItemRec;
  ItemRec = record
    Id : integer;
    Parent: integer;
    CCount: integer;
  end;

TIBXTreeView=class(TTreeView)
private
     IBConnection  : TIBDatabase;
     IBTransaction : TIBTransaction;
     IBTableName : String;
     IBSQL : TIBSQL;
     procedure BuildNode(Node:TTreeNode);
protected
     procedure Delete(Node: TTreeNode); override;
     function CanExpand(Node: TTreeNode): Boolean; override;
     // Rebuild children for ParentNode
     procedure RebuildNode(ParentNode: TTreeNode; Node_Id: integer); virtual;
public
     procedure BuildTree(RootName: String);
     procedure ClearTree;
     //
     constructor Create(AOwner:TComponent); override;
     destructor  Destroy; override;
     //
     procedure InsertNode(Parent_Id: integer; Name: String);
     //
     procedure MoveNode(Node_Id, NewParent_Id: integer);
     //
     procedure RenameNode(Node:TTreeNode; Name: String);
     //
     procedure DeleteNode(Node:TTreeNode);
     //
     function  GetId(Node: TTreeNode) : Integer;
     //
     function GetNode(Id: Integer) : TTreeNode;
published
     property Database : TIBDatabase read IBConnection write IBConnection;
     property Transaction : TIBTransaction read IBTransaction write IBTransaction;
     property TableName : string read IBTableName write IBTableName;
end;

procedure Register;

implementation

function TIBXTreeView.GetId(Node: TTreeNode) : Integer;
var R: PItemRec;
begin
     R:=PItemRec(Node.Data);
     Result := R^.ID;
end;

function TIBXTreeView.GetNode(Id: Integer) : TTreeNode;
var R: PItemRec;
    i: integer;
begin
     Result:=nil;
     i:=0;
     While i < Items.Count do begin
       R:=PItemRec(Items[i].Data);
       if R^.ID = Id then begin
          Result := Items[i];
          break;
       end;
       inc(i);
     end;
end;

constructor TIBXTreeView.Create(AOwner:TComponent);
begin
  inherited Create(AOwner);
  IBSQL:=TIBSQL.Create(Self);
end;

procedure TIBXTreeView.Delete(Node: TTreeNode);
begin
  inherited Delete(Node);
  if Assigned(Node) then
    if Assigned(Node.Data) then Dispose(PItemRec(Node.Data));
end;

function TIBXTreeView.CanExpand(Node: TTreeNode): Boolean;
begin
  Result:=inherited CanExpand(Node);
  if Assigned(Node.Data) then
  Items.BeginUpdate;
  BuildNode(Node);
  Items.EndUpdate;
end;

destructor TIBXTreeView.Destroy;
begin
  IBSQL.Free;
  inherited;
end;

procedure TIBXTreeView.BuildNode(Node:TTreeNode);
var NewNode: TTreeNode;
    R: PItemRec;
begin
  if not IBTransaction.inTransaction then IBTransaction.StartTransaction;
  IBSQL.Close;
  IBSQL.Sql.Text:='select * from '+IBTableName+' where PARENT=:Parent ';
  R:=Node.Data;
  IBSQL.ParamByName('Parent').asInteger:=R^.Id;
  Node.DeleteChildren;
  IBSQL.ExecQuery;
  while not IBSQL.EOF do
    begin
      New(R);
      R^.Id:=IBSQL.FieldByName('ID').asInteger;
      R^.Parent:=IBSQL.FieldByName('PARENT').asInteger;
      R^.CCount:=IBSQL.FieldByName('CCOUNT').asInteger;
      NewNode:=Items.AddChild(Node,Trim(IBSQL.FieldByName('NAME').asString));
      NewNode.Data:=PItemRec(R);
      NewNode.HasChildren:=R^.CCount > 0;
      if assigned(Images) then begin
         NewNode.ImageIndex:=2;
         NewNode.SelectedIndex:=3;
      end;
      IBSQL.Next;
    end;
  IBSQL.Close;
end;

procedure TIBXTreeView.InsertNode(Parent_Id: integer; Name: String);
var ParentNode: TTreeNode;
begin
    if not IBTransaction.inTransaction then IBTransaction.StartTransaction;
    IBSQL.Close;
    IBSQL.Sql.Text:='insert into '+IBTableName+' (PARENT,NAME) values(:Parent,:Name)';
    IBSQL.ParamByName('Parent').asInteger:=Parent_Id;
    IBSQL.ParamByName('Name').asString:=Name;
    IBSQL.ExecQuery;
    IBTransaction.Commit;
    ParentNode:=GetNode(Parent_id);
    if ParentNode <> nil then RebuildNode(ParentNode, -1); // if parent visible
end;

procedure TIBXTreeView.MoveNode(Node_Id, NewParent_Id: integer);
var Node,NodeParent: TTreeNode;
begin
  if Node_Id = NewParent_Id then raise exception.create('Parent Node can not be equal Selected Node!');
  if Node_Id = 0 then raise exception.create('Root Node can not be moved!');
    if not IBTransaction.inTransaction then IBTransaction.StartTransaction;
    IBSQL.Close;
    // TEST CICLE NODE
    IBSQL.Sql.Text:='select * from GETPARENTS(:Id)';
    IBSQL.ParamByName('Id').asInteger:=NewParent_Id;
    IBSQL.ExecQuery;
    while not IBSQL.EOF do begin
      if IBSQL.FieldByName('DID').asInteger = Node_Id then
         raise exception.create('Cicle Node!');
      IBSQL.Next;
    end;
    IBSQL.Close;
    // UPDATE
    IBSQL.Sql.Text:='update '+IBTableName+' set PARENT=:Parent where ID=:ID';
    IBSQL.ParamByName('Parent').asInteger:=NewParent_Id;
    IBSQL.ParamByName('ID').asInteger:=Node_Id;
    IBSQL.ExecQuery;
    IBTransaction.Commit;
  Node:=GetNode(Node_Id);
  if (Node <> nil) and Node.Parent.Expanded then items.delete(Node);
  NodeParent:=GetNode(NewParent_Id);
  if (NodeParent <> nil) then RebuildNode(NodeParent,Node_Id);  // if newparent visible
end;

procedure TIBXTreeView.RenameNode(Node:TTreeNode; Name: String);
var R: PItemRec;
begin
  if Node.Parent = nil then raise exception.create('Root Node can not be renamed!');
    if not IBTransaction.inTransaction then IBTransaction.StartTransaction;
    IBSQL.Close;
    IBSQL.Sql.Text:='update '+IBTableName+' set NAME=:Name where ID=:ID';
    R:=Node.Data;
    IBSQL.ParamByName('ID').asInteger:=R^.ID;
    IBSQL.ParamByName('Name').asString:=Name;
    IBSQL.ExecQuery;
    IBTransaction.Commit;
    RebuildNode(Node.Parent,R^.ID);
end;

procedure TIBXTreeView.DeleteNode(Node:TTreeNode);
var R: PItemRec;
begin
  if Node.Parent = nil then raise exception.create('Root Node can not be deleted!');
  if Node.HasChildren then raise exception.Create('This Node has Children!');
     if not IBTransaction.inTransaction then IBTransaction.StartTransaction;
     IBSQL.Close;
     IBSQL.Sql.Text:='delete from '+IBTableName+' where ID=:ID';
     R:=PItemRec(Node.Data);
     IBSQL.ParamByName('ID').asInteger:=R^.ID;
     IBSQL.ExecQuery;
     IBTransaction.Commit;
     RebuildNode(Node.Parent,-1);
end;

procedure TIBXTreeView.BuildTree(RootName: String);
var RootNode: TTreeNode;
    R: PItemRec;
begin
  IBSQL.Database:=IBConnection;
  IBSQL.Transaction:=IBTransaction;
  if (not assigned(IBConnection)) or (not assigned(IBTransaction)) or (IBTableName = '') then
          raise exception.create('IBConnection,IBTransaction or IBTableName is not defined!');
  items.BeginUpdate;
  ClearTree;
  RootNode:=items.Add(nil, RootName); { Add a root node }
  if assigned(Images) then begin
     RootNode.ImageIndex:=0;
     RootNode.SelectedIndex:=1;
  end;
  new(r);
  r^.id:=0;    // id root = 0 !!!
  RootNode.Data:=r;
  BuildNode(RootNode);
  RootNode.Expand(False);
  Items.EndUpdate;
end;

{Rebuild children for ParentNode}
procedure TIBXTreeView.RebuildNode(ParentNode: TTreeNode; Node_Id: integer);
var Node: TTreeNode;
begin
  if ParentNode <> nil then begin
     items.BeginUpdate;
     BuildNode(ParentNode);
     ParentNode.Expand(False);
     if Node_Id >= 0 then begin
        Node:=GetNode(Node_Id);
        if Node <> nil then Node.Selected:=True;
     end;
     items.EndUpdate;
  end;
end;

procedure TIBXTreeView.ClearTree;
begin
  While Items.Count>0 do Items.Delete(Items[0]);
end;

procedure Register;
begin
  RegisterComponents('InterBase', [TIBXTreeView]);
end;

end.

[chenzhaochun]

哇～好多的代码～了解了解～

[cnlong]

good

[lclichao2006]

学习了谢谢分享

[bdmh]

这个好像可以从数据库读取数据然后生成树形结构

[lgx0914]

procedure BuildTree(RootName: String);//创建树
procedure ClearTree;//清空树     
procedure InsertNode(Parent_Id: integer; Name: String);//插入节点
procedure MoveNode(Node_Id, NewParent_Id: integer);//移动节点
procedure RenameNode(Node:TTreeNode; Name: String);//重命名节点
procedure DeleteNode(Node:TTreeNode);//删除节点
function  GetId(Node: TTreeNode) : Integer;//获得节点ID
function GetNode(Id: Integer) : TTreeNode;//通过ID获得节点信息

[de410]

关于树操作的单元，树的生成，节点的添加、删除、移动、修改、刷新等功能

[bdmh]

TIBXTreeView.BuildNode(Node:TTreeNode);
根据Node.Data中存储的id值,从数据库中取得该id记录的所属下级记录,这也是形成树形结构的核心

[不得闲]

如楼上所说

[bdmh]

这个类应该把字段'PARENT'放开,作为一个属性,否则他人使用时,只能用'PARENT'作为字段名,应该想dxtreelist那样,设置keyid和parentid

[cht_1988]

学习了谢谢分享

[xjlnjut730]

不太清楚，有空再研究研究。

[nbman2013]

对树的操作，很全，很经典的代码

[youyouzui]

这个有点看不懂呢

[youyouzui]

似乎是呢 。。。好像对啊 。。。。。

[boss1215]

努力學習中~謝謝分享^^

[kevin]

代码写的相当好.

作者是继承TTreeview编写树型控件,
并在它的基础上增加了三个属性： 数据库，事务还有 表名。

1、procedure TIBXTreeView.BuildTree(RootName: String)；
传入树的根节点，并将给Record结构的ID赋初始值，然后调用BuildNode(Node)来遍历tablename的行，将其存入到Record结构，并填充BuildNode(Node)里
node的子节点。这里没有递归，似乎存在一点问题，无法再提取出Node的下个中间层的子节点。

2、其他的我和三楼相同。

[yct0605]

应该是从数据库中动态读取数据，然后用树状控件显示出来树结构。

[书生行走]

它在整个数据库设计中如何实现，作用就是读取数据吗，真的不懂，请指教