checktreeview.~pas

来自「自己封装的：日期控件(dataX)」· ~PAS 代码 · 共 71 行

unit CheckTreeView;

interface

uses
  SysUtils, Classes, Controls, ComCtrls;
const
TVIS_CHECKED = $2000;//什么意思

type
  CheckTreeView = class(TTreeView)
  private
    { Private declarations }
  protected
      procedure CreateParams(var Params: TCreateParams); override;

  public
      function IsChecked(Node :TTreeNode) :Boolean;
      procedure SetChecked(Node :TTreeNode; Checked :Boolean);
  published
    { Published declarations }
  end;

procedure Register;

implementation

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

{ CheckTreeView }

procedure CheckTreeView.CreateParams(var Params: TCreateParams);
begin
  inherited;
    Params.Style:=Params.Style or TVS_CHECKBOXES;
end;

function CheckTreeView.IsChecked(Node: TTreeNode): Boolean;
var
TvItem :TTVItem;
begin
  TvItem.Mask := TVIF_STATE;//什么意思
  TvItem.hItem := Node.ItemId;//什么意思
  TreeView_GetItem(Node.TreeView.Handle, TvItem);//什么意思
  Result := (TvItem.State and TVIS_CHECKED) = TVIS_CHECKED;//什么意思
end;

procedure CheckTreeView.SetChecked(Node: TTreeNode; Checked: Boolean);
var
TvItem :TTVItem;
begin
  FillChar(TvItem, SizeOf(TvItem), 0);
  with TvItem do
  begin
    hItem := Node.ItemId;
    Mask := TVIF_STATE;
    StateMask := TVIS_STATEIMAGEMASK;
    if Checked then
        TvItem.State :=TVIS_CHECKED
    else
        TvItem.State :=TVIS_CHECKED shr 1;
        TreeView_SetItem(Node.TreeView.Handle, TvItem);
  end;

end;

end.