Delphi VirtualStringTree OnMouseEnter 和 OnMouseLeave

Question

您好，请问是否有包含这 2 个鼠标事件的 VirtualStringTree 版本:

OnMouseEnter 和 OnMouseLeave ？

Answer 1

如果您的字符串树尚不支持这些事件，那么添加这些事件很容易。

  TMyImprovedVirtualStringTree = class(TSomeVirtualStringTree)
  private
    FOnMouseEnter: TNotifyEvent;
    FOnMouseLeave: TNotifyEvent;

    // Watch for MouseEnter and MouseLeave messages...
    procedure CMMouseEnter(var Message: TMessage); message CM_MOUSEENTER;
    procedure CMMouseLeave(var Message: TMessage); message CM_MOUSELEAVE;
  protected
    // Provide MouseEnter() and MouseLeave() methods
    // for descendent controls to override if needed.
    procedure MouseEnter; virtual;
    procedure MouseLeave; virtual;
  published
    // Publish the events so they show in Delphi's object inspecter.
    property OnMouseEnter: TNotifyEvent read FOnMouseEnter write FOnMouseEnter;
    property OnMouseLeave: TNotifyEvent read FOnMouseLeave write FOnMouseLeave;
  end;

implementation

{ TMyImprovedVirtualStringTree }

procedure TMyImprovedVirtualStringTree.CMMouseEnter(var Message: TMessage);
begin
  inherited;
  MouseEnter;
end;

procedure TMyImprovedVirtualStringTree.CMMouseLeave(var Message: TMessage);
begin
  inherited;
  MouseLeave;
end;

procedure TMyImprovedVirtualStringTree.MouseEnter;
begin
  if Assigned(FOnMouseEnter) then
    FOnMouseEnter(Self);
end;

procedure TMyImprovedVirtualStringTree.MouseLeave;
begin
  if Assigned(FOnMouseLeave) then
    FOnMouseLeave(Self);
end;