《TypeScript图形渲染实战：2D架构设计与实现》 —3.2.8 将DOM Event事件转换为CanvasInpu

3.2.8  将DOM Event事件转换为CanvasInputEvent事件

　　使用了自己定义的CanvasInputEvent事件体系，因此需要将DOM Event事件转换为CanvasInputEvent对应的子类。具体代码如下：

// 将DOM Event对象信息转换为自己定义的CanvasMouseEvent事件

private _toCanvasMouseEvent ( evt : Event ) : CanvasMouseEvent {

    // 向下转型，将Event转换为MouseEvent

    let event : MouseEvent = evt as MouseEvent ;

    // 将客户区的鼠标pos变换到Canvas坐标系中表示

    let mousePosition : vec2 = this . _viewportToCanvasCoordinate ( event ) ;

    // 将Event一些要用到的信息传递给CanvasMouseEvent并返回

    let canvasMouseEvent : CanvasMouseEvent = new CanvasMouseEvent

     (  mousePosition , event . button , event . altKey , event . ctrlKey ,

    event .shiftKey ) ;

    return canvasMouseEvent ;

}

// 将DOM Event对象信息转换为自己定义的Keyboard事件

private _toCanvasKeyBoardEvent ( evt : Event ) : CanvasKeyBoardEvent {

    let event : KeyboardEvent = evt as KeyboardEvent ;

    // 将Event一些要用到的信息传递给CanvasKeyBoardEvent并返回

    let canvasKeyboardEvent : CanvasKeyBoardEvent = new CanvasKeyBoardEvent

    ( event . key , event . keyCode , event . repeat , event . altKey , event .

    ctrlKey , event . shiftKey ) ;

    return canvasKeyboardEvent ;

}