LabelPlus.PicView.PicView_Zooming_MouseWheel C# (CSharp) Method

        void PicView_Zooming_MouseWheel(object sender, MouseEventArgs e)
        {
            //if (Control.ModifierKeys != Keys.Control) return;

            var beforeValue = this.Zoom;
            if (e.Delta > 0) {
                this.Zoom += 0.1f;
            } else {
                this.Zoom -= 0.1f;
            }
            if (beforeValue == this.Zoom) return;   //未做改变 不刷新

            //只有进程结束后 才能再执行一次
            if(zooming_thread ==null){
                zooming_thread = new Thread(zooming_drawing);
                zooming_thread.Start();
            }
        }