【C#】添加鼠標管輪事件

對FlowLayoutPanel添加鼠標滾輪事件

在mainform中添加事件

his.flowLayoutPanel1.MouseWheel +=
                new System.Windows.Forms.MouseEventHandler(this.flowLayoutPanel1_MouseWheel);

添加滾輪事件函數：

private void flowLayoutPanel1_MouseWheel(object sender, MouseEventArgs e) { if (!(flowLayoutPanel1.VerticalScroll.Visible == false || (flowLayoutPanel1.VerticalScroll.Value == 0 && e.Delta > 0) || (flowLayoutPanel1.VerticalScroll.Value == lastRightPanelVerticalScrollValue && e.Delta < 0))) { flowLayoutPanel1.VerticalScroll.Value += 10; lastRightPanelVerticalScrollValue = flowLayoutPanel1.VerticalScroll.Value; flowLayoutPanel1.Refresh(); flowLayoutPanel1.Invalidate(); flowLayoutPanel1.Update(); } }

 

除此以外還要說的一點是，觸發鼠標的滾動事件後，處理事件的函數參數 MouseEventArgs e 中有個Delta屬性，默認狀況下向上滾動e.Delta=120，向下滾動e.Delta=-120。以上的程序還不是特別完美，由於當Panel控件較大而沒有顯示滾動條時，或滾動條已在最上方而滾輪又是向上滾動，或滾動條已在最下方而滾輪又是向下滾動時，一樣會執行Panel.Refresh();Panel.Invalidate();Panel.Update();等窗體重繪代碼，佔用較多資源。所以能夠在執行這些代碼前先對Panel的當前情況作判斷。

int lastRightPanelVerticalScrollValue = -1;//爲鼠標滾動事件提供一個靜態變量，用來存儲上次滾動後的VerticalScroll.Value

添加FlowLayoutPanel的鼠標進入事件和鼠標點擊事件

private void flowLayoutPanel1_MouseEnter(object sender, EventArgs e) { flowLayoutPanel1.Focus(); } private void flowLayoutPanel1_MouseClick(object sender, MouseEventArgs e) { flowLayoutPanel1.Focus(); }