VB制作控件之图片命令按钮➁

续 VB制作控件之图片命令按钮➀

这一节我们实现鼠标动作事件。首先我们需要创建一个计时器Timer对象，代码如下：

➀定义一个计时器对象变量，类型为Timer ➁定义一个变量来判断鼠标是否按下或移出控件内，类型为Boolean

Dim WithEvents Tim As Timer Dim Action As Boolean

创建计时器对象

Private Sub UserControl_Initialize() Set Tim = Controls.Add("vb.Timer", "Tim") Tim.Enabled = False: Tim.Interval = 100 End Sub

创建好计时器，我们还要用到两个API函数"GetCursorPos"和"WindowFromPoint"，来判断鼠标是否在控件范围内，声明如下：

函数	说明
GetCursorPos	获取鼠标指针的当前位置
WindowFromPoint	返回包含了指定点的窗口的句柄。忽略屏蔽、隐藏以及透明窗口
声明
Private Declare Function GetCursorPos Lib "user32" (lpPoint As POINTAPI) As Long Private Declare Function WindowFromPoint Lib "user32" (ByVal xPoint As Long, ByVal yPoint As Long) As Long Private Type POINTAPI x As Long y As Long End Type
自定义函数
Private Function IsMouseOver(hwnd As Long) As Boolean Dim pt As POINTAPI GetCursorPos pt IsMouseOver = (WindowFromPoint(pt.x, pt.y) = hwnd) End Function

计时器事件：

Private Sub Tim_Timer()     If IsMouseOver(UserControl.hwnd) <> True Then        Call ImageSlide(0)        Action = False        Tim.Enabled = False     End If End Sub

计时器事件编写好之后，我们再定义四个鼠标事件函数：

鼠标单击事件

Public Event Click()

鼠标按下事件

Public Event MouseDown(Button As Integer, Shift As Integer, x As Single, y As Single)

鼠标经过事件

Public Event MouseMove(Button As Integer, Shift As Integer, x As Single, y As Single)

鼠标弹起事件

Public Event MouseUp(Button As Integer, Shift As Integer, x As Single, y As Single)

下面实现鼠标单击、按下、经过、弹起以及背景图片和文本颜色的切换：

鼠标单击事件(内部)

Private Sub UserControl_Click() RaiseEvent Click End Sub

鼠标按下事件(内部)

Private Sub UserControl_MouseDown(Button As Integer, Shift As Integer, x As Single, y As Single) If Button <> 1 Then Exit Sub Action = True Call ImageSlide(2) RaiseEvent MouseDown(Button, Shift, x, y) End Sub

鼠标经过事件(内部)

Private Sub UserControl_MouseMove(Button As Integer, Shift As Integer, x As Single, y As Single) Tim.Enabled = True If Action <> True And (x > 0 And x < UserControl.ScaleWidth) And (y > 0 And y < UserControl.ScaleHeight) Then Call ImageSlide(1) End If RaiseEvent MouseMove(Button, Shift, x, y) End Sub

鼠标弹起事件(内部)

Private Sub UserControl_MouseUp(Button As Integer, Shift As Integer, x As Single, y As Single) If Button <> 1 Then Exit Sub Call ImageSlide(0) If Action Then RaiseEvent MouseUp(Button, Shift, x, y) Action = False End Sub

事件编写完成之后，这里编写控件的"Enabled"属性，决定对象是否响应用户生成事件：

返回 Enabled 的值

Public Property Get Enabled() As Boolean Enabled = UserControl.Enabled End Property

设置 Enabled 的值

Public Property Let Enabled(ByVal vNewValue As Boolean) UserControl.Enabled = vNewValue PropertyChanged "Enabled" If vNewValue Then Call ImageSlide(0) Else Tim.Enabled = False Call ImageSlide(3) End If End Property

即将属性值读写到"ReadProperties"和"WriteProperties"事件里：

写入

Private Sub UserControl_WriteProperties(PropBag As PropertyBag) '存 Call PropBag.WriteProperty("Enabled", UserControl.Enabled, True) End Sub

读出

Private Sub UserControl_ReadProperties(PropBag As PropertyBag) '读 UserControl.Enabled = PropBag.ReadProperty("Enabled", True) If UserControl.Enabled Then Call ImageSlide(0) Else Call ImageSlide(3) End If End Sub

 

  

到这里，一个简单的图片命令按钮就接近尾声了，最后一步编写控件的一些初始化：

初始化

Private Sub UserControl_Initialize() UserControl.AutoRedraw = True         '持久性图位输出 UserControl.ScaleMode = vbPixels     '以像素单位显示 tColor(1) = RGB(255, 255, 0)              '鼠标经过时文本的颜色 tColor(2) = RGB(0, 0, 0)                      '鼠标按下时文本的颜色 tColor(3) = RGB(240, 240, 240)          '控件无效时文本的颜色 End Sub

改变控件大小时显示第一块图片

Private Sub UserControl_Resize() Call ImageSlide(0) End Sub

获得控件名称

Private Sub UserControl_InitProperties() Text = Extender.Name                         '获得对象名称到文本变量 Call ImageSlide(0)                               '显示第一块图片 End Sub

工程包下载地址：https://download.youkuaiyun.com/download/ty5858/85346566