朋友发来一个 VB6 的小要求：自行绘制按钮，并且按钮不能有句柄，不得用 Image 控件，需要支持单击事件，鼠标移动上去会变化。感觉像个考试题啊！

先贴代码：

VERSION 5.00 Begin VB.Form Form1 Caption = "Form1" ClientHeight = 3090 ClientLeft = 60 ClientTop = 450 ClientWidth = 4680 LinkTopic = "Form1" ScaleHeight = 3090 ScaleWidth = 4680 StartUpPosition = 3 '窗口缺省 Begin VB.Image Image3 Height = 1215 Left = 1560 Top = 1680 Width = 2655 End End Attribute VB_Name = "Form1" Attribute VB_GlobalNameSpace = False Attribute VB_Creatable = False Attribute VB_PredeclaredId = True Attribute VB_Exposed = False Dim pic1 As StdPicture,pic2 As StdPicture Dim btnLeft As Single,btnTop As Single Dim btnRight As Single,btnBottom As Single Dim inButton As Boolean,last As Boolean Private Sub Form_Load() Set pic1 = LoadPicture(App.Path + "/111.bmp") Set pic2 = LoadPicture(App.Path + "/112.bmp") btnLeft = 150: btnTop = 150 ' 亮点在这里啊 btnRight = ScaleX(pic1.Width,vbHimetric,vbPixels) * 15 + btnLeft btnBottom = btnTop + ScaleY(pic1.Height,vbPixels) * 15 inButton = False: last = inButton Image3.Picture = pic1 Msg<a href="https://www.jb51.cc/tag/Box/" target="_blank" class="keywords">Box</a> Image3.Picture.Width & " x " & Image3.Picture.Height & vbNewLine & _ Image3.Width & " x " & Image3.Height End Sub Private Function IsMouseInButton(X As Single,Y As Single) As Boolean IsMouseInButton = (X <= btnRight And X >= btnLeft) And (Y <= btnBottom And Y >= btnTop) End Function Private Sub Form_MouseMove(Button As Integer,Shift As Integer,X As Single,Y As Single) Debug.Print "x: " & X & " y: " & Y & " Button: " & Button inButton = IsMouseInButton(X,Y) If inButton <> last Then Me.Refresh Debug.Print "InButton: " & inButton & ",last: " & last End If last = inButton End Sub Private Sub Form_MouseUp(Button As Integer,Y As Single) If inButton Then Msg<a href="https://www.jb51.cc/tag/Box/" target="_blank" class="keywords">Box</a> ("button clicked.") End If End Sub Private Sub Form_Paint() If inButton Then PaintPicture pic2,btnLeft,btnTop Else PaintPicture pic1,btnTop End If End Sub

思路就是 使用 PaintPicture 在窗体上作图，使用MouseMove事件判定鼠标是否在图片的位置上，如果是则绘制鼠标移动浮动后的图片，否则就绘制原始按钮图片。

在判断鼠标位置是否在图片位置的这块功能中发现一个问题，StdPicture.Width比图片的实际长度要大，不知道是什么原因造成的。使用必应搜索MS网站无结果，最后依靠伟大的google搜索外国网友的疑问找到解决方法，必须使用 ScaleX 和 ScaleY 函数计算图片在设备（此处是窗体）上的实际大小。

花了大约两个小时的时间，好在有一点收获。不错。