运用VB编程实现鼠标平滑移动图像

与应用【M】．北京：清华大 学出版社，2007． 相同时间取一次坐标值的办法来实现平滑。当然这个时间 间隔不能太小，也不能太大，通过实验发现其取值在 20～ 80ms之间效果较好，这与机器的运算速度和 Picture控件显 示区域大小有关，可通过具体测试而定。 3程序代码 Option Explicit Private Type POINTAPI x As L)Ilg Y As Long End Type StretchBh API函数声明 Private Declare Function StrctchBh Lib gdi32 (ByVM hDC As Long，ByVMx AS 呜 ByV8l Y As Lo ng，ByVM nWidth As Lo ng~ ByVal nHeight As Long，ByVal hSrcDC As Long, _ ByVal xSrc As Long．ByVal ySrc As Long， ByVal nSrcWidth AS Long， ． ． ByVal nSrcHeight As Long。ByVal dwRop As Long) As Long GetCumorPos API函数声明 Private Declare Function GctCursorPos Lib user32”(1pPoint As POINTAPI)As ng Dim oldX AS Long Dim oldY As Long Dim ScrX As Ilg Dim ScrY As Long Dim da As POIN．FAPI Private Sub Command 1_Click() On Error G0，r0 ERR1 CD1．CaneelError= True CD1．Filter= 图片文件 (·．bmp； ．dib； ．g ．JPg； ．wraf)l ．bmp；’．dib； ．S4f； ．jPg；’．wmf- CD1．ShowOpen Picture1．Picture=LoadPicture() PicL．Picture=LoadPictur~(CD1．FileName) Call StretchBh(Picture1．hDC，0，0， Pie— ture1．ScaleWidth，Picture1．ScMeHeiSat， 一 PicL．hDC，0，0， Picture1．ScaleWidtIl， Pie— ture1．ScaleHeight，vbSrcCopy) Exit Sub ERRl： End Sub 2界面设计 新建一个工程，在窗体中放入两个图片框控件 Picture! 和 PicL，Picture1用于显示图片内容，PicL用于装入原始图 片：一个计时器控件 Timerl；一个通用对话框控件 CD1：两 个命令按钮 Commandl和 Command2。 Picture1．MousePointer= 0 Timer1．Enabled = False End Sub Private Sub Command2—Click() Unload Me End Sub Priv~e Sub Form_load() Picture1．ScaleMode = 3 Picture1．AutoRedraw ； Tnle Picture1．AutoSize ： Falsc PicL．ScaleMode = 3 PieL．AutoRedraw = Tme PieL．AutoSize = Tnle PieL．Visible = False Timer1．Enabled = False ScrX = 0 scrY = 0 End Sub Private Sub PictureI — MouseDowitl (Button As Integer，Shift As Integer，x As Single， y AS Single) Picture1．MousePointer= 99 CaⅡ GetCursorPos(da) 01dX = da．x oldY = da．y Timer1．Enablecl= Tme End Sub Private Sub Picturel — MouseMove (Button As Integer, Shift As Integer，x As Single。 Y As Single) H Timer1．Enabled then C8U GetCursorPos(d8) End Ⅱ End Sub Private Sub Picture1 _ MouscUp (Button As Integer，Sh As Integer，x As Single，Y As Single) 4结束语 在程序中用到两个 API函数，StretchBh函数用于将一幅 位图从一个设备场景复制到另一个设备场景。在复制前，语 句 Picture1．Picture=LoadPicture()不可少，用于设置 Pic— turel的设备场景。GetCursorPos函数用于获取鼠标指针的当 前位置。 参考文献 Private Sub Timed_Timet() Dim pWidth As ng Dim pHeisat As Long Dim dltaX As L0ng Dim dltaY As Long pWidth = PietureI．ScaleWidth pHeisat=Pieture1．ScaleHeisat Can GctCmsorPos(da) dltaX = oldX — da．x dltaY = oldY — da．y SerX = ScrX 4-dltaX ScrY = SerY 4-dhaY oldX =da．x oldY =da．Y If$erX < 0 'rhea ScrX = 0 ElseIf SerX > PicL．Sc8lew_idth — Pieture1． SealeWidth Then ScrX = PicL．Sc8leWidth- Picture1．$caleW— idth End If H scrY < 0 Then - ScrY = 0 ElseH Sc f>PieL．ScaleHeisat—Pictum1． ScaleHeisat Then ScrY = PicL．ScaleHeight— Picture1．Scale- Hei曲t End If Picture1．Picture=LoadPictur~() Call StretehBh(Picture1．hI)C，0．o．pWidth， pHei曲t，一 PicL．hDC， ScrX,ScrY。pWidth,pHeight, vbSrcCopy) End Sub 【l】(美)Rogers D F著．计算机图形学的算法基础．北京；机械工 业出版社，2004--03． 【2】马靖．利用 API增强VB的图像处理功能．北京：微计算机信息 (测控仪表 自动化)，2003(9)． 【3】臧玉琴．Visual Basic界面、多媒体与操作系统程序设计．北京： 人民邮电出版社．20o5-01． · 73 ·