VB系统的坐标原点在左上角,X轴的正方向是水平向右,而Y轴的正方向是垂直向下。所以,要绘制三角函数的曲线,自己可以通过改变点坐标的方法来实现,当然,VB.NET提供了相应的方法可以来实现坐标变换,也可以通过VB.Net的Graphics类提供的平移、旋转等转换来实现。
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下面是我通过自己变换实现的示例,提供参考;我的环境是VB.NET 2010
Imports System.Math
Public Class Form1
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
'1,获得一个Graphics对象
Dim MyGraphics As Graphics
MyGraphics = PictureBox1.CreateGraphics
'2,定义一个Pen对象,用于绘制图形(轮廓线)
Dim MyPen As New Pen(Color.Black, 1)
'3,定义一个Brush对象,用于填充图形(如果需要填充的话)
Dim MyBrush As New SolidBrush(Color.Orange)
MyGraphics.DrawLine(MyPen, 0, 200, 700, 200)
End Sub
Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
'1,获得一个Graphics对象
Dim MyGraphics As Graphics
MyGraphics = PictureBox1.CreateGraphics
'2,定义一个Pen对象,用于绘制图形(轮廓线)
Dim MyPen As New Pen(Color.Black, 1)
'3,定义一个Brush对象,用于填充图形(如果需要填充的话)
Dim MyBrush As New SolidBrush(Color.Orange)
'声明横向和纵向比例变量
Dim Heng As Integer = 20
Dim Zong As Integer = 50
'先获得正弦值,保存到点坐标数组
Dim MyPoints(700) As Point
Dim i As Integer
For i = 0 To 700
MyPoints(i) = New Point(i * Heng, 200 + Sin(i) * Zong)
Next
'采用绘制光滑线连接点的方式绘制曲线
MyGraphics.DrawCurve(MyPen, MyPoints)
End Sub
End Class
显示的效果图:
很简单的方法,貌似没有。这个需要自己写很多代码:
用一个ListView控件。
判断滚动条当前所显示的图片集合,获取它们的物理路径。
用Bitmap.FromImage方法把这些图片读出来,
然后获取缩略图,
把缩略图用Graphics.DrawImage()绘制出来。
我可以提供Bitmap如何获取缩略图的方法:
''' summary必须创建一个委托并将对此委托的引用作为获取缩略图 callback 参数传递,但不使用此委托。/summary
Public Function ThumbnailCallback() As Boolean
Return False
End Function
''' summary返回Image,表示图像指定 宽 和 高 的缩略图。/summary
Public Function 获取缩略图(位图 As Bitmap, 宽 As Integer, 高 As Integer) As Image
Dim myCallback As New Image.GetThumbnailImageAbort(ThumbnailCallback)
Return 位图.GetThumbnailImage(宽, 高, myCallback, IntPtr.Zero)
End Function
只要将VB窗口内的需要部分保存成图片文件就可以了
要用到API函数的:
Private Type POINTAPI
x As Long
y As Long
End Type
Private Declare Function BitBlt Lib "gdi32" (ByVal hDestDC As Long, ByVal x As Long, ByVal y As Long, ByVal nWidth As Long, ByVal nHeight As Long, ByVal hSrcDC As Long, ByVal xSrc As Long, ByVal ySrc As Long, ByVal dwRop As Long) As Long
Private Declare Function GetDC Lib "user32" (ByVal hwnd As Long) As Long
Private Declare Function GetCursorPos Lib "user32" (lpPoint As POINTAPI) As Long
Private Declare Function DrawIcon Lib "user32" (ByVal hdc As Long, ByVal x As Long, ByVal y As Long, ByVal hIcon As Long) As Long
Private Declare Function ReleaseDC Lib "user32" (ByVal hwnd As Long, ByVal hdc As Long) As Long
Private Sub Command1_Click()
Dim hdc As Long
Dim sw As Integer
Dim sh As Integer
Dim CurPos As POINTAPI
Dim Cur As Long
Me.Hide
DoEvents
Picture1.AutoRedraw = True
hdc = GetDC(0)
GetCursorPos CurPos
Cur = GetCursor
Picture1.Width = Screen.Width
Picture1.Height = Screen.Height
sw = Screen.Width / Screen.TwipsPerPixelX
sh = Screen.Height / Screen.TwipsPerPixelY
BitBlt Picture1.hdc, 0, 0, sw, sh, hdc, 0, 0, vbSrcCopy
Me.Show
DrawIcon Picture1.hdc, CurPos.x - 10, CurPos.y - 10, Cur
ReleaseDC 0, hdc
Picture1.AutoRedraw = False
以下放到模块里:
Option Explicit
Type RECT_Type
left As Long
top As Long
right As Long
bottom As Long
End Type
'The following declare statements are case sensitive.
Declare Function GetActiveWindow Lib "User32" () As Long
Declare Function GetDesktopWindow Lib "User32" () As Long
Declare Sub GetWindowRect Lib "User32" (ByVal Hwnd As Long, _
lpRect As RECT_Type)
Declare Function GetDC Lib "User32" (ByVal Hwnd As Long) As Long
Declare Function CreateCompatibleDC Lib "Gdi32" (ByVal hdc As Long) _
As Long
Declare Function CreateCompatibleBitmap Lib "Gdi32" (ByVal hdc _
As Long, ByVal nWidth As Long, _
ByVal nHeight As Long) As Long
Declare Function SelectObject Lib "Gdi32" (ByVal hdc As Long, _
ByVal hObject As Long) As Long
Declare Function BitBlt Lib "Gdi32" (ByVal hDestDC As Long, _
ByVal X As Long, ByVal Y _
As Long, ByVal nWidth As Long, _
ByVal nHeight As Long, _
ByVal hSrcDC As Long, _
ByVal XSrc As Long, _
ByVal YSrc As Long, _
ByVal dwRop As Long) As Long
Declare Function OpenClipboard Lib "User32" (ByVal Hwnd As Long) As Long
Declare Function EmptyClipboard Lib "User32" () As Long
Declare Function SetClipboardData Lib "User32" (ByVal wFormat As Long, _
ByVal hMem As Long) As Long
Declare Function CloseClipboard Lib "User32" () As Long
Declare Function ReleaseDC Lib "User32" (ByVal Hwnd As Long, _
ByVal hdc As Long) As Long
Declare Function DeleteDC Lib "Gdi32" (ByVal hdc As Long) As Long
Declare Sub Sleep Lib "kernel32" (ByVal dwMilliseconds As Long)
Global Const SRCCOPY = HCC0020
Global Const CF_BITMAP = 2
Function ScreenDump()
Dim AccessHwnd As Long, DeskHwnd As Long
Dim hdc As Long
Dim hdcMem As Long
Dim rect As RECT_Type
Dim junk As Long
Dim fwidth As Long, fheight As Long
Dim hBitmap As Long
' DoCmd.Hourglass True
'---------------------------------------------------
' Get window handle to Windows and Microsoft Access
'---------------------------------------------------
DoEvents
DeskHwnd = GetDesktopWindow()
AccessHwnd = GetActiveWindow()
'---------------------------------------------------
' Get screen coordinates of Microsoft Access
'---------------------------------------------------
Call GetWindowRect(AccessHwnd, rect)
fwidth = rect.right - rect.left
fheight = rect.bottom - rect.top
'---------------------------------------------------
' Get the device context of Desktop and allocate memory
'---------------------------------------------------
hdc = GetDC(DeskHwnd)
hdcMem = CreateCompatibleDC(hdc)
hBitmap = CreateCompatibleBitmap(hdc, fwidth, fheight)
If hBitmap 0 Then
junk = SelectObject(hdcMem, hBitmap)
'---------------------------------------------
' Copy the Desktop bitmap to memory location
' based on Microsoft Access coordinates.
'---------------------------------------------
junk = BitBlt(hdcMem, 0, 0, fwidth, fheight, hdc, rect.left, _
rect.top, SRCCOPY)
'---------------------------------------------
' Set up the Clipboard and copy bitmap
'---------------------------------------------
junk = OpenClipboard(DeskHwnd)
junk = EmptyClipboard()
junk = SetClipboardData(CF_BITMAP, hBitmap)
junk = CloseClipboard()
End If
'---------------------------------------------
' Clean up handles
'---------------------------------------------
junk = DeleteDC(hdcMem)
junk = ReleaseDC(DeskHwnd, hdc)
' DoCmd.Hourglass False
End Function
这里是拖动鼠标的框里内容截取,你也可以改成固定范围的截取。
这样了:
CType(Me.Controls("PictureBox11"), PictureBox).Image = My.Resources.image1
Find 返回数组,元素类型为Object。
Item() 可以把控件名作关键字,但也返回Object。这个方法是默认的,可以省略。
CType 转换引用类型。
大概如此,我是2008,没vb6那般的控件数组。