利用BitBlt画的图，如何重画？

[neighbornet]

用BitBlt在PictureBox上画图成功，但如果把PictureBox前面挡住的窗口移走后，PictureBox被挡住部分没有更新，请问应该如何刷新呢？用OnPaint事件也不行。


Public Class Form1

Declare Auto Function BitBlt Lib "GDI32.DLL" ( _
ByVal hdcDest As IntPtr, _
ByVal nXDest As Integer, _
ByVal nYDest As Integer, _
ByVal nWidth As Integer, _
ByVal nHeight As Integer, _
ByVal hdcSrc As IntPtr, _
ByVal nXSrc As Integer, _
ByVal nYSrc As Integer, _
ByVal dwRop As Int32) As Boolean

Private Const ROP_SrcCopy As Integer = &HCC0020


Private Declare Function SelectObject Lib "GDI32" (ByVal hDC As Integer, ByVal hObject As Integer) As Integer



Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click

TestBitBlt()
End Sub

Private Sub PictureBox1_Paint(ByVal sender As System.Object, ByVal e As System.Windows.Forms.PaintEventArgs) Handles PictureBox1.Paint

End Sub


Private Sub TestBitBlt()
Dim bmp As Bitmap = Image.FromFile("C:\Documents and Settings\All Users\Documents\My Pictures\Sample Pictures\Sunset.jpg")

Dim g1 As Graphics = Graphics.FromImage(bmp)
Dim g2 As Graphics = Me.PictureBox1.CreateGraphics
Dim hdc1 As IntPtr = g1.GetHdc
Dim hdc2 As IntPtr = g2.GetHdc
SelectObject(hdc1, bmp.GetHbitmap()) '
BitBlt(hdc2, 0, 0, bmp.Width, bmp.Height, hdc1, 0, 0, ROP_SrcCopy)
g1.ReleaseHdc()
g2.ReleaseHdc()
g1.Dispose()
g2.Dispose()
End Sub


End Class

[jiantheone]

先用 PictureBox.Invalidate() 清除图片 然后再重画 重画代码可以写在Paint事件里

[jiantheone]

GDI绘图不错 图不是很大的话 没必要用API BitBlt

[devmiao]

不好意思可能还得画一次哦，没办法恢复的，喵~

[jiantheone]

PictureBox.Invalidate() 要写在别的地方 然后Paint事件里写重画代码

[neighbornet]

试过了，没用。难为死了！！！！

[Quote=引用 5 楼 jiantheone 的回复:]
PictureBox.Invalidate() 要写在别的地方 然后Paint事件里写重画代码
[/Quote]

[jiantheone]

你画到哪里的？ Me.PictureBox1？

[jiantheone]

直接用GDI好了 GDI用完干嘛还要绕个圈子去用 BitBlt

[neighbornet]

试过了，Paint事件也不行的

[Quote=引用 1 楼 jiantheone 的回复:]
先用 PictureBox.Invalidate() 清除图片 然后再重画 重画代码可以写在Paint事件里
[/Quote]

[jiantheone]

直接用GDI好了
Private Sub PictureBox1_Paint(ByVal sender As System.Object, ByVal e As System.Windows.Forms.PaintEventArgs) Handles PictureBox1.Paint

Dim bmp As Bitmap = Image.FromFile("C:\Documents and Settings\All Users\Documents\My Pictures\Sample Pictures\Sunset.jpg")

Dim g As Graphics = e.Graphics
g.DrawImage(bmp, 0, 0)
End Sub

然后其他地方用PictureBox.Invalidate()就可以清除了 也能达到你想要的效果

[hhddzz]

OnPaint里面g2不要用CreateGraphics，用e.Graphics
后面也不能Dispose g2,Hdc要释放掉。

[neighbornet]

画到Me.PictureBox1。
尝试把TestBitBlt函数放到PictureBox的OnPaint事件中，在窗口或PictureBox1的Resize或其它事件中用PictureBox1.Invalidate或Refresh都没办法实现重画。

[Quote=引用 7 楼 jiantheone 的回复:]
你画到哪里的？ Me.PictureBox1？
[/Quote]