VB.NET加載圖片問題

'先建立一個(gè)bitmap對象，指向圖像文件

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Dim pic As Bitmap = New Bitmap("e:\1.jpg")

'定義一個(gè)圖片框的graphics對象

Dim g As Graphics = PictureBox1.CreateGraphics()

'在圖片框上繪圖

g.DrawImage(pic, 0, 0, pic.Width, pic.Height)

'釋放bitmap對象

pic.Dispose()

'現(xiàn)在即可對文件進(jìn)行操作

在vbnet中，我在picturebox里面畫線，用滾動(dòng)條拉動(dòng)picturebox顯示最新畫出的圖

vb點(diǎn)虐 沒有自動(dòng)重畫功能，要在Paint事件中寫代碼對圖形重畫。

另外一種情況，如果在Image屬性設(shè)置了一幅圖像，圖像能夠保持完整性的。所以你可以把圖形繪在位圖上，把位圖綁定到Image屬性上。

先綁定一幅位圖：

Dim bm as New BitMap(800,600)

PictureBox1.Image=bm

作圖時(shí)不是對圖片框，而是在位圖上作圖。

dim gr As Grapthics=Graphics.FromImage(bm) '建立位圖的繪圖設(shè)備

接下來就可用gr 的繪圖方法作圖

作完圖，PictureBox1.Refresh 刷新一下。

請問如何用vb的圖片框畫圖？要求是鼠標(biāo)按下來畫矩形、圓之類的圖（旁邊有單選按鈕來選擇圖形）。

Dim x1 As Single, y1 As Single, s As Integer

Const pi = 3.14159265

Private Sub Form_Load()

Command1.Caption = "圓"

Command2.Caption = "矩形"

Command3.Caption = "三角"

Command4.Caption = "五角"

Command5.Caption = "清"

End Sub

Private Sub Command1_Click()

s = 1

End Sub

Private Sub Command2_Click()

s = 2

End Sub

Private Sub Command3_Click()

s = 3

End Sub

Private Sub Command4_Click()

s = 4

End Sub

Private Sub Command5_Click()

Picture1.Cls

End Sub

Private Sub Picture1_MouseDown(Button As Integer, Shift As Integer, x As Single, y As Single)

If Button = 1 Then x1 = x: y1 = y

End Sub

Private Sub Picture1_MouseMove(Button As Integer, Shift As Integer, x As Single, y As Single)

If Button = 1 Then

Picture1.AutoRedraw = False

Picture1.Refresh

Picture1.PSet (x1, y1)

Select Case s

Case 1

Picture1.Circle (x1, y1), Sqr((x - x1) ^ 2 + (y - y1) ^ 2)

Case 2

Picture1.Line (x1, y1)-(x, y), , B

Case 3

duobianxing x1, y1, x, y, 3, 60

Case 4

duobianxing x1, y1, x, y, 5, 36

End Select

End If

End Sub

Private Sub Picture1_MouseUp(Button As Integer, Shift As Integer, x As Single, y As Single)

If Button = 1 Then

Picture1.AutoRedraw = True

Select Case s

Case 1

Picture1.Circle (x1, y1), Sqr((x - x1) ^ 2 + (y - y1) ^ 2)

Case 2

Picture1.Line (x1, y1)-(x, y), , B

Case 3

duobianxing x1, y1, x, y, 3, 60

Case 4

duobianxing x1, y1, x, y, 5, 36

End Select

End If

End Sub

'duobianxing函數(shù)參數(shù)：

'zhongxinX-多邊形中心的橫坐標(biāo)

'zhongxinY-多邊形中心的縱坐標(biāo)

'dingdianX-多邊形一個(gè)頂點(diǎn)的橫坐標(biāo)

'dingdianY-多邊形一個(gè)頂點(diǎn)的縱坐標(biāo)

'bianhuoxing-正多邊形的邊數(shù)或者星形的星角數(shù)，例如biaohuoxing=5,dingjiao=72則為正五邊形,若dingjiao=36則為五角星(該函數(shù)將正多邊形按相鄰頂角點(diǎn)間的折點(diǎn)成直線的特殊星形繪制)

'dingjiao-多邊形的頂角的角度(角度制°)

Function duobianxing(ByVal zhongxinX As Single, ByVal zhongxinY As Single, ByVal dingdianX As Single, ByVal dingdianY As Single, ByVal bianhuoxing As Integer, ByVal dingjiao As Single)

If bianhuoxing = 0 Then Exit Function

l = Sqr((zhongxinX - dingdianX) ^ 2 + (zhongxinY - dingdianY) ^ 2) '星形中心到頂角距離

t1 = Abs(Tan((dingjiao / 2) * pi / 180)) '星形頂角的1/2求正切

t2 = Abs(Tan((360 / (2 * bianhuoxing)) * pi / 180)) '星形每條邊所對應(yīng)的中心角的1/2求正切

r = l * t2 / (t1 + t2) / Cos((dingjiao / 2) * pi / 180) '星形邊長

If zhongxinX = dingdianX Then '求星形中心到頂角這條線的角度j

j = IIf(dingdianY zhongxinY, 90, -90)

Else

j = Atn((zhongxinY - dingdianY) / (dingdianX - zhongxinX)) * 180 / pi

If dingdianX zhongxinX Then

If dingdianY zhongxinY Then

j = j - 180

Else

j = j + 180

End If

End If

End If

j1 = j - dingjiao / 2 '邊偏離初始角1

j2 = 360 / bianhuoxing + dingjiao + j - dingjiao / 2 '邊偏離初始角2(如果是正多邊形j1=j2)

px1 = dingdianX: py1 = dingdianY '指定星形的第一個(gè)頂點(diǎn)

For i = 1 To bianhuoxing * 2

If i Mod 2 = 0 Then

px2 = px1 + r * Cos(j2 * pi / 180): py2 = py1 - r * Sin(j2 * pi / 180) '指定星形下一個(gè)頂點(diǎn)

j2 = j2 + 360 / bianhuoxing '邊偏角+2個(gè)邊長對應(yīng)的中心角

Else

px2 = px1 - r * Cos(j1 * pi / 180): py2 = py1 + r * Sin(j1 * pi / 180)

j1 = j1 + 360 / bianhuoxing

End If

Picture1.Line (px1, py1)-(px2, py2) '畫線

px1 = px2: py1 = py2

Next

End Function