Question

VB里怎样在image或picture控件内按比例缩小显示图片

image控件srtetch属性会使图片变形，picture控件的AutoRedraw和AutoSize不能按控件大小缩小图片,用loadpicture函数可以显示固定尺寸的图片吗？

Answer 1

可以用代码实现。
以下代码是我原来做过的实例里剪出来的，你可以参考一下，imgPreview 为Image对象。

Private Type PreviewSize
sngLeft As Single
sngTop As Single
sngWidth As Single
sngHeight As Single
intZoon As Integer
End Type

Private muPreviewSize As PreviewSize
Private Const cmChangeSize = 1.2

'// 缩小
Private Sub Command1_Click()
With muPreviewSize
.intZoon = .intZoon - 1
.sngHeight = .sngHeight / cmChangeSize
.sngWidth = .sngWidth / cmChangeSize

imgPreview.Stretch = True
imgPreview.Move .sngLeft, .sngTop, .sngWidth, .sngHeight

'// 如果已经缩小了9倍则缩小按钮不可用
If .intZoon < -9 Then
Command1.Enabled = False
Command2.Enabled = True
Else
Command2.Enabled = True
End If
End With
End Sub

'// 放大
Private Sub Command2_Click()
With muPreviewSize
.intZoon = .intZoon + 1
.sngHeight = .sngHeight * cmChangeSize
.sngWidth = .sngWidth * cmChangeSize

imgPreview.Stretch = True
imgPreview.Move .sngLeft, .sngTop, .sngWidth, .sngHeight

'// 如果已经放大了9倍则放大按钮不可用
If .intZoon > 9 Then
Command2.Enabled = False
Command1.Enabled = True
Else
Command1.Enabled = True
End If
End With
End Sub

Private Sub Form_Load()
With muPreviewSize
.intZoon = 0
'// + 0.5 为Image的边框
.sngHeight = imgPreview.Height + 0.5
.sngWidth = imgPreview.Width + 0.5
.sngLeft = imgPreview.Left
.sngTop = imgPreview.Top
End With
End Sub

Answer 2

用image(strenth设为flase)就可以了,把图片装入后重新按比例计算并设定(strenth=true)image的大小

Answer 3

loadpicture是调用图片,并不能控制它的大小

Answer 4

VB控件无此功能.