GDI+ image zoom

[Iamthewalrus15]

Hey guys, I rarely have to deal with images so excuse my noobness. Anyway I downloaded the 101 examples from MS for vb.net and opened the GDI image manipulation.

' Make the PictureBox dimensions larger by 25% to effect the Zoom.
picImage.Width = CInt(picImage.Width * 1.25)
picImage.Height = CInt(picImage.Height * 1.25)

This zoom works great, the only problem is that it increases the size of the picturebox. I want to ZOOM in and out on the image, leaving the picturebox the same size. Anyone have any ideas?

[Hu Flung Dung]

Originally posted by Iamthewalrus15
Hey guys, I rarely have to deal with images so excuse my noobness. Anyway I downloaded the 101 examples from MS for vb.net and opened the GDI image manipulation.

' Make the PictureBox dimensions larger by 25% to effect the Zoom.
picImage.Width = CInt(picImage.Width * 1.25)
picImage.Height = CInt(picImage.Height * 1.25)

This zoom works great, the only problem is that it increases the size of the picturebox. I want to ZOOM in and out on the image, leaving the picturebox the same size. Anyone have any ideas?

I think the easiest way is to just put the picture box inside a Panel control.

However, there's got to be a way to do this without using Windows Forms controls.

[oxbow123]

Panel1 is used for options
Panel2 contain PictureBox

PictureArray is an array with pictures ;-)

I load the listbox with x items corresponding to X images in array

Private Sub ListBox1_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles ListBox1.SelectedIndexChanged
        Dim Width As Integer
        Dim Height As Integer
        Dim Ratio As Decimal
 
        If ListBox1.SelectedIndex > -1 Then
            If RadioButton1.Checked = True Then 'ZOOM 100%
                Height = PictureArray(ListBox1.SelectedIndex).Height
                Width = PictureArray(ListBox1.SelectedIndex).Width
                PictureBox1.Height = PictureArray(ListBox1.SelectedIndex).Height
                PictureBox1.Width = PictureArray(ListBox1.SelectedIndex).Width
            Else 'ZOOM to Fit into Panel2
                PictureBox1.Height = Panel2.Height
                PictureBox1.Width = Panel2.Width
 
                Ratio = PictureArray(ListBox1.SelectedIndex).width / PictureArray(ListBox1.SelectedIndex).height
                If Ratio < (PictureBox1.Width / PictureBox1.Height) Then
                    Height = PictureBox1.Height
                    Width = PictureBox1.Width * Ratio
                Else
                    Height = PictureBox1.Height / Ratio
                    Width = PictureBox1.Width
                End If
            End If
            PictureBox1.Image = PictureArray(ListBox1.SelectedIndex).GetThumbnailImage(Width, Height, Nothing, Nothing)
            PictureBox1.Tag = ListBox1.SelectedIndex
        End If
    End Sub

Hope this will help you

[MrPolite]

you have to use the drawimage function and only draw the visible portion of the image on the picturebox (without resizing the picturebox). Do this if you wanna be a little more efficient