Possible g.Transform usage

Question

I have the following output onto a picturebox that I would like to home in on a specific part of the image so I can zoom in on that part. I am not familiar much with the Transform property and am wondering if I am approaching what I am trying to achieve properly. If you look at the following picture that whole image is on a picturebox surface and the square black box I placed there I would like to focus in on it and have it fill the picturebox in essence zooming in. Hopefully I am making myself clear.

Thanks

Les

Answer 1

Hi @Les ,

how to we find all posts that I have made here like the old site did?

You can see them in 'Activity'.

For picture zoom, also check : https://www.codeproject.com/Articles/21097/PictureBox-Zoom
In Visual Basic, the code looks like:

    Private _ZoomFactor As Integer  
    Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load  
        TrackBar1.Minimum = 1  
        TrackBar1.Maximum = 3  
        TrackBar1.Value = 2  
        _ZoomFactor = TrackBar1.Value  
        PictureBox2.SizeMode = PictureBoxSizeMode.StretchImage  
        PictureBox1.Image = Image.FromFile("your picture path")  
    End Sub  
    Private Sub TrackBar1_ValueChanged(sender As Object, e As EventArgs) Handles TrackBar1.ValueChanged  
        _ZoomFactor = TrackBar1.Value  
        Label1.Text = String.Format("x{0}", _ZoomFactor)  
    End Sub  
  
    Private Sub PictureBox1_MouseMove(sender As Object, e As MouseEventArgs) Handles PictureBox1.MouseMove  
        If PictureBox1.Image Is Nothing Then Return  
        UpdateZoomedImage(e)  
    End Sub  
    Private Sub UpdateZoomedImage(ByVal e As MouseEventArgs)  
        Dim zoomWidth As Integer = PictureBox2.Width / _ZoomFactor  
        Dim zoomHeight As Integer = PictureBox2.Height / _ZoomFactor  
        Dim halfWidth As Integer = zoomWidth / 2  
        Dim halfHeight As Integer = zoomHeight / 2  
        Dim tempBitmap As Bitmap = New Bitmap(zoomWidth, zoomHeight, PixelFormat.Format24bppRgb)  
        Dim bmGraphics As Graphics = Graphics.FromImage(tempBitmap)  
        bmGraphics.InterpolationMode = InterpolationMode.HighQualityBicubic  
        bmGraphics.DrawImage(PictureBox1.Image, New Rectangle(0, 0, zoomWidth, zoomHeight), New Rectangle(e.X - halfWidth, e.Y - halfHeight, zoomWidth, zoomHeight), GraphicsUnit.Pixel)  
        PictureBox2.Image = tempBitmap  
        bmGraphics.DrawLine(Pens.Black, halfWidth + 1, halfHeight - 4, halfWidth + 1, halfHeight - 1)  
        bmGraphics.DrawLine(Pens.Black, halfWidth + 1, halfHeight + 6, halfWidth + 1, halfHeight + 3)  
        bmGraphics.DrawLine(Pens.Black, halfWidth - 4, halfHeight + 1, halfWidth - 1, halfHeight + 1)  
        bmGraphics.DrawLine(Pens.Black, halfWidth + 6, halfHeight + 1, halfWidth + 3, halfHeight + 1)  
        bmGraphics.Dispose()  
        PictureBox2.Refresh()  
    End Sub  

Result of my test.

Hope it could be helpful.

Best Regards,
Xingyu Zhao
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Answer 2

You can zoom by resizing an image with DrawImage
Like in the second example in MSDN at Cropping and Scaling Images in GDI+

Answer 3

No one has answered this post. I need to know what I am doing thanks

Les