Rotating an Image from 0 to 360 degrees in Zoom Mode. Any possibilities ?

[nkvb]

Hello

Will it be possible to rotate an image from 0 to 360 in Zoom mode ? If No then there is no point in continuing further more.

if Yes and with some possibilities then below basic coding from my end

Have two images and their original sizes are as follows
Img A. ) Size is 800 W and 779 H

For ImgA Coding

Public Class Frm
Private imgPathA As String = "C:\Images\imgA.jpg"

Private Sub Frm_Load(sender As Object, e As EventArgs) Handles MyBase.Load
       Call FormLayout()    
End Sub

Private Sub FormLayout()
        PictureBox1.Size = New Size(800, 700)  
        PictureBox1.Image = Image.FromFile(imgPathA)
End Sub

ImgA is rotating as per below _PaintEvent

Private Sub PictureBox1_Paint(sender As Object, e As PaintEventArgs) Handles PictureBox1.Paint
  Dim dgr As Double
  If dgr = 360 Then dgr = 0
     dgr += txtBxDegrees.Text 
     PictureBox1.Invalidate()    
     PictureBox1.Image = Image.FromFile(imgPathA)
     PictureBox1.SizeMode = PictureBoxSizeMode.Zoom

        With e.Graphics
            .TranslateTransform(PictureBox1.Width \ 2, PictureBox1.Height \ 2)
            .RotateTransform(CSng(dgr))
            Dim imgBmp = New Bitmap(imgPathA)
            .DrawImage(imgBmp, -imgBmp.Width \ 2, -imgBmp.Height \ 2)
        End With

End Sub
End Class

Original size for below
Img B. ) size is 500 W and 500 H

ImgB Coding

Public Class Frm
Private imgPathB As String = "C:\Images\imgB.jpg"

Private Sub Frm_Load(sender As Object, e As EventArgs) Handles MyBase.Load
       Call FormLayout()    
End Sub

Private Sub FormLayout()
        PictureBox1.Size = New Size(800, 700)  
        PictureBox1.Image = Image.FromFile(imgPathB)
End Sub

ImgB is Not Rotating as per below _PaintEvent

Private Sub PictureBox1_Paint(sender As Object, e As PaintEventArgs) Handles PictureBox1.Paint
  Dim dgr As Double
  If dgr = 360 Then dgr = 0
     dgr += txtBxDegrees.Text 
     PictureBox1.Invalidate()    
     PictureBox1.Image = Image.FromFile(imgPathB)
     PictureBox1.SizeMode = PictureBoxSizeMode.Zoom

        With e.Graphics
            .TranslateTransform(PictureBox1.Width \ 2, PictureBox1.Height \ 2)
            .RotateTransform(CSng(dgr))
            Dim imgBmp = New Bitmap(imgPathB)
            .DrawImage(imgBmp, -imgBmp.Width \ 2, -imgBmp.Height \ 2)
        End With

End Sub
End Class

Is there any possiblity for Zoomed imageB to rotate 0 to 360 degrees ?

Thanks
nkVb

[Shaggy Hiker]

If it works for one image, it will work for the other, so if it is not, then there's something else going on here. I see a few oddities. For one thing, the call to Invalidate probably does nothing. It doesn't help, but it probably doesn't do anything much at all. After all, it would just cause the image to become 'dirty' such that it paints...but it's going to do that anyways, because you're changing the image (as far as the control knows), so it will be dirty anyways. I don't think this will matter, but it could have a negative impact depending on exactly what happens.

The other point that I trip over is that you create a new bitmap every time through the Paint event. That should happen a LOT, and that can't be good. In fact, you appear to be doing it twice, because you call Image.FromFile, then later create a new Bitmap. Both of those create new Images, and do so in every Paint event, and Paint events happen in response to all kinds of things, including debugging. One way or another, I would guess that this is the cause. I'm actually a bit surprised that the first one does work, as it feels like you're rotating the wrong thing, but then again, I haven't rotated images and don't know the quirks around it.

[nkvb]

SH Sir,

Thank you so much for the response

the call to Invalidate probably does nothing. It doesn't help, but it probably doesn't do anything much at all. After all, it would just cause the image to become 'dirty' such that it paints...but it's going to do that anyways, because you're changing the image (as far as the control knows), so it will be dirty anyways. I don't think this will matter, but it could have a negative impact depending on exactly what happens

If I put ' mark before PictureBox1.Invalidate(). The imageA does not rotate which was rotating. FYI
Probably PictureBox1.Invalidate() is required for rotating the image.

In fact, you appear to be doing it twice, because you call Image.FromFile, then later create a new Bitmap. Both of those create new Images, and do so in every Paint event, and Paint events happen in response to all kinds of things, including debugging. One way or another, I would guess that this is the cause. I'm actually a bit surprised that the first one does work

Informative. Let me check on this and revert back

nkVb

[nkvb]

Dear SH sir,

because you call Image.FromFile

Have removed the full command 'PictureBox1.Image = Image.FromFile(imgPathA) from both the examples as mentioned above

Also emphasized on your remark

After all, it would just cause the image to become 'dirty'

which made me think practically to change and increase the size of imgB from 500 W X 500 H to 730 W and 730 H which I did through https://imageresizer.com/. Also changed the Picturebox1.Size to suit the desired requirements.

Under the circumstances, Though not satisfied with sharpness of image, I am moving on.

Thank you so much Sir, for the information that you have provided here.

nkVb

[build]

Indeed, it is possible to turn an image from 0 to 360 degrees in the Zoom mode. The problem is that you’re using the SizeMode = PictureBoxSizeMode.Zoom property which fits the image to the PictureBox then the rotation is applied. To rectify this draw the image by loading it into a Bitmap, apply the rotation transformation on the Bitmap then draw the new Bitmap on the PictureBox.

[.paul.]

…then draw the new Bitmap on the PictureBox.

Set the .Image property of the PictureBox. DON’T draw on the PictureBox.

[nkvb]

I thought I resolved the issue from very different perspective but it seems there is coding to this.

build

Indeed, it is possible to turn an image from 0 to 360 degrees in the Zoom mode. The problem is that you’re using the SizeMode = PictureBoxSizeMode.Zoom property which fits the image to the PictureBox then the rotation is applied. To rectify this draw the image by loading it into a Bitmap, apply the rotation transformation on the Bitmap then draw the new Bitmap on the PictureBox.

.Paul

Set the .Image property of the PictureBox. DON’T draw on the PictureBox

Can you please elaborate it. I am confused as I am working with Images, Picturebox , .DrawImage etc for first time. I tried to adopt your meaning to the below coding but somewhere I've made blunder.
What i've understood I've removed the PictureBox1.sizeMode = PictureSizeMode.Zoom
below my Paint event is completely wrong after going though your replies and implementing the same and against posted in #1

Public Class Frm
Private imgPathB As String = "C:\Images\imgB.jpg"

Private Sub Frm_Load(sender As Object, e As EventArgs) Handles MyBase.Load
       Call FormLayout()    
End Sub

Private Sub FormLayout()
        PictureBox1.Size = New Size(800, 700)  
        PictureBox1.Image = Image.FromFile(imgPathB)
End Sub
Private Sub PictureBox1_Paint(sender As Object, e As PaintEventArgs) Handles PictureBox1.Paint
  Dim dgr As Double
  If dgr = 360 Then dgr = 0
     dgr += txtBxDegrees.Text 
     PictureBox1.Invalidate()    
     'PictureBox1.Image = Image.FromFile(imgPathB)
     'PictureBox1.SizeMode = PictureBoxSizeMode.Zoom

     With e.Graphics

            .DrawImage(Image.FromFile(imgPathB), New Point(100, 5))
            .TranslateTransform(PictureBox1.Width \ 2, PictureBox1.Height \ 2)
            .RotateTransform(CSng(dgr)) 
      
            'PictureBox1.Image = imgBmp 'Image.FromFile(imgPathB)
        End With

End Sub

Thanks
nkVb

[.paul.]

This code loads a bitmap in a picturebox…

PictureBox1.Image = Image.FromFile(imgPathB)

This code draws on a picturebox…

Private Sub PictureBox1_Paint(sender As Object, e As PaintEventArgs) Handles PictureBox1.Paint
  Dim dgr As Double
  If dgr = 360 Then dgr = 0
     dgr += txtBxDegrees.Text
     ‘ text is a String. It is not a double
     PictureBox1.Invalidate()    

     With e.Graphics

            .DrawImage(Image.FromFile(imgPathB), New Point(100, 5))
            .TranslateTransform(PictureBox1.Width \ 2, PictureBox1.Height \ 2)
            .RotateTransform(CSng(dgr))

        End With

End Sub

This code draws in a bitmap, which you then load into your picturebox image…
(Don’t put this code in your PictureBox_Paint event handler sub)

Dim img As New Bitmap(PictureBox1.Width, PictureBox1.Height)
Dim gr As Graphics = Graphics.FromImage(img)

With gr

    .TranslateTransform(img.Width \ 2, img.Height \ 2)
    .RotateTransform(CSng(dgr)) 
    .DrawImage(Image.FromFile(imgPathB), New Point(100, 5))
      
End With

PictureBox1.Image = img

Edit: The first two code snippets are just to show you the differences between loading an image in a picturebox, and alternatively drawing on a picturebox.
The third code snippet shows you the best way to achieve what you’re trying to achieve…

[nkvb]

.Paul

Indeed Good Explanation with 3 Code snippets of respective differentation

The third code snippet shows you the best way to achieve what you’re trying to achieve…

This code draws in a bitmap, which you then load into your picturebox image…
(Don’t put this code in your PictureBox_Paint event handler sub)

I incorporated your code in formlayout

Private Sub FormLayout()
PictureBox1.Size = New Size(800, 700)  

Dim img As New Bitmap(PictureBox1.Width, PictureBox1.Height)
Dim gr As Graphics = Graphics.FromImage(img)

With gr
    '.TranslateTransform(img.Width \ 2, img.Height \ 2)
    '.RotateTransform(CSng(dgr)) 
    .DrawImage(Image.FromFile(imgPathB), New Point(100, 5))
End With
PictureBox1.Image = img
End Sub

I've temporarily removed the .TranslateTransform(img.Width \ 2, img.Height) \ & .RotateTransform(CSng(dgr))

How do I zoom the above image ? because PictureBox1.SizeMode = PictureBoxSizeMode.Zoom has no effect

How to rotate the same using below Paint Event because the image shifts from original location to center, towards right side, below,
right down corner of PictureBox etc... and not rotating from center

Private Sub PictureBox1_Paint(sender As Object, e As PaintEventArgs) Handles PictureBox1.Paint
  Dim dgr As Double
  If dgr = 360 Then dgr = 0
     dgr += Val(txtBxDegrees.Text)
     PictureBox1.Invalidate()    
 With e.Graphics
            .TranslateTransform(PictureBox1.Width \ 2, PictureBox1.Height \ 2)
            .RotateTransform(CSng(dgr))
             Dim img As New Bitmap(PictureBox1.Width, PictureBox1.Height)
            .DrawImage(Image.FromFile(imgPathB), -img.Width \ 2, -img.Height \ 2)
 End With
End Sub

Wanting to Zoom Image and rotate the same

Thanks nkvb

[.paul.]

I’ve told you how the picturebox works. If you’re drawing on the picturebox, as you are, the zoom is going to have absolutely no effect. Zoom only works on images in the picturebox, not painted on the picturebox.

[.paul.]

https://learn.microsoft.com/en-us/do...owsdesktop-8.0

[.paul.]

If your bitmap is the same size as the picturebox you’re using to display the bitmap, your pictureboxSizeMode.zoom won’t stretch or shrink your image, because it already fits your picturebox. I really don’t know what you expect to happen…

[.paul.]

This is a simple example of rotating a square in a PictureBox. I used a NumericUpDown control instead of a TextBox...

Private Sub NumericUpDown1_ValueChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles NumericUpDown1.ValueChanged
    Dim img As New Bitmap(PictureBox1.Width, PictureBox1.Height)
    Dim gr As Graphics = Graphics.FromImage(img)

    With gr

        .TranslateTransform(img.Width \ 2, img.Height \ 2)
        .RotateTransform(CSng(NumericUpDown1.Value))
        .FillRectangle(Brushes.Red, New Rectangle(-150, -150, 300, 300))

    End With

    PictureBox1.Image = img
End Sub

[nkvb]

Thank you .Paul for your comments in #10, #11 & #12. this made the concept quite clear of Picture box and Images.

I've not tried your solution as per #13 but definately will give it a try.
I had almost given up but what i could achieve from StackOverflow Link https://stackoverflow.com/questions/2144592/resizing-images-in-vb-net
and my re-coding goes as below

Public Class Frm
Private imgPathB As String = "C:\Images\imgB.jpg"

Private Sub Frm_Load(sender As Object, e As EventArgs) Handles MyBase.Load
       Call FormLayout()    
End Sub

Private Sub FormLayout()
        PictureBox1.Size = New Size(800, 700)  
        PictureBox1.Image = Image.FromFile(imgPathB)
End Sub
Private Sub PictureBox1_Paint(sender As Object, e As PaintEventArgs) Handles PictureBox1.Paint
  Dim dgr As Double
  If dgr = 360 Then dgr = 0
     dgr += txtBxDegrees.Text 
     PictureBox1.Invalidate()    
  
  With e.Graphics
            .TranslateTransform(PictureBox1.Width \ 2, PictureBox1.Height \ 2)
            .RotateTransform(CSng(dgr))
            Dim imgBmp = New Bitmap(imgPathB)
            imgBmp = ResizeImage(imgBmp, PictureBox1.Width, PictureBox1.Height)
            .DrawImage(imgBmp, -imgBmp.Width \ 2, -imgBmp.Height \ 2)
            'the above rotates
        End With
End Sub

Public Shared Function ResizeImage(ByVal InputBitmap As Bitmap, width As Integer, height As Integer) As Bitmap
        Return New Bitmap(InputBitmap, New Size(width, height))
End Function

With the above one can re-size the image as being represented as Zoomed Image and happy to rotate it.

Thanks
nkvb

[nkvb]

.Paul

Have tried your coding as per #13 and beautiful Red Square rotating.
and if I click down in NumericUpDown ie below 0. it does not go in negative value and to rotate the image in reverse direction.

Thanks
nkvb

[.paul.]

.Paul

…and if I click down in NumericUpDown ie below 0. it does not go in negative value and to rotate the image in reverse direction.

Thanks
nkvb

Is that a good thing or a bad thing?

[.paul.]

The NumericUpDown has Minimum, Maximum, and increment Properties that you might find useful