vb.net align imported coordinates to an image

Hi All,

I am working on a simple tool that will import coordinates with some other info, which all works great. What I am having an issue with is, I am actually creating buttons that are placed at the center of particular points on an image in my form. The coordinates match the physical dimensions of a circuit board. I am using a very flat high quality image of the board as the image background, but of course there is a certain amount of stretch and skew of the image. Is there a way to adjust an image so that I can align it to the button coordinates perfectly? Or even better, is there a way to click on several points to perfectly align the buttons to the image? I hope I am making sense explaining what I am trying to do. Thanks

Better to show us your code...

Instead of using the image of your circuit board as your backgroundimage, use you form.paint event, and draw the circuit board image at actual size on your form…

Code:

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Private Sub Form1_Paint(sender as Object, e as PaintEventArgs) Handles Me.Paint
    e.Graphics.DrawImage(yourImage, Point.Empty)
End Sub

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Hi paul... so what I am doing right now with the image is trying to get it to be a 1:1 copy of the physical circuit board dimensions, but no matter what it is always off just a bit. The dimensions on the circuit board are quite accurate and basically a .CAD file. So if I use the CAD file to import into my project, I know the placement of the buttons are perfect, but the image of course never is quite perfect as I cannot get just the right alignment. I was hoping for a way to use some reference point on the imported file and then use the same on the image to get a perfect alignment between the two. It seems like the larger the image, the more it starts to skew off in both X & Y.

If it really is a case that all of your coordinates are off by a uniform amount, it would be easy to use a couple of NumericUpDown controls to align one button manually, then when you’re happy with it, load the entire set of buttons using your file of coordinates, with each coordinate offset by your previously determined number of pixels for the left and top positions…

Thanks paul. Do you mean change the file of coordinates with the offset of that first button?

I meant loading your full set of buttons with the offset, but if changing your file works for you, do that.

Thanks paul, I will give this a try

Hi paul, ok I have tried a couple of small things to get proper adjustment but have had no luck. There seems to be enough stretch in the image where I cannot get alignment from corner to corner set properly. With the file coordinates being exact. I convert the board image from inch to pixels and adjust the size to that. I have even gone as far as placing the board over my screen image and see that the alignment is almost exact. I make the form sizeable so I can try and tweak the size to match the buttons on the screen only to see that the offset is not uniform across the image. I'm not really sure how I will get around this.... my search continues.

You realise that size, ie height and width are the external dimensions of the form?
Use (in form_load) Me.SetClientSizeCore(exact width in pixels, exact height in pixels)

BTW. I’d make the form fixedsingle or fixeddialog.

Also, stretching or compressing the image will never have any good results with exact coordinates

That is what I am finding. The only way I have found to do this is in Excel, where it lets you resize the image in increments from top, bottom, left, right. For vb.net, I have checked every dimension possible and everything matches until the data loads on the screen. The variation is generally at the top and bottom of the image, maybe 1mm of offset. The center of the image is pretty well aligned. My image is 715px, 672px

https://docs.microsoft.com/en-us/dot...owsdesktop-6.0

Set your Form BackgroundImageLayout property to None

Ok, that at least seems to have placed buttons in a uniform offset. I have approx 125 buttons and they are off roughly 1mm to the right and 1mm down.

you had mentioned before about form1_paint event? what would that do different?

Quote:

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Originally Posted by mikeg71

you had mentioned before about form1_paint event? what would that do different?

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Compared to what you have now, it probably wouldn't do anything, as i posted, but try this...

Code:

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Private Sub Form1_Paint(sender as Object, e as PaintEventArgs) Handles Me.Paint
    e.Graphics.DrawImage(yourImage, New Point(-1, -1))
End Sub

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I can't guarantee this'll work with other images

That code will draw the unstretched image full size, at the point (top-left) specified

It gives me a bunch of overloads with 'DrawImage' underlined

That is the correct overload. A bitmap, and a point

E.graphics.DrawImage(New BitMap(“path”), New Point(-1,-1))

It attempts to load but I get an invalid parameter error with no details.

Code:

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    Private Sub Form1_Paint(sender As Object, e As PaintEventArgs) Handles Me.Paint
        e.Graphics.DrawImage(New Bitmap("4-946020.bmp"), New Point(-1, -1))
    End Sub

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* update.... I need coffee, thats not a path

However, you are correct, it does do strange things to the image size. So for now, I am using:

Code:

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    Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
        Me.SetClientSizeCore(715, 672)
        Call CreateBtns()
    End Sub

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And my image is sized to 715 x 672 pixels.

The form paint code will draw your image at 100% no stretching, no compressing.
If your stored image isn’t 715px*672px, then if that is the size at which all of your coordinates were calculated, you need to resize the image to that size before drawing the image in form paint. The New Point(x,y) argument can be used to offset the position the image is drawn at. A negative -1px x value will move the button positions 1px to the right. A positive x value will move your on-form button positions to the left… The most important part is to use the correct sized image. Offsets can be tested by a process of trial and error.