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VB.NET - Picture box - Highligting Rectanle area on picturebox.

Posted on 2009-04-13
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Last Modified: 2013-11-26
Dear Experts

I have a jpeg file that I am displaying in my Vb.NET application using picture box control
I have the word coordinate position of all these words present in the jpeg file.

Right now I am using the pictirebox sizemode as stretch mode. I am able to highlight the word at the correct position as per the code snippet attached below.

But, as per a new requirement, I can no longer go with stretch mode of picturebox. I have to use the zoom mode.

How do I adjust the "rect" coordinates now so that it highlights the words in zoom mode. I have tried many ways to adjust the coordinates but no success.

I appreciate any help on this.

Thanks in advance

' READ target image file

 

        Dim origImage As New Bitmap(imageFileName)

        Dim targetimage As Bitmap = New Bitmap(origImage, origImage.Width , origImage.Height )

        PictBox_Target_Height_Ratio = PictureBox1.Height / targetimage.Height

        PictBox_Target_Width_Ratio = PictureBox1.Width / targetimage.Width

        PictureBox1.SizeMode = PictureBoxSizeMode.StretchImage

 

 

    Private Sub PictureBox1_Paint(ByVal sender As Object, ByVal e As System.Windows.Forms.PaintEventArgs) Handles PictureBox1.Paint

        Dim highlightColor As Color = Color.FromArgb(196, 255, 255, 0)

        Dim brush As New SolidBrush(highlightColor)

        Dim rect As New Rectangle(iLeft * PictBox_Target_Width_Ratio, iTop * PictBox_Target_Height_Ratio, (iRight - iLeft) * PictBox_Target_Width_Ratio, (iBottom - iTop) * PictBox_Target_Height_Ratio)

 

        e.Graphics.FillRectangle(brush, rect)

        brush.Dispose()

    End Sub

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Question by:arsmed840
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oobayly earned 500 total points
Comment Utility
The following method will convert a point in control coordinates to a point in Image coordinates. All it does is determine the bounds of the actual image in control coordinates that the, and then maps the control coordinates to image coordinates.
Private Function GetImagePoint(ByVal pb As PictureBox, ByVal p As Point) As Point

    ' Get the Client rectangle and the scale at which the image is displayed

    Dim client As Rectangle = pb.ClientRectangle

    Dim scale As Double = Math.Min(CDbl(client.Width) / pb.Image.Width, CDbl(client.Height) / pb.Image.Height)

    

    ' Get the bounds of the image in control coordinates

    Dim imgBounds As New Rectangle(0, 0, CInt((pb.Image.Width * scale)), CInt((pb.Image.Height * scale)))

    imgBounds.X = CInt(((client.Width - imgBounds.Width) / 2))

    imgBounds.Y = CInt(((client.Height - imgBounds.Height) / 2))

    

    ' Return the point in image coordinates

    Return New Point(CInt(((p.X - imgBounds.X) / scale)), CInt(((p.Y - imgBounds.Y) / scale)))

End Function

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