如何使用factor变量使位图适合pictureBox1？

Question

In form1 constructor I have:

currentfactor = factor;
bitmapwithclouds = new Bitmap(@"D:\C-Sharp\Download File\Downloading-File-Project-Version-012\Downloading File\Resources\radar090.png");
pictureBox1.Image = ResizeImage(bitmapwithclouds, new Size((int)(bitmapwithclouds.Width * factor), (int)(bitmapwithclouds.Height * factor)));

The variable factor is now 2.5

The method ResizeImage is:

public Image ResizeImage(Image img, Size size)
{
    return new Bitmap(img, size);
}

The variable bitmapwithclouds is 512,512 and also pictureBox1 is 512,512 but once im doing the line with the factor in the constructor so the image in the pictureBox1 is resized to 1280,1280 and the pictureBox1 size is 512,512

The reason im using the factor is that later on the code i have a Load button where i load points/pixels i drawed coordinates List and draw them again on the pictureBox1 :

public static void Paint(Graphics e, double currentFactor, float kilometers)
        {
            float distance = kilometers / (float)1.09;
            Pen p;
            p = new Pen(Brushes.Green);
            if (points == null)
            {
                return;
            }
            foreach (PointF pt in points)
            {
                e.FillEllipse(Brushes.Red, (pt.X - distance) * (float)currentFactor, pt.Y * (float)currentFactor, 3f, 3f);
            }

So to see the points/pixels when i load them back on the right place im using the currentFactor variable.

The problem is that when im running my program the image is 1280,1280 while the pictureBox1 size is 512,512 I could make some math to divide or minus to reduce the size back again: But how ? And is that should be the way ?

If in the constructor i will not make

pictureBox1.Image = ResizeImage(bitmapwithclouds, new Size((int)(bitmapwithclouds.Width * factor), (int)(bitmapwithclouds.Height * factor)));

Then the points/pixels in the List points in the painth method will be show somewhere out of the pictureBox1 area.

Answer 1

If all you really need is to resize your picturebox based on the image it contains there is a much easier way.

pictureBox1.SizeMode = PictureBoxSizeMode.AutoSize;

This will fit the picturebox to the content.

I made a small example demonstrating this.

Hope it's helpful to you.

Kind regards.

Test project