Help with System.Drawing.Region & System.Drawing.Bitmap

What I am trying to do is make a routine that take a System.Drawing.Color and a System.Drawing.Bitmap in and returns a region excluding the passed in color. Sounds kinda easy. At least I thought so..... I have overflow in System.Drawing.dll......

Code:

---

public System.Drawing.Region ToRegion(System.Drawing.Color color, System.Drawing.Bitmap image)
{
        System.Drawing.Color c;
            System.Drawing.Region r1 = null;
            System.Drawing.Region r2 = null;

            int[] colors = new int[] {System.Drawing.ColorTranslator.ToWin32(color),0}
   
        for(int x = 0; x < image.Width; x++)
            {
                for(int y = 0; y < image.Height; y++)
                {
                        c = image.GetPixel(x, y);
                        colors[1] = System.Drawing.ColorTranslator.ToWin32(c);
                        if(color[0] != color[1])
                        {
                                if(r1 == null)
                                {
                                        r1 = new System.Drawing.Region(new System.Drawing.Rectangle(x, y, x + 1, y + 1));
                                }
                                else
                                {
                                              r2 = new System.Drawing.Region(new System.Drawing.Rectangle(x, y, x + 1, y + 1));
                                              r1.Union(r2); //I'm not sure on this either
                                }
                        }
                }
            }
            return r1;
}

---

As far as I can tel that code should work and it returns with no errors, BUT when you go say

Code:

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frm.Region = ToRegion(System.Drawing.Color.Black, imgIGotFromFile);

---

it runs, and runs, and runs, and System.OverFlowExeption in system.drawing.dll

I also tried GrapicsPath.AddRectangle and the contructing a Region from the path but same overflow error.

I don't want to use API if I can avoid it. Especially since it should work in the framework. I have vb6 code just like this using Region Api and SetWindowRgn that works......

Help!!!!

Are you calling this in OnPaint or something that redraws UI ?

No right now I call it in a form that creates a test form.

Code:

---

Form frm = new Form();
Region r = ToRegion(Color.Black, imageFromAFile);
frm.Region = r;

---

I get r fine but the frm.Region = r causes overflow and to be honest I can't find a way to validate r very well.....

I don't know and or at least I can't test this but you may try replacing these (x, y) in r1 with numbers . Otherwise , I've got no clue .

Me either but I'm thinking about it....

this code is actualy not all full of errors

Code:

---

namespace Ezekiel.Windows.Forms
{
        /// <summary>
        /// Collection of usefull functions.
        /// </summary>
        public class Helpers
        {
                /// <summary>
                /// Helper methods for System.Drawing.Regions.
                /// </summary>
                public class Region
                {
                        /// <summary>
                        /// Gets a System.Drawing.Region equal to <paramref name="image"/> excluding <paramref name="excludeColor"/>.
                        /// </summary>
                        /// <param name="excludeColor">System.Drawing.Color to exclude from the generated System.Drawing.Region.</param>
                        /// <param name="image">System.Drawing.Bitmap the the generated System.Drawing.Region will equal ecluding <paramref name="excludeColor"/></param>
                        /// <returns>System.Drawing.Region equal to <paramref name="image"/> excluding <paramref name="excludeColor"/>.</returns>
                        public static System.Drawing.Region FromBitmap(System.Drawing.Color excludeColor, System.Drawing.Bitmap image)
                        {
                                System.Drawing.Color c;
                                System.Drawing.Region r1 = null;
                                System.Drawing.Region r2 = null;

                                int[] colors = new int[] {System.Drawing.ColorTranslator.ToWin32(excludeColor),0};
   
                                for(int x = 0; x < image.Width; x++)
                                {
                                        for(int y = 0; y < image.Height; y++)
                                        {
                                                c = image.GetPixel(x, y);
                                                colors[1] = System.Drawing.ColorTranslator.ToWin32(c);
                                                if(colors[0] != colors[1])
                                                {
                                                        if(r1 == null)
                                                        {
                                                                r1 = new System.Drawing.Region(new System.Drawing.Rectangle(x, y, x + 1, y + 1));
                                                        }
                                                        else
                                                        {
                                                                r2 = new System.Drawing.Region(new System.Drawing.Rectangle(x, y, x + 1, y + 1));
                                                                r1.Union(r2); //I'm not sure on this either
                                                        }
                                                }
                                        }
                                }
                                return r1;
                        }
                }
        }
}

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I hate not being able to make something work. I haven't slept since I started this because my brain won't shut up about why won't it work.....