Unhandled Exception: System.ArgumentException: Cannot widen from source type to target type

Question

the following scripts have unhandled exceptions.Unhandled Exception: System.ArgumentException: Cannot widen from source type to target type either because the source type is a not a primitive type or the conversion cannot be accomplished. do anybody know? i set the breakpoint. it is the setvalue line give me this error. but i do not know whats wrong.

    System.Array pixelDataO;
    IPixelBlock3 pBlockO_3 = (IPixelBlock3)pBlockO;
    pixelDataO = (System.Array)pBlockO_3.get_PixelData(0);
   // Console.WriteLine(pixelDataO);
    int maxy = -1;
    Console.WriteLine("going rastermerge");
    //loop through each pixel in the pixelblock and do calculation
    for (int x = 0; x < pBlock1_3.Width; x++)
    {
        for (int y = 0; y < pBlock1_3.Height; y++)
        {
            // check to see if it's a valid data  point
            object oval1 = pBlock1_3.GetVal(0, x, y);
            object oval2 = pBlock2_3.GetVal(0, x, y);
            object oval3 =null;
            if (oval1 != null && oval2 != null)
            {
                //Console.WriteLine(oval1);
                int val1 = Convert.ToByte(oval1);
                //Console.WriteLine("finish");
                // set out of range values to 1
                if (val1 < 1 || val1 > 5) val1 = 1;
                // S5 must be coded as a 4
                if (val1 == 5) val1 = 4;
                int val2 = Convert.ToByte(oval2); ;
                //          int val3 = 10 * slval[val1] + val2;
                int val3 = 10 * val1 + val2;
                if (val3 > 10 && y > maxy) maxy = y;
                oval3 = Convert.ToSByte(val3);
                //Console.WriteLine(oval3);
            }
            Console.WriteLine(oval3);
            pixelDataO.SetValue(oval3, x, y);
        }
    }

Answer 1

Unhandled Exception: System.ArgumentException: Cannot widen from source type to target type either because the source type is a not a primitive type or the conversion cannot be accomplished

This is occurring because you are trying to stuff a type that can't be converted to the target type. Let's take a look at your code...

Take this line: pixelDataO = (System.Array)pBlockO_3.get_PixelData(0);

I asked in the comment's about what type this is, what does pBlockO_3.get_PixelData(0); return? According to the comment's, it's a System.SByte[,] .

Further down in your code, specifically the loop you're in, you have:

 oval3 = Convert.ToByte(val3);

When you do this, you are getting a 8-bit-unsigned integer . Next you are then trying to set a value to the element at the specified position in the two-dimensional pixelDataO array.

 pixelDataO.SetValue(oval3, x, y);

The concern is oval3 isn't a System.SByte it's a 8-bit unsigned integer ; the wrong type and the reason it's can't widen.

To fix the issue you need to use the Convert.ToSByte()

Now this line, oval3 = Convert.ToByte(val3); becomes :

  oval3 = Convert.ToSByte(val3);

On another note, you may need to adjust other code as well, as you could have the issue again depending on what you are doing with other fields.