/// <summary>
/// Detects the color order of a stored byte array. Byte order may change between platforms, you should call this once before writting a PNG or if you have any issues with colors changing.
/// </summary>
public static void DetectWBByteOrder()
{
// We should only ever run the detection once (assuming it succeeded at least).
if (WBBODetectionRun == true)
{
return;
}
// Create a 3x1 WriteableBitmap to write RGB colors to.
var TestWB = new WriteableBitmap(3, 1);
//// Create the red 1 pixel rectangle.
//var redRectangle = new Rectangle();
//redRectangle.Width = 1;
//redRectangle.Height = 1;
//redRectangle.Fill = new SolidColorBrush( Colors.Red );
//// Create the green 1 pixel rectangle.
//var greenRectangle = new Rectangle();
//greenRectangle.Width = 1;
//greenRectangle.Height = 1;
//greenRectangle.Fill = new SolidColorBrush( Colors.Green );
//// Create the blue 1 pixel rectangle.
//var blueRectangle = new Rectangle();
//blueRectangle.Width = 1;
//blueRectangle.Height = 1;
//blueRectangle.Fill = new SolidColorBrush( Colors.Blue );
// Render the three 1 px rectangles.
TestWB.SetPixel(0, 0, Colors.Red);
TestWB.SetPixel(1, 0, Colors.Green);
TestWB.SetPixel(2, 0, Colors.Blue);
// Invalidate the bitmap to make it actually render.
TestWB.Invalidate();
// Go get the 4 byte arrays of each red/green/blue pixels that we just rendered.
var redColor = TestWB.GetPixel(0, 0);
var greenColor = TestWB.GetPixel(1, 0);
var blueColor = TestWB.GetPixel(2, 0);
byte[] redBytes = { redColor.A, redColor.R, redColor.G, redColor.B };
byte[] greenBytes = { greenColor.A, greenColor.R, greenColor.G, greenColor.B };
byte[] blueBytes = { blueColor.A, blueColor.R, blueColor.G, blueColor.B };
// Just in case something goes terrible wrong, set all the color values to invalid settings.
int trans = 4;
int red = 4;
int green = 4;
int blue = 4;
// Find the alpha channel, this wil be the only byte that is the same in all three pixels.
if (redBytes[0] == greenBytes[0] && blueBytes[0] == greenBytes[0]) { trans = 0; }
if (redBytes[1] == greenBytes[1] && blueBytes[1] == greenBytes[1]) { trans = 1; }
if (redBytes[2] == greenBytes[2] && blueBytes[2] == greenBytes[2]) { trans = 2; }
if (redBytes[3] == greenBytes[3] && blueBytes[3] == greenBytes[3]) { trans = 3; }
// if we didn't detect the alpha channel, just give up :(
if (trans != 4)
{
// now set all the alpha channel's to zero to get them out of the way.
redBytes[trans] = 0;
greenBytes[trans] = 0;
blueBytes[trans] = 0;
// Find the red channel.
if (redBytes[0] == 255) { red = 0; }
else if (redBytes[1] == 255) { red = 1; }
else if (redBytes[2] == 255) { red = 2; }
else if (redBytes[3] == 255) { red = 3; }
// Find the green channel, note that Colors.Green is not dark green, but light green so use 128 instead of 255 to detect it.
if (greenBytes[0] == 128) { green = 0; }
else if (greenBytes[1] == 128) { green = 1; }
else if (greenBytes[2] == 128) { green = 2; }
else if (greenBytes[3] == 128) { green = 3; }
// Find the blue channel.
if (blueBytes[0] == 255) { blue = 0; }
else if (blueBytes[1] == 255) { blue = 1; }
else if (blueBytes[2] == 255) { blue = 2; }
else if (blueBytes[3] == 255) { blue = 3; }
}
// Now set the byte order, if any of the values are still set to 4, something went wrong and return the default values.
if (red == 4 || green == 4 || blue == 4 || trans == 4)
{
WBByteOrder = new int[] { 2, 1, 0, 3 };
}
else
{
WBBODetectionRun = true;
WBByteOrder = new int[] { red, green, blue, trans };
}
}
