[platform-swt-dev] Color mask issues with PalleteData

[lipe! <lipeandrade@xxxxxxxxx>]

Hi all,

I have noticied "strange" behavior with SWT PalleteData and different color Depths.

With a 16 bit-color display, PalleteData uses a mask with 5 bit per color and the representation orientation is RGB, from most significant bit to less significant bit. Also, the not used bits are all at the left.

 

-------------------------------------------------
Image depth: 16
Direct pallete: true
-
     Black: 00000000000000000000000000000000
       Red: 00000000000000000 111110000000000
     Green: 00000000000000000000001111100000
      Blue: 00000000000000000000000000011111
     White: 00000000000000000111111111111111
-------------------------------------------------

 

But with a 32 bit-color display, PalleteData uses a mask with 8 bit per color and representation orientation is BGR, from most significant bit to less significant bit. And here, the not user bits are all at the right!

-------------------------------------------------
Image depth: 32
Direct pallete: true
-
     Black: 00000000000000000000000000000000
       Red: 0000000000000000 1111111100000000
     Green: 00000000111111110000000000000000
      Blue: 11111111000000000000000000000000
     White: 11111111111111111111111100000000
-------------------------------------------------

 

The question is: there is any good reason to color-bits orientation changing from a color-depth to another?!
 

 

The code snippet used to generate this report is attached (i using SWT 3.2 / JDK 1.5).

 

Thanks for any explanation,

--
[ ]s,
Felipe Santos Andrade
<lipeandrade@xxxxxxxxx>

import org.eclipse.swt.SWT;
import org.eclipse.swt.events.DisposeEvent;
import org.eclipse.swt.events.DisposeListener;
import org.eclipse.swt.events.PaintEvent;
import org.eclipse.swt.events.PaintListener;
import org.eclipse.swt.graphics.Color;
import org.eclipse.swt.graphics.GC;
import org.eclipse.swt.graphics.Image;
import org.eclipse.swt.graphics.ImageData;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Shell;


public class ColorTest {

	final static Display display = Display.getDefault();
	
	public static void main(String args[]) {
		new ColorTest();
	}
	
	Image lastImg = null;
	
	final static int stripHeight = 30;
	final static int stripWidth = 150;
	
	final Color[] colors = new Color[] {
		display.getSystemColor(SWT.COLOR_BLACK),
		display.getSystemColor(SWT.COLOR_RED),
		display.getSystemColor(SWT.COLOR_GREEN),
		display.getSystemColor(SWT.COLOR_BLUE),
		display.getSystemColor(SWT.COLOR_WHITE)
	};
	
	final String[] colorNames = new String[] { "Black", "Red", "Green", "Blue", "White" };
	
	
	public ColorTest() {
		Shell shell = new Shell(display, SWT.TOOL | SWT.DIALOG_TRIM);
		
		shell.setText("Color Test");
		shell.setSize(stripWidth, colors.length * stripHeight + (shell.getSize().y - shell.getClientArea().height));
		
		shell.addPaintListener(new PaintListener() {
			public void paintControl(PaintEvent e) {
				if (lastImg == null) {
					lastImg = generateImage();
					debugImageColors();
				}
				
				e.gc.drawImage(lastImg, 0, 0);	
			}
		});
		shell.addDisposeListener(new DisposeListener() {
			public void widgetDisposed(DisposeEvent e) {
				if (lastImg != null)
					lastImg.dispose();
			}
		});
		shell.open();
		shell.layout();
		while (!shell.isDisposed()) {
			if (!display.readAndDispatch())
				display.sleep();
		}
	}

	protected Image generateImage() {
		Image img = new Image(display, stripWidth, colors.length * stripHeight);
		int y = 0;
		
		GC gc = new GC(img);
		
		for (Color c : colors) {
			gc.setBackground(c);
			gc.fillRectangle(0, y, stripWidth, stripHeight);
			y += stripHeight;
		}

		gc.dispose();
		return img;
	}
	
	private void debugImageColors() {
		int y = 0;
		
		System.out.println("Image depth: " + lastImg.getImageData().depth);
		System.out.println("Direct pallete: " + lastImg.getImageData().palette.isDirect);		
		System.out.println("-");		
		
		for (String colorName : colorNames) {
			int pixelColor = lastImg.getImageData().getPixel(0, y);
			StringBuilder representation = new StringBuilder();
			representation.append(Integer.toBinaryString(pixelColor));
			int appendLen = (32 - representation.length());
			for (int i = 0; i < appendLen; i++)
				representation.insert(0, "0");
			System.out.println(String.format("%10s: %32s", new Object[] { colorName, representation.toString() }));
			y += stripHeight;
		}
	}

	
}