package ie.dcu.segment.painters;


import ie.dcu.segment.*;
import ie.dcu.swt.ObservableImage;

import org.eclipse.swt.graphics.*;
import org.eclipse.swt.widgets.*;

/**
 * Shows the foreground region of the image. The background is greyed out.
 * 
 * @author Kevin McGuinness
 */
public class ForegroundOnlyPainter implements SegmentationPainter {
	
	private ImageData maskData;
	private Image maskImage;
	
	public String getName() {
		return "Foreground Only";
	}


	public String getDescription() {
		return "Shows the foreground region of the image.";
	}
	
	public ImageData getMaskData(SegmentationContext ctx) {
		return maskData;
	}

	public void paint(SegmentationContext ctx, ObservableImage im) {
		GC gc = im.beginPaint();

		// Paint image
		gc.drawImage(ctx.getImage(), 0, 0);

		// Paint mask
		createVisibleMask(ctx.getMask());
		gc.drawImage(maskImage, 0, 0);
				
		// Commit changes
		im.endPaint();
	}

	
	private void createVisibleMask(SegmentationMask mask) {
		dispose();
		
		if (isNewMaskDataRequired(mask.getBounds())) {
			maskData = createMaskData(mask.getBounds());
		} 
		
		// Blit in pixels
		byte[] buff = new byte[maskData.width];
		for (int y = 0, i = 0; y < mask.height; y++) {
			for (int x = 0; x < mask.width; x++) {
				switch (mask.values[i++]) {
				case SegmentationMask.BACKGROUND:
					// black
					buff[x] = 1; 
					break;
				default:
					// transparent
					buff[x] = 0; 
				}
			}
			maskData.setPixels(0, y, buff.length, buff, 0);
		}
		
		// Create new mask
		maskImage = new Image(Display.getCurrent(), maskData);
	}
	
	
	private boolean isNewMaskDataRequired(Rectangle bounds) {
		if (maskData == null) {
			return true;
		} else {
			return maskData.width != bounds.width || maskData.height != bounds.height;
		}
	}


	private static ImageData createMaskData(Rectangle bounds) {
		RGB[] colors = new RGB[] {
			new RGB(255,255,255),
			new RGB(128,128,128)
		};
		
		// Create binary indexed palette
		PaletteData palette = new PaletteData(colors);
		
		// Create 1 bit indexed image 
		ImageData data = new ImageData(
				bounds.width, bounds.height, 1, palette);
		
		// Set transparent pixel
		data.transparentPixel = 0;
		
		// Create and return the image
		return data;
	}
	

	public void dispose() {
		// Dispose mask
		if (maskImage != null) {
			if (!maskImage.isDisposed()) {
				maskImage.dispose();
			}
			maskImage = null;
		}
	}
}