/********************************************************************
 * 
 * PhotoGrok Script
 *
 * Draw a histogram and show highlights/shadow areas. 
 *
 * Very slow on Java 6 and 7 - especially on Apple's old Java 6 JVM. 
 * Quite speedy on Java 8 and above (6 seconds vs 30ms on my machine).
 *
 * Histogram heavily inspired/borrowed from Bill Mill's article found
 * here: http://billmill.org/the_histogram.html
 *
 *
 **********************************************************************/



// syntax for rhino compatibility

var red = new Color['(int,int,int,int)'](255,0,0,100);
var green = new Color['(int,int,int,int)'](0,255,0,100);
var blue = new Color['(int,int,int,int)'](0,0,255,100);

var name = '';
var max = 0;
var rvals, gvals, bvals;

function array256(default_value) {
  arr = [];
  for (var i=0; i<256; i++) { arr[i] = default_value; }
  return arr;
}

// register a painter function

setPainter(function(gfx, image, ig, pp){
	if(pp.dragging || pp.zooming || pp.resizing)
		return;
	
	if(image != null){

		// use file name to determine if new image (optimization)
		var newImage = pp.file != name;
		name = pp.file;

		if(newImage){			
			rvals = array256(0);
			gvals = array256(0);
			bvals = array256(0);
		}

		for(var i = 0; i < image.getWidth(); i++){
			for(var j = 0; j < image.getHeight(); j++){

				var pixel = image.getRGB(i,j);

				var b = (pixel) & 0xff;
				var g = (pixel >> 8) & 0xff;
				var r = (pixel >> 16) & 0xff;
				if(newImage){
  					rvals[r]++;
  					gvals[g]++;
  					bvals[b]++;
				}
				
				// draw highlights
				gfx.setColor(Color.RED);
				if(r > 250 && g > 250 && b > 250){

					gfx.drawLine(i + pp.imageX, j + pp.imageY, i + pp.imageX, j + pp.imageY);
				}	

				// draw shadows
				gfx.setColor(Color.BLUE);
				if(r < 5 && g < 5 && b < 5){
					gfx.drawLine(i + pp.imageX, j + pp.imageY, i + pp.imageX, j + pp.imageY);
						
				}	
				
			}
		}
		if(newImage){
			var redMax = Math.max.apply(null, rvals);
			var gMax = Math.max.apply(null, gvals);
			var bMax = Math.max.apply(null, bvals);
			max = Math.max(redMax, gMax, bMax);
		}
		
		// draw histogram box
		gfx.setColor(Color.YELLOW);
		var offX = 10;		
		gfx.drawRect(offX, 6, 258, 102);

		// draw histogram
		histogram(gfx, red, rvals, offX, 6, max);
		histogram(gfx, green, gvals, offX, 6, max);
		histogram(gfx, blue, bvals, offX, 6, max);

		// show file name on screen

		gfx.setColor(Color.RED);
		gfx.drawString(pp.file, 20, 30);

		// show ElapsedTime on screen - for efficiency, use getTagValue
        	// when not in full screen mode

		if(pp.fullScreen){
			var ex = getExifData(pp.dir, pp.file);
			for(var i = 0; i < ex.length; i++){
				if(ex[i].startsWith("ElapsedTime")){
					gfx.drawString(ex[i].substring(13), 20, 50);
					break;
				}
			}
		}else{
			var et = getTagValue("ElapsedTime");
			if(et != null)
				gfx.drawString(et, 20, 50);
		}

	}
});

function histogram(gfx, color, vals, offX, offY, max){

	gfx.setColor(color);
	
	for(var c = 0; c < 256; c++){
		var pct = (vals[c] / max) * 100;
		var pt = 101 - Math.round(pct);
		gfx.drawRect(c + 1 + offX, offY  + pt, 1, Math.round(pct));

	}
}