piskel/js/drawingtools/BaseTool.js

/*
 * @provide pskl.drawingtools.BaseTool
 *
 * @require pskl.utils
 */
(function() {
	var ns = $.namespace("pskl.drawingtools");

	ns.BaseTool = function() {};

	ns.BaseTool.prototype.applyToolAt = function(col, row, color, frame, overlay) {};
	
	ns.BaseTool.prototype.moveToolAt = function(col, row, color, frame, overlay) {};

	ns.BaseTool.prototype.moveUnactiveToolAt = function(col, row, color, frame, overlay) {
		if (overlay.containsPixel(col, row)) {
			if (!isNaN(this.highlightedPixelCol) &&
				!isNaN(this.highlightedPixelRow) &&
				(this.highlightedPixelRow != row ||
					this.highlightedPixelCol != col)) {

				// Clean the previously highlighted pixel:
				overlay.clear();
			}

			// Show the current pixel targeted by the tool:
			overlay.setPixel(col, row, Constants.TOOL_TARGET_HIGHLIGHT_COLOR);

			this.highlightedPixelCol = col;
			this.highlightedPixelRow = row;	
		}
	};

	ns.BaseTool.prototype.releaseToolAt = function(col, row, color, frame, overlay) {};

	/**
	 * Bresenham line algorihtm: Get an array of pixels from
	 * start and end coordinates.
	 *
	 * http://en.wikipedia.org/wiki/Bresenham's_line_algorithm
	 * http://stackoverflow.com/questions/4672279/bresenham-algorithm-in-javascript
	 *
	 * @private
	 */
	ns.BaseTool.prototype.getLinePixels_ = function(x0, x1, y0, y1) {
		
		var pixels = [];
		var dx = Math.abs(x1-x0);
		var dy = Math.abs(y1-y0);
		var sx = (x0 < x1) ? 1 : -1;
		var sy = (y0 < y1) ? 1 : -1;
		var err = dx-dy;

		while(true){

			// Do what you need to for this
			pixels.push({"col": x0, "row": y0});

			if ((x0==x1) && (y0==y1)) break;
			var e2 = 2*err;
			if (e2>-dy){
				err -= dy;
				x0  += sx;
			}
			if (e2 < dx) {
				err += dx;
				y0  += sy;
			}
		}
		return pixels;
	};
})();