piskel/js/drawingtools/Circle.js

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

	ns.Circle = function() {
		this.toolId = "tool-circle";
		this.helpText = "Circle tool";
		
		// Circle's first point coordinates (set in applyToolAt)
		this.startCol = null;
		this.startRow = null;
	};

	pskl.utils.inherit(ns.Circle, ns.BaseTool);
	
	/**
	 * @override
	 */
	ns.Circle.prototype.applyToolAt = function(col, row, color, frame, overlay) {
		this.startCol = col;
		this.startRow = row;
		
		// Drawing the first point of the rectangle in the fake overlay canvas:
		overlay.setPixel(col, row, color);
	};

	ns.Circle.prototype.moveToolAt = function(col, row, color, frame, overlay) {
		overlay.clear();
		if(color == Constants.TRANSPARENT_COLOR) {
			color = Constants.SELECTION_TRANSPARENT_COLOR;
		}

		// draw in overlay
		this.drawCircle_(col, row, color, overlay);
	};

	/**
	 * @override
	 */
	ns.Circle.prototype.releaseToolAt = function(col, row, color, frame, overlay) {		
		overlay.clear();
		if(frame.containsPixel(col, row)) { // cancel if outside of canvas
			// draw in frame to finalize
			this.drawCircle_(col, row, color, frame);
		}
	};

	ns.Circle.prototype.drawCircle_ = function (col, row, color, targetFrame) {
		var circlePoints = this.getCirclePixels_(this.startCol, this.startRow, col, row);
		for(var i = 0; i< circlePoints.length; i++) {
			// Change model:
			targetFrame.setPixel(circlePoints[i].col, circlePoints[i].row, color);
		}
	};

	ns.Circle.prototype.getCirclePixels_ = function (x0, y0, x1, y1) {
		var coords = pskl.PixelUtils.getOrderedRectangleCoordinates(x0, y0, x1, y1);
		var xC = (coords.x0 + coords.x1)/2;
		var yC = (coords.y0 + coords.y1)/2;
		
		var rX = coords.x1 - xC;
		var rY = coords.y1 - yC;

		var pixels = [];
		var x, y, angle;
		for (x = coords.x0 ; x < coords.x1 ; x++) {
			angle = Math.acos((x - xC)/rX);
			y = Math.round(rY * Math.sin(angle) + yC);
			pixels.push({"col": x, "row": y});
			pixels.push({"col": 2*xC - x, "row": 2*yC - y});
		}

		for (y = coords.y0 ; y < coords.y1 ; y++) {
			angle = Math.asin((y - yC)/rY);
			x = Math.round(rX * Math.cos(angle) + xC);
			pixels.push({"col": x, "row": y});
			pixels.push({"col": 2*xC - x, "row": 2*yC - y});
		}
		return pixels;
	};
})();