piskel/js/drawingtools/Stroke.js

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

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

	pskl.utils.inherit(ns.Stroke, ns.BaseTool);
	
	/**
	 * @override
	 */
	ns.Stroke.prototype.applyToolAt = function(col, row, color, drawer) {
		this.startCol = col;
		this.startRow = row;
		
		// When drawing a stroke we don't change the model instantly, since the
		// user can move his cursor to change the stroke direction and length
		// dynamically. Instead we draw the (preview) stroke in a fake canvas that
		// overlay the drawing canvas.
		// We wait for the releaseToolAt callback to impact both the
		// frame model and canvas rendering.

		// The fake canvas where we will draw the preview of the stroke:
		// Drawing the first point of the stroke in the fake overlay canvas:
		drawer.updateOverlay(col, row, color);
		drawer.renderOverlay();
	};

	ns.Stroke.prototype.moveToolAt = function(col, row, color, drawer) {
		// When the user moussemove (before releasing), we dynamically compute the 
		// pixel to draw the line and draw this line in the overlay canvas:
		var strokePoints = this.getLinePixels_(this.startCol, col, this.startRow, row);

		// Clean overlay canvas:
		this.canvasOverlay.getContext("2d").clearRect(
			0, 0, this.canvasOverlay.width, this.canvasOverlay.height);
		
		// Drawing current stroke:
		for(var i = 0; i< strokePoints.length; i++) {

			if(color == Constants.TRANSPARENT_COLOR) {
				// When mousemoving the stroke tool, we draw in the canvas overlay above the drawing canvas.
				// If the stroke color is transparent, we won't be
				// able to see it during the movement.
				// We set it to a semi-opaque white during the tool mousemove allowing to see colors below the stroke.
				// When the stroke tool will be released, It will draw a transparent stroke, 
				// eg deleting the equivalent of a stroke.		
				color = Constants.SELECTION_TRANSPARENT_COLOR;
			}			
			drawer.updateOverlay(strokePoints[i].col, strokePoints[i].row, color);
		}
	};

	/**
	 * @override
	 */
	ns.Stroke.prototype.releaseToolAt = function(col, row, color, drawer) {
		// If the stroke tool is released outside of the canvas, we cancel the stroke:
		// TODO: Mutualize this check in common method
		if(drawer.frame.containsPixel(col, row)) {
			// The user released the tool to draw a line. We will compute the pixel coordinate, impact
			// the model and draw them in the drawing canvas (not the fake overlay anymore)
			var strokePoints = this.getLinePixels_(this.startCol, col, this.startRow, row);
			for(var i = 0; i< strokePoints.length; i++) {
				// Change model:
				drawer.updateFrame(strokePoints[i].col, strokePoints[i].row, color);
			}
			// Draw in canvas:
			// TODO: Remove that when we have the centralized redraw loop
			drawer.renderFrame();
		} 
		// For now, we are done with the stroke tool and don't need an overlay anymore:
		drawer.clearOverlay();   
	};
})();