org.pepstock.charba.client.colors.tiles.PointStyleRectRounded Maven / Gradle / Ivy

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Charba - J2CL and GWT charts library based on CHART.JS
There is a newer version: 6.5-gwt
/**
    Copyright 2017 Andrea "Stock" Stocchero

    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
    You may obtain a copy of the License at

	    http://www.apache.org/licenses/LICENSE-2.0

    Unless required by applicable law or agreed to in writing, software
    distributed under the License is distributed on an "AS IS" BASIS,
    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    See the License for the specific language governing permissions and
    limitations under the License.
*/
package org.pepstock.charba.client.colors.tiles;

import org.pepstock.charba.client.dom.elements.Context2dItem;
import org.pepstock.charba.client.enums.PointStyle;

/**
 * RECTROUNDED drawer to design a {@link PointStyle#RECT_ROUNDED} into tile.

 * It designs the point style into the following tile section (A):

 * 

 * 
 *  * +---------+---------+
 * |                   |
 * |                   |
 * |                   |
 * |         A         |
 * |                   |
 * |                   |
 * |                   |
 * +---------+---------+
 * 
 * 
 * @author Andrea "Stock" Stocchero
 *
 */
final class PointStyleRectRounded extends AbstractPointStyleShapeDrawer {

	/**
	 * Draws the tile using the point style applying the requested shape.
	 * 
	 * @param context context of canvas to design the shape
	 * @param size the size of tile, which is a square
	 * @param x x point center of canvas
	 * @param y y point center of canvas
	 * @param radius the radius of the tile, only for {@link PointStyle} drawing
	 * @param rotation the rotation (in degrees) to create the tile, only for {@link PointStyle} drawing
	 * @param rad rad calculates on rotation
	 */
	@Override
	protected void drawPointStyle(Context2dItem context, int size, double x, double y, double radius, double rotation, double rad) {
		// NOTE: the rounded rect implementation changed to use `arc` instead of
		// `quadraticCurveTo` since it generates better results when rect is
		// almost a circle. 0.516 (instead of 0.5) produces results with visually
		// closer proportion to the previous impl and it is inscribed in the
		// circle with `radius`. For more details, see the following PRs:
		// https://github.com/chartjs/Chart.js/issues/5597
		// https://github.com/chartjs/Chart.js/issues/5858
		double cornerRadius = radius * 0.516;
		double changedSize = radius - cornerRadius;
		double xOffset = Math.cos(rad + QUARTER_PI) * changedSize;
		double yOffset = Math.sin(rad + QUARTER_PI) * changedSize;
		context.arc(x - xOffset, y - yOffset, cornerRadius, rad - PI, rad - HALF_PI);
		context.arc(x + yOffset, y - xOffset, cornerRadius, rad - HALF_PI, rad);
		context.arc(x + xOffset, y + yOffset, cornerRadius, rad, rad + HALF_PI);
		context.arc(x - yOffset, y + xOffset, cornerRadius, rad + HALF_PI, rad + PI);
	}

}