Zoom.java

/**
 * Copyright (C) 2009, 2010 SC 4ViewSoft SRL
 *  
 * 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 com.androsz.achartengine.tools;

import com.androsz.achartengine.chart.XYChart;

/**
 * The zoom tool.
 */
public class Zoom extends AbstractTool {
	/** A flag to be used to know if this is a zoom in or out. */
	private final boolean mZoomIn;
	/** The zoom rate. */
	private float mZoomRate;

	/**
	 * Builds the zoom tool.
	 * 
	 * @param chart
	 *            the chart
	 * @param in
	 *            zoom in or out
	 * @param rate
	 *            the zoom rate
	 */
	public Zoom(XYChart chart, boolean in, float rate) {
		super(chart);
		mZoomIn = in;
		setZoomRate(rate);
	}

	/**
	 * Apply the zoom.
	 */
	public void apply() {
		final double[] range = getRange();
		checkRange(range);
		final double[] limits = mRenderer.getZoomLimits();
		final boolean limited = limits != null && limits.length == 4;

		final double centerX = (range[0] + range[1]) / 2;
		final double centerY = (range[2] + range[3]) / 2;
		double newWidth = range[1] - range[0];
		double newHeight = range[3] - range[2];
		if (mZoomIn) {
			if (mRenderer.isZoomXEnabled()) {
				newWidth /= mZoomRate;
			}
			if (mRenderer.isZoomYEnabled()) {
				newHeight /= mZoomRate;
			}
		} else {
			if (mRenderer.isZoomXEnabled()) {
				newWidth *= mZoomRate;
			}
			if (mRenderer.isZoomYEnabled()) {
				newHeight *= mZoomRate;
			}
		}

		if (mRenderer.isZoomXEnabled()) {
			final double newXMin = centerX - newWidth / 2;
			final double newXMax = centerX + newWidth / 2;
			if (!limited || limits[0] <= newXMin && limits[1] >= newXMax) {
				setXRange(newXMin, newXMax);
			}
		}
		if (mRenderer.isZoomYEnabled()) {
			final double newYMin = centerY - newHeight / 2;
			final double newYMax = centerY + newHeight / 2;
			if (!limited || limits[2] <= newYMin && limits[3] >= newYMax) {
				setYRange(newYMin, newYMax);
			}
		}
	}

	/**
	 * Sets the zoom rate.
	 * 
	 * @param rate
	 */
	public void setZoomRate(float rate) {
		mZoomRate = rate;
	}

}