bundles/common/org.eclipse.apogy.common.widgets.ui/src/org/eclipse/apogy/common/widgets/ui/BatteryStatComposite.java

/*******************************************************************************
 * Copyright (c) 2018 Agence spatiale canadienne / Canadian Space Agency 
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     Pierre Allard,
 *     Regent L'Archeveque,  
 *     Sebastien Gemme - initial API and implementation
 *
 * SPDX-License-Identifier: EPL-1.0
 *     
 *******************************************************************************/
package org.eclipse.apogy.common.widgets.ui;

import java.net.URL;
import java.text.DecimalFormat;

import org.eclipse.swt.SWT;
import org.eclipse.swt.events.DisposeEvent;
import org.eclipse.swt.events.DisposeListener;
import org.eclipse.swt.events.PaintEvent;
import org.eclipse.swt.events.PaintListener;
import org.eclipse.swt.graphics.Color;
import org.eclipse.swt.graphics.Device;
import org.eclipse.swt.graphics.Font;
import org.eclipse.swt.graphics.GC;
import org.eclipse.swt.graphics.Image;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.Display;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class BatteryStatComposite extends Composite {

	private static final Logger Logger = LoggerFactory.getLogger(BatteryStatComposite.class);

	private static final int ALPHA_VALUE = 100; // Transparency value range: (0-255)
	private static final int LINE_WIDTH = 4; // Line width
	private static final int LOWER_BOUND_VALUE = 33;
	private static final int UPPER_BOUND_VALUE = 66;
	private static final int MIN_VALUE = 0;
	private static final double MAX_VALUE = 100; // Maximum possible value for this widget
	private static final float POLE_HEIGHT_FRACTION = 0.392857f; // Fraction of the pole height of the battery
	private static final float BATTERY_BEFORE_POLE_FRACTION = 0.789473f; // Fraction of the full battery before getting
																			// the pole.

	private static final String IMAGES_FOLDER = "platform:/plugin/org.eclipse.apogy.common.widgets.ui/images/"; // Images
																												// path
	private Image background; // Background image.
	private double actualValue; // This is the actual value in percent. Minimum is 0 and maximum is 100.
	private Color red;
	private Color green;
	private Color yellow;

	/**
	 * Constructor parameter information:
	 * 
	 * @param initialValue This is the initial value of the battery. Its a percent
	 *                     and should be more of equal than 0 but less or equal than
	 *                     100.
	 */
	public BatteryStatComposite(Composite parent, int style, double initialValue) {
		super(parent, style | SWT.DOUBLE_BUFFERED);

		setActualValue(initialValue);

		// Initialize colors.
		initColors();

		// Initialize images.
		initImages();

		// Create listeners
		createPaintListener();
		createDisposeListener();
	}

	// Return actual value.
	public synchronized double getActualValue() {
		return this.actualValue;
	}

	// Set actual value.
	public void setActualValue(double actualValue) {
		// Validate new value.
		if (actualValue < MIN_VALUE)
			actualValue = MIN_VALUE;
		else if (actualValue > MAX_VALUE)
			actualValue = MAX_VALUE;
		this.actualValue = actualValue;
		redraw();
	}

	/**
	 * Initialize colors.
	 */
	private void initColors() {
		this.green = new Color(Display.getCurrent(), 0, 255, 0);
		this.yellow = new Color(Display.getCurrent(), 255, 255, 0);
		this.red = new Color(Display.getCurrent(), 255, 0, 0);
	}

	/**
	 * Initialize images.
	 */
	private void initImages() {
		try {
			Device device = Display.getCurrent();
			URL url = new URL(IMAGES_FOLDER + "battery.png");
			this.background = new Image(device, url.openStream());
		} catch (Exception e) {
			Logger.error(e.getMessage(), e);
		}
	}

	/**
	 * This method paint the battery.
	 */
	private void paintMeter(GC gc) {
		if (this.background != null) // Draw background
			gc.drawImage(this.background, 0, 0, this.background.getBounds().width, this.background.getBounds().height,
					0, 0, getBounds().width, getBounds().height);
		else // Draw a black rectangle (This code is only useful in windows builder to see
				// the widget without loading images).
			drawBlackRectangle(gc);

		drawChargeOnBattery(gc);

		drawNumberOnBattery(gc);
	}

	private void createPaintListener() {
		addPaintListener(new PaintListener() {
			@Override
			public void paintControl(PaintEvent e) {
				paintMeter(e.gc);
			}
		});
	}

	private void createDisposeListener() {
		addDisposeListener(new DisposeListener() {
			@Override
			public void widgetDisposed(DisposeEvent e) {
				if (BatteryStatComposite.this.background != null)
					BatteryStatComposite.this.background.dispose();
				BatteryStatComposite.this.green.dispose();
				BatteryStatComposite.this.yellow.dispose();
				BatteryStatComposite.this.red.dispose();
			}
		});
	}

	private void drawBlackRectangle(GC gc) {
		Color color = new Color(getDisplay(), 0, 0, 0);
		gc.setForeground(color);
		gc.setLineWidth(LINE_WIDTH);
		gc.drawRectangle(2, 2, getBounds().width - 4, getBounds().height - 4);
		color.dispose();
	}

	private void drawChargeOnBattery(GC gc) {
		double chargeWidth = getBounds().width - 2;
		int actualCharge = (int) Math.round(chargeWidth * (this.actualValue / MAX_VALUE));

		gc.setAlpha(ALPHA_VALUE);

		if (this.actualValue >= UPPER_BOUND_VALUE)
			gc.setBackground(this.green);
		else if (this.actualValue >= LOWER_BOUND_VALUE && this.actualValue < UPPER_BOUND_VALUE)
			gc.setBackground(this.yellow);
		else
			gc.setBackground(this.red);

		if (actualCharge > Math.round((chargeWidth * BATTERY_BEFORE_POLE_FRACTION))) {
			gc.fillRectangle(1, 1, (int) Math.round(chargeWidth * BATTERY_BEFORE_POLE_FRACTION),
					getBounds().height - 2);
			int xStartDraw = (int) Math.round(chargeWidth * BATTERY_BEFORE_POLE_FRACTION) + 1;
			int yStarDraw = (int) (getBounds().height * (1f / 3f));
			int chargeWidthToDraw = actualCharge - xStartDraw + 1;
			int chargeHeightToDraw = Math.round((getBounds().height - 2) * POLE_HEIGHT_FRACTION);
			gc.fillRectangle(xStartDraw, yStarDraw, chargeWidthToDraw, chargeHeightToDraw);
		} else {
			gc.fillRectangle(1, 1, actualCharge, getBounds().height - 2);
		}
	}

	private void drawNumberOnBattery(GC gc) {
		// Initialize center.
		int centerXMeter = getBounds().width / 2;
		int centerYMeter = getBounds().height / 2;

		float XScaleFactor = 0f;
		float YScaleFactor = 0f;

		// Initialize scale factor.
		if (this.background != null) {
			XScaleFactor = (((float) getBounds().width) / ((float) this.background.getBounds().width));
			YScaleFactor = (((float) getBounds().height) / ((float) this.background.getBounds().height));
		}

		// draw number on battery
		DecimalFormat df = new DecimalFormat("0");
		int size = 0;
		if (XScaleFactor > YScaleFactor)
			size = Math.round(5.5f * YScaleFactor);
		else
			size = Math.round(5.5f * XScaleFactor);

		Font font = new Font(getDisplay(), "Tahoma", size, SWT.BOLD);
		gc.setFont(font);
		gc.setAlpha(255);
		String numberPercent = df.format(this.actualValue) + "%";
		int widthOfNumber = 0;
		for (int i = 0; i < numberPercent.length(); i++) {
			widthOfNumber += gc.getAdvanceWidth(numberPercent.charAt(i));
		}
		int heightOfNumber = gc.getFontMetrics().getHeight();

		Color c = new Color(Display.getCurrent(), 0, 0, 0);
		gc.setForeground(c);
		gc.drawString(numberPercent, centerXMeter - (Math.round((widthOfNumber) / 1.5f)) + 1,
				centerYMeter - (heightOfNumber / 2) + 1, true);
		c.dispose();

		c = new Color(Display.getCurrent(), 255, 255, 255);
		gc.setForeground(c);
		gc.drawString(numberPercent, centerXMeter - (Math.round((widthOfNumber) / 1.5f)),
				centerYMeter - (heightOfNumber / 2), true);
		c.dispose();

		font.dispose();
	}
}