RedGreenBar.java

/*******************************************************************************
 * Copyright (c) 2006, 2016 Mountainminds GmbH & Co. KG and Contributors
 * 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:
 *    Marc R. Hoffmann - initial API and implementation
 *    
 ******************************************************************************/
package com.mountainminds.eclemma.internal.ui;

import java.text.DecimalFormat;

import org.eclipse.swt.widgets.Event;
import org.jacoco.core.analysis.ICounter;

/**
 * Utility methods to draw red/green bars into table cells.
 */
public final class RedGreenBar {

  private static final int BORDER_LEFT = 2;
  private static final int BORDER_RIGHT = 10;
  private static final int BORDER_TOP = 3;
  private static final int BORDER_BOTTOM = 4;

  private static final String MAX_PERCENTAGE_STRING = new DecimalFormat(
      UIMessages.CoverageView_columnCoverageValue).format(1.0);

  private RedGreenBar() {
  }

  public static void draw(Event event, int columnWith, ICounter counter) {
    draw(event, columnWith, counter, counter.getTotalCount());
  }

  public static void draw(Event event, int columnWith, ICounter counter,
      int maxTotal) {
    if (maxTotal == 0) {
      return;
    }
    final int maxWidth = getMaxWidth(event, columnWith);
    final int redLength = maxWidth * counter.getMissedCount() / maxTotal;
    bar(event, EclEmmaUIPlugin.DGM_REDBAR, 0, redLength);
    final int greenLength = maxWidth * counter.getCoveredCount() / maxTotal;
    bar(event, EclEmmaUIPlugin.DGM_GREENBAR, redLength, greenLength);
  }

  private static void bar(Event event, String image, int xOffset, int width) {
    final int height = event.getBounds().height - BORDER_TOP - BORDER_BOTTOM;
    event.gc.drawImage(EclEmmaUIPlugin.getImage(image), 0, 0, 1, 10, event.x
        + xOffset + BORDER_LEFT, event.y + BORDER_TOP, width, height);
  }

  private static int getMaxWidth(Event event, int columnWith) {
    final int textWidth = event.gc.textExtent(MAX_PERCENTAGE_STRING).x;
    final int max = columnWith - BORDER_LEFT - BORDER_RIGHT - textWidth;
    return Math.max(0, max);
  }

}