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/*******************************************************************************
 * Copyright (c) 2000, 2008 IBM Corporation and others.
 * 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:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.swt.layout;

import org.eclipse.swt.*;
import org.eclipse.swt.graphics.*;
import org.eclipse.swt.widgets.*;

/**
 * <code>FillLayout</code> is the simplest layout class. It lays out 
 * controls in a single row or column, forcing them to be the same size. 
 * <p>
 * Initially, the controls will all be as tall as the tallest control, 
 * and as wide as the widest. <code>FillLayout</code> does not wrap, 
 * but you can specify margins and spacing. You might use it to 
 * lay out buttons in a task bar or tool bar, or to stack checkboxes 
 * in a <code>Group</code>. <code>FillLayout</code> can also be used 
 * when a <code>Composite</code> only has one child. For example, 
 * if a <code>Shell</code> has a single <code>Group</code> child, 
 * <code>FillLayout</code> will cause the <code>Group</code> to 
 * completely fill the <code>Shell</code> (if margins are 0).
 * </p>
 * <p>
 * Example code: first a <code>FillLayout</code> is created and
 * its type field is set, and then the layout is set into the 
 * <code>Composite</code>. Note that in a <code>FillLayout</code>,
 * children are always the same size, and they fill all available space.
 * <pre>
 *     FillLayout fillLayout = new FillLayout();
 *     fillLayout.type = SWT.VERTICAL;
 *     shell.setLayout(fillLayout);
 * </pre>
 * </p>
 *
 * @see <a href="http://www.eclipse.org/swt/examples.php">SWT Example: LayoutExample</a>
 * @see <a href="http://www.eclipse.org/swt/">Sample code and further information</a>
 */
public final class FillLayout extends Layout {
  /**
   * type specifies how controls will be positioned 
   * within the layout.
   *
   * The default value is HORIZONTAL.
   *
   * Possible values are: <ul>
   *    <li>HORIZONTAL: Position the controls horizontally from left to right</li>
   *    <li>VERTICAL: Position the controls vertically from top to bottom</li>
   * </ul>
   */
  public int type = SWT.HORIZONTAL;
  
  /**
   * marginWidth specifies the number of pixels of horizontal margin
   * that will be placed along the left and right edges of the layout.
   *
   * The default value is 0.
   * 
   * @since 3.0
   */
   public int marginWidth = 0;
   
  /**
   * marginHeight specifies the number of pixels of vertical margin
   * that will be placed along the top and bottom edges of the layout.
   *
   * The default value is 0.
   * 
   * @since 3.0
   */
   public int marginHeight = 0;
   
   /**
   * spacing specifies the number of pixels between the edge of one cell
   * and the edge of its neighbouring cell.
   *
   * The default value is 0.
   * 
   * @since 3.0
   */
  public int spacing = 0;
  
/**
 * Constructs a new instance of this class.
 */
public FillLayout () {
}

/**
 * Constructs a new instance of this class given the type.
 *
 * @param type the type of fill layout
 * 
 * @since 2.0
 */
public FillLayout (int type) {
  this.type = type;
}

protected Point computeSize (Composite composite, int wHint, int hHint, boolean flushCache) {
  Control [] children = composite.getChildren ();
  int count = children.length;
  int maxWidth = 0, maxHeight = 0;
  for (int i=0; i<count; i++) {
    Control child = children [i];
    int w = wHint, h = hHint;
    if (count > 0) {
      if (type == SWT.HORIZONTAL && wHint != SWT.DEFAULT) {
        w = Math.max (0, (wHint - (count - 1) * spacing) / count);
      }
      if (type == SWT.VERTICAL && hHint != SWT.DEFAULT) {
        h = Math.max (0, (hHint - (count - 1) * spacing) / count);
      }
    }
    Point size = computeChildSize (child, w, h, flushCache);
    maxWidth = Math.max (maxWidth, size.x);
    maxHeight = Math.max (maxHeight, size.y);
  }
  int width = 0, height = 0;
  if (type == SWT.HORIZONTAL) {
    width = count * maxWidth;
    if (count != 0) width += (count - 1) * spacing;
    height = maxHeight;
  } else {
    width = maxWidth;
    height = count * maxHeight;
    if (count != 0) height += (count - 1) * spacing;
  }
  width += marginWidth * 2;
  height += marginHeight * 2;
  if (wHint != SWT.DEFAULT) width = wHint;
  if (hHint != SWT.DEFAULT) height = hHint;
  return new Point (width, height);
}

Point computeChildSize (Control control, int wHint, int hHint, boolean flushCache) {
  FillData data = (FillData)control.getLayoutData ();
  if (data == null) {
    data = new FillData ();
    control.setLayoutData (data);
  }
  Point size = null;
  if (wHint == SWT.DEFAULT && hHint == SWT.DEFAULT) {
    size = data.computeSize (control, wHint, hHint, flushCache);
  } else {
    // TEMPORARY CODE
    int trimX, trimY;
    if (control instanceof Scrollable) {
      Rectangle rect = ((Scrollable) control).computeTrim (0, 0, 0, 0);
      trimX = rect.width;
      trimY = rect.height;
    } else {
      trimX = trimY = control.getBorderWidth () * 2;
    }
    int w = wHint == SWT.DEFAULT ? wHint : Math.max (0, wHint - trimX);
    int h = hHint == SWT.DEFAULT ? hHint : Math.max (0, hHint - trimY);
    size = data.computeSize (control, w, h, flushCache);
  }
  return size;
}

protected boolean flushCache (Control control) {
  Object data = control.getLayoutData();
  if (data != null) ((FillData)data).flushCache();
  return true;
}

String getName () {
  String string = getClass ().getName ();
  int index = string.lastIndexOf ('.');
  if (index == -1) return string;
  return string.substring (index + 1, string.length ());
}

protected void layout (Composite composite, boolean flushCache) {
  Rectangle rect = composite.getClientArea ();
  Control [] children = composite.getChildren ();
  int count = children.length;
  if (count == 0) return;
  int width = rect.width - marginWidth * 2;
  int height = rect.height - marginHeight * 2;
  if (type == SWT.HORIZONTAL) {
    width -= (count - 1) * spacing;
    int x = rect.x + marginWidth, extra = width % count;
    int y = rect.y + marginHeight, cellWidth = width / count;
    for (int i=0; i<count; i++) {
      Control child = children [i];
      int childWidth = cellWidth;
      if (i == 0) {
        childWidth += extra / 2;
      } else {
        if (i == count - 1) childWidth += (extra + 1) / 2;
      }
      child.setBounds (x, y, childWidth, height);
      x += childWidth + spacing;
    }
  } else {
    height -= (count - 1) * spacing;
    int x = rect.x + marginWidth, cellHeight = height / count;
    int y = rect.y + marginHeight, extra = height % count;
    for (int i=0; i<count; i++) {
      Control child = children [i];
      int childHeight = cellHeight;
      if (i == 0) {
        childHeight += extra / 2;
      } else {
        if (i == count - 1) childHeight += (extra + 1) / 2;
      }
      child.setBounds (x, y, width, childHeight);
      y += childHeight + spacing;
    }
  }
}

/**
 * Returns a string containing a concise, human-readable
 * description of the receiver.
 *
 * @return a string representation of the layout
 */
public String toString () {
   String string = getName ()+" {";
   string += "type="+((type == SWT.VERTICAL) ? "SWT.VERTICAL" : "SWT.HORIZONTAL")+" ";
   if (marginWidth != 0) string += "marginWidth="+marginWidth+" ";
   if (marginHeight != 0) string += "marginHeight="+marginHeight+" ";
   if (spacing != 0) string += "spacing="+spacing+" ";
   string = string.trim();
   string += "}";
   return string;
}
}
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