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/*******************************************************************************
 * Copyright (c) 2000, 2004 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.custom;

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

/**
 * A ScrolledComposite provides scrollbars and will scroll its content when the user
 * uses the scrollbars.
 *
 *
 * <p>There are two ways to use the ScrolledComposite:
 * 
 * <p>
 * 1) Set the size of the control that is being scrolled and the ScrolledComposite 
 * will show scrollbars when the contained control can not be fully seen.
 * 
 * 2) The second way imitates the way a browser would work.  Set the minimum size of
 * the control and the ScrolledComposite will show scroll bars if the visible area is 
 * less than the minimum size of the control and it will expand the size of the control 
 * if the visible area is greater than the minimum size.  This requires invoking 
 * both setMinWidth(), setMinHeight() and setExpandHorizontal(), setExpandVertical().
 * 
 * <code><pre>
 * public static void main (String [] args) {
 *      Display display = new Display ();
 *      Color red = display.getSystemColor(SWT.COLOR_RED);
 *      Color blue = display.getSystemColor(SWT.COLOR_BLUE);
 *      Shell shell = new Shell (display);
 *      shell.setLayout(new FillLayout());
 *   
 *      // set the size of the scrolled content - method 1
 *      final ScrolledComposite sc1 = new ScrolledComposite(shell, SWT.H_SCROLL | SWT.V_SCROLL | SWT.BORDER);
 *      final Composite c1 = new Composite(sc1, SWT.NONE);
 *      sc1.setContent(c1);
 *      c1.setBackground(red);
 *      GridLayout layout = new GridLayout();
 *      layout.numColumns = 4;
 *      c1.setLayout(layout);
 *      Button b1 = new Button (c1, SWT.PUSH);
 *      b1.setText("first button");
 *      c1.setSize(c1.computeSize(SWT.DEFAULT, SWT.DEFAULT));
 *      
 *      // set the minimum width and height of the scrolled content - method 2
 *      final ScrolledComposite sc2 = new ScrolledComposite(shell, SWT.H_SCROLL | SWT.V_SCROLL | SWT.BORDER);
 *      sc2.setExpandHorizontal(true);
 *      sc2.setExpandVertical(true);
 *      final Composite c2 = new Composite(sc2, SWT.NONE);
 *      sc2.setContent(c2);
 *      c2.setBackground(blue);
 *      layout = new GridLayout();
 *      layout.numColumns = 4;
 *      c2.setLayout(layout);
 *      Button b2 = new Button (c2, SWT.PUSH);
 *      b2.setText("first button");
 *      sc2.setMinSize(c2.computeSize(SWT.DEFAULT, SWT.DEFAULT));
 *      
 *      Button add = new Button (shell, SWT.PUSH);
 *      add.setText("add children");
 *      final int[] index = new int[]{0};
 *      add.addListener(SWT.Selection, new Listener() {
 *          public void handleEvent(Event e) {
 *              index[0]++;
 *              Button button = new Button(c1, SWT.PUSH);
 *              button.setText("button "+index[0]);
 *              // reset size of content so children can be seen - method 1
 *              c1.setSize(c1.computeSize(SWT.DEFAULT, SWT.DEFAULT));
 *              c1.layout();
 *              
 *              button = new Button(c2, SWT.PUSH);
 *              button.setText("button "+index[0]);
 *              // reset the minimum width and height so children can be seen - method 2
 *              sc2.setMinSize(c2.computeSize(SWT.DEFAULT, SWT.DEFAULT));
 *              c2.layout();
 *          }
 *      });
 * 
 *      shell.open ();
 *      while (!shell.isDisposed ()) {
 *          if (!display.readAndDispatch ()) display.sleep ();
 *      }
 *      display.dispose ();
 * }
 * </pre></code>
 *
 * <dl>
 * <dt><b>Styles:</b><dd>H_SCROLL, V_SCROLL
 * </dl>
 */
public class ScrolledComposite extends Composite {

  Control content;
  Listener contentListener;
  
  int minHeight = 0;
  int minWidth = 0;
  boolean expandHorizontal = false;
  boolean expandVertical = false;
  boolean alwaysShowScroll = false;

/**
 * Constructs a new instance of this class given its parent
 * and a style value describing its behavior and appearance.
 * <p>
 * The style value is either one of the style constants defined in
 * class <code>SWT</code> which is applicable to instances of this
 * class, or must be built by <em>bitwise OR</em>'ing together 
 * (that is, using the <code>int</code> "|" operator) two or more
 * of those <code>SWT</code> style constants. The class description
 * lists the style constants that are applicable to the class.
 * Style bits are also inherited from superclasses.
 * </p>
 *
 * @param parent a widget which will be the parent of the new instance (cannot be null)
 * @param style the style of widget to construct
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if the parent is null</li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the parent</li>
 * </ul>
 *
 * @see SWT#H_SCROLL
 * @see SWT#V_SCROLL
 * @see #getStyle()
 */  
public ScrolledComposite(Composite parent, int style) {
  super(parent, checkStyle(style));
  super.setLayout(new ScrolledCompositeLayout());
}

static int checkStyle (int style) {
  int mask = SWT.H_SCROLL | SWT.V_SCROLL | SWT.BORDER | SWT.LEFT_TO_RIGHT | SWT.RIGHT_TO_LEFT;
  return style & mask;
}

/**
 * Returns the Always Show Scrollbars flag.  True if the scrollbars are 
 * always shown even if they are not required.  False if the scrollbars are only 
 * visible when some part of the composite needs to be scrolled to be seen.
 * The H_SCROLL and V_SCROLL style bits are also required to enable scrollbars in the 
 * horizontal and vertical directions.
 * 
 * @return the Always Show Scrollbars flag value
 */
public boolean getAlwaysShowScrollBars() {
  //checkWidget();
  return alwaysShowScroll;
}

/**
 * Get the content that is being scrolled.
 * 
 * @return the control displayed in the content area
 */
public Control getContent() {
  //checkWidget();
  return content;
}

void hScroll() {
  if (content == null) return;
  Point location = content.getLocation ();
  ScrollBar hBar = getHorizontalBar ();
  int hSelection = hBar.getSelection ();
  content.setLocation (-hSelection, location.y);
}
boolean needHScroll(Rectangle contentRect, boolean vVisible) {
  ScrollBar hBar = getHorizontalBar();
  if (hBar == null) return false;
  
  Rectangle hostRect = getBounds();
  int border = getBorderWidth();
  hostRect.width -= 2*border;
  ScrollBar vBar = getVerticalBar();
  if (vVisible && vBar != null) hostRect.width -= vBar.getSize().x;
  
  if (!expandHorizontal && contentRect.width > hostRect.width) return true;
  if (expandHorizontal && minWidth > hostRect.width) return true;
  return false;
}

boolean needVScroll(Rectangle contentRect, boolean hVisible) {
  ScrollBar vBar = getVerticalBar();
  if (vBar == null) return false;
  
  Rectangle hostRect = getBounds();
  int border = getBorderWidth();
  hostRect.height -= 2*border;
  ScrollBar hBar = getHorizontalBar();
  if (hVisible && hBar != null) hostRect.height -= hBar.getSize().y;
  
  if (!expandVertical && contentRect.height > hostRect.height) return true;
  if (expandVertical && minHeight > hostRect.height) return true;
  return false;
}

/**
 * Return the point in the content that currenly appears in the top left 
 * corner of the scrolled composite.
 * 
 * @return the point in the content that currenly appears in the top left 
 * corner of the scrolled composite.  If no content has been set, this returns
 * (0, 0).
 * 
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 * 
 * @since 2.0
 */
public Point getOrigin() {
  checkWidget();
  if (content == null) return new Point(0, 0);
  Point location = content.getLocation();
  return new Point(-location.x, -location.y);
}
/**
 * Scrolls the content so that the specified point in the content is in the top 
 * left corner.  If no content has been set, nothing will occur.  
 * 
 * Negative values will be ignored.  Values greater than the maximum scroll 
 * distance will result in scrolling to the end of the scrollbar.
 *
 * @param origin the point on the content to appear in the top left corner 
 * 
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 *    <li>ERROR_INVALID_ARGUMENT - value of origin is outside of content
 * </ul>
 * @since 2.0
 */
public void setOrigin(Point origin) {
  setOrigin(origin.x, origin.y);
}
/**
 * Scrolls the content so that the specified point in the content is in the top 
 * left corner.  If no content has been set, nothing will occur.  
 * 
 * Negative values will be ignored.  Values greater than the maximum scroll 
 * distance will result in scrolling to the end of the scrollbar.
 *
 * @param x the x coordinate of the content to appear in the top left corner 
 * 
 * @param y the y coordinate of the content to appear in the top left corner 
 * 
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 * 
 * @since 2.0
 */
public void setOrigin(int x, int y) {
  checkWidget();
  if (content == null) return;
  ScrollBar hBar = getHorizontalBar ();
  if (hBar != null) {
    hBar.setSelection(x);
    x = -hBar.getSelection ();
  } else {
    x = 0;
  }
  ScrollBar vBar = getVerticalBar ();
  if (vBar != null) {
    vBar.setSelection(y);
    y = -vBar.getSelection ();
  } else {
    y = 0;
  }
  content.setLocation(x, y);
}
/**
 * Set the Always Show Scrollbars flag.  True if the scrollbars are 
 * always shown even if they are not required.  False if the scrollbars are only 
 * visible when some part of the composite needs to be scrolled to be seen.
 * The H_SCROLL and V_SCROLL style bits are also required to enable scrollbars in the 
 * horizontal and vertical directions.
 * 
 * @param show true to show the scrollbars even when not required, false to show scrollbars only when required
 * 
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 */
public void setAlwaysShowScrollBars(boolean show) {
  checkWidget();
  if (show == alwaysShowScroll) return;
  alwaysShowScroll = show;
  ScrollBar hBar = getHorizontalBar ();
  if (hBar != null && alwaysShowScroll) hBar.setVisible(true);
  ScrollBar vBar = getVerticalBar ();
  if (vBar != null && alwaysShowScroll) vBar.setVisible(true);
  layout(false);
}

/**
 * Set the content that will be scrolled.
 * 
 * @param content the control to be displayed in the content area
 * 
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 */
public void setContent(Control content) {
  checkWidget();
  if (this.content != null && !this.content.isDisposed()) {
    this.content.removeListener(SWT.Resize, contentListener);
    this.content.setBounds(new Rectangle(-200, -200, 0, 0));  
  }
  
  this.content = content;
  ScrollBar vBar = getVerticalBar ();
  ScrollBar hBar = getHorizontalBar ();
  if (this.content != null) {
    if (vBar != null) {
      vBar.setMaximum (0);
      vBar.setThumb (0);
      vBar.setSelection(0);
    }
    if (hBar != null) {
      hBar.setMaximum (0);
      hBar.setThumb (0);
      hBar.setSelection(0);
    }
    content.setLocation(0, 0);
    layout(false);
    this.content.addListener(SWT.Resize, contentListener);
  } else {
    if (hBar != null) hBar.setVisible(alwaysShowScroll);
    if (vBar != null) vBar.setVisible(alwaysShowScroll);
  }
}
/**
 * Configure the ScrolledComposite to resize the content object to be as wide as the 
 * ScrolledComposite when the width of the ScrolledComposite is greater than the
 * minimum width specified in setMinWidth.  If the ScrolledComposite is less than the
 * minimum width, the content will not resized and instead the horizontal scroll bar will be
 * used to view the entire width.
 * If expand is false, this behaviour is turned off.  By default, this behaviour is turned off.
 * 
 * @param expand true to expand the content control to fill available horizontal space
 * 
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 */
public void setExpandHorizontal(boolean expand) {
  checkWidget();
  if (expand == expandHorizontal) return;
  expandHorizontal = expand;
  layout(false);
}
/**
 * Configure the ScrolledComposite to resize the content object to be as tall as the 
 * ScrolledComposite when the height of the ScrolledComposite is greater than the
 * minimum height specified in setMinHeight.  If the ScrolledComposite is less than the
 * minimum height, the content will not resized and instead the vertical scroll bar will be
 * used to view the entire height.
 * If expand is false, this behaviour is turned off.  By default, this behaviour is turned off.
 * 
 * @param expand true to expand the content control to fill available vertical space
 * 
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 */
public void setExpandVertical(boolean expand) {
  checkWidget();
  if (expand == expandVertical) return;
  expandVertical = expand;
  layout(false);
}
/**
 * Sets the layout which is associated with the receiver to be
 * the argument which may be null.
 * <p>
 * Note : No Layout can be set on this Control because it already
 * manages the size and position of its children.
 * </p>
 *
 * @param layout the receiver's new layout or null
 *
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 */
public void setLayout (Layout layout) {
  checkWidget();
  return;
}
/**
 * Specify the minimum height at which the ScrolledComposite will begin scrolling the
 * content with the vertical scroll bar.  This value is only relevant if  
 * setExpandVertical(true) has been set.
 * 
 * @param height the minimum height or 0 for default height
 * 
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 */
public void setMinHeight(int height) {
  setMinSize(minWidth, height);
}
/**
 * Specify the minimum width and height at which the ScrolledComposite will begin scrolling the
 * content with the horizontal scroll bar.  This value is only relevant if  
 * setExpandHorizontal(true) and setExpandVertical(true) have been set.
 * 
 * @param size the minimum size or null for the default size
 * 
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 */
public void setMinSize(Point size) {
  if (size == null) {
    setMinSize(0, 0);
  } else {
    setMinSize(size.x, size.y);
  }
}
/**
 * Specify the minimum width and height at which the ScrolledComposite will begin scrolling the
 * content with the horizontal scroll bar.  This value is only relevant if  
 * setExpandHorizontal(true) and setExpandVertical(true) have been set.
 * 
 * @param width the minimum width or 0 for default width
 * @param height the minimum height or 0 for default height
 * 
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 */
public void setMinSize(int width, int height) {
  checkWidget();
  if (width == minWidth && height == minHeight) return;
  minWidth = Math.max(0, width);
  minHeight = Math.max(0, height);
  layout(false);
}
/**
 * Specify the minimum width at which the ScrolledComposite will begin scrolling the
 * content with the horizontal scroll bar.  This value is only relevant if  
 * setExpandHorizontal(true) has been set.
 * 
 * @param width the minimum width or 0 for default width
 * 
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 */
public void setMinWidth(int width) {
  setMinSize(width, minHeight);
}

void vScroll() {
  if (content == null) return;
  Point location = content.getLocation ();
  ScrollBar vBar = getVerticalBar ();
  int vSelection = vBar.getSelection ();
  content.setLocation (location.x, -vSelection);
}
protected void createHandle () {
  super.createHandle();
//  ScrollBar hBar = getHorizontalBar ();
//  if (hBar != null) {
//    hBar.addListener (SWT.Selection, new Listener () {
//      public void handleEvent (Event e) {
//        hScroll();
//      }
//    });
//  }
  
//  ScrollBar vBar = getVerticalBar ();
//  if (vBar != null) {
//    vBar.addListener (SWT.Selection, new Listener () {
//      public void handleEvent (Event e) {
//        vScroll();
//      }
//    });
//  }
  
//  contentListener = new Listener() {
//    public void handleEvent(Event e) {
//      if (e.type != SWT.Resize) return;
//      layout(false);
//    }
//  };

}

protected boolean useNativeScrollBar() {
  return true;
}

}
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