Class UIScroll

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Class UIScroll

public class UIScroll extends UIPanel implements IUIScroll, 
            IUIPosition
{
  // Fields
  public static final int NOHIDE;
  public static final int NOKEY;
  public static final int NONPROPORTIONAL;
  public static final int NOSHOW;
  public static final int PAGE_DOWN;
  public static final int PAGE_UP;
  public static final int THICK;
  public static final int THUMB;
  public static final int VERTICAL;

  // Constructors
  public UIScroll();
  public UIScroll(int style);
  public UIScroll(int style, int min, int max, int page, int line,
        int pos);

  // Methods
  public boolean action(Event e, Object o);
  public IUIComponent add(int index, IUIComponent comp);
  public synchronized void addAdjustmentListener(
        IUIAdjustmentListener l);
  public IUIComponent getLayoutComponent(int index);
  public Dimension getMinimumSize();
  public Point getPosition();
  public Dimension getPreferredSize();
  public int getRoleCode();
  public int getScrollLine();
  public int getScrollMax();
  public int getScrollMin();
  public int getScrollPage();
  public int getScrollPos();
  public int getStyle();
  public int getXPosition();
  public int getYPosition();
  public boolean isKeyable();
  public boolean isScrollable();
  public void layout();
  public boolean mouseDrag(Event e, int x, int y);
  protected void processAdjustmentEvent(UIAdjustmentEvent e);
  protected void processEvent(UIEvent e);
  public synchronized void removeAdjustmentListener(
        IUIAdjustmentListener l);
  public int scrollEnd();
  public int scrollHome();
  public int scrollLineDown();
  public int scrollLineUp();
  public int scrollPageDown();
  public int scrollPageUp();
  public void setPosition(Point pt);
  public void setPosition(int x, int y);
  public int setScrollInfo(int min, int max, int page, int line,
        int pos, boolean notify);
  public int setScrollInfo(int min, int max, int page, int line,
        int pos);
  public void setScrollLine(int line);
  public int setScrollLine(int line, boolean notify);
  public void setScrollMax(int max);
  public void setScrollMin(int min);
  public void setScrollPage(int page);
  public int setScrollPage(int page, boolean notify);
  public void setScrollPos(int pos);
  public int setScrollPos(int pos, boolean notify);
  public int setScrollRange(int min, int max);
  public void setStyle(int style);
  public void setXPosition(int x);
  public void setYPosition(int y);
}

This class implements a scroll track control. UIScroll defines the following five scroll track styles:

The following example shows how to construct a scroll track control using the defined styles.

// Construct a vertical scroll track that is always visible.
UIScroll sc1 = new UIScroll(UIScroll.VERTICAL | UIScroll.NOHIDE);

// Add sc1 to the container.
add(sc1);

In addition to setting styles, you can initialize the scroll track control's scroll information by specifying range, page, line, and current position values. The range indicates the possible number of scroll positions associated with the control. The page and line values define increments for adjusting the current position. The following example shows how to construct a scroll track control with specified scroll information.

// Construct a vertical scroll track that is always visible.
// Define its range to be 0 to 100, with a page of 4, a line 
// of 2, and an initial position of 50.
UIScroll sc2 = new UIScroll(UIScroll.VERTICAL | UIScroll.NOHIDE,
                            0, 100, 4, 2, 50);
// Add sc2 to the container.
add(sc2);

UIScroll manages three components that allow the user to move the scroll track control's current position. Each component is identified by a layout index, as defined in the following table.

Layout Index Component

THUMB The component used to indicate the current position of the scroll track control (by default, a UIScrollThumb object). When the THUMB component is dragged with the mouse, the current position is moved in increments or decrements of one scroll position.

PAGE_UP The track area above or to the left of the thumb component (by default, a UIRepeatButton object). When the PAGE_UP component is pressed with the mouse, the current position is moved in decrements of one line less than a page.

PAGE_DOWN The track area below or to the right of the thumb component (by default, a UIRepeatButton object). When the PAGE_DOWN component is pressed with the mouse, the current position is moved in increments of one line less than a page.

UIScrollBar extends UIScroll to implement a scroll bar control. In addition to the three components defined by UIScroll, UIScrollBar adds LINE_UP and LINE_DOWN components to the ends of the scroll track. For a description of these components, see the UIScrollBar overview. Other classes that extend UIScroll include UISlider and UISpinner.