Package org.eclipse.swt.custom

Class ScrolledComposite

  • All Implemented Interfaces:
    Drawable
    Direct Known Subclasses:
    SharedScrolledComposite
    public class ScrolledComposite
extends Composite
    A ScrolledComposite provides scrollbars and will scroll its content when the user uses the scrollbars.

    There are two ways to use the ScrolledComposite:

    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().
    
 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 ();
 }
    Styles:
    H_SCROLL, V_SCROLL
    See Also:
    ScrolledComposite snippets, Sample code and further information

    • Constructor Detail

      • ScrolledComposite

        public ScrolledComposite​(Composite parent,
                         int style)
        Constructs a new instance of this class given its parent and a style value describing its behavior and appearance.

        The style value is either one of the style constants defined in class SWT which is applicable to instances of this class, or must be built by bitwise OR'ing together (that is, using the int "|" operator) two or more of those SWT style constants. The class description lists the style constants that are applicable to the class. Style bits are also inherited from superclasses.

        Parameters:
        parent - a widget which will be the parent of the new instance (cannot be null)
        style - the style of widget to construct
        Throws:
        IllegalArgumentException -
        • ERROR_NULL_ARGUMENT - if the parent is null
        SWTException -
        • ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the parent
        See Also:
        SWT.H_SCROLL, SWT.V_SCROLL, Widget.getStyle()

    • Method Detail

      • getAlwaysShowScrollBars

        public boolean getAlwaysShowScrollBars()
        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.
        Returns:
        the Always Show Scrollbars flag value

      • getExpandHorizontal

        public boolean getExpandHorizontal()
        Returns true if the content control will be expanded to fill available horizontal space.
        Returns:
        the receiver's horizontal expansion state
        Throws:
        SWTException -
        • ERROR_WIDGET_DISPOSED - if the receiver has been disposed
        • ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
        Since:
        3.2

      • getExpandVertical

        public boolean getExpandVertical()
        Returns true if the content control will be expanded to fill available vertical space.
        Returns:
        the receiver's vertical expansion state
        Throws:
        SWTException -
        • ERROR_WIDGET_DISPOSED - if the receiver has been disposed
        • ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
        Since:
        3.2

      • getMinWidth

        public int getMinWidth()
        Returns the minimum width of the content control.
        Returns:
        the minimum width
        Throws:
        SWTException -
        • ERROR_WIDGET_DISPOSED - if the receiver has been disposed
        • ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
        Since:
        3.2

      • getMinHeight

        public int getMinHeight()
        Returns the minimum height of the content control.
        Returns:
        the minimum height
        Throws:
        SWTException -
        • ERROR_WIDGET_DISPOSED - if the receiver has been disposed
        • ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
        Since:
        3.2

      • getContent

        public Control getContent()
        Get the content that is being scrolled.
        Returns:
        the control displayed in the content area

      • getShowFocusedControl

        public boolean getShowFocusedControl()
        Returns true if the receiver automatically scrolls to a focused child control to make it visible. Otherwise, returns false.
        Returns:
        a boolean indicating whether focused child controls are automatically scrolled into the viewport
        Throws:
        SWTException -
        • ERROR_WIDGET_DISPOSED - if the receiver has been disposed
        • ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
        Since:
        3.4

      • getOrigin

        public Point getOrigin()
        Return the point in the content that currently appears in the top left corner of the scrolled composite.
        Returns:
        the point in the content that currently appears in the top left corner of the scrolled composite. If no content has been set, this returns (0, 0).
        Throws:
        SWTException -
        • ERROR_WIDGET_DISPOSED - if the receiver has been disposed
        • ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
        Since:
        2.0

      • setOrigin

        public void setOrigin​(Point origin)
        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.
        Parameters:
        origin - the point on the content to appear in the top left corner
        Throws:
        SWTException -
        • ERROR_WIDGET_DISPOSED - if the receiver has been disposed
        • ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
        • ERROR_INVALID_ARGUMENT - value of origin is outside of content
        Since:
        2.0

      • setOrigin

        public void setOrigin​(int x,
                      int 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.
        Parameters:
        x - the x coordinate of the content to appear in the top left corner
        y - the y coordinate of the content to appear in the top left corner
        Throws:
        SWTException -
        • ERROR_WIDGET_DISPOSED - if the receiver has been disposed
        • ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
        Since:
        2.0

      • setAlwaysShowScrollBars

        public void setAlwaysShowScrollBars​(boolean show)
        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.
        Parameters:
        show - true to show the scrollbars even when not required, false to show scrollbars only when required
        Throws:
        SWTException -
        • ERROR_WIDGET_DISPOSED - if the receiver has been disposed
        • ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver

      • setContent

        public void setContent​(Control content)
        Set the content that will be scrolled.
        Parameters:
        content - the control to be displayed in the content area
        Throws:
        SWTException -
        • ERROR_WIDGET_DISPOSED - if the receiver has been disposed
        • ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver

      • setExpandHorizontal

        public void setExpandHorizontal​(boolean expand)
        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 be 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.
        Parameters:
        expand - true to expand the content control to fill available horizontal space
        Throws:
        SWTException -
        • ERROR_WIDGET_DISPOSED - if the receiver has been disposed
        • ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver

      • setExpandVertical

        public void setExpandVertical​(boolean expand)
        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 be 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.
        Parameters:
        expand - true to expand the content control to fill available vertical space
        Throws:
        SWTException -
        • ERROR_WIDGET_DISPOSED - if the receiver has been disposed
        • ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver

      • setLayout

        public void setLayout​(Layout layout)
        Sets the layout which is associated with the receiver to be the argument which may be null.

        Note: No Layout can be set on this Control because it already manages the size and position of its children.

        Overrides:
        setLayout in class Composite
        Parameters:
        layout - the receiver's new layout or null
        Throws:
        SWTException -
        • ERROR_WIDGET_DISPOSED - if the receiver has been disposed
        • ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver

      • setMinHeight

        public void setMinHeight​(int height)
        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.
        Parameters:
        height - the minimum height or 0 for default height
        Throws:
        SWTException -
        • ERROR_WIDGET_DISPOSED - if the receiver has been disposed
        • ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver

      • setMinSize

        public void setMinSize​(Point size)
        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.
        Parameters:
        size - the minimum size or null for the default size
        Throws:
        SWTException -
        • ERROR_WIDGET_DISPOSED - if the receiver has been disposed
        • ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver

      • setMinSize

        public void setMinSize​(int width,
                       int 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.
        Parameters:
        width - the minimum width or 0 for default width
        height - the minimum height or 0 for default height
        Throws:
        SWTException -
        • ERROR_WIDGET_DISPOSED - if the receiver has been disposed
        • ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver

      • setMinWidth

        public void setMinWidth​(int width)
        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.
        Parameters:
        width - the minimum width or 0 for default width
        Throws:
        SWTException -
        • ERROR_WIDGET_DISPOSED - if the receiver has been disposed
        • ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver

      • setShowFocusedControl

        public void setShowFocusedControl​(boolean show)
        Configure the receiver to automatically scroll to a focused child control to make it visible. If show is false, show a focused control is off. By default, show a focused control is off.
        Parameters:
        show - true to show a focused control.
        Throws:
        SWTException -
        • ERROR_WIDGET_DISPOSED - if the receiver has been disposed
        • ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
        Since:
        3.4

      • showControl

        public void showControl​(Control control)
        Scrolls the content of the receiver so that the control is visible.
        Parameters:
        control - the control to be shown
        Throws:
        IllegalArgumentException -
        • ERROR_NULL_ARGUMENT - if the control is null
        • ERROR_INVALID_ARGUMENT - if the control has been disposed
        SWTException -
        • ERROR_WIDGET_DISPOSED - if the receiver has been disposed
        • ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
        Since:
        3.4