Class Scale

All Implemented Interfaces:
Adaptable, Drawable

public class Scale extends Control
Instances of the receiver represent a selectable user interface object that present a range of continuous numeric values.
Styles:
HORIZONTAL, VERTICAL
Events:
Selection

Note: Only one of the styles HORIZONTAL and VERTICAL may be specified.

IMPORTANT: This class is intended to be subclassed only within the SWT implementation.

Since:
1.2
  • Constructor Details

    • Scale

      public Scale(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 composite control which will be the parent of the new instance (cannot be null)
      style - the style of control 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
      • ERROR_INVALID_SUBCLASS - if this class is not an allowed subclass
      See Also:
  • Method Details

    • addSelectionListener

      public void addSelectionListener(SelectionListener listener)
      Adds the listener to the collection of listeners who will be notified when the user changes the receiver's value, by sending it one of the messages defined in the SelectionListener interface.

      widgetSelected is called when the user changes the receiver's value. widgetDefaultSelected is not called.

      Parameters:
      listener - the listener which should be notified
      Throws:
      IllegalArgumentException -
      • ERROR_NULL_ARGUMENT - if the listener is null
      SWTException -
      • ERROR_WIDGET_DISPOSED - if the receiver has been disposed
      • ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
      See Also:
    • removeSelectionListener

      public void removeSelectionListener(SelectionListener listener)
      Removes the listener from the collection of listeners who will be notified when the user changes the receiver's value.
      Parameters:
      listener - the listener which should no longer be notified
      Throws:
      IllegalArgumentException -
      • ERROR_NULL_ARGUMENT - if the listener is null
      SWTException -
      • ERROR_WIDGET_DISPOSED - if the receiver has been disposed
      • ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
      See Also:
    • computeSize

      public Point computeSize(int wHint, int hHint, boolean changed)
      Description copied from class: Control
      Returns the preferred size of the receiver.

      The preferred size of a control is the size that it would best be displayed at. The width hint and height hint arguments allow the caller to ask a control questions such as "Given a particular width, how high does the control need to be to show all of the contents?" To indicate that the caller does not wish to constrain a particular dimension, the constant SWT.DEFAULT is passed for the hint.

      If the changed flag is true, it indicates that the receiver's contents have changed, therefore any caches that a layout manager containing the control may have been keeping need to be flushed. When the control is resized, the changed flag will be false, so layout manager caches can be retained.

      Overrides:
      computeSize in class Control
      Parameters:
      wHint - the width hint (can be SWT.DEFAULT)
      hHint - the height hint (can be SWT.DEFAULT)
      changed - true if the control's contents have changed, and false otherwise
      Returns:
      the preferred size of the control.
      See Also:
    • getIncrement

      public int getIncrement()
      Returns the amount that the receiver's value will be modified by when the up/down (or right/left) arrows are pressed.
      Returns:
      the increment
      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
    • getMaximum

      public int getMaximum()
      Returns the maximum value which the receiver will allow.
      Returns:
      the maximum
      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
    • getMinimum

      public int getMinimum()
      Returns the minimum value which the receiver will allow.
      Returns:
      the minimum
      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
    • getPageIncrement

      public int getPageIncrement()
      Returns the amount that the receiver's value will be modified by when the page increment/decrement areas are selected.
      Returns:
      the page increment
      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
    • getSelection

      public int getSelection()
      Returns the 'selection', which is the receiver's position.
      Returns:
      the selection
      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
    • setIncrement

      public void setIncrement(int increment)
      Sets the amount that the receiver's value will be modified by when the up/down (or right/left) arrows are pressed to the argument, which must be at least one.
      Parameters:
      increment - the new increment (must be greater than zero)
      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
    • setMaximum

      public void setMaximum(int maximum)
      Sets the maximum value that the receiver will allow. This new value will be ignored if it is not greater than the receiver's current minimum value. If the new maximum is applied then the receiver's selection value will be adjusted if necessary to fall within its new range.
      Parameters:
      maximum - the new maximum, which must be greater than the current minimum
      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
    • setMinimum

      public void setMinimum(int minimum)
      Sets the minimum value that the receiver will allow. This new value will be ignored if it is negative or is not less than the receiver's current maximum value. If the new minimum is applied then the receiver's selection value will be adjusted if necessary to fall within its new range.
      Parameters:
      minimum - the new minimum, which must be nonnegative and less than the current maximum
      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
    • setPageIncrement

      public void setPageIncrement(int pageIncrement)
      Sets the amount that the receiver's value will be modified by when the page increment/decrement areas are selected to the argument, which must be at least one.
      Parameters:
      pageIncrement - the page increment (must be greater than zero)
      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
    • setSelection

      public void setSelection(int selection)
      Sets the 'selection', which is the receiver's value, to the argument which must be greater than or equal to zero.
      Parameters:
      selection - the new selection (must be zero or greater)
      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
    • getAdapter

      public <T> T getAdapter(Class<T> adapter)
      Description copied from class: Widget
      Implementation of the Adaptable interface.

      IMPORTANT: This method is not part of the RWT public API. It is marked public only so that it can be shared within the packages provided by RWT. It should never be accessed from application code.

      Specified by:
      getAdapter in interface Adaptable
      Overrides:
      getAdapter in class Control
      Parameters:
      adapter - the lookup class
      Returns:
      an object that can be cast to the given class or null if there is no adapter associated with the given class.