asyncboxview.java

来自「linux下建立JAVA虚拟机的源码KAFFE」· Java 代码 · 共 1,481 行 · 第 1/3 页

     * and locked the document.
     */
    private void update()
    {
      int majorAxis = getMajorAxis();
      boolean minorUpdated = false;
      synchronized (this)
        {
          if (! minorValid)
            {
              int minorAxis = getMinorAxis();
              minimum = childView.getMinimumSpan(minorAxis);
              preferred = childView.getPreferredSpan(minorAxis);
              maximum = childView.getMaximumSpan(minorAxis);
              minorValid = true;
              minorUpdated = true;
            }
        }
      if (minorUpdated)
        minorRequirementChange(this);

      boolean majorUpdated = false;
      float delta = 0.0F;
      synchronized (this)
        {
          if (! majorValid)
            {
              float oldSpan = majorSpan;
              majorSpan = childView.getPreferredSpan(majorAxis);
              delta = majorSpan - oldSpan;
              majorValid = true;
              majorUpdated = true;
            }
        }
      if (majorUpdated)
        {
          majorRequirementChange(this, delta);
          locator.childChanged(this);
        }

      synchronized (this)
        {
          if (! childSizeValid)
            {
              float w;
              float h;
              if (majorAxis == X_AXIS)
                {
                  w = majorSpan;
                  h = getMinorSpan();
                }
              else
                {
                  w = getMinorSpan();
                  h = majorSpan;
                }
              childSizeValid = true;
              childView.setSize(w, h);
            }
        }
    }

    /**
     * Returns the span of the child view along the minor layout axis.
     *
     * @return the span of the child view along the minor layout axis
     */
    public float getMinorSpan()
    {
      float retVal;
      if (maximum < minorSpan)
        retVal = maximum;
      else
        retVal = Math.max(minimum, minorSpan);
      return retVal;
    }

    /**
     * Returns the offset of the child view along the minor layout axis.
     *
     * @return the offset of the child view along the minor layout axis
     */
    public float getMinorOffset()
    {
      float retVal;
      if (maximum < minorSpan)
        {
          float align = childView.getAlignment(getMinorAxis());
          retVal = ((minorSpan - maximum) * align);
        }
      else
        retVal = 0f;

      return retVal;
    }

    /**
     * Returns the span of the child view along the major layout axis.
     *
     * @return the span of the child view along the major layout axis
     */

    public float getMajorSpan()
    {
      return majorSpan;
    }

    /**
     * Returns the offset of the child view along the major layout axis.
     *
     * @return the offset of the child view along the major layout axis
     */
    public float getMajorOffset()
    {
      return majorOffset;
    }

    /**
     * Sets the offset of the child view along the major layout axis. This
     * should only be called by the ChildLocator of that child view.
     *
     * @param offset the offset to set
     */
    public void setMajorOffset(float offset)
    {
      majorOffset = offset;
    }

    /**
     * Mark the preferences changed for that child. This forwards to
     * {@link AsyncBoxView#preferenceChanged}.
     *
     * @param width <code>true</code> if the width preference has changed
     * @param height <code>true</code> if the height preference has changed
     */
    public void preferenceChanged(boolean width, boolean height)
    {
      if (getMajorAxis() == X_AXIS)
        {
          if (width)
            majorValid = false;
          if (height)
            minorValid = false;
        }
      else
        {
          if (width)
            minorValid = false;
          if (height)
            majorValid = false;
        }
      childSizeValid = false;
    }
  }

  /**
   * Flushes the requirements changes upwards asynchronously.
   */
  private class FlushTask implements Runnable
  {
    /**
     * Starts the flush task. This obtains a readLock on the document
     * and then flushes all the updates using
     * {@link AsyncBoxView#flushRequirementChanges()} after updating the
     * requirements.
     */
    public void run()
    {
      try
        {
          // Acquire a lock on the document.
          Document doc = getDocument();
          if (doc instanceof AbstractDocument)
            {
              AbstractDocument abstractDoc = (AbstractDocument) doc;
              abstractDoc.readLock();
            }

          int n = getViewCount();
          if (minorChanged && (n > 0))
            {
              LayoutQueue q = getLayoutQueue();
              ChildState min = getChildState(0);
              ChildState pref = getChildState(0);
              for (int i = 1; i < n; i++)
                {
                  ChildState cs = getChildState(i);
                  if (cs.minimum > min.minimum)
                    min = cs;
                  if (cs.preferred > pref.preferred)
                    pref = cs;
                }
              synchronized (AsyncBoxView.this)
              {
                minReq = min;
                prefReq = pref;
              }
            }

          flushRequirementChanges();
        }
      finally
      {
        // Release the lock on the document.
        Document doc = getDocument();
        if (doc instanceof AbstractDocument)
          {
            AbstractDocument abstractDoc = (AbstractDocument) doc;
            abstractDoc.readUnlock();
          }
      }
    }

  }

  /**
   * The major layout axis.
   */
  private int majorAxis;

  /**
   * The top inset.
   */
  private float topInset;

  /**
   * The bottom inset.
   */
  private float bottomInset;

  /**
   * The left inset.
   */
  private float leftInset;

  /**
   * Indicates if the major span should be treated as beeing estimated or not.
   */
  private boolean estimatedMajorSpan;

  /**
   * The right inset.
   */
  private float rightInset;

  /**
   * The children and their layout statistics.
   */
  private ArrayList childStates;

  /**
   * The currently changing child state. May be null if there is no child state
   * updating at the moment. This is package private to avoid a synthetic
   * accessor method inside ChildState.
   */
  ChildState changing;

  /**
   * Represents the minimum requirements. This is used in
   * {@link #getMinimumSpan(int)}.
   */
  ChildState minReq;

  /**
   * Represents the minimum requirements. This is used in
   * {@link #getPreferredSpan(int)}.
   */
  ChildState prefReq;

  /**
   * Indicates that the major axis requirements have changed.
   */
  private boolean majorChanged;

  /**
   * Indicates that the minor axis requirements have changed. This is package
   * private to avoid synthetic accessor method.
   */
  boolean minorChanged;

  /**
   * The current span along the major layout axis. This is package private to
   * avoid synthetic accessor method.
   */
  float majorSpan;

  /**
   * The current span along the minor layout axis. This is package private to
   * avoid synthetic accessor method.
   */
  float minorSpan;

  /**
   * This tasked is placed on the layout queue to flush updates up to the
   * parent view.
   */
  private Runnable flushTask;

  /**
   * The child locator for this view.
   */
  protected ChildLocator locator;

  /**
   * Creates a new <code>AsyncBoxView</code> that represents the specified
   * element and layouts its children along the specified axis.
   *
   * @param elem the element
   * @param axis the layout axis
   */
  public AsyncBoxView(Element elem, int axis)
  {
    super(elem);
    majorAxis = axis;
    childStates = new ArrayList();
    flushTask = new FlushTask();
    locator = new ChildLocator();
    minorSpan = Short.MAX_VALUE;
  }

  /**
   * Returns the major layout axis.
   *
   * @return the major layout axis
   */
  public int getMajorAxis()
  {
    return majorAxis;
  }

  /**
   * Returns the minor layout axis, that is the axis orthogonal to the major
   * layout axis.
   *
   * @return the minor layout axis
   */
  public int getMinorAxis()
  {
    return majorAxis == X_AXIS ? Y_AXIS : X_AXIS;
  }

  /**
   * Returns the view at the specified <code>index</code>.
   *
   * @param index the index of the requested child view
   *
   * @return the view at the specified <code>index</code>
   */
  public View getView(int index)
  {
    View view = null;
    synchronized(childStates)
      {
        if ((index >= 0) && (index < childStates.size()))
          {
            ChildState cs = (ChildState) childStates.get(index);
            view = cs.getChildView();
          }
      }
    return view;
  }

  /**
   * Returns the number of child views.
   *
   * @return the number of child views
   */
  public int getViewCount()
  {
    synchronized(childStates)
    {
      return childStates.size();
    }
  }

  /**
   * Returns the view index of the child view that represents the specified
   * model position.
   *
   * @param pos the model position for which we search the view index
   * @param bias the bias
   *
   * @return the view index of the child view that represents the specified
   *         model position
   */
  public int getViewIndex(int pos, Position.Bias bias)
  {
    int retVal = -1;

    if (bias == Position.Bias.Backward)
      pos = Math.max(0, pos - 1);

    // TODO: A possible optimization would be to implement a binary search
    // here.
    int numChildren = childStates.size();
    if (numChildren > 0)
      {
        for (int i = 0; i < numChildren; ++i)
          {
            View child = ((ChildState) childStates.get(i)).getChildView();
            if (child.getStartOffset() <= pos && child.getEndOffset() > pos)
              {
                retVal = i;
                break;
              }
          }
      }
    return retVal;
  }

  /**
   * Returns the top inset.
   *
   * @return the top inset
   */
  public float getTopInset()
  {
    return topInset;
  }

  /**
   * Sets the top inset.
   *
   * @param top the top inset
   */
  public void setTopInset(float top)
  {
    topInset = top;
  }

  /**
   * Returns the bottom inset.
   *
   * @return the bottom inset
   */
  public float getBottomInset()
  {
    return bottomInset;
  }

  /**
   * Sets the bottom inset.
   *
   * @param bottom the bottom inset
   */
  public void setBottomInset(float bottom)
  {
    bottomInset = bottom;
  }

  /**
   * Returns the left inset.
   *
   * @return the left inset
   */
  public float getLeftInset()
  {
    return leftInset;
  }

  /**
   * Sets the left inset.
   *
   * @param left the left inset
   */
  public void setLeftInset(float left)
  {
    leftInset = left;
  }

  /**
   * Returns the right inset.
   *
   * @return the right inset
   */
  public float getRightInset()
  {
    return rightInset;
  }

  /**
   * Sets the right inset.
   *
   * @param right the right inset
   */
  public void setRightInset(float right)
  {
    rightInset = right;
  }

  /**
   * Loads the child views of this view. This is triggered by
   * {@link #setParent(View)}.
   *