grouplayout.java

j2me设计的界面包

            throw new IllegalArgumentException(
                    "GroupLayout can only be used with one Container at a time");
        }
    }
    
    /**
     * Returns the <code>ComponentInfo</code> for the specified Component.
     */
    private ComponentInfo getComponentInfo(Component component) {
        ComponentInfo info = (ComponentInfo)componentInfos.get(component);
        if (info == null) {
            info = new ComponentInfo(component);
            componentInfos.put(component, info);
            if (component.getParent() != host) {
                host.addComponent(component);
            }
        }
        return info;
    }
    
    /**
     * Adjusts the autopadding springs for the horizontal and vertical
     * groups.  If <code>insert</code> is true this will insert auto padding
     * springs, otherwise this will only adjust the springs that
     * comprise auto preferred padding springs.
     */
    private void insertAutopadding(boolean insert) {
        horizontalGroup.insertAutopadding(HORIZONTAL, new Vector(1),
                new Vector(1), new Vector(1), new Vector(1), insert);
        verticalGroup.insertAutopadding(VERTICAL, new Vector(1),
                new Vector(1), new Vector(1), new Vector(1), insert);
    }
    
    /**
     * Returns true if the two Components have a common ParallelGroup ancestor
     * along the particular axis.
     */
    private boolean areParallelSiblings(Component source, Component target,
            int axis) {
        ComponentInfo sourceInfo = getComponentInfo(source);
        ComponentInfo targetInfo = getComponentInfo(target);
        Spring sourceSpring;
        Spring targetSpring;
        if (axis == HORIZONTAL) {
            sourceSpring = sourceInfo.horizontalSpring;
            targetSpring = targetInfo.horizontalSpring;
        } else {
            sourceSpring = sourceInfo.verticalSpring;
            targetSpring = targetInfo.verticalSpring;
        }
        Vector sourcePath = tmpParallelSet;
        sourcePath.removeAllElements();
        Spring spring = sourceSpring.getParent();
        while (spring != null) {
            sourcePath.addElement(spring);
            spring = spring.getParent();
        }
        spring = targetSpring.getParent();
        while (spring != null) {
            if (sourcePath.contains(spring)) {
                sourcePath.removeAllElements();
                while (spring != null) {
                    if (spring instanceof ParallelGroup) {
                        return true;
                    }
                    spring = spring.getParent();
                }
                return false;
            }
            spring = spring.getParent();
        }
        sourcePath.removeAllElements();
        return false;
    }
    
    private boolean isLeftToRight() {
        // Need bidi support...
        return true;
        //return host.getComponentOrientation().isLeftToRight();
    }
    
    /**
     * Spring consists of a range: min, pref and max a value some where in
     * the middle of that and a location.  Subclasses must override
     * methods to get the min/max/pref and will likely want to override
     * the <code>setSize</code> method.  Spring automatically caches the
     * min/max/pref.  If the min/pref/max has internally changes, or needs
     * to be updated you must invoked clear.
     */
    abstract class Spring {
        private int size;
        private int min;
        private int max;
        private int pref;
        private Spring parent;
        
        private int alignment;
        
        Spring() {
            min = pref = max = UNSET;
        }
        
        /**
         * Calculates and returns the minimum size.
         *
         * @param axis the axis of layout; one of HORIZONTAL or VERTICAL
         * @return the minimum size
         */
        abstract int calculateMinimumSize(int axis);
        
        /**
         * Calculates and returns the preferred size.
         *
         * @param axis the axis of layout; one of HORIZONTAL or VERTICAL
         * @return the preferred size
         */
        abstract int calculatePreferredSize(int axis);
        
        /**
         * Calculates and returns the minimum size.
         *
         * @param axis the axis of layout; one of HORIZONTAL or VERTICAL
         * @return the minimum size
         */
        abstract int calculateMaximumSize(int axis);
        
        /**
         * Sets the parent of this Spring.
         */
        void setParent(Spring parent) {
            this.parent = parent;
        }
        
        /**
         * Returns the parent of this spring.
         */
        Spring getParent() {
            return parent;
        }
        
        // This is here purely as a conveniance for ParallelGroup to avoid
        // having to track alignment separately.
        void setAlignment(int alignment) {
            this.alignment = alignment;
        }
        
        int getAlignment() {
            return alignment;
        }
        
        /**
         * Returns the minimum size.
         */
        final int getMinimumSize(int axis) {
            if (min == UNSET) {
                min = constrain(calculateMinimumSize(axis));
            }
            return min;
        }
        
        /**
         * Returns the preferred size.
         */
        final int getPreferredSize(int axis) {
            if (pref == UNSET) {
                pref = constrain(calculatePreferredSize(axis));
            }
            return pref;
        }
        
        /**
         * Returns the maximum size.
         */
        final int getMaximumSize(int axis) {
            if (max == UNSET) {
                max = constrain(calculateMaximumSize(axis));
            }
            return max;
        }
        
        /**
         * Resets the cached min/max/pref.
         */
        void unset() {
            size = min = pref = max = UNSET;
        }
        
        /**
         * Sets the value and location of the spring.  Subclasses
         * will want to invoke super, then do any additional sizing.
         *
         * @param axis HORIZONTAL or VERTICAL
         * @param origin of this Spring
         * @param size of the Spring.  If size is UNSET, this invokes
         *        clear.
         */
        void setSize(int axis, int origin, int size) {
            this.size = size;
            if (size == UNSET) {
                unset();
            }
        }
        
        /**
         * Returns the current size.
         */
        int getSize() {
            return size;
        }
        
        int constrain(int value) {
            return Math.min(value, Short.MAX_VALUE);
        }

        int getBaseline() {
            return -1;
        }
        
        int getBaselineResizeBehavior() {
            return Component.BRB_OTHER;
        }
        
        final boolean isResizable(int axis) {
            int min = getMinimumSize(axis);
            int pref = getPreferredSize(axis);
            return (min != pref || pref != getMaximumSize(axis));
        }
        
        /**
         * Returns true if this Spring will ALWAYS have a zero size. This should 
         * NOT check the current size, rather it's meant to 
         * quickly test if this Spring will always have a zero size.
         */
        abstract boolean willHaveZeroSize(boolean treatAutopaddingAsZeroSized);
    }
    
    /**
     * Simple copy constructor for vector
     */
    private static Vector create(Vector v) {
        int size = v.size();
        Vector vec = new Vector(size);
        for(int iter = 0 ; iter < size ; iter++) {
            vec.addElement(v.elementAt(iter));
        }
        return vec;
    }
    
    /**
     * Adds all vector elements from source to dest
     */
    private static void addAll(Vector dest, Vector source) {
        int size = source.size();
        for(int iter = 0 ; iter < size ; iter++) {
            dest.addElement(source.elementAt(iter));
        }
    }
    
    /**
     * Group provides for commonality between the two types of operations
     * supported by <code>GroupLayout</code>: laying out components one
     * after another (<code>SequentialGroup</code>) or layout on top
     * of each other (<code>ParallelGroup</code>). Use one of
     * <code>createSequentialGroup</code> or
     * <code>createParallelGroup</code> to create one.
     */
    public abstract class Group extends Spring {
        // private int origin;
        // private int size;
        Vector springs;
        
        Group() {
            springs = new Vector();
        }
        
        int indexOf(Spring spring) {
            return springs.indexOf(spring);
        }
        
        /**
         * Adds the Spring to the list of <code>Spring</code>s and returns
         * the receiver.
         */
        Group addSpring(Spring spring) {
            springs.addElement(spring);
            spring.setParent(this);
            if (!(spring instanceof AutopaddingSpring) ||
                    !((AutopaddingSpring)spring).getUserCreated()) {
                springsChanged = true;
            }
            return this;
        }
        
        //
        // Spring methods
        //
        
        void setSize(int axis, int origin, int size) {
            super.setSize(axis, origin, size);
            if (size == UNSET) {
                for (int counter = springs.size() - 1; counter >= 0;
                     counter--) {
                    getSpring(counter).setSize(axis, origin, size);
                }
            } else {
                setValidSize(axis, origin, size);
            }
        }
        
        /**
         * This is invoked from <code>setSize</code> if passed a value
         * other than UNSET.
         */
        abstract void setValidSize(int axis, int origin, int size);
        
        int calculateMinimumSize(int axis) {
            return calculateSize(axis, MIN_SIZE);
        }
        
        int calculatePreferredSize(int axis) {
            return calculateSize(axis, PREF_SIZE);
        }
        
        int calculateMaximumSize(int axis) {
            return calculateSize(axis, MAX_SIZE);
        }
        
        /**
         * Used to compute how the two values representing two springs
         * will be combined.  For example, a group that layed things out
         * one after the next would return <code>a + b</code>.
         */
        abstract int operator(int a, int b);
        
        /**
         * Calculates the specified size.  This is called from
         * one of the <code>getMinimumSize0</code>,
         * <code>getPreferredSize0</code> or
         * <code>getMaximumSize0</code> methods.  This will invoke
         * to <code>operator</code> to combine the values.
         */
        int calculateSize(int axis, int type) {
            int count = springs.size();