framesetview.java

Mobile 应用程序使用 Java Micro Edition (Java ME) 平台

/*
 * @(#)FrameSetView.java	1.21 05/11/17
 *
 * Copyright 2006 Sun Microsystems, Inc. All rights reserved.
 * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */
package javax.swing.text.html;

import java.awt.*;
import java.util.*;
import javax.swing.*;
import javax.swing.text.*;
import javax.swing.event.*;

/**
 * Implements a FrameSetView, intended to support the HTML 
 * <FRAMESET> tag.  Supports the ROWS and COLS attributes.
 *
 * @author  Sunita Mani
 *
 *          Credit also to the hotjava browser engineers that
 *          worked on making the allocation of space algorithms
 *          conform to the HTML 4.0 standard and also be netscape
 *          compatible.
 *
 * @version 1.21 11/17/05
 */

class FrameSetView extends javax.swing.text.BoxView {

    String[] children;
    int[] percentChildren;
    int[] absoluteChildren;
    int[] relativeChildren;
    int percentTotals;
    int absoluteTotals;
    int relativeTotals;

    /**
     * Constructs a FrameSetView for the given element.
     * 
     * @param elem the element that this view is responsible for
     */
    public FrameSetView(Element elem, int axis) {
	super(elem, axis);
	children = null;
    }

    /**
     * Parses the ROW or COL attributes and returns
     * an array of strings that represent the space
     * distribution.
     * 
     */
    private String[] parseRowColSpec(HTML.Attribute key) {
	
	AttributeSet attributes = getElement().getAttributes();
	String spec = "*";
	if (attributes != null) {
	    if (attributes.getAttribute(key) != null) {
		spec = (String)attributes.getAttribute(key);
	    }
	}

	StringTokenizer tokenizer = new StringTokenizer(spec, ",");
	int nTokens = tokenizer.countTokens();
	int n = getViewCount();
        String[] items = new String[Math.max(nTokens, n)];
	int i = 0;
	for (; i < nTokens; i++) {
	    items[i] = tokenizer.nextToken().trim();
	    // As per the spec, 100% is the same as *
	    // hence the mapping.
	    //
	    if (items[i].equals("100%")) {
		items[i] = "*";
	    }
	}
        // extend spec if we have more children than specified
        // in ROWS or COLS attribute
        for (; i < items.length; i++) {
            items[i] = "*";
        }
	return items;
    }


    /**
     * Initializes a number of internal state variables
     * that store information about space allocation
     * for the frames contained within the frameset.
     */
    private void init() {
	if (getAxis() == View.Y_AXIS) {
	    children = parseRowColSpec(HTML.Attribute.ROWS);
	} else {
	    children = parseRowColSpec(HTML.Attribute.COLS);
	}
	percentChildren = new int[children.length];
	relativeChildren = new int[children.length];
	absoluteChildren = new int[children.length];

	for (int i = 0; i < children.length; i++) {
	    percentChildren[i] = -1;
	    relativeChildren[i] = -1;
	    absoluteChildren[i] = -1;

	    if (children[i].endsWith("*")) {
		if (children[i].length() > 1) {
		    relativeChildren[i] =
			Integer.parseInt(children[i].substring(
			    0, children[i].length()-1));
		    relativeTotals += relativeChildren[i];
		} else {
		    relativeChildren[i] = 1;
		    relativeTotals += 1;
		}
	    } else if (children[i].indexOf('%') != -1) {
		percentChildren[i] = parseDigits(children[i]);
		percentTotals += percentChildren[i];
	    } else {
		absoluteChildren[i] = Integer.parseInt(children[i]);
	    }
	}
	if (percentTotals > 100) {
	    for (int i = 0; i < percentChildren.length; i++) {
		if (percentChildren[i] > 0) {
		    percentChildren[i] = 
			(percentChildren[i] * 100) / percentTotals;
		}
	    }
	    percentTotals = 100;
	}
    }

    /**
     * Perform layout for the major axis of the box (i.e. the
     * axis that it represents).  The results of the layout should
     * be placed in the given arrays which represent the allocations
     * to the children along the major axis.
     *
     * @param targetSpan the total span given to the view, which
     *  whould be used to layout the children
     * @param axis the axis being layed out
     * @param offsets the offsets from the origin of the view for
     *  each of the child views; this is a return value and is
     *  filled in by the implementation of this method
     * @param spans the span of each child view; this is a return
     *  value and is filled in by the implementation of this method
     * @return the offset and span for each child view in the
     *  offsets and spans parameters
     */
    protected void layoutMajorAxis(int targetSpan, int axis, int[] offsets, 
				   int[] spans) {
	if (children == null) {
	    init();
	}
	SizeRequirements.calculateTiledPositions(targetSpan, null, 
						 getChildRequests(targetSpan,
								  axis),
						 offsets, spans);
    }

    protected SizeRequirements[] getChildRequests(int targetSpan, int axis) {

	int span[] = new int[children.length];

	spread(targetSpan, span);
	int n = getViewCount();
	SizeRequirements[] reqs = new SizeRequirements[n];
	for (int i = 0, sIndex = 0; i < n; i++) {
	    View v = getView(i);
	    if ((v instanceof FrameView) || (v instanceof FrameSetView)) {
		reqs[i] = new SizeRequirements((int) v.getMinimumSpan(axis),
					       span[sIndex], 
					       (int) v.getMaximumSpan(axis),
					       0.5f);
                sIndex++;
	    } else {
		int min = (int) v.getMinimumSpan(axis);
		int pref = (int) v.getPreferredSpan(axis);
		int max = (int) v.getMaximumSpan(axis);
		float a = v.getAlignment(axis);
		reqs[i] = new SizeRequirements(min, pref, max, a);
	    }
	}
	return reqs;
    }


    /**
     * This method is responsible for returning in span[] the 
     * span for each child view along the major axis.  it
     * computes this based on the information that extracted
     * from the value of the ROW/COL attribute.
     */
    private void spread(int targetSpan, int span[]) {

	if (targetSpan == 0) {
	    return;
	}

	int tempSpace = 0;
	int remainingSpace = targetSpan;
	
	// allocate the absolute's first, they have
	// precedence
	//
	for (int i = 0; i < span.length; i++) {
	    if (absoluteChildren[i] > 0) {
		span[i] = absoluteChildren[i];
		remainingSpace -= span[i];
	    }
	}
	
	// then deal with percents.
	//
	tempSpace = remainingSpace;
	for (int i = 0; i < span.length; i++) {
	    if (percentChildren[i] > 0 && tempSpace > 0) {
		span[i] = (percentChildren[i] * tempSpace) / 100;
		remainingSpace -= span[i];
	    } else if (percentChildren[i] > 0 && tempSpace <= 0) {
		span[i] = targetSpan / span.length;
		remainingSpace -= span[i];
	    }
	}

	// allocate remainingSpace to relative
	if (remainingSpace > 0 && relativeTotals > 0) {
	    for (int i = 0; i < span.length; i++) {
		if (relativeChildren[i] > 0) {
		    span[i] = (remainingSpace *
				relativeChildren[i]) / relativeTotals;
		}
	    }
	} else if (remainingSpace > 0) {
	    // There are no relative columns and the space has been
	    // under- or overallocated.  In this case, turn all the 
	    // percentage and pixel specified columns to percentage 
	    // columns based on the ratio of their pixel count to the
	    // total "virtual" size. (In the case of percentage columns,
	    // the pixel count would equal the specified percentage
	    // of the screen size.
      
	    // This action is in accordance with the HTML
	    // 4.0 spec (see section 8.3, the end of the discussion of
	    // the FRAMESET tag).  The precedence of percentage and pixel
	    // specified columns is unclear (spec seems to indicate that
	    // they share priority, however, unspecified what happens when
	    // overallocation occurs.)
	    
	    // addendum is that we behave similiar to netscape in that specified
	    // widths have precedance over percentage widths...
    
	    float vTotal = (float)(targetSpan - remainingSpace);
	    float[] tempPercents = new float[span.length];
	    remainingSpace = targetSpan;
	    for (int i = 0; i < span.length; i++) {
	    	// ok we know what our total space is, and we know how large each
	    	// column should be relative to each other... therefore we can use
	    	// that relative information to deduce their percentages of a whole
	    	// and then scale them appropriately for the correct size
	    	tempPercents[i] = ((float)span[i] / vTotal) * 100.00f;
	        span[i] = (int) ( ((float)targetSpan * tempPercents[i]) / 100.00f);
		remainingSpace -= span[i];
	    }

	       
	    // this is for just in case there is something left over.. if there is we just
	    // add it one pixel at a time to the frames in order.. We shouldn't really ever get
	    // here and if we do it shouldn't be with more than 1 pixel, maybe two.
	    int i = 0;
	    while (remainingSpace != 0) {
	    	if (remainingSpace < 0) {
	    	    span[i++]--;
	    	    remainingSpace++;
	    	}
	    	else {
	    	    span[i++]++;
	    	    remainingSpace--;
	    	}
	    	
	    	// just in case there are more pixels than frames...should never happen..
	    	if (i == span.length)i = 0;
	    }  
	}
    }

    /*
     * Users have been known to type things like "%25" and "25 %".  Deal
     * with it.
     */
    private int parseDigits(String mixedStr) {
	int result = 0;
	for (int i = 0; i < mixedStr.length(); i++) {
	    char ch = mixedStr.charAt(i);
	    if (Character.isDigit(ch)) {
		result = (result * 10) + Character.digit(ch, 10);
	    }
	}
	return result;
    }

}