/*
 * Copyright (c) 2000 David Flanagan.  All rights reserved.
 * This code is from the book Java Examples in a Nutshell, 2nd Edition.
 * It is provided AS-IS, WITHOUT ANY WARRANTY either expressed or implied.
 * You may study, use, and modify it for any non-commercial purpose.
 * You may distribute it non-commercially as long as you retain this notice.
 * For a commercial use license, or to purchase the book (recommended),
 * visit http://www.davidflanagan.com/javaexamples2.
 */
package com.davidflanagan.examples.gui;
import java.awt.*;
import java.awt.print.*;
import java.awt.geom.*;
import java.awt.font.*;
import javax.swing.*;
import javax.swing.text.*;
import java.util.*;

/**
 * This class implements the Pageable and Printable interfaces and allows
 * the contents of any JTextComponent to be printed using the java.awt.print
 * printing API.
 **/
public class PrintableDocument implements Pageable, Printable {
    View root;              // The root View to be printed
    PageFormat format;      // Paper plus page orientation
    int numPages;           // How many pages in the document
    double printX, printY;  // coordinates of upper-left of print area
    double printWidth;      // Width of the printable area
    double printHeight;     // Height of the printable area
    Rectangle drawRect;     // The rectangle in which the document is painted

    // How lenient are we with the bottom margin in widow/orphan prevention?
    static final double MARGIN_ADJUST = .97;

    // The font we use for printing page numbers
    static final Font headerFont = new Font("Serif", Font.PLAIN, 12);

    /**
     * This constructor allows printing the contents of any JTextComponent
     * using a default PageFormat
     */
    public PrintableDocument(JTextComponent textComponent) {
	this(textComponent, new PageFormat());
    }

    /** 
     * This constructor allows the contents of any JTextComponent to be
     * printed, using any specified PageFormat object
     **/
    public PrintableDocument(JTextComponent textComponent, PageFormat format) {
	// Remember the page format, and ask it for the printable area
	this.format = format;
	this.printX = format.getImageableX();
	this.printY = format.getImageableY();
	this.printWidth = format.getImageableWidth();
	this.printHeight = format.getImageableHeight();
	double paperWidth = format.getWidth();

	// Get the document and its root Element from the text component
	Document document = textComponent.getDocument();
	Element rootElement = document.getDefaultRootElement();
	// Get the EditorKit and its ViewFactory from the text component
	EditorKit editorKit =textComponent.getUI().getEditorKit(textComponent);
	ViewFactory viewFactory = editorKit.getViewFactory();

	// Use the ViewFactory to create a root View object for the document
	// This is the object we'll print.  
	root = viewFactory.create(rootElement);

	// The Swing text architecture requires us to call setParent() on
	// our root View before we use it for anything.  In order to do this,
	// we need a View object that can serve as the parent.  We use a 
	// custom implementation defined below.
	root.setParent(new ParentView(root, viewFactory, textComponent));

	// Tell the view how wide the page is; it has to format itself
	// to fit within this width.  The height doesn't really matter here
	root.setSize((float)printWidth, (float)printHeight);

	// Now that the view has formatted itself for the specified width,
	// Ask it how tall it is.  
	double documentHeight = root.getPreferredSpan(View.Y_AXIS);

	// Set up the rectangle that tells the view where to draw itself
	// We'll use it in other methods of this class.
	drawRect = new Rectangle((int)printX, (int)printY,
				 (int)printWidth, (int)documentHeight);

	// Now if the document is taller than one page, we have to 
	// figure out where the page breaks are.
	if (documentHeight > printHeight) paginate(root, drawRect);

	// Once we've broken it into pages, figure out how man pages.
	numPages = pageLengths.size() + 1;
    }

    // This is the starting offset of the page we're currently working on
    double pageStart = 0;
    
    /**
     * This method loops through the children of the specified view,
     * recursing as necessary, and inserts pages breaks when needed.
     * It makes a rudimentary attempt to avoid "widows" and "orphans".
     **/
    protected void paginate(View v, Rectangle2D allocation) {
	// Figure out how tall this view is, and tell it to allocate
	// that space among its children
	double myheight = v.getPreferredSpan(View.Y_AXIS);
	v.setSize((float)printWidth, (float)myheight);

	// Now loop through each of the children
	int numkids = v.getViewCount();
	for(int i = 0; i < numkids; i++) {
	    View kid = v.getView(i);  // this is the child we're working with
	    // Figure out its size and location
	    Shape kidshape = v.getChildAllocation(i, allocation);
	    if (kidshape == null) continue;
	    Rectangle2D kidbox = kidshape.getBounds2D();

	    // This is the Y coordinate of the bottom of the child
	    double kidpos = kidbox.getY() + kidbox.getHeight() - pageStart;
	   
	    // If this is the first child of a group, then we want to ensure
	    // that it doesn't get left by itself at the bottom of a page.
	    // I.e. we want to prevent "widows"
	    if ((numkids > 1) && (i == 0)) {
		// If it is not near the end of the page, then just move
		// on to the next child
		if (kidpos < printY + printHeight*MARGIN_ADJUST) continue;

		// Otherwise, the child is near the bottom of the page, so
		// break the page before this child and place this child on
		// the new page.
		breakPage(kidbox.getY());
		continue;
	    }

	    // If this is the last child of a group, we don't want it to
	    // appear by itself at the top of a new page, so allow it to
	    // squeeze past the bottom margin if necessary.  This helps to
	    // prevent "orphans"
	    if ((numkids > 1) && (i == numkids-1)) {
		// If it fits normally, just move on to the next one
		if (kidpos < printY + printHeight) continue;

		// Otherwise, if it fits with extra space, then break the
		// at the end of the group
		if (kidpos < printY + printHeight/MARGIN_ADJUST) {
		    breakPage(allocation.getY() + allocation.getHeight());
		    continue;
		}
	    }

	    // If the child is not the first or last of a group, then we use
	    // the bottom margin strictly.  If the child fits on the page,
	    // then move on to the next child.
	    if (kidpos < printY+printHeight) continue;

	    // If we get here, the child doesn't fit on this page.  If it has
	    // no children, then break the page before this child and continue.
	    if (kid.getViewCount() == 0) {
		breakPage(kidbox.getY());
		continue;
	    }

	    // If we get here, then the child did not fit on the page, but it
	    // has kids of its own, so recurse to see if any of those kids
	    // will fit on the page.
	    paginate(kid, kidbox);
	}
    }

    // For a document of n pages, this list stores the lengths of pages 
    // 0 through n-2.  The last page is assumed to have a full length
    ArrayList pageLengths = new ArrayList();

    // For a document of n pages, this list stores the starting offset of
    // pages 1 through n-1.  The offset of page 0 is always 0
    ArrayList pageOffsets = new ArrayList();

    /** 
     * Break a page at the specified Y coordinate.  Store the necessary
     * information into the pageLengths and pageOffsets lists
     **/
    void breakPage(double y) {
	double pageLength = y-pageStart-printY;
	pageStart = y-printY;
	pageLengths.add(new Double(pageLength));
	pageOffsets.add(new Double(pageStart));
    }

    /** Return the number of pages. This is a Pageable method.   */
    public int getNumberOfPages() { return numPages; }

    /** 
     * Return the PageFormat object for the specified page.  This
     * implementation uses the computed length of the page in the returned
     * PageFormat object.  The PrinterJob will use this as a clipping region,
     * which will prevent extraneous parts of the document from being drawn
     * in the top and bottom margins.
     **/
    public PageFormat getPageFormat(int pagenum) {
	// On the last page, just return the user-specified page format
	if (pagenum == numPages-1) return format;

	// Otherwise, look up the height of this page and return an
	// appropriate PageFormat.
	double pageLength = ((Double)pageLengths.get(pagenum)).doubleValue();
	PageFormat f = (PageFormat) format.clone();
	Paper p = f.getPaper();
	if (f.getOrientation() == PageFormat.PORTRAIT)
	    p.setImageableArea(printX, printY, printWidth, pageLength);
	else 
	    p.setImageableArea(printY, printX, pageLength, printWidth);
	f.setPaper(p);
	return f;
    }

    /**
     * This Printable method returns the Printable object for the specified
     * page.  Since this class implements both Pageable and Printable, it just
     * returns this.
     **/
    public Printable getPrintable(int pagenum) { return this; }

    /**
     * This is the basic Printable method that prints a specified page
     **/
    public int print(Graphics g, PageFormat format, int pageIndex) {
	// Return an error code on attempts to print past the end of the doc
	if (pageIndex >= numPages) return NO_SUCH_PAGE;

	// Cast the Graphics object so we can use Java2D operations
	Graphics2D g2 = (Graphics2D)g;

	// Display a page number centered in the area of the top margin.
	// Set a new clipping region so we can draw into the top margin
	// But remember the original clipping region so we can restore it
	Shape originalClip = g.getClip();
	g.setClip(new Rectangle(0, 0, (int)printWidth, (int)printY));
	// Compute the header to display, measure it, then display it
	String numString = "- " + (pageIndex+1) + " -";
	Rectangle2D numBounds =   // Get the width and height of the string
	    headerFont.getStringBounds(numString, g2.getFontRenderContext());
	LineMetrics metrics =     // Get the ascent and descent of the font
	    headerFont.getLineMetrics(numString, g2.getFontRenderContext());
	g.setFont(headerFont);    // Set the font
	g.setColor(Color.black);  // Print with black ink
	g.drawString(numString,   // Display the string
	      (int)(printX + (printWidth-numBounds.getWidth())/2),
	      (int)((printY-numBounds.getHeight())/2 + metrics.getAscent()));
	g.setClip(originalClip);  // Restore the clipping region

	// Figure out the staring position of the page within the document
	double pageStart = 0.0;
	if (pageIndex > 0)
	    pageStart = ((Double)pageOffsets.get(pageIndex-1)).doubleValue();

	// Scroll so that the appropriate part of the document is lined up
	// with the upper-left corner of the page
	g2.translate(0.0, -pageStart);

	// Now paint the entire document.  The PrinterJob will have
	// established a clipping region, so that only the desired portion
	// of the document will actually be drawn on this sheet of paper.
	root.paint(g, drawRect);

	// Finally return a success code
	return PAGE_EXISTS;
    }

    /** 
     * This inner class is a concrete implementation of View, with a 
     * couple of key method implementations.  An instance of this class
     * is used as the parent of the root View object we want to print
     **/
    static class ParentView extends View {
	ViewFactory viewFactory; // The ViewFactory for the hierarchy of views
	Container container;     // The Container for the hierarchy of views

	public ParentView(View v, ViewFactory viewFactory, Container container)
	{
	    super(v.getElement());
	    this.viewFactory = viewFactory;
	    this.container = container;
	}

	// These methods return key pieces of information required by
	// the View hierarchy.
	public ViewFactory getViewFactory() { return viewFactory; }
	public Container getContainer() { return container; }

	// These methods are abstract in View, so we've got to provide
	// dummy implementations of them here, even though they're never used.
	public void paint(Graphics g, Shape allocation) {}
	public float getPreferredSpan(int axis) { return 0.0f; }
	public int viewToModel(float x,float y,Shape a,Position.Bias[] bias) {
	    return 0;
	}
	public Shape modelToView(int pos, Shape a, Position.Bias b)
	    throws BadLocationException {
	    return a;
	}
    }
}