/*
 * @(#)FieldView.java	1.18 00/02/02
 *
 * Copyright 1997-2000 Sun Microsystems, Inc. All Rights Reserved.
 * 
 * This software is the proprietary information of Sun Microsystems, Inc.  
 * Use is subject to license terms.
 * 
 */
package javax.swing.text;

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

/**
 * Extends the multi-line plain text view to be suitable
 * for a single-line editor view.  If the view is 
 * allocated extra space, the field must adjust for it.
 * If the hosting component is a JTextField, this view
 * will manage the ranges of the associated BoundedRangeModel
 * and will adjust the horizontal allocation to match the
 * current visibility settings of the JTextField.
 *
 * @author  Timothy Prinzing
 * @version 1.18 02/02/00
 * @see     View
 */
public class FieldView extends PlainView {

    /**
     * Constructs a new FieldView wrapped on an element.
     *
     * @param elem the element
     */
    public FieldView(Element elem) {
	super(elem);
    }

    /**
     * Fetches the font metrics associated with the component hosting
     * this view.
     *
     * @return the metrics
     */
    protected FontMetrics getFontMetrics() {
	Component c = getContainer();
	return c.getFontMetrics(c.getFont());
    }

    /**
     * Adjusts the allocation given to the view
     * to be a suitable allocation for a text field.
     * If the view has been allocated more than the 
     * preferred span vertically, the allocation is
     * changed to be centered vertically.  Horizontally
     * the view is adjusted according to the horizontal
     * alignment property set on the associated JTextField
     * (if that is the type of the hosting component).
     *
     * @param a the allocation given to the view, which may need
     *  to be adjusted.
     * @return the allocation that the superclass should use.
     */
    protected Shape adjustAllocation(Shape a) {
	if (a != null) {
	    Rectangle bounds = a.getBounds();
	    int vspan = (int) getPreferredSpan(Y_AXIS);
	    int hspan = (int) getPreferredSpan(X_AXIS);
	    if (bounds.height != vspan) {
		int slop = bounds.height - vspan;
		bounds.y += slop / 2;
		bounds.height -= slop;
	    }

	    // horizontal adjustments
	    Component c = getContainer();
	    if (c instanceof JTextField) {
		JTextField field = (JTextField) c;
		BoundedRangeModel vis = field.getHorizontalVisibility();
		int max = Math.max(hspan, bounds.width);
		int value = vis.getValue();
		int extent = Math.min(max, bounds.width - 1);
		if ((value + extent) > max) {
		    value = max - extent;
		}
		vis.setRangeProperties(value, extent, vis.getMinimum(),
				       max, false);
		if (hspan < bounds.width) {
		    // horizontally align the interior
		    int slop = bounds.width - 1 - hspan;

		    int align = ((JTextField)c).getHorizontalAlignment();
		    if(Utilities.isLeftToRight(c)) {
		        if(align==LEADING) {
			    align = LEFT;
			}
			else if(align==TRAILING) {
			    align = RIGHT;
			}
		    }
		    else {
		        if(align==LEADING) {
			    align = RIGHT;
			}
			else if(align==TRAILING) {
			    align = LEFT;
			}
		    }

		    switch (align) {
		    case SwingConstants.CENTER:
			bounds.x += slop / 2;
			bounds.width -= slop;
			break;
		    case SwingConstants.RIGHT:
			bounds.x += slop;
			bounds.width -= slop;
			break;
		    }
		} else {
		    // adjust the allocation to match the bounded range.
		    bounds.width = hspan;
		    bounds.x -= vis.getValue();
		}
	    }
	    return bounds;
	}
	return null;
    }

    /**
     * Update the visibility model with the associated JTextField
     * (if there is one) to reflect the current visibility as a
     * result of changes to the document model.  The bounded
     * range properties are updated.  If the view hasn't yet been
     * shown the extent will be zero and we just set it to be full
     * until determined otherwise.
     */
    void updateVisibilityModel() {
	Component c = getContainer();
	if (c instanceof JTextField) {
	    JTextField field = (JTextField) c;
	    BoundedRangeModel vis = field.getHorizontalVisibility();
	    int hspan = (int) getPreferredSpan(X_AXIS);
	    int extent = vis.getExtent();
	    int maximum = Math.max(hspan, extent);
	    extent = (extent == 0) ? maximum : extent;
	    int value = maximum - extent;
	    int oldValue = vis.getValue();
	    if ((oldValue + extent) > maximum) {
		oldValue = maximum - extent;
	    }
	    value = Math.max(0, Math.min(value, oldValue));
	    vis.setRangeProperties(value, extent, 0, maximum, false);
	}
    }

    // --- View methods -------------------------------------------

    /**
     * Renders using the given rendering surface and area on that surface.
     * The view may need to do layout and create child views to enable
     * itself to render into the given allocation.
     *
     * @param g the rendering surface to use
     * @param a the allocated region to render into
     *
     * @see View#paint
     */
    public void paint(Graphics g, Shape a) {
	Rectangle r = (Rectangle) a;
	g.clipRect(r.x, r.y, r.width, r.height);
	super.paint(g, a);
    }

    /**
     * Adjusts <code>a</code> based on the visible region and returns it.
     */
    Shape adjustPaintRegion(Shape a) {
	return adjustAllocation(a);
    }

    /**
     * Determines the preferred span for this view along an
     * axis.
     *
     * @param axis may be either View.X_AXIS or View.Y_AXIS
     * @returns  the span the view would like to be rendered into >= 0.
     *           Typically the view is told to render into the span
     *           that is returned, although there is no guarantee.  
     *           The parent may choose to resize or break the view.
     */
    public float getPreferredSpan(int axis) {
	switch (axis) {
	case View.X_AXIS:
	    Segment buff = getLineBuffer();
	    Document doc = getDocument();
	    int width;
	    try {
		doc.getText(0, doc.getLength(), buff);
		width = Utilities.getTabbedTextWidth(buff, getFontMetrics(), 0, this, 0);
	    } catch (BadLocationException bl) {
		width = 0; 
	    }
	    return width;
	default:
	    return super.getPreferredSpan(axis);
	}
    }

    /**
     * Determines the resizability of the view along the
     * given axis.  A value of 0 or less is not resizable.
     *
     * @param axis View.X_AXIS or View.Y_AXIS
     * @return the weight -> 1 for View.X_AXIS, else 0
     */
    public int getResizeWeight(int axis) {
	if (axis == View.X_AXIS) {
	    return 1;
	}
	return 0;
    }

    /**
     * Provides a mapping from the document model coordinate space
     * to the coordinate space of the view mapped to it.
     *
     * @param pos the position to convert >= 0
     * @param a the allocated region to render into
     * @return the bounding box of the given position
     * @exception BadLocationException  if the given position does not
     *   represent a valid location in the associated document
     * @see View#modelToView
     */
    public Shape modelToView(int pos, Shape a, Position.Bias b) throws BadLocationException {
	return super.modelToView(pos, adjustAllocation(a), b);
    }

    /**
     * Provides a mapping from the view coordinate space to the logical
     * coordinate space of the model.
     *
     * @param fx the X coordinate >= 0.0f
     * @param fy the Y coordinate >= 0.0f
     * @param a the allocated region to render into
     * @return the location within the model that best represents the
     *  given point in the view
     * @see View#viewToModel
     */
    public int viewToModel(float fx, float fy, Shape a, Position.Bias[] bias) {
	return super.viewToModel(fx, fy, adjustAllocation(a), bias);
    }

    /**
     * Gives notification that something was inserted into the document
     * in a location that this view is responsible for.
     *
     * @param changes the change information from the associated document
     * @param a the current allocation of the view
     * @param f the factory to use to rebuild if the view has children
     * @see View#insertUpdate
     */
    public void insertUpdate(DocumentEvent changes, Shape a, ViewFactory f) {
	super.insertUpdate(changes, adjustAllocation(a), f);
	updateVisibilityModel();
    }

    /**
     * Gives notification that something was removed from the document
     * in a location that this view is responsible for.
     *
     * @param changes the change information from the associated document
     * @param a the current allocation of the view
     * @param f the factory to use to rebuild if the view has children
     * @see View#removeUpdate
     */
    public void removeUpdate(DocumentEvent changes, Shape a, ViewFactory f) {
	super.removeUpdate(changes, adjustAllocation(a), f);
	updateVisibilityModel();
    }

}