texteffect.java

j2me polish学习的经典代码

//#condition polish.usePolishGui
/*
 * Created on 16-Nov-2005 at 11:59:50.
 * 
 * Copyright (c) 2005 Robert Virkus / Enough Software
 *
 * This file is part of J2ME Polish.
 *
 * J2ME Polish is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 * 
 * J2ME Polish is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with J2ME Polish; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 * 
 * Commercial licenses are also available, please
 * refer to the accompanying LICENSE.txt or visit
 * http://www.j2mepolish.org for details.
 */
// package de.enough.polish.ui;

import javax.microedition.lcdui.Font;
import javax.microedition.lcdui.Graphics;

/**
 * <p>Allows text effects for StringItems, IconItems and ChoiceItems.</p>
 *
 * <p>Copyright (c) 2005, 2006 Enough Software</p>
 * <pre>
 * history
 *        16-Nov-2005 - rob creation
 * </pre>
 * @author Robert Virkus, [e-mail]
 */
public abstract class TextEffect {

	/**
	 * Creates a new effect
	 */
	public TextEffect() {
		super();
	}
	
	/**
	 * Sets the style of this item.
	 * Subclasses can override this method for getting specific settings.
	 * 
	 * @param style the new style for this item.
	 * @throws NullPointerException when style is null
	 */
	public void setStyle( Style style ) {
		// the default implementation does nothing
	}
	
	/**
	 * Animates this effect.
	 * Subclasses can override this method to create animations.
	 * 
	 * @return true when this effect has been animated.
	 */
	public boolean animate() {
		return false;
	}
	
	/**
	 * Paints the text and applies the text effect.
	 * The default implementation calls drawText( String, int, int, int, int, int, Graphics)
	 * 
	 * @param textLines the text
	 * @param textColor the color of the text
	 * @param x horizontal start coordinate
	 * @param y vertical start coordinate
	 * @param leftBorder the left border, nothing must be painted left of this position
	 * @param rightBorder the right border, nothing must be painted right of this position
	 * @param lineHeight the height of a single text line
	 * @param maxWidth the width of the longest line
	 * @param layout the anchor or the text, e.g. Item.LAYOUT_CENTER or Item.LAYOUT_RIGHT
	 * @param g the graphics context
	 * @see #drawString( String,int,int,int,int,Graphics)
	 */
	public void drawStrings( String[] textLines, int textColor, int x, int y, int leftBorder, int rightBorder, int lineHeight, int maxWidth, int layout, Graphics g ) {
		boolean isLayoutRight = false;
		boolean isLayoutCenter = false;
		int centerX = 0;
		if ( ( layout & Item.LAYOUT_CENTER ) == Item.LAYOUT_CENTER ) {
			isLayoutCenter = true;
			centerX = leftBorder + (rightBorder - leftBorder) / 2;
		} else if ( ( layout & Item.LAYOUT_RIGHT ) == Item.LAYOUT_RIGHT ) {
			isLayoutRight = true;
		}
		for (int i = 0; i < textLines.length; i++) {
			String line = textLines[i];
			int lineX = x;
			int lineY = y;
			int orientation = 0;
			// adjust the painting according to the layout:
			if (isLayoutRight) {
				lineX = rightBorder;
				orientation = Graphics.TOP | Graphics.RIGHT;
			} else if (isLayoutCenter) {
				lineX = centerX;
				orientation = Graphics.TOP | Graphics.HCENTER;
			} else {
				orientation = Graphics.TOP | Graphics.LEFT;
			}
			drawString( line, textColor, lineX, lineY, orientation, g );
			x = leftBorder;
			y += lineHeight;
		}
		
	}

	/**
	 * Paints the text and applies the text effect.
	 * 
	 * @param text the text
	 * @param textColor the color of the text
	 * @param x x coordinate
	 * @param y y coordinate
	 * @param orientation the orientation, e.g. Graphics.TOP | Graphics.LEFT or Graphics.TOP | Graphics.HCENTER
	 * @param g the graphics context
	 */
	public abstract void drawString( String text, int textColor, int x, int y, int orientation, Graphics g );

	/**
	 * Retrieves the left start position for a text.
	 * 
	 * @param x the x position given in drawString()
	 * @param orientation the orientation given in drawString()
	 * @param textWidth the width of the text given in drawString()
	 * @return the left x position
	 */
	public int getLeftX( int x, int orientation, int textWidth  ) {
		if ( (orientation & Graphics.LEFT) == Graphics.LEFT) {
			return x;
		} else if ( (orientation & Graphics.RIGHT) == Graphics.RIGHT) {
			return x - textWidth;
		} else {
			return x - textWidth / 2;
		}
	}

	/**
	 * Retrieves the top y position for a text.
	 *  
	 * @param y the y position given in drawString()
	 * @param orientation the orientation given in drawString()
	 * @param font the used font, usually g.getFont()
	 * @return the top y position.
	 */
	public int getTopY( int y, int orientation, Font font ) {
		return getTopY(y, orientation, font.getHeight(), font.getBaselinePosition() );
	}

	/**
	 * Retrieves the top y position for a text.
	 *  
	 * @param y the y position given in drawString()
	 * @param orientation the orientation given in drawString()
	 * @param height the height of the used font
	 * @param baseLine the base line of the used font
	 * @return the top y position.
	 */
	public int getTopY( int y, int orientation, int height, int baseLine ) {
		if ( (orientation & Graphics.TOP) == Graphics.TOP) {
			return y;
		} else if ( (orientation & Graphics.BOTTOM) == Graphics.BOTTOM) {
			return y - height;
		} else {
			return y - (height - baseLine);
		}
	}

	/**
	 * Notifies this effect that the corresponding item is to be shown.
	 * The default implementation is empty. 
	 */
	public void showNotify() {
		// default implementation is empty
	}
	
	/**
	 * Notifies this effect that the corresponding item is to be hidden.
	 * The default implementation is empty. 
	 */
	public void hideNotify() {
		// default implementation is empty
	}

	/**
	 * Releases any resources this effect might contain.
	 * For staying future proof subclasses should call super.releaseResources() first, when overriding this method.
	 */
	public void releaseResources() {
		// do nothing
	}

}