textpane.java

开发j2me 手机程序必须的用到的。文件较小

package com.jmobilecore.ui.core;

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

/**
 * @author Greg Gridin
 */
public class TextPane extends Component {

    /**
     * The <code>TextPaneText</code> represents content of this <code>TextPane</code>.
     * @see #getText()
     * @see #setText(String)
     */
    protected TextPaneText textPane;

    /**
     * Constructs a new <code>TextPane</code> with the specified string of text,
     * left justified.
     * @param text the string that the textpane presents.
     *        A <code>null</code> value
     *        will be accepted without causing a NullPointerException
     *        to be thrown.
     *        Unlike text for labels this text can be multiline.
     */
    public TextPane(String text) {
        this(text, Style.TEXT_FONT);
    }

    /**
     * Constructs a new <code>TextPane</code> with the specified string of text,
     * left justified.
     * @param text the string that the textpane presents.
     *        A <code>null</code> value
     *        will be accepted without causing a NullPointerException
     *        to be thrown.
     *        Unlike text for labels this text can be multiline.
     * @param font   the <code>TextPane</code> font
     */
    public TextPane(String text, Font font) {
        textPane = new TextPaneText(text, font, ScreenCanvas.WIDTH);
        super.setFont(font);
    }

    /**
     * Gets the text of this text pane.
     * @return     the text of this text pane, or <code>null</code> if
     *             the text has been set to <code>null</code>.
     * @see        #setText(String)
     */
    public String getText() {

        return new String(textPane.buffer);
    }

    /**
     * Sets the text for this text pane to the specified value.
     * @param      text the text that this text pane displays.
     * @see        #getText()
     */
    public void setText(String text) {
        textPane.setText(text, font, ScreenCanvas.WIDTH);
        setHeight();
        invalidate();
    }

    /**
     * Sets the font of this component.
     * @param _font the font to become this component's font;
     * 		if this parameter is <code>null</code> then this
     *		component font won't be changed
     */
    public void setFont(Font _font) {
        textPane.setText(getText(), _font, ScreenCanvas.WIDTH);
        super.setFont(_font);
    }

    /**
     * Paints the <code>TextPane</code> to the screen.
     *
     * @param g The Graphics object to render to.
     */
    public void paint(Graphics g) {

        paintBackground(g);
        prepareForeground(g);
        final int fHeight = font.getHeight();
        int y = screenY + Style.V_GAP;

        final int numLines = textPane.getNumLines();
        int strlen, offset;
        for (int i = 0; i < numLines; i++) {
            offset = textPane.lineBreaks[i * 2];
            strlen = textPane.lineBreaks[i * 2 + 1] - offset;
            if (strlen != 0) {
                if (alignment == CENTER)
                  g.drawChars(textPane.buffer, offset, strlen, getWidth() / 2, y, Graphics.TOP | Graphics.HCENTER);
                else if (alignment == RIGHT)
                  g.drawChars(textPane.buffer, offset, strlen, getWidth() - Style.H_GAP, y, Graphics.TOP | Graphics.RIGHT);
                else
                  g.drawChars(textPane.buffer, offset, strlen, Style.H_GAP, y, Graphics.TOP | Graphics.LEFT);
            }
            y += fHeight;
        }
    }

    /**
     * Calculates the text pane height
     */
    protected void setHeight() {
        this.height = (font.getHeight()) * textPane.maxLine + Style.V_GAP;
    }
}

class TextPaneText {

    public static final int PAGE_LINES = 1;

    /**
     * The text to display
     */
    protected char[] buffer;

    /**
     * Array of pointers to line breaks
     */
    protected int[] lineBreaks;

    /**
     * The number of lines
     */
    protected int maxLine;

    /**
     * Constructs a new <code>TextPaneText</code> with the text, font for specified
     * max width.
     * @param text the string that the <code>TextPaneText</code> presents.
     * @param font   the font for the text
     * @param maxWidth   the width of the <code>TextPane</code>. Usually it is width of the  screen
     */
    public TextPaneText(String text, Font font, int maxWidth) {

        setText(text, font, maxWidth);
    }

    /**
     * Adds line pointer. Increases <code>lineBreaks</code> array if necessary
     * @param startPos the starting position of the line in <code>buffer</code> array.
     * @param endPos the ending position of the line in <code>buffer</code> array.
     */
    protected void addLine(int startPos, int endPos) {

        if (maxLine * 2 >= lineBreaks.length) {
            int temp [] = new int[lineBreaks.length * 2 + 2];
            System.arraycopy(lineBreaks, 0, temp, 0, lineBreaks.length);
            lineBreaks = temp;
        }
        lineBreaks[maxLine * 2] = startPos;
        lineBreaks[maxLine * 2 + 1] = endPos;
        maxLine++;
    }

    /**
     * Sets a new text, font for specified max width.
     * @param _text the string that the <code>TextPaneText</code> presents.
     * @param _font   the font for the text
     * @param _maxWidth   the width of the <code>TextPane</code>. Usually it is width of the  screen
     */
    public void setText(String _text, Font _font, int _maxWidth) {

        clear();
        if (_text == null || _font == null || _maxWidth <= 0) return;

        int start = 0, end = 0, lastSpace = -1;
        int curWidth = Style.H_GAP;
        char ch;

        final int length = _text.length();
        reset(_text);
        for (int pos = 0; pos < length; pos++) {
            ch = buffer[pos];
            if (ch == '\n') {
                addLine(start, pos);
                curWidth = Style.H_GAP;
                buffer[pos] = ' ';
                lastSpace = start = pos + 1;
                continue;
            }
            if (ch == ' ') {
                lastSpace = pos;
                if (start == pos) {
                    start++;
                    continue;
                }
            }
            curWidth += _font.charWidth(ch);
            if (curWidth >= _maxWidth - Style.H_GAP) {
                end = (lastSpace > start) ? lastSpace + 1 : pos;
                addLine(start, end);
                curWidth = Style.H_GAP;
                lastSpace = start = end;
                pos = end - 1;
            }
        }
        addLine(start, length);
    }

    /**
     * Get number of lines
     * @return     the number of lines for the <code>TextPaneText</code>
     */
    public int getNumLines() {

        return maxLine;
    }

    /**
     * Get specified line
     * @param num the number of the line in <code>TextPaneText</code>.
     *
     * @return  the text for <code>num</code>-th line
     */
    public String getLine(int num) {

        if (num >= maxLine)
            return null;
        int offset = lineBreaks[num * 2];
        int strlen = lineBreaks[num * 2 + 1] - offset;
        return new String(buffer, offset, strlen);
    }

    /**
     * Clears the <code>TextPaneText</code>
     */
    public void clear() {
        buffer = null;
        lineBreaks = null;
        maxLine = 0;
    }

    /**
     * Sets the <code>TextPaneText</code> to the specified string
     * @param text the new text.
     */
    private void reset(String text) {
        buffer = text.toCharArray();
        lineBreaks = new int[PAGE_LINES * 2];
        maxLine = 0;
    }

} // class TextPaneText