21.06 Ein Low-Level Informations Bildschirm

Die Klasse TextTools

package de.jbb.info;

import javax.microedition.lcdui.Font;

public class TextTools {

  public static String[] getViewableTextLines(String text, Font f, int width) {

    String[] ret = new String[f.stringWidth(text) / (width - f.stringWidth("012345")) + 1];
    if (ret.length == 1) {
      return new String[]{text};
    }
    int arPos = 0;
    for (int curPos = 0, lastCut = 0, lastAcceptPos = 0, lastWord = 0;;) {
      if (arPos >= ret.length) {
        String[] tmp = new String[ret.length + 1];
        System.arraycopy(ret, 0, tmp, 0, ret.length);
        ret = tmp;
      }
      lastWord = curPos;
      curPos = text.indexOf(' ', curPos + 1);
      if (curPos < 0) {
        if (f.substringWidth(text, lastCut, text.length() - lastCut) < width
            || lastCut == lastAcceptPos) {
          ret[arPos] = text.substring(lastCut);
          break;
        }
        else {
          ret[arPos++] = text.substring(lastCut, lastAcceptPos);
          lastCut = lastAcceptPos;
          curPos = lastCut;
        }
      }
      else {
        if (f.substringWidth(text, lastCut, curPos - lastCut) < width) {
          lastAcceptPos = curPos + 1;
        }
        else if (lastAcceptPos != lastCut) {
          ret[arPos++] = text.substring(lastCut, lastAcceptPos);
          lastCut = lastAcceptPos;
        }
        else {
          ret[arPos++] = text.substring(lastCut, lastWord);
          curPos = lastWord;
          lastAcceptPos = curPos + 1;
          lastCut = lastAcceptPos;
        }
      }
    }
    if (arPos + 1 != ret.length) {
      String[] tmp = new String[arPos + 1];
      System.arraycopy(ret, 0, tmp, 0, tmp.length);
      ret = tmp;
    }
    return ret;
  }
}

Der InfoScreen

package de.jbb.info;

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

public class InfoScreen extends Canvas {

  private String[] heads;
  private String[][] txts;
  private Font font;

  private int backgroundColor;
  private int backgroundHeadColor;
  private int foregroundColor;
  private int foregroundHeadColor;
  private int scrollColor;
  private int scrollBarColor;

  private int maxHeight;
  private int curY;

  private int lastY;

  public InfoScreen(String[] heads, String[] txts, Font font) {

    if (heads.length != txts.length) {
      throw new IllegalArgumentException("heads.length and txts.length must be equal");
    }
    this.font = font;
    this.heads = heads;
    this.txts = new String[txts.length][0];
    int txtLineCount = 0;
    for (int i = 0; i < txts.length; i++) {
      this.txts[i] = TextTools.getViewableTextLines(txts[i], font, getWidth() - 15);
      txtLineCount += this.txts[i].length;
    }
    this.maxHeight = (font.getHeight() + 2) * (heads.length + txtLineCount);
  }

  protected void paint(Graphics g) {

    int curHeight = this.curY;
    g.setColor(this.backgroundColor);
    g.fillRect(0, 0, getWidth(), getHeight());
    g.setFont(font);
    for (int i = 0; i < this.heads.length; i++) {
      curHeight = drawHeadline(g, this.heads[i], curHeight);
      curHeight = drawText(g, this.txts[i], curHeight);
    }
    if (this.maxHeight > getHeight()) {
      g.setColor(this.scrollColor);
      g.fillRect(getWidth() - 5, 0, 4, getHeight());
      g.setColor(this.scrollBarColor);
      g.fillRect(
        getWidth() - 5, 
        (-this.curY * 100) / ((this.maxHeight * 100) / getHeight()), 
        4, 
        (getHeight() * 100) / ((this.maxHeight * 100) / getHeight())
      );
    }
  }

  private int drawHeadline(Graphics g, String head, int curHeight) {

    g.setColor(this.backgroundHeadColor);
    g.fillRect(0, curHeight, getWidth() - 5, g.getFont().getHeight() + 2);
    g.setColor(this.foregroundHeadColor);
    g.drawString(head, 5, curHeight, Graphics.LEFT | Graphics.TOP);
    curHeight += g.getFont().getHeight() + 2;
    return curHeight;
  }

  private int drawText(Graphics g, String[] text, int curHeight) {

    g.setColor(this.foregroundColor);
    for (int i = 0; i < text.length; i++) {
      g.drawString(text[i], 5, curHeight, Graphics.LEFT | Graphics.TOP);
      curHeight += g.getFont().getHeight() + 2;
    }
    return curHeight;
  }

  protected void keyPressed(int keyCode) {
    doStep(keyCode);
  }

  protected void keyRepeated(int keyCode) {
    doStep(keyCode);
  }

  protected void pointerPressed(int x, int y) {
    this.lastY = y;
  }

  protected void pointerDragged(int x, int y) {
    if (this.lastY != y) {
      this.curY += y - this.lastY;
        if (this.curY > 0) {
          this.curY = 0;
        }
        else if (this.curY < getHeight() - this.maxHeight) {
          this.curY = getHeight() - this.maxHeight;
        }
        this.lastY = y;
        repaint();
    }
  }

  private void doStep(int keyCode) {

    if (this.maxHeight > getHeight()) {
      if (keyCode == KEY_NUM2 || getGameAction(keyCode) == UP) {
        this.curY += font.getHeight();
        if (this.curY > 0) {
          this.curY = 0;
        }
        repaint();
      }
      else if (keyCode == KEY_NUM8 || getGameAction(keyCode) == DOWN) {
        this.curY -= font.getHeight();
        if (this.curY < getHeight() - this.maxHeight) {
          this.curY = getHeight() - this.maxHeight;
        }
        repaint();
      }
    }
  }

  public int getBackgroundColor() {
    return this.backgroundColor;
  }

  public void setBackgroundColor(int backgroundColor) {
    this.backgroundColor = backgroundColor;
  }

  public int getBackgroundHeadColor() {
    return this.backgroundHeadColor;
  }

  public void setBackgroundHeadColor(int backgroundHeadColor) {
    this.backgroundHeadColor = backgroundHeadColor;
  }

  public int getForegroundColor() {
    return this.foregroundColor;
  }

  public void setForegroundColor(int foregroundColor) {
    this.foregroundColor = foregroundColor;
  }

  public int getForegroundHeadColor() {
    return this.foregroundHeadColor;
  }

  public void setForegroundHeadColor(int foregroundHeadColor) {
    this.foregroundHeadColor = foregroundHeadColor;
  }

  public int getScrollBarColor() {
    return this.scrollBarColor;
  }

  public void setScrollBarColor(int scrollBarColor) {
    this.scrollBarColor = scrollBarColor;
  }

  public int getScrollColor() {
    return this.scrollColor;
  }

  public void setScrollColor(int scrollColor) {
    this.scrollColor = scrollColor;
  }
}

Ein Beispiel-MIDlet

package de.jbb.info;

import javax.microedition.lcdui.Command;
import javax.microedition.lcdui.CommandListener;
import javax.microedition.lcdui.Display;
import javax.microedition.lcdui.Displayable;
import javax.microedition.lcdui.Font;
import javax.microedition.midlet.*;

public class InfoMIDlet extends MIDlet implements CommandListener {

  private boolean first = true;

  private Display disp;
  private Command exit;
  private InfoScreen info;

  public void startApp() {

    if (first) {
      String[] heads = { 
        "Info", 
        "Verwendung", 
        "Copyright"
      };
      String[] txts = {
        "Dies ist ein Informationsbildschirm, der für Low-Level Java ME " + 
          "Anwendungen genutzt werden kann. Er ermöglicht die Darstellung " + 
          "von viel Text mit jeweils einer Überschrift. Ist der Text zu " + 
          "groß für das Display, kann auch mit den Richtungstasten oder " + 
          "'2' und '8' gescrollt werden.", 
        "Der InfoScreen ist ein gewöhnliches Canvas, welchem im Konstruktor " + 
          "als ersten Parameter die Überschriften, und als zweiten Parameter " + 
          "die eigentlichen Texte zu den Überschriften übergeben werden.", 
        "Java-Blog-Buch.de, Stefan Kiesel, 2010"
      };

      disp = Display.getDisplay(this);
      exit = new Command("Beenden", Command.EXIT, 0);
      info = new InfoScreen(heads, txts, Font.getFont(Font.FONT_STATIC_TEXT));

      info.addCommand(exit);
      info.setCommandListener(this);

      info.setBackgroundColor(0); // Schwarz
      info.setBackgroundHeadColor(255 << 16 | 255 << 8 | 255); // Weiß
      info.setForegroundColor(info.getBackgroundHeadColor());
      info.setForegroundHeadColor(info.getBackgroundColor());
      info.setScrollColor(200 << 16 | 200 << 8 | 200); // helles Grau
      info.setScrollBarColor(50 << 16 | 50 << 8 | 50); // dunkles Grau

      first = false;
    }

    disp.setCurrent(info);
  }

  public void commandAction(Command c, Displayable d) {
    destroyApp(true);
  }

  public void destroyApp(boolean unconditional) {
    notifyDestroyed();
  }

  public void pauseApp() {}
}