scanvas.java

来自「塞迪网校J2ME移动应用开发教程的所有源代码.」· Java 代码 · 共 48 行

import javax.microedition.lcdui.*;

public class SCanvas extends Canvas {
  private Display display;
  
  public SCanvas(Display d) {
    super();
    display = d;
  }

  void start() {
    display.setCurrent(this);
    repaint();
  }

  public void paint(Graphics g) {
    // Clear the canvas
    g.setColor(0, 0, 0);        // black
    g.fillRect(0, 0, getWidth(), getHeight());
    g.setColor(255, 255, 255);  // white

    // Draw the available screen size
    int y = 0;
    String screenSize = "Screen size: " + Integer.toString(getWidth()) + " x " +
      Integer.toString(getHeight());
    g.drawString(screenSize, 0, y, Graphics.TOP | Graphics.LEFT);

    // Draw the number of available colors
    y += Font.getDefaultFont().getHeight();
    String numColors = "# of colors: " + Integer.toString(display.numColors());
    g.drawString(numColors, 0, y, Graphics.TOP | Graphics.LEFT);

    // Draw the number of available alpha levels
    y += Font.getDefaultFont().getHeight();
    String numAlphas = "# of alphas: " + Integer.toString(display.numAlphaLevels());
    g.drawString(numAlphas, 0, y, Graphics.TOP | Graphics.LEFT);

    // Draw the amount of total and free memory
    Runtime runtime = Runtime.getRuntime();
    y += Font.getDefaultFont().getHeight();
    String totalMem = "Total memory: " + Long.toString(runtime.totalMemory() / 1024) + "KB";
    g.drawString(totalMem, 0, y, Graphics.TOP | Graphics.LEFT);
    y += Font.getDefaultFont().getHeight();
    String freeMem = "Free memory: " + Long.toString(runtime.freeMemory() / 1024) + "KB";
    g.drawString(freeMem, 0, y, Graphics.TOP | Graphics.LEFT);
  }
}