Affine4.java

import javax.microedition.midlet.*;
import javax.microedition.lcdui.*;

import java.io.IOException;

// Affine

public class Affine4 extends MIDlet
{
  public Affine4()
    {
      Affine4Canvas c = new Affine4Canvas();
      Display.getDisplay(this).setCurrent(c);
    }

  protected void startApp() {}
  protected void pauseApp() {}
  protected void destroyApp(boolean flag) {}
}

class Affine4Canvas extends Canvas
{
  public static final int BLACK  = 0x00000000;
  public static final int YELLOW = 0x00FFFF00;
  public static final int WHITE  = 0x00FFFFFF;

  private double[] m;

  public Affine3Canvas()
    {
      super();
      this.m = new double[6];
      loadIdentity();  // 変換の初期状態は恒等変換
    }

  // 恒等変換 (何もしない変換) を設定する
  public void loadIdentity()
    {
      this.m[0] = 1.0; this.m[1] = 0.0; this.m[2] = 0.0;
      this.m[3] = 0.0; this.m[4] = 1.0; this.m[5] = 0.0;
    }

  // 変換を合成する
  public void combine(double[] mm)
    {
      double[] old = {
        this.m[0], this.m[1], this.m[2],
        this.m[3], this.m[4], this.m[5] };

      this.m[0] = mm[0]*old[0] + mm[1]*old[3];
      this.m[1] = mm[0]*old[1] + mm[1]*old[4];
      this.m[2] = mm[0]*old[2] + mm[1]*old[5] + mm[2];

      this.m[3] = mm[3]*old[0] + mm[4]*old[3];
      this.m[4] = mm[3]*old[1] + mm[4]*old[4];
      this.m[5] = mm[3]*old[2] + mm[4]*old[5] + mm[5];
    }

  // 拡大縮小 (スケーリング)
  //
  // @param sx  magnification of the X direction (X 方向の倍率)
  // @param sy  magnification of the Y direction (Y 方向の倍率)
  public void scale(double sx, double sy)
    {
      double[] mm = {
        sx,  0.0, 0.0,
        0.0, sy,  0.0 };
      combine(mm);
    }

  // 原点を中心とする回転
  //
  // @param degrees  the angle of rotation in degrees
  public void rotate(double degrees)
    {
      double radians = deg2rad(degrees);
      double c = Math.cos(radians);
      double s = Math.sin(radians);
      double[] mm = {
        c, -s, 0.0,
        s,  c, 0.0 };
      combine(mm);
    }

  private double deg2rad(double degrees)
    {
      return Math.PI * degrees / 180.0;
    }

  // 平行移動
  //
  // @param tx  the amount of translation along the X-angle
  // @param ty  the amount of translation along the Y-angle
  public void translate(double tx, double ty)
    {
      double[] mm = {
        1.0, 0.0, tx,
        0.0, 1.0, ty };
      combine(mm);
    }

  public double transformX(double x, double y)
    {
      return this.m[0]*x + this.m[1]*y + this.m[2];
    }

  public double transformY(double x, double y)
    {
      return this.m[3]*x + this.m[4]*y + this.m[5];
    }

  public double reverseTransformX(double xx, double yy)
    {
      double d = this.m[0]*this.m[4] - this.m[1]*this.m[3];
      return (this.m[4]*xx - this.m[1]*yy
              + (this.m[1]*this.m[5] - this.m[2]*this.m[4]))/d;
    }

  public double reverseTransformY(double xx, double yy)
    {
      double d = this.m[0]*this.m[4] - this.m[1]*this.m[3];
      return (-this.m[3]*xx + this.m[0]*yy
              + (this.m[2]*this.m[3] - this.m[0]*this.m[5]))/d;
    }

  protected void paint(Graphics g)
    {
      // setup a pixel data
      PixelData pixels = new PixelData(getWidth(), getHeight()); // <*>
      pixels.fillRect(0, 0, getWidth(), getHeight(), WHITE); // <*>

      // load image file
      try {
        PixelData sample_pixels = PixelData.createPixelData("/nekobean.png");

        // (0) 画像サイズを画面に合わせる
        //double sx = pixels.getWidth()  / (double)sample_pixels.getWidth();
        //double sy = pixels.getHeight() / (double)sample_pixels.getHeight();
        //scale(sx, sy);

        // (1) 画面の中心を原点に移動
        translate(-sample_pixels.getWidth()  / 2.0,
                  -sample_pixels.getHeight() / 2.0);
        // (2) 原点を中心に45度回転
        rotate(25.0);

        // (3) 原点を適切に移動する
        translate(sample_pixels.getWidth() / 2.0,
                  sample_pixels.getHeight() / 2.0);

        // (4) 縦横を 1.05 倍する。
        // scale(0.5, 0.5);

        // 画面全体に対して描く
        for (int yy = 0; yy < pixels.getHeight(); ++yy) {
          for (int xx = 0; xx < pixels.getWidth(); ++xx) {
            // 画面の座標 (xx, yy) から画像の座標 (x, y) を求める
            int x = (int)reverseTransformX(xx, yy);
            int y = (int)reverseTransformY(xx, yy);
            if (0 <= x && x < sample_pixels.getWidth() &&
                0 <= y && y < sample_pixels.getHeight()) {
              // 描く
              int v = sample_pixels.getPixel(x, y);
              pixels.setPixel(xx, yy, v);
            }
          }
        }
      }
      catch (IOException e) {
      }

      // fill the screen black
      g.setColor(BLACK);
      g.fillRect(0, 0, getWidth(), getHeight());

      // create image from pixel data
      Image img = pixels.createRGBImage(); // <*>

      // draw image
      g.drawImage(img, 0, 0, Graphics.LEFT | Graphics.TOP);
    }
}