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Nostalgie Post: j2me, Schwerkraft trotzt, 64kb

Dieser Artikel verfolgt keine praktischen Ziele - ich habe mich nur gefragt, wie es Entwicklern vor etwa 15 Jahren gelungen ist, voll funktionsfähige Anwendungen und Spiele für schwache Telefone der damaligen Zeit zu entwickeln.



  • Wenn überhaupt, habe ich nichts mit diesem Spiel zu tun.

, floating-point , . "3" — fixed-point . , . , j2me Android.


, j2me — java (, 1.3), .jar PC. — . , - — API j2me .


.


, , , .


Nokia 5200, " " :


  • 2006
  • 128x160 1.8
  • 262 . ( , 6 R, G, B ).
  • - bluetooth .
  • ( , 7 )
  • microSd , , , 256 .
  • - opera mini (, , )
  • 640x480 .
  • MIDP 2.0 (wiki)
  • usb
  • -
  • , , — 100 , , floating-point . , - .

, — , 50-200 .


Write once, run everywhere


java . , . , platform- , .


, — . — . . , .jar j2me .class java. , Canvas, MIDlet javax.microedition.


, . Android : .class , .dex ( , .. dex 65 ), apk, ART.


, . , . , . , Vector synchronized. Vector , ArrayList ArrayList , .


— java . (int, boolean, ...) . Vector Object, .


, go , java 1.3. go - , java 2004 1.5 . 1.3.


j2me — .jar .class ( 1.3, 20 ), Gravity defied PC. "" java javax.microedition , . , : , java.awt.Image javax.microedition.lcdui.Image.


J2ME



javax.microedition. , - , , - , , — . javax.microedition.lcdui.


MIDlet.


startApp().
— pauseApp() startApp() . destroyApp().


, notifyPaused() notifyDestroyed() — , .
, " " resumeRequest()


, notifyPaused(), , .


, lifecycle .


, Runnable - :


Thread thread;
boolean isRunning;
boolean needToDestroy = false;

public void startApp() {
    isRunning = true;
    if (thread != null) {
        thread = new Thread(this);
        thread.start();
    }
}

public void pauseApp() {
    isRunning = false;
}

public void destroyApp(boolean unconditional) {
    needToDestroy = true;
}

, .


void run(){
    while(!needToDestroy) {
        //   
        //     - .
        while (!isRunning) {
            Thread.sleep(100);
        }
    }
    notifyDestroyed();
}

, 100 — , . , pauseApp() startApp()


Canvas


— Canvas. Canvas java.


repaint(), , . UI- paint(Graphics g). , - , Canvas — . — repaint() paint(...) .


, :
hasPointerEvents(), hasPointerMotionEvents(), hasRepeatEvents(), true. pointerDragged(int x, int y) ( ), pressed( ) released( ).
— , .



, — , . . , , . , 240360 . — — .


- , "" , . j2me - , , .., . , nokia 5800 , .


MIDlet Pascal


- , . java2me , , MIDlet pascal . j2me — , , java.


?


, , , Gravity Defied 64 .


-, .jar — zip , 122.1 kB


  • META-INF MANIFEST.MF 3.8 kB, SHA-1 MD5 . .
  • levels.mrg 5.1 kB 30 . 170 . .
  • 11 . 10.8 kB.
  • .class , 98.3 kB, 15 . — 127 , 24.3 kB. :
    • , (4 ), 127 174 .
    • — 470 .
    • 9 — 1.6 6 kB.
    • god-like :


. fernflower — , intelliJ IDEA. — , . .


IDEA — , .


: /gradlew jar, build .jar
: mkdir decompiled && java -jar fernflower.jar -ren=1 GravityDefied_java decompiled


ren , if for. , java . ren=1 field_42 method_135 — , .


2004 — , , :


  • - , . .class .
  • else, int ..
  • . "" Micro, .
  • , fixed-point , . , (int)((long)a * b >> 16)
  • , , .


— , . , , -. , .


- Netbeans, j2me SDK. , , ant. .


, Linux. gradle . — javax.microedition.*. — PC- java. . , .


watch ./gradlew run . ctrl+S .


.
19 :


  • 8 javax.microedition.rms.
  • 10 .lcdui, , , Canvas ..).
  • MIDlet — , .

, .


Micro, . - , startApp MIDlet .


:


protected void pauseApp() {
    c = true;
    if (!b) {
        this.gameToMenu();
    }
    System.gc();
}

, c isPaused.


"" :


public void a() {
    if (this.recordStore != null) {
        try {
            this.e.closeRecordStore();
            return;
        } catch (RecordStoreException var1) {
        }
    }
}

- closeMethodStore.


, intelliJ IDEA - . — , , Image.loadImage(name):


this.p = Image.createImage("/splash.png");

, p splashImage.


- — , . , … Jetbrains — , — . , , .


- . — loadImage()… null . .


: , Image:


public class Image {
    public final java.awt.Image image;

    private Image(java.at.Image image) {
        this.image = image;
    }

    public Graphics getGraphics() {
        throw new RuntimeException();
    }

    public int getWidth() {
        return image.getWidth(null);
    }

    public static Image createImage(int w, int h) {
        return new Image(new BufferedImage(w, h, BufferedImage.TYPE_INT_ARGB));
    }
    ...
}

, API , .


CanvasImpl, JPanel. Canvas.
, c :


public void paintComponent(Graphics g) {
    if (upscale == 1) {
        canvas.paint(new javax.microedition.lcdui.Graphics(g));
    } else {
        canvas.paint(new javax.microedition.lcdui.Graphics(screen.getGraphics()));
        g.drawImage(screen, 0, 0, width * upscale, height * upscale, Color.WHITE, null);
    }
}

javax.microedition.lcdui.Graphics(g) — awt.Graphics, .


, . "" , .


, , , , — . PC. ? - 64 * 64, , 1 * 1 , 240 * 320 . , , , , .


, . , , , , , .


, , j2me PC. — 2010 -, - . - - — .


!


, .


.jar . . , , . - Alert Canvas Displayable , Canvas. , .


gradle :


  • emulator , , . , , .
  • app-original, .jar
  • app-from-sources - . .


, , . "" , , .


, .


Fixed-point physics


. , 16 — . , , -32768.0 32767.999984 c 1.0 / 65536.


— .


int.


: int, , "". long. 64 32 . 16 16- int.


: . long, 16 . - , 32 — 16.


sin, cos atan2.


— 64 — 0 90 . , — . . , .




, . Canvas.hasPointerEvents() true, , . — " ", " ", " " - "" . , , .


Level format


, — 170 . ? — .


, — / .., . . 0xff, int , , — dx , dy.


for (int i = 1; i < pointsCount; ++i) {
    byte modeOrDx;
    if ((modeOrDx = var1.readByte()) == -1) {
        offsetY = 0;
        offsetX = 0;
        pointX = var1.readInt();
        pointY = var1.readInt();
    } else {
        pointX = modeOrDx;
        pointY = var1.readByte();
    }
    offsetX += pointX;
    offsetY += pointY;
    this.addPointSimple(offsetX, offsetY);
}


.



GPU full hd , (128*160 240*320). 3 - , api . , — 90-180-270 .


, — .
, 32 16 . 48*48 1091 .


, , - API 3 3 - 3-. , - .


— 2 3.



. — 100 "23" "64".


if (time10MsToStringCache[time10MsPart] == null) {
    String zeroPadding;
    if (time10MsPart >= 10) {
        zeroPadding = "";
    } else {
        zeroPadding = "0";
    }
    time10MsToStringCache[time10MsPart] = zeroPadding + time10Ms % 100L;
}

, , . , -.


No-MVP


MenuManager ( ) . - , — - , .


, - , . : Android:


  • layout . .
  • stings.txt.
  • Activity, .
  • LifecycleObserver, Adapter , Activity .
  • Adapter DataSource.
  • " ", Bundle DataSource .
  • DataSouce SQLite .

: , ? , .



, TimerOrMotoPartOrMenuElem .
, , :


  • -
  • , " "

, , , — .


, , 64 . , - , "" .



, , , , . ", " — .


:


public void init() {
    long timeToLoading = 3000L;
    Thread.yield();
    this.gameCanvas = new GameCanvas(this);
    Display.getDisplay(this).setCurrent(this.gameCanvas);
    this.gameCanvas.requestRepaint(1);

    while (!this.gameCanvas.isShown()) {
        this.goLoadingStep();
    }

    long deltaTimeMs;
    while (timeToLoading > 0L) {
        deltaTimeMs = this.goLoadingStep();
        timeToLoading -= deltaTimeMs;
    }

    this.gameCanvas.requestRepaint(2);

    for (timeToLoading = 3000L; timeToLoading > 0L; timeToLoading -= deltaTimeMs) {
        deltaTimeMs = this.goLoadingStep();
    }

    while (gameLoadingStateStage < 10) {
        this.goLoadingStep();
    }

    this.gameCanvas.requestRepaint(0);
    this.isInited = true;
}

goLoadingStep() . goLoadingStep(). goLoadingStep , .


goLoadingStep() :


private long goLoadingStep() {
    ++gameLoadingStateStage;
    this.gameCanvas.repaint();
    long startTimeMillis = System.currentTimeMillis();
    switch (gameLoadingStateStage) {
        case 1:
            this.levelLoader = new LevelLoader();
            break;
        case 2:
            this.gamePhysics = new GamePhysics(this.levelLoader);
            this.gameCanvas.init(this.gamePhysics);
            break;
        case 3:
            this.menuManager = new MenuManager(this);
            this.menuManager.initPart(1);
            break;
            .... ///   5-8
        case 9:
            this.menuManager.initPart(7);
            break;
        case 10:
            this.gameCanvas.setMenuManager(this.menuManager);
            this.gameCanvas.setViewPosition(-50, 150);
            this.setMode(1);
            break;
        default:
            --gameLoadingStateStage;

            try {
                Thread.sleep(100L);
            } catch (InterruptedException var3) {
            }
    }

    return System.currentTimeMillis() - startTimeMillis;
}

MenuManager.initPart() switch case .


, , . , .



2004 . Excitera Mobile Awards 2004 (EMA04) best-in-show. Codebrew Software :


  • Tors Björn Henrik Johansson — system/game logic/interface, testing, levels design
  • Set Elis Norman — graphics/physics/mathematics/system/tools programming, levels design
  • Per David Jacobsson — physics programming, game graphics, levels design

Darüber hinaus gibt es eine Portierung dieses Spiels für Android, die von unseren Landsleuten erstellt wurde, aber nur einen dekompilierten Code verwendet.


Da es seit fünf Jahren keine Beschwerden über diesen Code gibt, denke ich, dass mein Versuch, die ursprüngliche Anwendung zu dekompilieren und zu verstehen, keinen Schaden anrichten wird. Jetzt ist das Spiel von historischem Interesse und ermöglicht es Ihnen, die Ära der kleinen Smartphones, die sie könnten, genauer zu betrachten.

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