🤹🏻 ☂️ 👧🏽 Nostalgia Post: j2me, Gravity Defied, 64kb 👎🏽 😊 🌂

Cet article ne poursuit aucun objectif pratique - je me demandais simplement comment il y a environ 15 ans, les développeurs ont réussi à créer des applications et des jeux entièrement fonctionnels pour les téléphones faibles de l'époque.

Si quoi que ce soit, je n'ai rien à voir avec ce jeu.

, 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 :
  - m ( MenuManager) — 24.3kB, . layout.xml strings.txt :). .
  - i (GameCanvas) 15.2 kB: , , , , .
  - b (GamePhysics) 20.6 kB: - , .

. 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

De plus, il existe un portage de ce jeu pour android fait par nos compatriotes, mais il utilise juste un code décompilé.

Puisqu'il n'y a eu aucune plainte concernant ce code depuis cinq ans, je pense que ma tentative de décompiler l'application d'origine et de comprendre qu'elle ne fera aucun mal. Maintenant, le jeu présente un intérêt historique et vous permet de regarder de plus près l'ère des petits smartphones qu'ils pouvaient.

Nostalgia Post: j2me, Gravity Defied, 64kb

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