👨‍👦 🚫 🤦🏿 Nostalgia Post: j2me, Gravity Defied, 64kb 🏄 💭 🐘

Artikel ini tidak mengejar tujuan praktis - Saya hanya ingin tahu bagaimana sekitar 15 tahun yang lalu, pengembang berhasil membuat aplikasi dan game yang berfungsi penuh untuk ponsel yang lemah saat itu.

Jika ada, saya tidak ada hubungannya dengan game ini.

, 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

Selain itu, ada porta dari game ini untuk android yang dibuat oleh rekan kami, tetapi hanya menggunakan kode yang di-decompile.

Karena tidak ada keluhan tentang kode itu selama lima tahun, saya pikir upaya saya untuk mendekompilasi aplikasi asli dan memahaminya tidak akan membahayakan. Sekarang gim ini menarik sejarah dan memungkinkan Anda untuk melihat lebih dekat era smartphone kecil yang mereka bisa.

Nostalgia Post: j2me, Gravity Defied, 64kb

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