pxt-spritewrapper

This extension allows you to easily wrap a sprite in a class and get the corresponding class instance when given a given sprite. Your class needs to extend the SpriteWrapper.Support base class. Your object’s onDestroyed method is set as a callback to the sprite’s onDestroyed method. Whenever the sprite gets destroyed, the onDestroyed method of your object is called, so that you can do some clanup. To destroy an object yourself, call the destroy method of its sprite or call the destroy method directly on the object.

Here’s a very simple space shooter game that demonstrates how to use it:

class EnemySpaceShip extends SpriteWrapper.Support {
    private static readonly image: Image = img`
        5 5 5 5 5 5 d
        . 5 5 5 5 d .
        . . 5 5 d . .
        . . . 5 . . .
    `;

    constructor(xPos: number) {
        super(sprites.create(EnemySpaceShip.image, SpriteKind.Enemy));
        this.sprite.setFlag(SpriteFlag.AutoDestroy, true);
        this.sprite.y = 0;
        this.sprite.x = xPos;
        this.sprite.vy = 50;
    }

    public gotHit() {
        info.changeScoreBy(10);
        this.destroy();
    }
}

class SpaceShip extends SpriteWrapper.Support {
    private static readonly image: Image = img`
        . . . d . . .
        . . 1 1 d . .
        . 1 1 1 1 d .
        1 1 1 1 1 1 d
    `;

    constructor() {
        super(sprites.create(SpaceShip.image, SpriteKind.Player));
        this.sprite.setFlag(SpriteFlag.AutoDestroy, true);
        this.sprite.y = scene.screenHeight() - 10;
        this.sprite.setFlag(SpriteFlag.StayInScreen, true);

        controller.left.onEvent(ControllerButtonEvent.Pressed, function () {
            this.flyLeft();
        });
        controller.right.onEvent(ControllerButtonEvent.Pressed, function () {
            this.flyRight();
        });
        controller.A.onEvent(ControllerButtonEvent.Pressed, function () {
            this.shoot();
        });
    }

    public onDestroyed() {
        music.powerDown.play();
        game.over(false);
    }

    public flyLeft() {
        this.sprite.vy = 0;
        this.sprite.vx = -50;
    }

    public flyRight() {
        this.sprite.vy = 0;
        this.sprite.vx = 50;
    }

    public shoot() {
        sprites.createProjectileFromSprite(img`
            1
        `, this.sprite, 0, -70);
    }
}

const player: SpaceShip = new SpaceShip();

game.onUpdateInterval(1000, () => {
   new EnemySpaceShip(randint(0, scene.screenWidth()));
});

sprites.onOverlap(SpriteKind.Player, SpriteKind.Enemy, (playerSprite: Sprite, enemySprite: Sprite) => {
    SpriteWrapper.fromSprite(playerSprite).destroy();
    SpriteWrapper.fromSprite(enemySprite).destroy();
});

sprites.onOverlap(SpriteKind.Projectile, SpriteKind.Enemy, (projectileSprite: Sprite, enemySprite: Sprite) => {
    (SpriteWrapper.fromSprite(enemySprite) as EnemySpaceShip).gotHit();
    projectileSprite.destroy();
});

Using it in your project

To use this extension in your project, choose “Advanced > Extensions…” and enter https://github.com/ractive/pxt-spritewrapper in the search box.

Metadata (used for search, rendering)

• for PXT/arcade