pxt-common-packages/libs/animation/legacy.ts

Microsoft MakeCode (PXT) common packages

/*
    Animation library for sprites
*/
namespace animation {
    //Handles all the updates
    let animations: Animation[];

    let animationStateStack: {
        state: Animation[],
        scene: scene.Scene
    }[];

    game.addScenePushHandler(oldScene => {
        if (animations) {
            if (!animationStateStack) animationStateStack = [];
            animationStateStack.push({
                state: animations,
                scene: oldScene
            });
            animations = undefined;
        }
    });

    game.addScenePopHandler(() => {
        const scene = game.currentScene();
        animations = undefined;
        if (animationStateStack && animationStateStack.length) {
            const nextState = animationStateStack.pop();
            if (nextState.scene == scene) {
                animations = nextState.state;
            } else {
                animationStateStack.push(nextState);
            }
        }
    });

    export class Animation {

        sprites: Sprite[];
        frames: Image[];
        index: number;
        interval: number;
        action: number;
        lastTime: number;

        constructor(action: number, interval: number) {
            this.interval = interval;
            this.index = -1;
            this.action = action;
            this.frames = [];
            this.sprites = [];
            this.lastTime = control.millis();

            this._init();
        }

        _init() {
            if (!animations) {
                animations = [];
                game.eventContext().registerFrameHandler(scene.ANIMATION_UPDATE_PRIORITY, () => {
                    animations.forEach(anim => anim.update());
                });
            }
            animations.push(this);
        }

        update() {
            let currentTime = control.millis();
            let dt = currentTime - this.lastTime;
            if (dt >= this.interval && this.frames.length) {
                this.index = (this.index + 1) % this.frames.length;
                this.lastTime = currentTime;
            }

            this.sprites = this.sprites.filter(sprite => !(sprite.flags & sprites.Flag.Destroyed));

            this.sprites.forEach(sprite => {
                if (sprite._action === this.action) {
                    let newImage = this.getImage();
                    //Update only if the image has changed
                    if (sprite.image !== newImage) {
                        sprite.setImage(newImage);
                    }
                }
            });
        }

        getImage() {
            return this.frames[this.index];
        }

        getAction() {
            return this.action;
        }

        getInterval() {
            return this.interval;
        }

        setInterval(interval: number) {
            this.interval = interval;
        }

        /**
        * Add an image frame to an animation
        */
        //% blockId=addAnimationFrame
        //% block="add frame $frame=screen_image_picker to $this=variables_get(anim)"
        //% group="Advanced"
        //% weight=40
        //% help=animation/add-animation-frame
        addAnimationFrame(frame: Image) {
            this.frames[++this.index] = frame;
        }

        registerSprite(sprite: Sprite) {
            if (this.sprites.indexOf(sprite) === -1) {
                this.sprites.push(sprite);
            }
        }

    }

    //% shim=ENUM_GET
    //% blockId=action_enum_shim
    //% block="%arg"
    //% group="Advanced"
    //% enumName="ActionKind"
    //% enumMemberName="action"
    //% enumPromptHint="e.g. Walking, Idle, Jumping, ..."
    //% enumInitialMembers="Walking, Idle, Jumping"
    //% weight=10
    export function _actionEnumShim(arg: number) {
        // This function should do nothing, but must take in a single
        // argument of type number and return a number value.
        return arg;
    }

    /**
     * Create an animation
     */
    //% blockId=createAnimation
    //% block="create animation of $action=action_enum_shim with interval $interval ms"
    //% group="Advanced"
    //% interval.defl=1000
    //% blockSetVariable="anim"
    //% weight=50
    //% help=animation/create-animation
    export function createAnimation(action: number, interval: number) {
        return new Animation(action, interval);
    }

    /**
     * Attach an animation to a sprite
     */
    //% blockId=attachAnimation
    //% block="attach animation $set=variables_get(anim) to sprite $sprite=variables_get(mySprite)"
    //% sprite.defl=mySprite
    //% group="Advanced"
    //% weight=30
    //% help=animation/attach-animation
    export function attachAnimation(sprite: Sprite, set: Animation) {
        set.registerSprite(sprite);
    }

    /**
     * Set an animation action to a sprite
     */
    //% blockId=setAction
    //% block="activate animation $action=action_enum_shim on $sprite=variables_get(mySprite)"
    //% sprite.defl=mySprite
    //% group="Advanced"
    //% weight=20
    //% help=animation/set-action
    export function setAction(sprite: Sprite, action: number) {
        sprite._action = action;
    }

}