Android/XixunPlayer/app/src/main/java/com/xixun/xixunplayer/EleScroll.java

package com.xixun.xixunplayer;

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.view.Choreographer;
import android.view.View;
import android.view.ViewGroup;

import gnph.util.JSMap;

public class EleScroll extends View implements Choreographer.FrameCallback {

    Bitmap img;
    int interval, cur, end, step;
    char effect;

    public EleScroll(String dirPre, JSMap json, Context context) {
        super(context);
        img = BitmapFactory.decodeFile(dirPre + json.stnn("id"));
        var effStr = json.str("effect");
        if(effStr==null || effStr.equals("no")) return;
        var scrollSpeed = json.dbl("scrollSpeed");
        if(scrollSpeed==0) {
            var scrollDur = json.dbl("effectSpeed");
            if(scrollDur==0) return;
            scrollSpeed = 1000 / scrollDur;
        }
        interval = step = 1;
        if(scrollSpeed > 60) step = (int) Math.round(scrollSpeed/60);
        else if(scrollSpeed < 60) interval = (int) Math.round(60/scrollSpeed);
        int idx = effStr.lastIndexOf(' ');
        if(idx > -1) {
            effect = effStr.charAt(idx+1);
            if(effect=='l') end = -(img.getWidth()-step);
            else if(effect=='r') end = img.getWidth()-step;
            else if(effect=='t') end = -(img.getHeight()-step);
            else if(effect=='b') end = img.getHeight()-step;
        }
    }
    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        if(img==null) return;
        try {
            if(effect=='l') {
                canvas.drawBitmap(img, cur, 0, null);
                canvas.drawBitmap(img, cur+img.getWidth(), 0, null);
            } else if(effect=='r') {
                canvas.drawBitmap(img, cur, 0, null);
                canvas.drawBitmap(img, cur-img.getWidth(), 0, null);
            } else if(effect=='t') {
                canvas.drawBitmap(img, 0, cur, null);
                canvas.drawBitmap(img, 0, cur+img.getHeight(), null);
            } else if(effect=='b') {
                canvas.drawBitmap(img, 0, cur, null);
                canvas.drawBitmap(img, 0, cur-img.getHeight(), null);
            } else canvas.drawBitmap(img, 0, 0, null);
            if(freshCnt==0 && effect!=0 && interval!=0) choreographer.postFrameCallback(this);
        } catch (Throwable e) {
            setVisibility(GONE);
            img = null;
            e.printStackTrace();
        }
    }

    Choreographer choreographer = Choreographer.getInstance();
    int freshCnt;

    @Override
    public void doFrame(long frameTimeNanos) {
        if(! isShown()) {
            freshCnt = cur = 0;
            return;
        }
        if(freshCnt < interval) freshCnt++;
        else {
            freshCnt = 1;
            if(effect=='t' || effect=='l') {
                if(cur <= end) cur -= end;
                else cur -= step;
            } else if(effect=='b' || effect=='r') {
                if(cur >= end) cur -= end;
                else cur += step;
            }
            invalidate();
        }
        choreographer.postFrameCallback(this);
    }
}