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

package com.xixun.xixunplayer;

import android.annotation.SuppressLint;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Rect;
import android.view.Choreographer;
import android.view.View;

import androidx.annotation.NonNull;

import java.util.ArrayList;
import java.util.List;

import gnph.util.JSMap;

@SuppressLint("ViewConstructor")
public class SrcScroll extends View implements Choreographer.FrameCallback {

    ArrayList<Bitmap> imgs = new ArrayList<>();
    Rect rect = new Rect();
    int imgsWidth;
    int interval, cur, end, step;
    char effect;

    public SrcScroll(Context context, JSMap json) {
        super(context);
        var img = BitmapFactory.decodeFile(Util.programDir+"/"+json.stnn("id"));
        imgsWidth = img.getWidth();
        if(imgsWidth <= 8192) imgs.add(img);
        else {
            var rem = img.getWidth();
            do {
                imgs.add(Bitmap.createBitmap(img, img.getWidth()-rem, 0, Math.min(8192, rem), img.getHeight()));
                rem -= 8192;
            } while (rem>0);
        }
        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 = -(imgsWidth-step);
            else if(effect=='r') end = imgsWidth-step;
            else if(effect=='t') end = -(imgs.get(0).getHeight()-step);
            else if(effect=='b') end = imgs.get(0).getHeight()-step;
        }
    }
    @Override
    protected void onDraw(@NonNull Canvas canvas) {
        super.onDraw(canvas);
        if(imgs.isEmpty()) return;
        try {
            drawOther(canvas);
            if(freshCnt==0 && effect!=0 && interval!=0) {
                choreographer.postFrameCallback(this);
                freshCnt = 1;
            }
        } catch (Throwable e) {
            setVisibility(GONE);
            imgs.clear();
            Util.printStackTrace(e);
        }
    }
    public void drawOther(Canvas canvas) {
        if(! canvas.getClipBounds(rect)) {
            rect.left = rect.top = 0;
            rect.right = getWidth();
            rect.bottom = getHeight();
        }
        if(effect=='l') {
            int ii = 0, x = cur;
            do {
                if(x > rect.left-imgs.get(ii).getWidth() && x < rect.right) canvas.drawBitmap(imgs.get(ii), x, 0, null);
                x += imgs.get(ii).getWidth();
                if(++ii >= imgs.size()) ii = 0;
            } while(x < rect.right);
        } else if(effect=='r') {
            int ii = imgs.size()-1, x = cur + getWidth();
            boolean con1;
            do {
                x -= imgs.get(ii).getWidth();
                con1 = x > rect.left-imgs.get(ii).getWidth();
                if(con1 && x < rect.right) canvas.drawBitmap(imgs.get(ii), x, 0, null);
                if(--ii < 0) ii = imgs.size()-1;
            } while(con1);
        } else if(effect=='t') {
            int ii = 0, y = cur;
            do {
                if(y > rect.top-imgs.get(ii).getHeight() && y < rect.bottom) canvas.drawBitmap(imgs.get(ii), 0, y, null);
                y += imgs.get(ii).getHeight();
                if(++ii >= imgs.size()) ii = 0;
            } while(y < rect.bottom);
        } else if(effect=='b') {
            int ii = imgs.size()-1, y = cur + getHeight();
            boolean con1;
            do {
                y -= imgs.get(ii).getHeight();
                con1 = y > rect.top-imgs.get(ii).getHeight();
                if(con1 && y < rect.bottom) canvas.drawBitmap(imgs.get(ii), 0, y, null);
                if(--ii < 0) ii = imgs.size()-1;
            } while(con1);
        } else canvas.drawBitmap(imgs.get(0), 0, 0, null);
    }

    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);
    }
}