Android 标题栏和状态栏随ScrollView滑动颜色改变轻松实现

01、概述：

在开发过程中，这样的需求也是常见的，随着ScrollView 的滑动，标题栏和状态栏背景透明度发生变化。有多中实现方式，在这里记录一下自己用到的一种。

02、效果：

03、代码实现：

public class ZpScrollViewActivity extends Activity{

    private View titleLine;
    private View titleLine1;
    private LinearLayout title;
    private LinearLayout top;
    private MyScrollView scrollView;

    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_scrollview);

        initView();
    }

    private void initView() {
        setTranslucentStatus(this, true);

        title = (LinearLayout) findViewById(R.id.ll_title);
        title.getBackground().mutate().setAlpha(0);
        top = (LinearLayout) findViewById(R.id.ll_title_top);
        titleLine1 = findViewById(R.id.v_title_line_1);
        titleLine = findViewById(R.id.v_title_line);
        scrollView = (MyScrollView) findViewById(R.id.sv_content);

        // 设置状态栏高度
        int statusBarHeight = this.getResources().getDimensionPixelSize(this.getResources().getIdentifier("status_bar_height", "dimen", "android"));
        LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, statusBarHeight);
        titleLine.setLayoutParams(params);
        titleLine1.setLayoutParams(params);

        // 设置滑动
        scrollView.setOnScrollistener(new MyScrollView.OnScrollistener() {

            @Override
            public void onScroll(int startY, int endY) {
                //根据scrollview滑动更改标题栏透明度
                changeAphla(startY, endY);
            }
        });
    }

    /**
     * 根据内容窗体的移动改变标题栏背景透明度
     *
     * @param startY scrollview开始滑动的y坐标（相对值）
     * @param endY   scrollview结束滑动的y坐标（相对值）
     */
    private void changeAphla(int startY, int endY) {
        //获取标题高度
        int titleHeight = title.getMeasuredHeight();
        //获取背景高度
        int backHeight = top.getMeasuredHeight();

        //获取控件的绝对位置坐标
        int[] location = new int[2];
        top.getLocationInWindow(location);
        //从屏幕顶部到控件顶部的坐标位置Y
        int currentY = location[1];
        //表示回到原位（滑动到顶部）
        if (currentY >= 0) {
            title.getBackground().mutate().setAlpha(0);
        }

        Log.e("zpan", "=titleHeight=" + titleHeight + "=backHeight=" + backHeight + "=currentY=" + currentY);
        //颜色透明度改变
        if (currentY < titleHeight && currentY >= -(backHeight - titleHeight)) {
            //计算出滚动过程中改变的透明值
            double y = Math.abs(currentY) * 1.0;
            double height = (backHeight - titleHeight) * 1.0;
            int changeValue = (int) (y / height * 255);

            Log.e("zpan", "changeValue=" + changeValue);
            //判断是向上还是向下
            if (endY > startY) {    //向上;透明度值增加，实际透明度减小
                title.getBackground().mutate().setAlpha(changeValue);
            } else if (endY < startY) {     //向下；透明度值减小，实际透明度增加
                title.getBackground().mutate().setAlpha(changeValue);
            }
        }
        //红色背景移除屏幕
        if (currentY < -(backHeight - titleHeight)) {
            title.getBackground().mutate().setAlpha(255);
        }
    }

    /**
     * 设置状态栏透明
     *
     * @param activity
     * @param on
     */
    public void setTranslucentStatus(Activity activity, boolean on) {
        Window win = activity.getWindow();
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
            win.clearFlags(WindowManager.LayoutParams.FLAG_TRANSLUCENT_STATUS
                    | WindowManager.LayoutParams.FLAG_TRANSLUCENT_NAVIGATION);
            win.getDecorView().setSystemUiVisibility(View.SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN
//                    | View.SYSTEM_UI_FLAG_LAYOUT_HIDE_NAVIGATION //保证华为虚拟键盘能显示
                    | View.SYSTEM_UI_FLAG_LAYOUT_STABLE);
            win.addFlags(WindowManager.LayoutParams.FLAG_DRAWS_SYSTEM_BAR_BACKGROUNDS);
            win.setStatusBarColor(Color.TRANSPARENT);
//            win.setNavigationBarColor(Color.TRANSPARENT); //保证华为虚拟键盘是系统色
        }
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT && Build.VERSION.SDK_INT < Build.VERSION_CODES.LOLLIPOP) {
            WindowManager.LayoutParams winParams = win.getAttributes();
            final int bits = WindowManager.LayoutParams.FLAG_TRANSLUCENT_STATUS;
            if (on) {
                winParams.flags |= bits;
            } else {
                winParams.flags &= ~bits;
            }
            win.setAttributes(winParams);
        }
    }
}

注：代码里面的关键位置，注释比较详细，在这里就不做过多的介绍，有兴趣可以实际的尝试一下。

04、布局：activity_scrollview

05、自定义ScrollView 滑动事件，是为了处理ScrollView 的向下兼容问题

public class MyScrollView extends ScrollView {

    private OnScrollistener onScrollistener;

    public OnScrollistener getOnScrollistener() {
        return onScrollistener;
    }

    public void setOnScrollistener(OnScrollistener onScrollistener) {
        this.onScrollistener = onScrollistener;
    }

    public MyScrollView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
    }

    public MyScrollView(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    public MyScrollView(Context context) {
        super(context);
    }

    public interface OnScrollistener {

        void onScroll(int startY, int endY);
    }

    @Override
    protected void onScrollChanged(int l, int t, int oldl, int oldt) {
        onScrollistener.onScroll(oldt, t);
        super.onScrollChanged(l, t, oldl, oldt);
    }
}

注：代码意思比较简单，不做过多的解释