Android(安卓)实现轮播图效果（二）底部圆点布局实现

1、准备底部圆点的素材、利用Drawable的功能，去实现一个圆点图片的展示

drawable下新建两个Drawable resource file：dot_normal.xml和dot_select.xml

dot_normal.xml

<?xml version="1.0" encoding="utf-8"?>

dot_select.xml

<?xml version="1.0" encoding="utf-8"?>

新建类ImageBannerFramLayout继承FrameLayout并Create constructor matching super（实现前面三个构造方法就行）

实现方法initImageBannerViewGroup()和initDotLinearlayout()并在三个构造方法中调用

    //构造方法    public ImageBannerFramLayout(@NonNull Context context) {        super(context);        initImageBannerViewGroup();        initDotLinearlayout();    }    public ImageBannerFramLayout(@NonNull Context context, @Nullable AttributeSet attrs){        super(context, attrs);        initImageBannerViewGroup();        initDotLinearlayout();    }    public ImageBannerFramLayout(@NonNull Context context, @Nullable AttributeSet attrs, int defStyleAttr) {        super(context, attrs, defStyleAttr);        initImageBannerViewGroup();        initDotLinearlayout();    }    /**     * 初始化自定义的图片轮播核心类     */    private void initImageBannerViewGroup() {        imageBannerViewGroup = new ImageBannerViewGroup(getContext());        //设置宽度和高度        FrameLayout.LayoutParams lp = new FrameLayout.LayoutParams(FrameLayout.LayoutParams.MATCH_PARENT, FrameLayout.LayoutParams.MATCH_PARENT);        imageBannerViewGroup.setLayoutParams(lp);        imageBannerViewGroup.setDotChangeListener(this);//这里将Listener传递给Framlayout        imageBannerViewGroup.setImageBannerLister(this);        addView(imageBannerViewGroup);    }    /**     * 初始化底部圆点布局     */    private void initDotLinearlayout() {        linearLayout = new LinearLayout(getContext());        FrameLayout.LayoutParams lp = new FrameLayout.LayoutParams(FrameLayout.LayoutParams.MATCH_PARENT, 40);        linearLayout.setLayoutParams(lp);        //水平并居中        linearLayout.setOrientation(LinearLayout.HORIZONTAL);        linearLayout.setGravity(Gravity.CENTER);        //设置背景颜色//        linearLayout.setBackgroundColor(Color.RED);        addView(linearLayout);        //将圆点放到底部        FrameLayout.LayoutParams layoutParams = (LayoutParams) linearLayout.getLayoutParams();        layoutParams.gravity = Gravity.BOTTOM;        linearLayout.setLayoutParams(layoutParams);        //设置底部圆点透明度 3.0之后使用setAlpha()，3.0之前也是使用这个方法，但调用者不同        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) {            linearLayout.setAlpha(0.5f);//传入float值        } else {            linearLayout.getBackground().setAlpha(100);//传入int值0~255        }    }

添加方法addDotToLinearlayout()和addBitmapToImageBannerViewGroup()并在addBitmaps()中调用

public void addBitmaps(List list) {        for (int i = 0; i < list.size(); i++) {            Bitmap bitmap = list.get(i);            addBitmapToImageBannerViewGroup(bitmap);            addDotToLinearlayout();        }    }    private void addDotToLinearlayout() {        ImageView imageView = new ImageView(getContext());        LinearLayout.LayoutParams lp = new LinearLayout.LayoutParams(LinearLayout.LayoutParams.WRAP_CONTENT, LinearLayout.LayoutParams.WRAP_CONTENT);        //设置圆点的距离        lp.setMargins(5, 5, 5, 5);        imageView.setLayoutParams(lp);        imageView.setImageResource(R.drawable.dot_normal);        linearLayout.addView(imageView);    }    private void addBitmapToImageBannerViewGroup(Bitmap bitmap) {        ImageView imageView = new ImageView(getContext());        imageView.setScaleType(ImageView.ScaleType.CENTER_CROP);        //设置宽度(设备的宽度存储在全局变量C.WIDTH中)和高度        imageView.setLayoutParams(new ViewGroup.LayoutParams(C.WIDTH, ViewGroup.LayoutParams.WRAP_CONTENT));        imageView.setImageBitmap(bitmap);        imageBannerViewGroup.addView(imageView);    }

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