Android 自定义轮播图
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android 自定义轮播图
定义Banner
主要使用ViewPager实现滑动
public class Banner extends FrameLayout
public Context context;
private @LayoutRes
int layoutId = R.layout.banner_view;
private View inflate;
private ViewPager pager;
private AutoHandler mHandler;
private PagerAdapter adapter;
public IndicatorView indicatorView;
public Banner(@NonNull Context context)
this(context, null);
public Banner(@NonNull Context context, @Nullable AttributeSet attrs)
this(context, attrs, -1);
public Banner(@NonNull Context context, @Nullable AttributeSet attrs, int defStyleAttr)
super(context, attrs, defStyleAttr);
init(context, attrs, defStyleAttr);
public void setAdapter(PagerAdapter adapter)
this.adapter = adapter;
pager.setAdapter(adapter);
indicatorView.setPager(pager);
private void init(Context context, AttributeSet attrs, int defStyleAttr)
this.context = context;
inflate = LayoutInflater.from(context).inflate(layoutId, this, true);
pager = inflate.findViewById(R.id.banner_pager);
indicatorView = inflate.findViewById(R.id.indicatorView);
mHandler = new AutoHandler(pager);
mHandler.start();
public abstract static class BannerAdapter extends PagerAdapter
private List list;
private Context context;
public BannerAdapter(List list, Context context)
this.list = list;
this.context = context;
@Override
public int getCount()
if (null == list || list.size() == 0)
return 1;
else
return list.size();
@Override
public boolean isViewFromObject(@NonNull View view, @NonNull Object object)
return view == object;
@NonNull
@Override
public Object instantiateItem(@NonNull ViewGroup container, int position)
if (getLayout() > 0)
View inflate = LayoutInflater.from(context).inflate(getLayout(), container, false);
container.addView(inflate);
setView(inflate, position);
return inflate;
else
ImageView imageView = new ImageView(context);
container.addView(imageView);
if (list.size() > 0)
Glide.with(context).load(list.get(position))
.apply(new RequestOptions().centerCrop())
.into(imageView);
else
// Glide.with(context)
// .load(R.mipmap.ic_launcher)
// .apply(new RequestOptions().centerCrop())
// .into(imageView);
imageView.setBackgroundResource(R.mipmap.ic_launcher);
return imageView;
@Override
public void destroyItem(@NonNull ViewGroup container, int position, @NonNull Object object)
container.removeView((View) object);
protected abstract void setView(View inflate, int position);
protected abstract int getLayout();
定义定时器Handler
主要处理ViewPager的滚动 开启定时任务 ViewPager自动滚动
public class AutoHandler extends Handler
private ViewPager pager;
public static int TIME = 1000 * 2;
public boolean stopHandler;
public AutoHandler(ViewPager pager)
this.pager = pager;
@Override
public void handleMessage(@NonNull Message msg)
super.handleMessage(msg);
switch (msg.what)
case 100:
if (!stopHandler)
sendEmptyMessageDelayed(100, TIME);
int position = pager.getCurrentItem() + 1;
if (position >= pager.getAdapter().getCount())
position = 0;
pager.setCurrentItem(position);
else
removeMessages(100);
break;
default:
removeMessages(100);
break;
public void start()
stopHandler = false;
if (!hasMessages(100))
sendEmptyMessageDelayed(100, TIME);
public void stop()
stopHandler = true;
if (hasMessages(100))
removeMessages(100);
绘制一个下标指示器
主要根据需求自行绘制 可有可无 和ViewPager关联在一起 实现联动
public class IndicatorView extends View
private Context context;
private ValueAnimator valueAnimator;
private float value;
public int indiWidth;
public int indiHeight;
public int indiDivide;
//0圆角 1直角
public int mode;
private int normalColor;
private int selectColor;
private int curPosition;
private int count;
private Paint paint;
private int width;
private int height;
private double lastPosition;
private ViewPager pager;
private PagerAdapter adapter;
private DataSetObserver dataSetObserver;
public void setPager(final ViewPager pager)
this.pager = pager;
this.adapter = pager.getAdapter();
dataSetObserver = new DataSetObserver()
@Override
public void onChanged()
super.onChanged();
setCount(adapter.getCount());
setCurPosition(pager.getCurrentItem());
;
if (null != adapter)
setCount(adapter.getCount());
setCurPosition(pager.getCurrentItem());
adapter.registerDataSetObserver(dataSetObserver);
pager.addOnPageChangeListener(new ViewPager.OnPageChangeListener()
@Override
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels)
lastPosition = position;
@Override
public void onPageSelected(int position)
curPosition = position;
setCurPosition(position);
@Override
public void onPageScrollStateChanged(int state)
);
pager.addOnAdapterChangeListener(new ViewPager.OnAdapterChangeListener()
@Override
public void onAdapterChanged(@NonNull ViewPager viewPager, @Nullable PagerAdapter oldAdapter, @Nullable PagerAdapter newAdapter)
if (oldAdapter != newAdapter)
adapter = newAdapter;
setCount(adapter.getCount());
setCurPosition(viewPager.getCurrentItem());
);
public void setCount(int count)
this.count = count;
if (count <= 1)
setVisibility(INVISIBLE);
requestLayout();
postInvalidate();
public void setCurPosition(int curPos)
/*记录上次记录*/
//lastPos = this.curPos;
this.curPosition = curPos;
//postInvalidate();
valueAnimator.start();
public IndicatorView(Context context)
this(context, null);
public IndicatorView(Context context, @Nullable AttributeSet attrs)
this(context, attrs, -1);
public IndicatorView(Context context, @Nullable AttributeSet attrs, int defStyleAttr)
super(context, attrs, defStyleAttr);
init(context, attrs, defStyleAttr);
private void init(Context context, AttributeSet attrs, int defStyleAttr)
this.context = context;
valueAnimator = ValueAnimator.ofFloat(0, 1f);
valueAnimator.setDuration(200);
valueAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener()
@Override
public void onAnimationUpdate(ValueAnimator animation)
value = (float) animation.getAnimatedValue();
postInvalidate();
);
TypedArray typedArray = context.obtainStyledAttributes(attrs, R.styleable.IndicatorView);
indiHeight = (int) typedArray.getDimension(R.styleable.IndicatorView_indi_height, getResources().getDimension(R.dimen.dp4));
indiWidth = (int) typedArray.getDimension(R.styleable.IndicatorView_indi_width, getResources().getDimension(R.dimen.dp4));
indiDivide = (int) typedArray.getDimension(R.styleable.IndicatorView_indi_divier, getResources().getDimension(R.dimen.dp4));
normalColor = typedArray.getColor(R.styleable.IndicatorView_indi_color, Color.parseColor("#66dddddd"));
selectColor = typedArray.getColor(R.styleable.IndicatorView_indi_color_select, Color.parseColor("#eedddddd"));
mode = typedArray.getInteger(R.styleable.IndicatorView_indi_mode, 0);
curPosition = 0;
count = 0;
paint = new Paint();
paint.setAntiAlias(true);
paint.setColor(normalColor);
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec)
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
width = indiWidth * count + (count - 1) * indiDivide;//每个的宽度加上中间间距的宽度
height = indiHeight;
setMeasuredDimension(width, height);
@Override
protected void onDraw(Canvas canvas)
super.onDraw(canvas);
for (int i = 0; i < count; i++)
int x = i * (indiDivide + indiWidth);
if (mode == 0)
paint.setColor(normalColor);
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP)
canvas.drawRoundRect(x, 0, x + indiWidth, indiHeight, indiHeight / 2, indiHeight / 2, paint);
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP)
if (curPosition == i)
paint.setColor(selectColor);
if (curPosition > lastPosition)
canvas.drawRoundRect(x, 0, x + value * indiWidth, indiHeight, indiHeight / 2, indiHeight / 2, paint);
else
canvas.drawRoundRect(x + (1 - value) * indiWidth, 0, x + indiWidth, indiHeight, indiHeight / 2, indiHeight / 2, paint);
if (mode == 1)
paint.setColor(normalColor);
canvas.drawRect(x, 0, x + indiWidth, indiHeight, paint);
if (curPosition == i)
paint.setColor(selectColor);
if (curPosition > lastPosition)
canvas.drawRect(x, 0, x + value * indiWidth, indiHeight, paint);
else
canvas.drawRect(x + (1 - value) * indiWidth, 0, x + indiWidth, indiHeight, paint);
在Activity中使用
banner.setAdapter(new Banner.BannerAdapter(strings, this)
@Override
protected void setView(View inflate, int position)
ImageView img = inflate.findViewById(R.id.img);
Glide.with(MainActivity.this).load(strings.get(position))
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