Banner

https://github.com/youth5201314/banner
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Banner is an Android carousel and looping banner component based on ViewPager2 that provides custom...
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### Banner Full Usage Example

Source: https://github.com/youth5201314/banner/blob/master/_autodocs/api-reference/Banner.md

Shows the complete initialization flow for a Banner, including lifecycle registration, adapter setup, indicator configuration, corner radius, and click listener.

```java
Banner<DataBean, ImageAdapter> banner = findViewById(R.id.banner);
banner.addBannerLifecycleObserver(this)
      .setStartPosition(0)
      .setAdapter(new ImageAdapter(DataBean.getTestData()))
      .setIndicator(new CircleIndicator(this))
      .setBannerRound(20f)
      .setOnBannerListener((data, position) -> {
          LogUtils.i("click: " + position);
      });
```

--------------------------------

### Full usage example

Source: https://github.com/youth5201314/banner/blob/master/_autodocs/api-reference/Banner.md

Complete example showing how to set up a Banner with lifecycle observer, adapter, indicator, rounded corners, and click listener.

```APIDOC
## Full usage example

### Description
Complete example showing how to set up a Banner with lifecycle observer, adapter, indicator, rounded corners, and click listener.

### Example
```java
Banner<DataBean, ImageAdapter> banner = findViewById(R.id.banner);
banner.addBannerLifecycleObserver(this)
      .setStartPosition(0)
      .setAdapter(new ImageAdapter(DataBean.getTestData()))
      .setIndicator(new CircleIndicator(this))
      .setBannerRound(20f)
      .setOnBannerListener((data, position) -> {
          LogUtils.i("click: " + position);
      });
```
```

--------------------------------

### BannerImageAdapter usage example

Source: https://github.com/youth5201314/banner/blob/master/_autodocs/api-reference/BannerAdapter.md

Example of setting the adapter and implementing onBindView to load images using Glide.

```java
banner.setAdapter(new BannerImageAdapter<DataBean>(DataBean.getTestData3()) {
    @Override
    public void onBindView(BannerImageHolder holder, DataBean data, int position, int size) {
        Glide.with(holder.itemView)
             .load(data.imageUrl)
             .into(holder.imageView);      // your own loader
    }
});
```

--------------------------------

### setOnBannerListener method

Source: https://github.com/youth5201314/banner/blob/master/_autodocs/api-reference/BannerAdapter.md

Installs the click callback listener, invoked by Banner.setOnBannerListener.

```java
public void setOnBannerListener(OnBannerListener<T> listener)
```

--------------------------------

### onStart

Source: https://github.com/youth5201314/banner/blob/master/_autodocs/api-reference/Banner.md

Lifecycle callback that calls start() when the owner's lifecycle reaches ON_START.

```APIDOC
## onStart

### Description
Lifecycle callback that calls start() when the owner's lifecycle reaches ON_START.

### Method
onStart

### Signature
public void onStart(LifecycleOwner owner)

### Parameters
- **owner** (LifecycleOwner) - Required - The lifecycle owner.

### Example
```java
@Override protected void onStart() { super.onStart(); banner.start(); }
```
```

--------------------------------

### Banner XML layout example

Source: https://github.com/youth5201314/banner/blob/master/_autodocs/configuration.md

Example layout for the com.youth.banner.Banner view using the app namespace. Shows how to set auto-loop interval, orientation, corner radius, and indicator colors via XML attributes.

```xml
<com.youth.banner.Banner
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:id="@+id/banner"
    android:layout_width="match_parent"
    android:layout_height="200dp"
    app:banner_loop_time="2500"
    app:banner_auto_loop="true"
    app:banner_orientation="horizontal"
    app:banner_radius="8dp"
    app:banner_indicator_selected_color="#88000000"
    app:banner_indicator_normal_color="#88ffffff" />
```

--------------------------------

### Effect combination example

Source: https://github.com/youth5201314/banner/blob/master/_autodocs/api-reference/transformers.md

Example of combining transformers for a 'Zoom + fade' effect, matching the README's claim that transformers can be combined for better results.

```APIDOC
## Effect combination example

### Description
Example of combining transformers for a 'Zoom + fade' effect, matching the README's claim that transformers can be combined for better results.

### Code Example
```java
// "Zoom + fade" stack, matching the README's claim that
// transformers can be combined for better results
banner.setBannerGalleryEffect(40, 10, 0.85f)        // internally adds MarginPageTransformer + ScaleInTransformer
      .addPageTransformer(new AlphaPageTransformer(0.6f));

try {
    banner.addPageTransformer(new MZScaleInTransformer());   // standalone use is discouraged
} catch (IllegalStateException e) {
    LogUtils.e("MZScaleInTransformer requires a ViewPager2 ancestor");
}
```
```

--------------------------------

### setDatas(List<T> datas)

Source: https://github.com/youth5201314/banner/blob/master/_autodocs/api-reference/Banner.md

Updates the banner data list. No-op unless an adapter is installed. Re-jumps to the start position, refreshes the indicator, and starts the loop.

```APIDOC
## setDatas(List<T> datas)

### Description
Updates the banner data list. No-op unless an adapter is installed. Re-jumps to the start position, refreshes the indicator, and starts the loop.

### Method Signature
```java
public Banner setDatas(List<T> datas)
```

### Parameters
- **datas** (List<T>) - Required - New data list; null or empty renders a blank banner (caller should provide placeholder UI)

### Behavior
- No-op unless an adapter is installed
- Calls getAdapter().setDatas(datas)
- Re-jumps to the start position without smooth scrolling
- Refreshes the indicator
- Starts the loop
- Returns this

### Example
```java
banner.setAdapter(new ImageAdapter(DataBean.getTestData()))
      .setDatas(DataBean.getTestData2());          // hot-replace data

// null / empty data -> banner goes blank; keep a placeholder view visible
banner.setDatas(null);
```
```

--------------------------------

### start()

Source: https://github.com/youth5201314/banner/blob/master/_autodocs/api-reference/Banner.md

Posts the auto-loop task after mLoopTime. No-op if auto-loop is disabled. Returns the Banner instance for chaining.

```APIDOC
## start()

### Description
Posts the auto-loop task after mLoopTime. No-op if auto-loop is disabled. Returns the Banner instance for chaining.

### Method
start

### Signature
public Banner start()

### Parameters
None.

### Returns
- **Banner** - This Banner instance for chaining.
```

--------------------------------

### Banner data configuration examples

Source: https://github.com/youth5201314/banner/blob/master/_autodocs/api-reference/Banner.md

Demonstrates hot-replacing data using setDatas and handling empty data states.

```java
banner.setAdapter(new ImageAdapter(DataBean.getTestData()))
      .setDatas(DataBean.getTestData2());          // hot-replace data

// null / empty data → banner goes blank; keep a placeholder view visible
banner.setDatas(null);
```

--------------------------------

### Reference BannerConfig constants

Source: https://github.com/youth5201314/banner/blob/master/_autodocs/configuration.md

Example of applying BannerConfig constants to a banner instance at runtime.

```java
banner.setLoopTime(BannerConfig.LOOP_TIME);
banner.setIndicatorSelectedColor(BannerConfig.INDICATOR_SELECTED_COLOR);
```

--------------------------------

### BannerUtils usage examples

Source: https://github.com/youth5201314/banner/blob/master/_autodocs/api-reference/utils.md

Demonstrates rounding an arbitrary view via clipping and converting dp values for px-based setters.

```java
// Round an arbitrary view (e.g. the image inside your adapter) via clipping
BannerUtils.setBannerRound(imageView, 20f);

// Convert dp values when feeding px-based setters
banner.setIndicatorWidth(BannerUtils.dp2px(5), BannerUtils.dp2px(9));
```

--------------------------------

### Configure Banner visual effects and rounding

Source: https://github.com/youth5201314/banner/blob/master/_autodocs/api-reference/Banner.md

Examples of applying gallery effects, Meizu-style layouts, and rounded corners to a Banner instance.

```java
// Gallery: peek 40dp on each side, 10dp page gap, neighbors at 85% scale
banner.setBannerGalleryEffect(40, 10, 0.85f);

// Meizu-style
banner.setBannerGalleryMZ(50);

// Rounded corners (fall back to setBannerRound2 on API 21+)
banner.setBannerRound(20f);
```

--------------------------------

### Setting OnBannerListener on a Banner

Source: https://github.com/youth5201314/banner/blob/master/_autodocs/api-reference/listeners.md

Example of implementing and setting the OnBannerListener to handle item clicks.

```java
banner.setOnBannerListener(new OnBannerListener<DataBean>() {
    @Override
    public void OnBannerClick(DataBean data, int position) {
        startActivity(DetailActivity.intent(DataBean.this, data));
    }
});
```

--------------------------------

### Configure Banner behavior

Source: https://github.com/youth5201314/banner/blob/master/_autodocs/api-reference/Banner.md

Examples of common configuration methods for the Banner component, such as disabling user input, setting orientation, and adjusting timing.

```java
banner.setUserInputEnabled(false);          // read-only banner
banner.setOrientation(Banner.VERTICAL);     // vertical carousel (e.g. 淘宝头条 style)
banner.setLoopTime(2000L).setScrollTime(400);
banner.setStartPosition(2);                 // before setAdapter(...)
banner.setCurrentItem(index, false);        // teleport after data is set
```

--------------------------------

### Configure built-in banner indicators

Source: https://github.com/youth5201314/banner/blob/master/_autodocs/api-reference/indicators.md

Examples of setting various indicator styles including circle dots, bitmap-based dots, rounded rectangles, and Meizu-style continuous tracks.

```java
// Circle dots, custom colors
banner.setIndicator(new CircleIndicator(this))
      .setIndicatorSelectedColor(0xffff0000);

// Bitmap-based dots
banner.setIndicator(new DrawableIndicator(this,
        R.drawable.indicator_normal, R.drawable.indicator_selected));

// Bar with rounded corners
banner.setIndicator(new RectangleIndicator(this))
      .setIndicatorWidth(BannerUtils.dp2px(5), BannerUtils.dp2px(12))
      .setIndicatorRadius(BannerUtils.dp2px(3));

// Meizu-style continuous track
banner.setIndicator(new RoundLinesIndicator(this))
      .setIndicatorSelectedWidth(BannerUtils.dp2px(15));
```

--------------------------------

### setOnBannerListener

Source: https://github.com/youth5201314/banner/blob/master/_autodocs/api-reference/Banner.md

Sets a click callback that receives the data and the real position (0-based). Only wired in if an adapter is installed.

```APIDOC
## setOnBannerListener

### Description
Sets a click callback that receives the data and the real position (0-based). Only wired in if an adapter is installed.

### Method
setOnBannerListener

### Signature
public Banner setOnBannerListener(OnBannerListener<T> listener)

### Parameters
- **listener** (OnBannerListener<T>) - Required - The click listener.

### Returns
- **Banner** - The Banner instance for chaining.

### Example
```java
banner.setOnBannerListener((data, position) ->
        Toast.makeText(this, "clicked " + position, Toast.LENGTH_SHORT).show());
```
```

--------------------------------

### Apply MarginDecoration to Banner

Source: https://github.com/youth5201314/banner/blob/master/_autodocs/api-reference/utils.md

Example of adding a MarginDecoration to a banner instance using dp2px conversion.

```java
banner.addItemDecoration(new MarginDecoration(BannerUtils.dp2px(10)));
```

--------------------------------

### Implement ImageAdapter with BannerAdapter

Source: https://github.com/youth5201314/banner/blob/master/_autodocs/api-reference/BannerAdapter.md

Example implementation of a custom adapter extending BannerAdapter. It requires overriding onCreateHolder to define the view and onBindView to populate data.

```java
public class ImageAdapter extends BannerAdapter<DataBean, ImageAdapter.BannerViewHolder> {

    public ImageAdapter(List<DataBean> mDatas) {
        super(mDatas);
    }

    @Override
    public BannerViewHolder onCreateHolder(ViewGroup parent, int viewType) {
        ImageView imageView = new ImageView(parent.getContext());
        imageView.setLayoutParams(new ViewGroup.LayoutParams(
                ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.MATCH_PARENT));
        imageView.setScaleType(ImageView.ScaleType.CENTER_CROP);
        return new BannerViewHolder(imageView);
    }

    @Override
    public void onBindView(BannerViewHolder holder, DataBean data, int position, int size) {
        holder.imageView.setImageResource(data.imageRes);
    }

    static class BannerViewHolder extends RecyclerView.ViewHolder {
        ImageView imageView;
        BannerViewHolder(@NonNull ImageView view) { super(view); this.imageView = view; }
    }
}
```

--------------------------------

### Adding OnPageChangeListener to a Banner

Source: https://github.com/youth5201314/banner/blob/master/_autodocs/api-reference/listeners.md

Example of implementing OnPageChangeListener to log scroll events and update UI elements based on the real page position.

```java
banner.addOnPageChangeListener(new OnPageChangeListener() {
    @Override public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
        LogUtils.d("scrolled: " + position + " offset=" + positionOffset);
    }

    @Override public void onPageSelected(int position) {
        titleView.setText(DataBean.getTestData().get(position).title);   // position is real
    }

    @Override public void onPageScrollStateChanged(int state) {
        if (state == ViewPager2.SCROLL_STATE_IDLE) {
            LogUtils.d("idle");
        }
    }
});
```

--------------------------------

### Indicator configuration via IndicatorConfig and Banner facade

Source: https://github.com/youth5201314/banner/blob/master/_autodocs/api-reference/IndicatorConfig.md

Demonstrates direct manipulation of IndicatorConfig and the equivalent configuration using the Banner facade methods.

```java
// Direct manipulation (the same object the banner's setters touch)
IndicatorConfig cfg = banner.getIndicatorConfig();       // null if no indicator!
cfg.setNormalWidth(BannerUtils.dp2px(5))
   .setSelectedWidth(BannerUtils.dp2px(9))
   .setIndicatorSpace(BannerUtils.dp2px(6));
banner.getIndicator().getIndicatorView().postInvalidate();

// Equivalent through the Banner facade
banner.setIndicatorWidth(BannerUtils.dp2px(5), BannerUtils.dp2px(9));
banner.setIndicatorSpace(BannerUtils.dp2px(6));
```

--------------------------------

### Initialize Banner in Activity

Source: https://github.com/youth5201314/banner/blob/master/README.md

Configure the banner with an adapter, lifecycle observer, and indicator in your Activity.

```java
public class BannerActivity extends AppCompatActivity {
    public void useBanner() {
        //--------------------------简单使用-------------------------------
        banner.addBannerLifecycleObserver(this)//添加生命周期观察者
                .setAdapter(new BannerExampleAdapter(DataBean.getTestData()))
                .setIndicator(new CircleIndicator(this));
        
        //—————————————————————————如果你想偷懒，而又只是图片轮播————————————————————————
         banner.setAdapter(new BannerImageAdapter<DataBean>(DataBean.getTestData3()) {
                    @Override
                    public void onBindView(BannerImageHolder holder, DataBean data, int position, int size) {
                        //图片加载自己实现
                        Glide.with(holder.itemView)
                             .load(data.imageUrl)
                             .apply(RequestOptions.bitmapTransform(new RoundedCorners(30)))
                             .into(holder.imageView);
                    }
                })
                .addBannerLifecycleObserver(this)//添加生命周期观察者
                .setIndicator(new CircleIndicator(this));
        //更多使用方法仔细阅读文档，或者查看demo
    }
}
```

--------------------------------

### getHeight / setHeight

Source: https://github.com/youth5201314/banner/blob/master/_autodocs/api-reference/IndicatorConfig.md

Get or set the height in pixels for bar-style indicators.

```APIDOC
## getHeight / setHeight

### Description
Get or set the height in pixels for bar-style indicators.

### Methods
- `public int getHeight()` - Returns the height in pixels.
- `public IndicatorConfig setHeight(int height)` - Sets the height and returns this config for chaining.
```

--------------------------------

### getCurrentPosition / setCurrentPosition

Source: https://github.com/youth5201314/banner/blob/master/_autodocs/api-reference/IndicatorConfig.md

Get or set the current selected index of the indicator.

```APIDOC
## getCurrentPosition / setCurrentPosition

### Description
Get or set the current selected index of the indicator.

### Methods
- `public int getCurrentPosition()` - Returns the current selected index.
- `public IndicatorConfig setCurrentPosition(int currentPosition)` - Sets the selected index and returns this config for chaining.
```

--------------------------------

### getIndicatorSpace / setIndicatorSpace

Source: https://github.com/youth5201314/banner/blob/master/_autodocs/api-reference/IndicatorConfig.md

Get or set the gap between indicator items in pixels.

```APIDOC
## getIndicatorSpace / setIndicatorSpace

### Description
Get or set the gap between indicator items in pixels.

### Methods
- `public int getIndicatorSpace()` - Returns the gap in pixels.
- `public IndicatorConfig setIndicatorSpace(int indicatorSpace)` - Sets the gap and returns this config for chaining.
```

--------------------------------

### getIndicatorSize / setIndicatorSize

Source: https://github.com/youth5201314/banner/blob/master/_autodocs/api-reference/IndicatorConfig.md

Get or set the total item count for the indicator.

```APIDOC
## getIndicatorSize / setIndicatorSize

### Description
Get or set the total item count for the indicator.

### Methods
- `public int getIndicatorSize()` - Returns the total item count.
- `public IndicatorConfig setIndicatorSize(int indicatorSize)` - Sets the total item count and returns this config for chaining.
```

--------------------------------

### Configure Banner Indicators

Source: https://github.com/youth5201314/banner/blob/master/_autodocs/api-reference/Banner.md

Demonstrates how to attach and style an indicator, as well as how to use an indicator defined in a layout file.

```java
banner.setIndicator(new CircleIndicator(this))
      .setIndicatorSelectedColor(0x88000000)
      .setIndicatorNormalColor(0x88ffffff)
      .setIndicatorGravity(IndicatorConfig.Direction.RIGHT)
      .setIndicatorMargins(new IndicatorConfig.Margins(0, 0, 20, 20))
      .setIndicatorWidth(
              BannerUtils.dp2px(5),
              BannerUtils.dp2px(7));

// Indicator declared in your own layout → don't attach it to the banner
NumIndicator indicator = layout.findViewById(R.id.indicator);
banner.setIndicator(indicator, false);
```

--------------------------------

### getRadius / setRadius

Source: https://github.com/youth5201314/banner/blob/master/_autodocs/api-reference/IndicatorConfig.md

Get or set the corner radius in pixels for RectangleIndicator or RoundLinesIndicator.

```APIDOC
## getRadius / setRadius

### Description
Get or set the corner radius in pixels for RectangleIndicator or RoundLinesIndicator.

### Methods
- `public int getRadius()` - Returns the corner radius in pixels.
- `public IndicatorConfig setRadius(int radius)` - Sets the corner radius and returns this config for chaining.
```

--------------------------------

### isAttachToBanner / setAttachToBanner

Source: https://github.com/youth5201314/banner/blob/master/_autodocs/api-reference/IndicatorConfig.md

Get or set whether the indicator is hosted inside the banner.

```APIDOC
## isAttachToBanner / setAttachToBanner

### Description
Get or set whether the indicator is hosted inside the banner.

### Methods
- `public boolean isAttachToBanner()` - Returns true if the indicator is hosted inside the banner.
- `public IndicatorConfig setAttachToBanner(boolean attachToBanner)` - Sets the hosting behavior and returns this config for chaining. Note: `Banner.setIndicator(indicator, false)` sets this to false.
```

--------------------------------

### getSelectedWidth / setSelectedWidth

Source: https://github.com/youth5201314/banner/blob/master/_autodocs/api-reference/IndicatorConfig.md

Get or set the width of active indicator items in pixels.

```APIDOC
## getSelectedWidth / setSelectedWidth

### Description
Get or set the width of active indicator items in pixels.

### Methods
- `public int getSelectedWidth()` - Returns the active item width.
- `public IndicatorConfig setSelectedWidth(int selectedWidth)` - Sets the active width and returns this config for chaining.
```

--------------------------------

### getNormalWidth / setNormalWidth

Source: https://github.com/youth5201314/banner/blob/master/_autodocs/api-reference/IndicatorConfig.md

Get or set the width of inactive indicator items in pixels.

```APIDOC
## getNormalWidth / setNormalWidth

### Description
Get or set the width of inactive indicator items in pixels.

### Methods
- `public int getNormalWidth()` - Returns the inactive item width.
- `public IndicatorConfig setNormalWidth(int normalWidth)` - Sets the inactive width and returns this config for chaining.
```

--------------------------------

### getSelectedColor / setSelectedColor

Source: https://github.com/youth5201314/banner/blob/master/_autodocs/api-reference/IndicatorConfig.md

Get or set the active indicator color as an ARGB integer.

```APIDOC
## getSelectedColor / setSelectedColor

### Description
Get or set the active indicator color as an ARGB integer.

### Methods
- `public int getSelectedColor()` - Returns the active indicator color.
- `public IndicatorConfig setSelectedColor(int selectedColor)` - Sets the active color and returns this config for chaining.
```

--------------------------------

### getNormalColor / setNormalColor

Source: https://github.com/youth5201314/banner/blob/master/_autodocs/api-reference/IndicatorConfig.md

Get or set the inactive indicator color as an ARGB integer.

```APIDOC
## getNormalColor / setNormalColor

### Description
Get or set the inactive indicator color as an ARGB integer.

### Methods
- `public int getNormalColor()` - Returns the inactive indicator color.
- `public IndicatorConfig setNormalColor(int normalColor)` - Sets the inactive color and returns this config for chaining.
```

--------------------------------

### setStartPosition(int mStartPosition)

Source: https://github.com/youth5201314/banner/blob/master/_autodocs/api-reference/Banner.md

Sets the initial position. Must be called before setAdapter or setDatas to take effect. Returns the Banner instance for chaining.

```APIDOC
## setStartPosition(int mStartPosition)

### Description
Sets the initial position. Must be called before setAdapter or setDatas to take effect. Returns the Banner instance for chaining.

### Method
setStartPosition

### Signature
public Banner setStartPosition(int mStartPosition)

### Parameters
- **mStartPosition** (int) - Required - The initial position.

### Returns
- **Banner** - This Banner instance for chaining.
```

--------------------------------

### Banner Lifecycle Management

Source: https://github.com/youth5201314/banner/blob/master/_autodocs/api-reference/Banner.md

Demonstrates automatic lifecycle management using addBannerLifecycleObserver compared to manual lifecycle method overrides.

```java
// Auto lifecycle: start/stoph on ON_START/ON_STOP, cleanup on ON_DESTROY
banner.addBannerLifecycleObserver(this);

// Manual equivalent
@Override protected void onStart() { super.onStart(); banner.start(); }
@Override protected void onStop()  { super.onStop();  banner.stop(); }
@Override protected void onDestroy(){ super.onDestroy(); banner.destroy(); }
```

--------------------------------

### BannerImageAdapter<T> constructor

Source: https://github.com/youth5201314/banner/blob/master/_autodocs/api-reference/BannerAdapter.md

Creates a BannerImageAdapter with the initial data list. The data is passed to the superclass constructor.

```APIDOC
## BannerImageAdapter<T> Constructor

### Description
Creates a BannerImageAdapter with the provided initial data list.

### Method
Constructor

### Signature
public BannerImageAdapter(List<T> mData)

### Parameters
- **mData** (List<T>) - Required - Initial data list.

### Usage Example
```java
BannerImageAdapter<DataBean> adapter = new BannerImageAdapter<DataBean>(DataBean.getTestData3()) {
    @Override
    public void onBindView(BannerImageHolder holder, DataBean data, int position, int size) {
        // Load image using your own loader
    }
};
```
```

--------------------------------

### getGravity / setGravity

Source: https://github.com/youth5201314/banner/blob/master/_autodocs/api-reference/IndicatorConfig.md

Get or set the gravity (position) of the indicator using Direction values.

```APIDOC
## getGravity / setGravity

### Description
Get or set the gravity (position) of the indicator using Direction values.

### Methods
- `public int getGravity()` - Returns the Direction value.
- `public IndicatorConfig setGravity(@Direction int gravity)` - Sets the position and returns this config for chaining.
```

--------------------------------

### BannerImageAdapter constructor

Source: https://github.com/youth5201314/banner/blob/master/_autodocs/api-reference/BannerAdapter.md

Constructor for initializing the adapter with a list of data.

```java
public BannerImageAdapter(List<T> mData)
```

--------------------------------

### BannerAdapter<T, VH>

Source: https://github.com/youth5201314/banner/blob/master/_autodocs/api-reference/BannerAdapter.md

Documentation for the BannerAdapter abstract class, including its constructor and public methods.

```APIDOC
## BannerAdapter<T, VH> — com.youth.banner.adapter

### Description
Abstract base adapter for the Banner library. Extends RecyclerView.Adapter and implements IViewHolder<T, VH>. Consumers must implement onCreateHolder(ViewGroup, int) and onBindView(VH, T, int, int).

### Class Declaration
```java
public abstract class BannerAdapter<T, VH extends RecyclerView.ViewHolder>
        extends RecyclerView.Adapter<VH>
        implements IViewHolder<T, VH>
```

### Type Parameters
- **T** - Data item type
- **VH** - Concrete view-holder type, must extend RecyclerView.ViewHolder

### Constructor
```java
public BannerAdapter(List<T> datas)
```

#### Parameters
- **datas** (List<T>) - Required - Initial data; null is normalized to an empty list by setDatas

### Methods

#### setDatas(List<T> datas)
```java
public void setDatas(List<T> datas)
```

##### Parameters
- **datas** (List<T>) - Required - null becomes an empty list

Clears mDatas, copies the new list, and invokes notifyDataSetChanged(). This is what Banner.setDatas(List<T>) calls internally.

#### getData(int position)
```java
public T getData(int position)
```

##### Parameters
- **position** (int) - Required - Real (0-based) position

Returns mDatas.get(position), or null when position > mDatas.size() - 1.

#### getRealData(int position)
```java
public T getRealData(int position)
```

##### Parameters
- **position** (int) - Required - Position in the virtual (loop-expanded) list

Maps the virtual position through getRealPosition(position) first, then returns the data item or null when out of range.

#### getItemCount()
```java
@Override
public int getItemCount()
```

Returns getRealCount() > 1 ? getRealCount() + mIncreaseCount : getRealCount() — i.e. the fake loop-sentinel items are only added when there is more than one real item.

#### getRealCount()
```java
public int getRealCount()
```

Returns mDatas.size() (or 0 for a null list); the true data count.

#### getRealPosition(int position)
```java
public int getRealPosition(int position)
```

##### Parameters
- **position** (int) - Required - Virtual position

Maps a virtual position to a real one via BannerUtils.getRealPosition(mIncreaseCount == BannerConfig.INCREASE_COUNT, position, getRealCount()). Note the sentinel mode is inferred by comparing the current mIncreaseCount to the default 2; Banner.setAdapter(adapter, false) calls setIncreaseCount(0), which switches this to pass-through mode.

#### setOnBannerListener(OnBannerListener<T> listener)
```java
public void setOnBannerListener(OnBannerListener<T> listener)
```

##### Parameters
- **listener** (OnBannerListener<T>) - Required - Click callback

Installs the click callback; invoked by Banner.setOnBannerListener.

#### getViewHolder()
```java
public VH getViewHolder()
```

Returns the last view holder bound by onBindViewHolder.

#### setIncreaseCount(int increaseCount)
```java
public void setIncreaseCount(int increaseCount)
```

##### Parameters
- **increaseCount** (int) - Required - Number of fake items; 0 disables infinite-loop virtualization

Adjusts the number of fake items; 0 disables infinite-loop virtualization.
```

--------------------------------

### Add Banner Dependency

Source: https://github.com/youth5201314/banner/blob/master/README.md

Add the repository and dependency to your project's build.gradle file.

```groovy

repositories {
    maven { url "https://s01.oss.sonatype.org/content/groups/public" }
}

dependencies{
    //2.1.0以前jcenter的依赖
    //implementation 'com.youth.banner:banner:2.1.0'
    //现在Maven Central
    implementation 'io.github.youth5201314:banner:2.2.3'

}
```

--------------------------------

### getMargins / setMargins

Source: https://github.com/youth5201314/banner/blob/master/_autodocs/api-reference/IndicatorConfig.md

Get or set the margins for the indicator. The getter lazily creates a new Margins instance if null.

```APIDOC
## getMargins / setMargins

### Description
Get or set the margins for the indicator. The getter lazily creates a new Margins instance if null.

### Methods
- `public Margins getMargins()` - Returns the current margins, creating a new instance if null.
- `public IndicatorConfig setMargins(Margins margins)` - Sets the margins and returns this config for chaining.
```

--------------------------------

### MarginDecoration Constructor

Source: https://github.com/youth5201314/banner/blob/master/_autodocs/api-reference/utils.md

Initializes the decoration with a specified margin in pixels.

```java
public MarginDecoration(@Px int margin)
```

--------------------------------

### addBannerLifecycleObserver

Source: https://github.com/youth5201314/banner/blob/master/_autodocs/api-reference/Banner.md

Registers a BannerLifecycleObserverAdapter on the given LifecycleOwner, automatically calling start(), stop(), and destroy() based on the owner's lifecycle events.

```APIDOC
## addBannerLifecycleObserver

### Description
Registers a BannerLifecycleObserverAdapter on the given LifecycleOwner, automatically calling start(), stop(), and destroy() based on the owner's lifecycle events.

### Method
addBannerLifecycleObserver

### Signature
public Banner addBannerLifecycleObserver(LifecycleOwner owner)

### Parameters
- **owner** (LifecycleOwner) - Required - The lifecycle owner to observe.

### Returns
- **Banner** - The Banner instance for chaining.

### Example
```java
banner.addBannerLifecycleObserver(this);
```
```

--------------------------------

### Set scroll time with recommended minimum

Source: https://github.com/youth5201314/banner/blob/master/_autodocs/errors.md

Scroll-speed reflection never surfaces exceptions; it is best-effort. Recommended speed is >= 100 ms — below that reflectLayoutManager returns early and no instrumentation happens.

```java
// 6. Scroll-speed reflection never surfaces exceptions; it is best-effort.
// Recommended speed is >= 100 ms — below that reflectLayoutManager returns
// early (ScrollSpeedManger.java line 37) and no instrumentation happens.
banner.setScrollTime(400);
```

--------------------------------

### setAdapter(BA adapter)

Source: https://github.com/youth5201314/banner/blob/master/_autodocs/api-reference/Banner.md

Sets the banner adapter. Throws NullPointerException if the adapter is null. Stores the adapter, configures infinite loop behavior, registers a data observer, and initializes the indicator.

```APIDOC
## setAdapter(BA adapter)

### Description
Sets the banner adapter. Throws NullPointerException if the adapter is null. Stores the adapter, configures infinite loop behavior, registers a data observer, and initializes the indicator.

### Method Signature
```java
public Banner setAdapter(BA adapter)
```

### Parameters
- **adapter** (BA) - Required - Non-null banner adapter

### Throws
- **NullPointerException** - If adapter == null, message is the resource string banner_adapter_null_error = "Adapter is NULL!"

### Behavior
- Stores the adapter
- If infinite loop is disabled, calls getAdapter().setIncreaseCount(0)
- Registers an internal RecyclerView.AdapterDataObserver (stops the loop when item count <= 1, restarts otherwise, and refreshes the indicator)
- Passes the adapter to ViewPager2.setAdapter
- Jumps to setCurrentItem(mStartPosition, false)
- Calls initIndicator() (attaches the indicator view and re-applies indicator attributes)
- Returns this for chaining
```

--------------------------------

### BannerAdapter constructor

Source: https://github.com/youth5201314/banner/blob/master/_autodocs/api-reference/BannerAdapter.md

Constructor that takes an initial data list. A null list is normalized to an empty list by setDatas.

```java
public BannerAdapter(List<T> datas)
```

--------------------------------

### BannerLifecycleObserver Interface

Source: https://github.com/youth5201314/banner/blob/master/_autodocs/api-reference/utils.md

Interface that extends LifecycleObserver to receive banner lifecycle events. Implemented by Banner to map lifecycle events to start(), stop(), and destroy() methods.

```APIDOC
## BannerLifecycleObserver Interface

### Description
Interface that extends LifecycleObserver to receive banner lifecycle events. Implemented by Banner to map lifecycle events to start(), stop(), and destroy() methods.

### Methods

#### onStart(LifecycleOwner owner)
- **Parameters**:
  - owner (LifecycleOwner) - Required - The lifecycle owner.
- **Description**: Invoked on ON_START.

#### onStop(LifecycleOwner owner)
- **Parameters**:
  - owner (LifecycleOwner) - Required - The lifecycle owner.
- **Description**: Invoked on ON_STOP.

#### onDestroy(LifecycleOwner owner)
- **Parameters**:
  - owner (LifecycleOwner) - Required - The lifecycle owner.
- **Description**: Invoked on ON_DESTROY.

### Example
```java
public class MyObserver implements BannerLifecycleObserver {
    @Override
    public void onStart(LifecycleOwner owner) { }
    @Override
    public void onStop(LifecycleOwner owner) { }
    @Override
    public void onDestroy(LifecycleOwner owner) { }
}
```
```

--------------------------------

### Gradle consumer integration for io.github.youth5201314:banner:2.2.3

Source: https://github.com/youth5201314/banner/blob/master/_autodocs/configuration.md

Add the Sonatype snapshot repository and the Banner dependency to your project's build.gradle. Required to use the library from Maven Central / Sonatype.

```groovy
repositories {
    maven { url "https://s01.oss.sonatype.org/content/groups/public" }
}
dependencies {
    implementation 'io.github.youth5201314:banner:2.2.3'
}
```

--------------------------------

### Attach page transformers with addPageTransformer and setPageTransformer

Source: https://github.com/youth5201314/banner/blob/master/_autodocs/api-reference/transformers.md

Shows how to attach built-in page transformers to a Banner. Use addPageTransformer to combine multiple effects, or setPageTransformer for a single effect.

```java
banner.addPageTransformer(new AlphaPageTransformer());          // combine effects
banner.addPageTransformer(new ScaleInTransformer(0.9f));
// or
banner.setPageTransformer(new DepthPageTransformer(0.7f));      // single effect
```

--------------------------------

### setAdapter(BA adapter, boolean isInfiniteLoop)

Source: https://github.com/youth5201314/banner/blob/master/_autodocs/api-reference/Banner.md

Sets the banner adapter with an option to enable or disable infinite loop transitions between the first and last items.

```APIDOC
## setAdapter(BA adapter, boolean isInfiniteLoop)

### Description
Sets the banner adapter with an option to enable or disable infinite loop transitions between the first and last items.

### Method Signature
```java
public Banner setAdapter(BA adapter, boolean isInfiniteLoop)
```

### Parameters
- **adapter** (BA) - Required - Banner adapter
- **isInfiniteLoop** (boolean) - Required - true allows first<->last direct transition

### Behavior
- Sets mIsInfiniteLoop
- Calls private setInfiniteLoop() which, when looping is disabled, disables auto-loop (isAutoLoop(false)) and forces setStartPosition(0)
- Delegates to setAdapter(adapter)
```

--------------------------------

### Indicator interface

Source: https://github.com/youth5201314/banner/blob/master/_autodocs/api-reference/indicators.md

The Indicator interface defines the contract for indicator views that can be attached to a Banner. It extends OnPageChangeListener and provides methods to get the indicator view, its configuration, and to handle page changes.

```APIDOC
## Indicator interface

### Description
The Indicator interface is implemented by indicator views that can be attached to a Banner. It extends OnPageChangeListener and provides methods to retrieve the indicator view, its configuration, and to handle page changes.

### Interface Declaration
```java
public interface Indicator extends OnPageChangeListener {
    @NonNull
    View getIndicatorView();

    IndicatorConfig getIndicatorConfig();

    void onPageChanged(int count, int currentPosition);
}
```

### Methods

#### getIndicatorView
- **Signature**: `@NonNull View getIndicatorView()`
- **Description**: Returns the View that Banner adds to its FrameLayout when attachToBanner is true.

#### getIndicatorConfig
- **Signature**: `IndicatorConfig getIndicatorConfig()`
- **Description**: Returns the mutable config consumed by Banner's setIndicator* methods.

#### onPageChanged
- **Signature**: `void onPageChanged(int count, int currentPosition)`
- **Description**: Called when the data set size or current position changes. The count parameter is the real item count.

#### onPageScrolled (inherited)
- **Signature**: `void onPageScrolled(int position, float positionOffset, @Px int positionOffsetPixels)`
- **Description**: Inherited from OnPageChangeListener.

#### onPageSelected (inherited)
- **Signature**: `void onPageSelected(int position)`
- **Description**: Inherited from OnPageChangeListener.

#### onPageScrollStateChanged (inherited)
- **Signature**: `void onPageScrollStateChanged(@ViewPager2.ScrollState int state)`
- **Description**: Inherited from OnPageChangeListener.

### Usage Notes
Banner drives all three onPage* callbacks from its internal BannerOnPageChangeCallback and calls onPageChanged via setIndicatorPageChange().
```

--------------------------------

### Indicator interface declaration

Source: https://github.com/youth5201314/banner/blob/master/_autodocs/api-reference/indicators.md

The Indicator interface extends OnPageChangeListener and defines methods for getting the indicator view, its config, and handling page changes. Banner calls these methods to manage the indicator.

```java
public interface Indicator extends OnPageChangeListener {
    @NonNull
    View getIndicatorView();

    IndicatorConfig getIndicatorConfig();

    void onPageChanged(int count, int currentPosition);
}
```

--------------------------------

### Banner Constructors

Source: https://github.com/youth5201314/banner/blob/master/_autodocs/api-reference/Banner.md

Constructors for creating a Banner instance. The three-argument constructor reads all XML attributes and initializes the internal ViewPager2.

```APIDOC
## Banner Constructors

### Description
Creates a Banner instance. The three-argument constructor reads all XML attributes and initializes the internal ViewPager2.

### Constructors
- **Banner(Context context)** - Creates a Banner with the given context.
- **Banner(Context context, AttributeSet attrs)** - Creates a Banner with the given context and attribute set.
- **Banner(Context context, AttributeSet attrs, int defStyleAttr)** - Creates a Banner with the given context, attribute set, and default style attribute. Reads all R.styleable.Banner XML attributes.

### Parameters
- **context** (Context) - Required - The context.
- **attrs** (AttributeSet) - Optional - The attribute set.
- **defStyleAttr** (int) - Optional - The default style attribute.

### Notes
- The three-argument constructor calls init(Context) which creates the internal ViewPager2, sets offscreen page limit to 2, registers a page change callback, installs a composite page transformer, and adds the pager to the FrameLayout.
- It also calls initTypedArray to read XML attributes and apply orientation and infinite loop settings.
```

--------------------------------

### Implement a custom indicator

Source: https://github.com/youth5201314/banner/blob/master/_autodocs/api-reference/indicators.md

Create a custom indicator by extending BaseIndicator and overriding onMeasure and onDraw. The config object provides access to indicator count, positions, colors, and sizes.

```java
public class NumIndicator extends BaseIndicator {
    public NumIndicator(Context context) { super(context); }

    @Override protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        int count = config.getIndicatorSize();
        if (count <= 1) return;
        setMeasuredDimension(config.getSelectedWidth() * count, config.getHeight());
    }

    @Override protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        int count = config.getIndicatorSize();
        if (count <= 1) return;
        RectF rectF = new RectF(0, 0, config.getSelectedWidth() * count, config.getHeight());
        mPaint.setColor(config.getNormalColor());
        canvas.drawRoundRect(rectF, config.getRadius(), config.getRadius(), mPaint);
        mPaint.setColor(config.getSelectedColor());
        canvas.drawRoundRect(new RectF(0, 0, config.getSelectedWidth() * (config.getCurrentPosition() + 1), config.getHeight()),
                config.getRadius(), config.getRadius(), mPaint);
    }
}
```

--------------------------------

### setBannerGalleryEffect (3-arg with scale)

Source: https://github.com/youth5201314/banner/blob/master/_autodocs/api-reference/Banner.md

Configures a gallery effect with equal peek widths and a custom scale.

```APIDOC
## setBannerGalleryEffect (3-arg with scale)

### Description
Configures a gallery effect with equal peek widths and a custom scale.

### Signature
public Banner setBannerGalleryEffect(int itemWidth, int pageMargin, float scale)

### Parameters
- **itemWidth** (int) - Required - The amount of adjacent page visible on each side, in dp.
- **pageMargin** (int) - Required - The gap between pages, in dp.
- **scale** (float) - Required - Size ratio of neighboring pages, in (0, 1]. 1 = no scaling.

### Returns
Banner - The Banner instance for chaining.
```

--------------------------------

### Combine Page Transformers

Source: https://github.com/youth5201314/banner/blob/master/_autodocs/api-reference/transformers.md

Demonstrates how to combine multiple transformers like MarginPageTransformer, ScaleInTransformer, and AlphaPageTransformer. Note that standalone use of MZScaleInTransformer is discouraged and requires a ViewPager2 ancestor.

```java
// "Zoom + fade" stack, matching the README's claim that
// transformers can be combined for better results
banner.setBannerGalleryEffect(40, 10, 0.85f)        // internally adds MarginPageTransformer + ScaleInTransformer
      .addPageTransformer(new AlphaPageTransformer(0.6f));

try {
    banner.addPageTransformer(new MZScaleInTransformer());   // standalone use is discouraged
} catch (IllegalStateException e) {
    LogUtils.e("MZScaleInTransformer requires a ViewPager2 ancestor");
}
```

--------------------------------

### BannerUtils.getView

Source: https://github.com/youth5201314/banner/blob/master/_autodocs/api-reference/utils.md

Inflates a layout for a banner page, ensuring it fills the parent.

```APIDOC
## `getView(ViewGroup parent, @LayoutRes int layoutId)`

### Description
Inflates a layout resource without attaching it to the parent, forcing both width and height to `MATCH_PARENT` as required by ViewPager2.

### Method
`public static View getView(@NonNull ViewGroup parent, @LayoutRes int layoutId)`

### Parameters
- `parent` (@NonNull ViewGroup) - Required - The ViewGroup providing the inflater context.
- `layoutId` (@LayoutRes int) - Required - Layout resource to inflate.

### Returns
- (View) - The inflated view with match-parent dimensions.
```

--------------------------------

### Implement Custom BannerAdapter

Source: https://github.com/youth5201314/banner/blob/master/README.md

Extend BannerAdapter to create a custom view holder for your banner items.

```java

/**
 * 自定义布局，下面是常见的图片样式，更多实现可以看demo，可以自己随意发挥
 */
public class ImageAdapter extends BannerAdapter<DataBean, ImageAdapter.BannerViewHolder> {

    public ImageAdapter(List<DataBean> mDatas) {
        //设置数据，也可以调用banner提供的方法,或者自己在adapter中实现
        super(mDatas);
    }

    //创建ViewHolder，可以用viewType这个字段来区分不同的ViewHolder
    @Override
    public BannerViewHolder onCreateHolder(ViewGroup parent, int viewType) {
        ImageView imageView = new ImageView(parent.getContext());
        //注意，必须设置为match_parent，这个是viewpager2强制要求的
        imageView.setLayoutParams(new ViewGroup.LayoutParams(
                ViewGroup.LayoutParams.MATCH_PARENT,
                ViewGroup.LayoutParams.MATCH_PARENT));
        imageView.setScaleType(ImageView.ScaleType.CENTER_CROP);
        return new BannerViewHolder(imageView);
    }

    @Override
    public void onBindView(BannerViewHolder holder, DataBean data, int position, int size) {
        holder.imageView.setImageResource(data.imageRes);
    }

    class BannerViewHolder extends RecyclerView.ViewHolder {
        ImageView imageView;

        public BannerViewHolder(@NonNull ImageView view) {
            super(view);
            this.imageView = view;
        }
    }
}
```

--------------------------------

### BannerUtils.dp2px method signature

Source: https://github.com/youth5201314/banner/blob/master/_autodocs/api-reference/utils.md

Defines the method to convert dp units to pixels using system display metrics.

```java
public static int dp2px(float dp)
```

--------------------------------

### 防止Banner获取焦点

Source: https://github.com/youth5201314/banner/blob/master/README.md

当父控件滑动导致Banner自动获取焦点时，可以通过在父控件中添加以下属性来禁止该行为。

```xml
        //banner也一定要用最新版哦！
        android:focusable="true"
        android:focusableInTouchMode="true"
```

--------------------------------

### setBannerGalleryEffect (3-arg)

Source: https://github.com/youth5201314/banner/blob/master/_autodocs/api-reference/Banner.md

Configures a gallery effect with distinct left and right peek widths and a default scale of 0.85f.

```APIDOC
## setBannerGalleryEffect (3-arg)

### Description
Configures a gallery effect with distinct left and right peek widths and a default scale of 0.85f.

### Signature
public Banner setBannerGalleryEffect(int leftItemWidth, int rightItemWidth, int pageMargin)

### Parameters
- **leftItemWidth** (int) - Required - The amount of adjacent page visible on the left, in dp.
- **rightItemWidth** (int) - Required - The amount of adjacent page visible on the right, in dp.
- **pageMargin** (int) - Required - The gap between pages, in dp.

### Returns
Banner - The Banner instance for chaining.
```

--------------------------------

### LogUtils.w(String msg)

Source: https://github.com/youth5201314/banner/blob/master/_autodocs/api-reference/utils.md

Logs a warning message with the tag 'banner_log' when the build is in debug mode. In release builds, this method does nothing.

```APIDOC
## LogUtils.w(String msg)

### Description
Logs a warning message with the tag 'banner_log' when the build is in debug mode. In release builds, this method does nothing.

### Method
Static method

### Parameters
- **msg** (String) - Required - The message to log.

### Behavior
Calls `Log.w(TAG, msg)` when `BuildConfig.DEBUG` is true; otherwise, no operation.
```
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