SoFunction
Updated on 2025-03-11

Android uses Gallery to implement special effects of photo dragging

Today I want to share a very simple feature:

Use Android native control Gallery to implement special effects of photo drag

The implementation idea is as follows:

  1. Define a Gallery control in the layout file
  2. Since I want to display multiple pictures, for convenience, I directly quoted the native image resources of Android
  3. Gallery is just a control. In order to bind image data to controls, a custom adapter that inherits BaseAdapter is also needed.

The source code is as follows:

1. Main activity and custom inner class ImageAdapter:

import ;
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public class SimpleGallery extends Activity {

  private static final String TAG = "SimpleGallery";

  @Override
  protected void onCreate(Bundle onSavedInstance) {
    (onSavedInstance);
    setContentView(.simple_gallery_layout);

    Gallery gallery = findViewById();
    (new ImageAdapter(this));
  }

  private class ImageAdapter extends BaseAdapter {

    // Here we use Android native resource icon    private int[] imageIds = {
        .btn_minus,
        .btn_radio,
        .ic_lock_idle_low_battery,
        .ic_menu_camera };

    private Context mContext;

    public ImageAdapter(Context context) {
      mContext = context;
    }

    @Override
    public int getCount() {
      return ;
    }

    @Override
    public Object getItem(int position) {
      return imageIds[position];
    }

    @Override
    public long getItemId(int position) {
      return position;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
      ImageView imageView;
      if (convertView == null) {
        (TAG, "convertView is null, create new imageview");
        imageView = new ImageView(mContext);
      } else {
        (TAG, "Cast convertView to ImageView");
        imageView = (ImageView) convertView;
      }

      (imageIds[position]);
      (.FIT_XY);
						
		  // Note that it should be used as the layout parameter type here. The source code gives (Views given to the Gallery should use			//  s their ayout parameters type）
			// Since the native Android image is very small, I set the height to 500 to facilitate the viewing of the effect      (new (.MATCH_PARENT, 500));
      return imageView;
    }
  }
}

2. The layout file simple_gallery_layout.xml is as follows:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:andro
       android:layout_width="match_parent"
       android:layout_height="match_parent">

  <Gallery
      android:
      android:layout_width="match_parent"
      android:layout_height="match_parent" />

</LinearLayout>

Notice:

The Gallery control has actually been abandoned. It is recommended to use HorizontalScrollView and ViewPager instead. The source code explains this:

@deprecated This widget is no longer supported. Other horizontally scrolling widgets include {@link HorizontalScrollView} and {@link .} from the support library.

We will share in the future how the two controls, HorizontalScrollView and ViewPager, are used.

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