ScatterLayout equivalent in classical Android XML

Question

I'm rewriting my Kivy app to Java and XML files.

What is an equivalent to ScatterLayout?

I have this code:

class MyScatter(ScatterLayout):
    pass

Builder.load_string('''
<MyScatter>:
    scale: 1
    do_scale: True 
    do_translation: True
    do_rotation: False
    auto_bring_to_front: False

    Image:
        id: img
        source: ''
        size_hint: (0.43, 0.6)
        pos_hint: {'center_x': 0.33, 'center_y': 0.5}
        keep_ratio: True
''')

...
def build(self):

        mainbox = FloatLayout()

        self.ms = MyScatter()
        mainbox.add_widget(self.ms)
...

What I want to achieve is the scaling functionality of an image.

Answer 1

For scaling an image in Android, you can use an ImageView along with a ScaleGestureDetector for handling scaling based on multi-touch events.

Here's a basic example of how you could set this up in Java:

public class MainActivity extends AppCompatActivity {
    private ImageView imageView;
    private ScaleGestureDetector scaleGestureDetector;

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

        imageView = findViewById(R.id.imageView);
        scaleGestureDetector = new ScaleGestureDetector(this, new ScaleListener());
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        scaleGestureDetector.onTouchEvent(event);
        return true;
    }

    private class ScaleListener extends ScaleGestureDetector.SimpleOnScaleGestureListener {
        @Override
        public boolean onScale(ScaleGestureDetector detector) {
            float scaleFactor = detector.getScaleFactor();
            scaleFactor = Math.max(0.1f, Math.min(scaleFactor, 5.0f));
            imageView.setScaleX(scaleFactor);
            imageView.setScaleY(scaleFactor);
            return true;
        }
    }
}

For the corresponding XML layout file (activity_main.xml), you would have something like this:

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <ImageView
        android:id="@+id/imageView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:src="@drawable/your_image_here" />

</RelativeLayout>