Android Support Library Custom View -Implementation of custom UI elements
Android Support Library Custom View -Implementation of custom UI elements
Introduction:
Android Support Library is a set of development libraries to help Android developers easily achieve rich user interface and interactive experience.By using SUPPORT LIBRARY, developers can be compatible with extensive Android devices and use the latest Android features on older devices.This article will introduce how to use Android Support Library to achieve custom UI elements and provide some Java code examples to help you get started.
Step 1: Create a custom view class
To realize custom UI elements, we need to create a custom view class. This class will expand the appropriate view class provided by SUPPORT LIBRARY, such as `AppCompattextView`,` appCompatimageView`, etc.The following is a simple example to show how to create a custom circular image view:
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Paint;
import androidx.appcompat.widget.AppCompatImageView;
public class CircleImageView extends AppCompatImageView {
private Paint circlePaint;
public CircleImageView(Context context) {
super(context);
init();
}
private void init() {
// Initialized brush
circlePaint = new Paint();
circlePaint.setColor(getResources().getColor(R.color.circle_color));
circlePaint.setAntiAlias(true);
}
@Override
protected void onDraw(Canvas canvas) {
// Get view width and height
int viewWidth = getWidth();
int viewHeight = getHeight();
// Calculate the radius of the circle
int radius = Math.min(viewWidth, viewHeight) / 2;
// Draw a circular background
canvas.drawCircle(viewWidth / 2, viewHeight / 2, radius, circlePaint);
// Call the parent class method to draw a picture
super.onDraw(canvas);
}
}
Step 2: Use a custom view in the layout file
In your layout file, you can use a custom view element like using other view elements.The following is an example:
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<com.example.myapplication.CircleImageView
android:layout_width="100dp"
android:layout_height="100dp"
android:src="@drawable/my_image" />
</LinearLayout>
Step 3: Use a custom view
By find the corresponding view in the Java code and operate it, you can use a custom view.The following is an example, showing how to use custom circular image views in Activity:
public class MainActivity extends AppCompatActivity {
private CircleImageView circleImageView;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// Find the custom view
circleImageView = findViewById(R.id.circle_image_view);
// Set the click event
circleImageView.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
// Treat the click event
Toast.makeText (MainActivity.this, "Click the circular picture", toast.length_short) .show ();
}
});
}
}
in conclusion:
By using Android Support Library, you can easily achieve custom UI elements and add unique user interface to your application.This article provides an example to show how to create and use custom circular image views.You can further expand and modify the custom view according to your needs.I hope this article will help your Android development journey!
