Custom Android Views in Eclipse Visual Editor

Custom Android Views in Eclipse Visual Editor

The Eclipse Visual Editor offers a powerful and intuitive way to design and build Android user interfaces. While it provides a wide range of built-in widgets, you often need custom views to implement unique functionality or enhance the user experience. This article will guide you through the process of creating custom Android views in Eclipse Visual Editor.

Creating a Custom View

Step 1: Create a New Custom View Class

• Right-click on your project’s package in the Package Explorer and select “New” > “Other”.
• In the wizard, expand “Android” and select “Android Class”.
• Give your custom view a suitable name (e.g., “MyCustomView”).
• Under “SuperClass”, choose “android.view.View”.
• Click “Finish”.

Step 2: Implementing the Custom View Logic

package com.example.myapplication;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.util.AttributeSet;
import android.view.View;

public class MyCustomView extends View {

    private Paint paint;

    public MyCustomView(Context context) {
        super(context);
        init();
    }

    public MyCustomView(Context context, AttributeSet attrs) {
        super(context, attrs);
        init();
    }

    public MyCustomView(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        init();
    }

    private void init() {
        paint = new Paint();
        paint.setColor(0xFF00FF00); // Set the color
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        canvas.drawCircle(getWidth() / 2, getHeight() / 2, 50, paint);
    }
}

Step 3: Adding the Custom View to Your Layout

• Open your layout XML file (e.g., activity_main.xml).
• In the Design tab of the Eclipse Visual Editor, drag and drop a “Custom View” widget from the Palette onto your layout.
• In the Properties tab of the “Custom View”, set the “Class” attribute to the fully qualified name of your custom view class (e.g., “com.example.myapplication.MyCustomView”).

Using the Custom View in Your Activity

package com.example.myapplication;

import android.os.Bundle;
import android.app.Activity;

public class MainActivity extends Activity {

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

Example: A Simple Custom View

Code

package com.example.customviewexample;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.util.AttributeSet;
import android.view.View;

public class MyCircleView extends View {

    private Paint paint;

    public MyCircleView(Context context) {
        super(context);
        init();
    }

    public MyCircleView(Context context, AttributeSet attrs) {
        super(context, attrs);
        init();
    }

    public MyCircleView(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        init();
    }

    private void init() {
        paint = new Paint();
        paint.setColor(0xFF00FF00); // Set the color
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        canvas.drawCircle(getWidth() / 2, getHeight() / 2, 50, paint);
    }
}

Layout (activity_main.xml)

Output

A green circle drawn in the center of the screen.

Creating Custom Views with Attributes

package com.example.customviewexample;

import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.util.AttributeSet;
import android.view.View;

public class MyCircleView extends View {

    private Paint paint;
    private int circleColor;

    public MyCircleView(Context context) {
        super(context);
        init(null, 0);
    }

    public MyCircleView(Context context, AttributeSet attrs) {
        super(context, attrs);
        init(attrs, 0);
    }

    public MyCircleView(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        init(attrs, defStyleAttr);
    }

    private void init(AttributeSet attrs, int defStyleAttr) {
        TypedArray a = getContext().obtainStyledAttributes(attrs,
                R.styleable.MyCircleView, defStyleAttr, 0);
        circleColor = a.getColor(R.styleable.MyCircleView_circleColor,
                0xFF00FF00); // Default color
        a.recycle();

        paint = new Paint();
        paint.setColor(circleColor);
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        canvas.drawCircle(getWidth() / 2, getHeight() / 2, 50, paint);
    }
}

Attributes (attrs.xml)

Layout (activity_main.xml)

Output

A red circle drawn in the center of the screen.

Table: Comparison of Built-in vs. Custom Views

Conclusion

Creating custom Android views in Eclipse Visual Editor empowers you to build highly personalized and engaging user interfaces. This process involves defining a custom view class, implementing its logic, and incorporating it into your layouts. By leveraging attributes and advanced techniques, you can design sophisticated custom views that enhance the functionality and aesthetics of your Android applications.