DrawableView in Android

In this article, we are going to show the implementation of the DrawableView. We are going to going to implement paint as we have on our laptop.  Let’s see the implementation of this feature. A sample video is given below to get an idea about what we are going to do in this article. Note that we are going to implement this project using the Java language. 

Feature Available 

• Increase the Stroke width
• Decrease the Stroke width
• Change the color of the stroke
• Undo the painting

Step by Step Implementation

Step 1: Create a New Project

To create a new project in Android Studio please refer to How to Create/Start a New Project in Android Studio. Note that select Java as the programming language.

Step 2: Add dependency

Navigate to the Gradle Scripts > build.gradle(Module:app) and add the below dependency in the dependencies section.   

compile ‘me.panavtec:drawableview:0.6.0’

Step 3: Working with the activity_main.xml file

Navigate to the app > res > layout > activity_main.xml and add the below code to that file. Below is the code for the activity_main.xml file. 

XML

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    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"
    android:orientation="vertical"
    tools:context=".MainActivity">

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal">

        <Button
            android:id="@+id/increase"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="+" />

        <Button
            android:id="@+id/decrease"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="-" />

        <Button
            android:id="@+id/color"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Color" />

        <Button
            android:id="@+id/undo"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Undo" />

    </LinearLayout>

    <me.panavtec.drawableview.DrawableView
        android:id="@+id/paintView"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="1" />

</LinearLayout>

Step 4: Working with the MainActivity.java file

Go to the MainActivity.java file and refer to the following code. Below is the code for the MainActivity.java file. Comments are added inside the code to understand the code in more detail.

Java

import android.graphics.Color;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;

import androidx.appcompat.app.AppCompatActivity;

import java.util.Random;

import me.panavtec.drawableview.DrawableView;
import me.panavtec.drawableview.DrawableViewConfig;

public class MainActivity extends AppCompatActivity {

    DrawableView drawableView;
    DrawableViewConfig config;
    Button increase, decrease, color, undo;

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

        // initialise the value
        initiaselayout();
    }

    private void initiaselayout() {

        // initialise the layout
        drawableView = findViewById(R.id.paintView);
        increase = findViewById(R.id.increase);
        decrease = findViewById(R.id.decrease);
        color = findViewById(R.id.color);
        undo = findViewById(R.id.undo);
        config = new DrawableViewConfig();

        // set stroke color as black initially
        config.setStrokeColor(getResources().getColor(android.R.color.black));

        // If the view is bigger than canvas,
        // with this the user will see the bounds (Recommended)
        config.setShowCanvasBounds(true);

        // set width as 20
        config.setStrokeWidth(20.0f);
        config.setMinZoom(1.0f);
        config.setMaxZoom(3.0f);

        // set canvas height
        config.setCanvasHeight(1080);

        // set canvas width
        config.setCanvasWidth(1920);
        drawableView.setConfig(config);
        increase.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                // increase the stroke width by 10
                config.setStrokeWidth(config.getStrokeWidth() + 10);
            }
        });
        decrease.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                // decrease stroke width by 10
                config.setStrokeWidth(config.getStrokeWidth() - 10);
            }
        });
        color.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                // initialise Random
                Random random = new Random();
                // set the color using random
                config.setStrokeColor(Color.rgb(255, random.nextInt(256), random.nextInt(256)));
            }
        });
        undo.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                // undo the most recent changes
                drawableView.undo();
            }
        });
    }
}

Output: