Android capture signature using Canvas and save in png format

Signature capture has a lot of uses in enterprise applications such as proof of delivery, inspection forms, sales order agreement, etc. Here is sample program that asks for the name of the person and its signature. The program uses a canvas view to get the signature and then save it as .png Image.

Android capture signature using Canvas
Android capture signature using Canvas
Please Note: Initially when I wrote the signature capture program it was saving data to the External Storage but then I changed that to the Internal Storage for security. In the example you will see references to External storage that I didn't remove when I posted this example so please ignore that. Comments from the readers made me realize that some people need help with storing data to Internal and External Storage, click below for sample code ...
Android Internal and External storage example

In case you want signature capture for a WEB app or a Hybrid app then no further, click below for sample code ...
Capture signature using HTML5 canvas - Use for iPad, iPhone, Android Tablets and Phones

Source for CaptureSignatureActivity.java

package com.as400samplecode;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.Gravity;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;

public class CaptureSignatureActivity extends Activity {

    public static final int SIGNATURE_ACTIVITY = 1;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        Button getSignature = (Button) findViewById(R.id.signature);
        getSignature.setOnClickListener(new View.OnClickListener() {
            public void onClick(View view) {
                Intent intent = new Intent(CaptureSignatureActivity.this, CaptureSignature.class); 
                startActivityForResult(intent,SIGNATURE_ACTIVITY);
            }
        });
    }

    protected void onActivityResult(int requestCode, int resultCode, Intent data)
    {
        switch(requestCode) {
        case SIGNATURE_ACTIVITY: 
            if (resultCode == RESULT_OK) {

                Bundle bundle = data.getExtras();
                String status  = bundle.getString("status");
                if(status.equalsIgnoreCase("done")){
                    Toast toast = Toast.makeText(this, "Signature capture successful!", Toast.LENGTH_SHORT);
                    toast.setGravity(Gravity.TOP, 105, 50);
                    toast.show();
                }
            }
            break;
        }

    }  

}

Source for CaptureSignature.java

package com.as400samplecode;

import java.io.File;
import java.io.FileOutputStream;
import java.util.Calendar;

import android.app.Activity;
import android.content.Context;
import android.content.ContextWrapper;
import android.content.Intent;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Path;
import android.graphics.RectF;
import android.os.Bundle;
import android.os.Environment;
import android.provider.MediaStore.Images;
import android.util.AttributeSet;
import android.util.Log;
import android.view.Gravity;
import android.view.MotionEvent;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewGroup.LayoutParams;
import android.view.Window;
import android.widget.Button;
import android.widget.EditText;
import android.widget.LinearLayout;
import android.widget.Toast;

public class CaptureSignature extends Activity { 

    LinearLayout mContent;
    signature mSignature;
    Button mClear, mGetSign, mCancel;
    public static String tempDir;
    public int count = 1;
    public String current = null;
    private Bitmap mBitmap;
    View mView;
    File mypath;

    private String uniqueId;
    private EditText yourName;

    @Override
    public void onCreate(Bundle savedInstanceState) 
    {
        super.onCreate(savedInstanceState);
        this.requestWindowFeature(Window.FEATURE_NO_TITLE);
        setContentView(R.layout.signature);
       
        tempDir = Environment.getExternalStorageDirectory() + "/" + getResources().getString(R.string.external_dir) + "/";
        ContextWrapper cw = new ContextWrapper(getApplicationContext());
        File directory = cw.getDir(getResources().getString(R.string.external_dir), Context.MODE_PRIVATE);

        prepareDirectory();
        uniqueId = getTodaysDate() + "_" + getCurrentTime() + "_" + Math.random();
        current = uniqueId + ".png";
        mypath= new File(directory,current);


        mContent = (LinearLayout) findViewById(R.id.linearLayout);
        mSignature = new signature(this, null);
        mSignature.setBackgroundColor(Color.WHITE);
        mContent.addView(mSignature, LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT);
        mClear = (Button)findViewById(R.id.clear);
        mGetSign = (Button)findViewById(R.id.getsign);
        mGetSign.setEnabled(false);
        mCancel = (Button)findViewById(R.id.cancel);
        mView = mContent;

        yourName = (EditText) findViewById(R.id.yourName);

        mClear.setOnClickListener(new OnClickListener() 
        {        
            public void onClick(View v) 
            {
                Log.v("log_tag", "Panel Cleared");
                mSignature.clear();
                mGetSign.setEnabled(false);
            }
        });

        mGetSign.setOnClickListener(new OnClickListener() 
        {        
            public void onClick(View v) 
            {
                Log.v("log_tag", "Panel Saved");
                boolean error = captureSignature();
                if(!error){
                    mView.setDrawingCacheEnabled(true);
                    mSignature.save(mView);
                    Bundle b = new Bundle();
                    b.putString("status", "done");
                    Intent intent = new Intent();
                    intent.putExtras(b);
                    setResult(RESULT_OK,intent);   
                    finish();
                }
            }
        });

        mCancel.setOnClickListener(new OnClickListener() 
        {        
            public void onClick(View v) 
            {
                Log.v("log_tag", "Panel Canceled");
                Bundle b = new Bundle();
                b.putString("status", "cancel");
                Intent intent = new Intent();
                intent.putExtras(b);
                setResult(RESULT_OK,intent);  
                finish();
            }
        });

    }

    @Override
    protected void onDestroy() {
        Log.w("GetSignature", "onDestory");
        super.onDestroy();
    }

    private boolean captureSignature() {

        boolean error = false;
        String errorMessage = "";


        if(yourName.getText().toString().equalsIgnoreCase("")){
            errorMessage = errorMessage + "Please enter your Name\n";
            error = true;
        }   

        if(error){
            Toast toast = Toast.makeText(this, errorMessage, Toast.LENGTH_SHORT);
            toast.setGravity(Gravity.TOP, 105, 50);
            toast.show();
        }

        return error;
    }

    private String getTodaysDate() { 

        final Calendar c = Calendar.getInstance();
        int todaysDate =     (c.get(Calendar.YEAR) * 10000) + 
        ((c.get(Calendar.MONTH) + 1) * 100) + 
        (c.get(Calendar.DAY_OF_MONTH));
        Log.w("DATE:",String.valueOf(todaysDate));
        return(String.valueOf(todaysDate));

    }

    private String getCurrentTime() {

        final Calendar c = Calendar.getInstance();
        int currentTime =     (c.get(Calendar.HOUR_OF_DAY) * 10000) + 
        (c.get(Calendar.MINUTE) * 100) + 
        (c.get(Calendar.SECOND));
        Log.w("TIME:",String.valueOf(currentTime));
        return(String.valueOf(currentTime));

    }


    private boolean prepareDirectory() 
    {
        try 
        {
            if (makedirs()) 
            {
                return true;
            } else {
                return false;
            }
        } catch (Exception e) 
        {
            e.printStackTrace();
            Toast.makeText(this, "Could not initiate File System.. Is Sdcard mounted properly?", 1000).show();
            return false;
        }
    }

    private boolean makedirs() 
    {
        File tempdir = new File(tempDir);
        if (!tempdir.exists())
            tempdir.mkdirs();

        if (tempdir.isDirectory()) 
        {
            File[] files = tempdir.listFiles();
            for (File file : files) 
            {
                if (!file.delete()) 
                {
                    System.out.println("Failed to delete " + file);
                }
            }
        }
        return (tempdir.isDirectory());
    }

    public class signature extends View 
    {
        private static final float STROKE_WIDTH = 5f;
        private static final float HALF_STROKE_WIDTH = STROKE_WIDTH / 2;
        private Paint paint = new Paint();
        private Path path = new Path();

        private float lastTouchX;
        private float lastTouchY;
        private final RectF dirtyRect = new RectF();

        public signature(Context context, AttributeSet attrs) 
        {
            super(context, attrs);
            paint.setAntiAlias(true);
            paint.setColor(Color.BLACK);
            paint.setStyle(Paint.Style.STROKE);
            paint.setStrokeJoin(Paint.Join.ROUND);
            paint.setStrokeWidth(STROKE_WIDTH);
        }

        public void save(View v) 
        {
            Log.v("log_tag", "Width: " + v.getWidth());
            Log.v("log_tag", "Height: " + v.getHeight());
            if(mBitmap == null)
            {
                mBitmap =  Bitmap.createBitmap (mContent.getWidth(), mContent.getHeight(), Bitmap.Config.RGB_565);;
            }
            Canvas canvas = new Canvas(mBitmap);
            try 
            {
                FileOutputStream mFileOutStream = new FileOutputStream(mypath);

                v.draw(canvas); 
                mBitmap.compress(Bitmap.CompressFormat.PNG, 90, mFileOutStream); 
                mFileOutStream.flush();
                mFileOutStream.close();
                String url = Images.Media.insertImage(getContentResolver(), mBitmap, "title", null);
                Log.v("log_tag","url: " + url);
                //In case you want to delete the file
                //boolean deleted = mypath.delete();
                //Log.v("log_tag","deleted: " + mypath.toString() + deleted);
                //If you want to convert the image to string use base64 converter

            }
            catch(Exception e) 
            { 
                Log.v("log_tag", e.toString()); 
            } 
        }

        public void clear() 
        {
            path.reset();
            invalidate();
        }

        @Override
        protected void onDraw(Canvas canvas) 
        {
            canvas.drawPath(path, paint);
        }

        @Override
        public boolean onTouchEvent(MotionEvent event) 
        {
            float eventX = event.getX();
            float eventY = event.getY();
            mGetSign.setEnabled(true);

            switch (event.getAction()) 
            {
            case MotionEvent.ACTION_DOWN:
                path.moveTo(eventX, eventY);
                lastTouchX = eventX;
                lastTouchY = eventY;
                return true;

            case MotionEvent.ACTION_MOVE:

            case MotionEvent.ACTION_UP:

                resetDirtyRect(eventX, eventY);
                int historySize = event.getHistorySize();
                for (int i = 0; i < historySize; i++) 
                {
                    float historicalX = event.getHistoricalX(i);
                    float historicalY = event.getHistoricalY(i);
                    expandDirtyRect(historicalX, historicalY);
                    path.lineTo(historicalX, historicalY);
                }
                path.lineTo(eventX, eventY);
                break;

            default:
                debug("Ignored touch event: " + event.toString());
                return false;
            }

            invalidate((int) (dirtyRect.left - HALF_STROKE_WIDTH),
                    (int) (dirtyRect.top - HALF_STROKE_WIDTH),
                    (int) (dirtyRect.right + HALF_STROKE_WIDTH),
                    (int) (dirtyRect.bottom + HALF_STROKE_WIDTH));

            lastTouchX = eventX;
            lastTouchY = eventY;

            return true;
        }

        private void debug(String string){
        }

        private void expandDirtyRect(float historicalX, float historicalY) 
        {
            if (historicalX < dirtyRect.left) 
            {
                dirtyRect.left = historicalX;
            } 
            else if (historicalX > dirtyRect.right) 
            {
                dirtyRect.right = historicalX;
            }

            if (historicalY < dirtyRect.top) 
            {
                dirtyRect.top = historicalY;
            } 
            else if (historicalY > dirtyRect.bottom) 
            {
                dirtyRect.bottom = historicalY;
            }
        }

        private void resetDirtyRect(float eventX, float eventY) 
        {
            dirtyRect.left = Math.min(lastTouchX, eventX);
            dirtyRect.right = Math.max(lastTouchX, eventX);
            dirtyRect.top = Math.min(lastTouchY, eventY);
            dirtyRect.bottom = Math.max(lastTouchY, eventY);
        }
    }
}

Source for main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical" android:layout_width="fill_parent"
    android:layout_height="fill_parent">
    <TextView android:layout_width="fill_parent"
        android:layout_height="wrap_content" android:text="@string/hello"
        android:textSize="25sp" android:paddingBottom="20dp"
        android:textStyle="bold" />
    <Button android:text="Get My Signature" android:id="@+id/signature"
        android:layout_width="wrap_content" android:layout_height="wrap_content" />
</LinearLayout>

Source for signature.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout android:id="@+id/linearLayout1"
    android:layout_width="600dp" android:layout_height="400dp"
    android:orientation="vertical" xmlns:android="http://schemas.android.com/apk/res/android">
    <LinearLayout android:layout_height="wrap_content"
        android:id="@+id/linearLayout2" android:layout_width="match_parent">
        <Button android:layout_height="50dp" android:layout_weight=".30"
            android:text="Cancel" android:layout_width="0dp" android:id="@+id/cancel" />
        <Button android:layout_height="50dp" android:layout_weight=".35"
            android:text="Clear" android:layout_width="0dp" android:id="@+id/clear" />
        <Button android:layout_height="50dp" android:layout_weight=".35"
            android:text="Save" android:layout_width="0dp" android:id="@+id/getsign" />
    </LinearLayout>
    <TableLayout android:layout_height="wrap_content"
        android:id="@+id/tableLayout1" android:layout_width="match_parent">
        <TableRow android:id="@+id/tableRow1" android:layout_width="wrap_content"
            android:layout_height="wrap_content">
            <TextView android:layout_height="wrap_content" android:id="@+id/textView2"
                android:text="Your Name" android:textAppearance="?android:attr/textAppearanceMedium"
                android:layout_width="wrap_content" android:paddingLeft="10sp"
                android:layout_gravity="right" />
            <EditText android:layout_height="wrap_content" android:id="@+id/yourName"
                android:layout_weight="1" android:layout_width="match_parent"
                android:maxLength="30">
                <requestFocus />
            </EditText>
        </TableRow>
        <TableRow android:id="@+id/tableRow3" android:layout_width="wrap_content"
            android:layout_height="wrap_content">
            <TextView android:layout_height="wrap_content" android:id="@+id/textView2"
                android:text="" android:maxLength="30"
                android:textAppearance="?android:attr/textAppearanceMedium"
                android:layout_width="wrap_content" />
            <TextView android:layout_height="wrap_content" android:id="@+id/textView2"
                android:text="Please Sign below ..." android:maxLength="30"
                android:textAppearance="?android:attr/textAppearanceMedium"
                android:layout_width="wrap_content" />
        </TableRow>
    </TableLayout>
    <LinearLayout android:layout_height="match_parent"
        android:id="@+id/linearLayout" android:layout_width="match_parent" />
</LinearLayout>

Source for AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.as400samplecode" android:versionCode="1"
    android:versionName="1.0">
    <uses-sdk android:minSdkVersion="13" />
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
   
    <application android:icon="@drawable/icon" android:label="@string/app_name"
        android:theme="@android:style/Theme.Holo.Light">
        <activity android:name=".CaptureSignatureActivity"
            android:label="@string/app_name">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
        <activity android:name=".CaptureSignature" android:label="Signature Confirmation"
            android:theme="@android:style/Theme.Holo.Light.Dialog" />
    </application>
</manifest>

Source for strings.xml

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <string name="hello">Hello World, CaptureSignatureActivity!</string>
    <string name="app_name">CaptureSignature</string>
    <string name="external_dir">GetSignature</string>
</resources>

Android capture signature using Canvas

Steps to Run the application on an Android Phone with Version 2.3.3 API level 10


1) Change your project build Target to Android 2.3.3


2) CaptureSignature manifest file Androidmanifest.xml with version and Theme changes as Holo theme is not available in API level 10.
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.as400samplecode" android:versionCode="1"
    android:versionName="1.0">
    <uses-sdk android:minSdkVersion="10" />
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
   
    <application android:icon="@drawable/icon" android:label="@string/app_name"
        android:theme="@android:style/Theme.Light">
        <activity android:name=".CaptureSignatureActivity"
            android:label="@string/app_name">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
        <activity android:name=".CaptureSignature" android:label="Signature Confirmation"
            android:theme="@android:style/Theme.Dialog" />
    </application>
</manifest>

3) Change the signature.xml file with new layout width and height
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout android:id="@+id/linearLayout1"
    android:layout_width="400dp" android:layout_height="300dp"
    .......


Signature capture in Android Phone with Version 2.3.3 API level 10
Signature capture in Android Phone with Version 2.3.3 API level 10

How to display the saved signature from base64 String

 //convert the string to byte array
 byte[] imageAsBytes = Base64.decode(myStringImage.getBytes());
 //get reference to the image view where you want to display the image
 ImageView image = (ImageView)this.findViewById(R.id.ImageView);
 //set the image by decoding the byte array to bitmap
 image.setImageBitmap(
  BitmapFactory.decodeByteArray(imageAsBytes, 0, imageAsBytes.length)
 );