How to convert a LinearLayout to image?

I tried the following code to convert the LinearLayout to image:

LinearLayout

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

LinearLayout lyt = (LinearLayout) findViewById(R.id.lyt);
lyt.setDrawingCacheEnabled(true);
lyt.buildDrawingCache(true);

Bitmap b = Bitmap.createBitmap(lyt.getDrawingCache());

ImageView img = (ImageView) findViewById(R.id.imageView1);
img.setImageBitmap(b);




but I got NullPointerException in :

NullPointerException

Bitmap b = Bitmap.createBitmap(lyt.getDrawingCache());


where the layout XML is :

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical" >


<LinearLayout
android:id="@+id/lyt"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical" >

<Button
android:id="@+id/button1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Button 1" />

<Button
android:id="@+id/button3"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Button 2" />

<Button
android:id="@+id/button2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Button 3" />

</LinearLayout>

<ImageView
android:id="@+id/imageView1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:src="@drawable/ic_launcher" />

</LinearLayout>


5 Answers
5

**Try below code, it works**

**Add below permission in manifest**

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
**MainActivity.java**

public class MainActivity extends Activity implements OnClickListener{
private LinearLayout linearLayout;
private Button saveBtn;

@Override
public void onCreate(Bundle savedInstanceState)
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
linearLayout = (LinearLayout) findViewById(R.id.linearLayout_view);
saveBtn = (Button) findViewById(R.id.save_btn);
saveBtn.setOnClickListener(this);


@Override
public void onClick(View v)
int id = v.getId();
switch (id)
case R.id.save_btn:
File file = saveBitMap(this, linearLayout); //which view you want to pass that view as parameter
if (file != null)
Log.i("TAG", "Drawing saved to the gallery!");
else
Log.i("TAG", "Oops! Image could not be saved.");

break;
default:
break;


private File saveBitMap(Context context, View drawView)
File pictureFileDir = new File(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES),"Handcare");
if (!pictureFileDir.exists())
boolean isDirectoryCreated = pictureFileDir.mkdirs();
if(!isDirectoryCreated)
Log.i("ATG", "Can't create directory to save the image");
return null;

String filename = pictureFileDir.getPath() +File.separator+ System.currentTimeMillis()+".jpg";
File pictureFile = new File(filename);
Bitmap bitmap =getBitmapFromView(drawView);
try
pictureFile.createNewFile();
FileOutputStream oStream = new FileOutputStream(pictureFile);
bitmap.compress(CompressFormat.PNG, 100, oStream);
oStream.flush();
oStream.close();
catch (IOException e)
e.printStackTrace();
Log.i("TAG", "There was an issue saving the image.");

scanGallery( context,pictureFile.getAbsolutePath());
return pictureFile;

//create bitmap from view and returns it
private Bitmap getBitmapFromView(View view)
//Define a bitmap with the same size as the view
Bitmap returnedBitmap = Bitmap.createBitmap(view.getWidth(), view.getHeight(),Bitmap.Config.ARGB_8888);
//Bind a canvas to it
Canvas canvas = new Canvas(returnedBitmap);
//Get the view's background
Drawable bgDrawable =view.getBackground();
if (bgDrawable!=null)
//has background drawable, then draw it on the canvas
bgDrawable.draw(canvas);
else
//does not have background drawable, then draw white background on the canvas
canvas.drawColor(Color.WHITE);

// draw the view on the canvas
view.draw(canvas);
//return the bitmap
return returnedBitmap;

// used for scanning gallery
private void scanGallery(Context cntx, String path)
try
MediaScannerConnection.scanFile(cntx, new String path ,null, new MediaScannerConnection.OnScanCompletedListener()
public void onScanCompleted(String path, Uri uri)

);
catch (Exception e)
e.printStackTrace();





My guess is that you are executing that code in onCreate. The problem with that is that the views are not layouted yet. Either call lyt.measure or call the code later. e.g: to onSizeChanged() or in onLayout() after you called super.onLayout().

Bitmap b = Bitmap.createBitmap(lyt.getDrawingCache());


the only thing that can be null in that line is lyt, the rest can't. You probably did not set the layout yet and findViewById() will return null in that case.

null

lyt

findViewById()

null

You have to do setContentView() before you can do findViewById()

setContentView()

findViewById()

Bitmap.createBitmap()

lyt.getDrawingCache()

See if that helps you:

Converting Views to Bitmap Images in Android

Below is the code snipet which converts xml layouts to Bitmap images

private Bitmap convertLayoutToImage()
LinearLayout linearView = (LinearLayout) this.getLayoutInflater(null).inflate(R.layout
.marker_layout, null, false); //you can pass your xml layout

linearView.measure(View.MeasureSpec.makeMeasureSpec(0, View.MeasureSpec.UNSPECIFIED),
View.MeasureSpec.makeMeasureSpec(0, View.MeasureSpec.UNSPECIFIED));
linearView.layout(0, 0, linearView.getMeasuredWidth(), linearView.getMeasuredHeight());

linearView.setDrawingCacheEnabled(true);
linearView.buildDrawingCache();
return linearView.getDrawingCache();// creates bitmap and returns the same



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