How to check if drawing layout is empty?

Question

I am using this library for make some drawing but I would be able to check if the field is empty ( so no drawing is in the layout ).

Because I'm printing the drawable on a thermal printer and if someone make no drawable is just wastes the paper.

Here is my method onClick where I get the drawable from the layout and set it to a bitmap:

 parentView.setDrawingCacheEnabled(true);

 bitmap = Bitmap.createScaledBitmap(parentView.getDrawingCache(),510, 360, false);
 BitmapDrawable ob = new BitmapDrawable(getResources(), bitmap);

@Lucefer oh i don't know how could i, so that's why i'm asking it here — NiceToMytyuk, Oct 24 '18 at 13:11
possibly a duplicate of https://stackoverflow.com/a/41538007/4342876 — abhil nair, Oct 24 '18 at 13:16
can you set a flag to true whenever user interacts with your view and use its value to determine the chagnes? — karan, Oct 24 '18 at 13:19
@abhilnair yet tryed it and it's not working with the library i'm using. — NiceToMytyuk, Oct 24 '18 at 13:20
@KaranMer this would be a nice solution but how can i set a listener or check if the user has interacted with the layout? — NiceToMytyuk, Oct 24 '18 at 13:25
I checked the library you have used, you will need to edit `CanvasView` class and set flag over there and create a method using which you can access value of that flag. — karan, Oct 24 '18 at 13:31

score 1 · Answer 1 · answered Oct 24 '18 at 13:15

1

BitmapCompat.getAllocationByteCount(bitmap) check size of bitmap before print. Most probably it could be zero approximately zero for empty drawable. Check it and pops dialog yes, no with a message like "seems like you print empty drawing". If user select yes print it. otherwise, cancel the operation

answered Oct 24 '18 at 13:15

PushpikaWan

2,437
3
14
23

by doing this the value is always 734400 – NiceToMytyuk Oct 24 '18 at 13:24
then u can do it. for size 734400. if it has 734400 then pops message like above mentioned. It will save users as well when it contains any drawing with that size – PushpikaWan Oct 24 '18 at 13:26
the point is even if there is a drawable the value is still 734400 so that make no sense – NiceToMytyuk Oct 24 '18 at 13:27
are checking after drawing ?? It should be increased. – PushpikaWan Oct 24 '18 at 13:29
you can create an empty bitmap using your lib and compare it with the current bitmap as well.https://stackoverflow.com/questions/6120439/comparing-bitmap-images-in-android will help to find compare it – PushpikaWan Oct 24 '18 at 13:34

How to check if drawing layout is empty?

1 Answers1