Develop Reference

Where are Full Bleed Layer image icons used?

My question is:
When creating an app icon, something called Full Bleed Layers is created as well and I don't know where this icon will be in use.

Full bleed layers = the base adaptive icon, which is being masked (it is only being shown masked).
The link in the SDK documentation is broken: see Designing Adaptive Icons.

How to Remove white Background from icon?

I have an app on android that create home shortcut icon.
The image of the icon is image that i set programmatically from the drawable
Now the problem is, when the shortcut was created on the home screen it's created with white background.
How do i remove that white backgroubd and set image to full size of icon?
Thank you all..
EDIT: the app i was talking about is app that i developed using android studio and just want to set full size of image when i create home shortcut

This is highly dependent on the launcher you use. The image looks like the standard google android 8+ (?) icon shape.
I theory it could be part of the icon you created but since you are asking this I doubt it.
In older versions of android the outer shape of the icons were individual, while rather cool and the outline correctly shown while dragging them etc many complained about the lack of a uniform look of all the icons in the app drawer etc.
It was introduced to make all icons seem more uniform.
Long pressing an empty space in the Google Pixel launcher for example shows a choice to go into the settings for the launcher and there you can change the shape all icons should have:
In addition to this, apps can take advantage of the various shapes and adapt to them and fill them out so to speak. See for example the Chrome icon while changing the icon shapes in the launcher settings.
Introduced in android 8: The feature is called adaptive icons.
See the docs about adaptive icons here:
https://developer.android.com/guide/practices/ui_guidelines/icon_design_adaptive

That is because of adaptive icons - a feature of Android 8 and can't or shouldn't be changed. You can at best change the colour of the background.

i removed the white background from the launcher icon by following these guidelines https://developer.android.com/studio/write/image-asset-studio
a few more points
in the background layer, move the slider to resize the icon until you see no what would have been the white background.
in the manifest file, change the icons to reference the mipmap folder;
android:icon="#mipmap/yourlogo"
android:roundIcon="#mipmap/yourlogo"

Why my flutter app launcher icon in a circle? Can I use a square icon to replace this one?

I was using the following website to generate several launcher icons for my flutter app.
https://romannurik.github.io/AndroidAssetStudio/icons-launcher.html
But after I replace the original flutter icons ( file path: myapp/android/app/src/main/res ) and run my app, my icon is in a circled icon. ( check the image I attached )
My Android Virtual Device is Nexus 5X API 28.
So can anyone tell me what was wrong? And Can I use a square icon to replace this one?

The launcher that comes on the emulator forces all icons to be round. If the icon isn't already round, it will add a round border around it, like you see in that screenshot.
This isn't something you can change. If you want your icon to be square, use a different launcher. It's ultimately up to the user how their icons display.
You may want to consider implementing adaptive icons, so if a user does use circle or squircle icons and their icon pack/launcher forces all icons to be round, it at least won't look terrible.

Galaxy S7 Nougat Full Icons

I wanted to ask how to change the app icon of my app on a Galaxy S7 running on Android Nougat (see attached screenshot) to fill the whole icon space.
Is there a way to do this?
EDIT: I think it's because these apps have square icons and mine is circular. Is there a way to make it square for Galaxy S7 Nougat devices and for all others round?

You can disable this by adding a meta-data element to your manifest:
<application>
<meta-data android:name="com.samsung.android.icon_container.has_icon_container" android:value="true"/>
</application>

This solution is only for user's end:
Go to settings -> display -> icon frames -> icon only.
This should change the icons into full size icons.

From https://developer.android.com/about/versions/nougat/android-7.1.html
Apps can now define circular launcher icons, which are used on devices that support them. When a launcher requests an app icon, the framework returns either android:icon or android:roundIcon, depending on the device build configuration. Because of this, apps should make sure to define both android:icon and android:roundIcon resources when responding to launcher intents. You can use Image Asset Studio to design round icons.
While that may not be sufficient to deal with Samsung's "special" white frame for icons, this gif shows a few ideas for creating icons that look good whether they are the normal size or framed "Squircle" style.
https://www.androidcentral.com/sites/androidcentral.com/files/article_images/2016/12/squircles.gif
In any event this means you now have to worry about a normal icon, a round icon and a Samsung-ized icon and there is no way to provide an icon for the Samsung-specific launcher design.

I met the same problem and tried various things. Now I found one interesting thing.
If you make an icon without any transparency, the icon will be the full size on the Nougat android phone. When I made an icon in the paint.exe and saved it as .png, there was no problem.
I think this will help you.
EDIT : below is what I met, explained in my comment
EDIT2 : the sizes and shapes of two icons (with and without transparency) are identical. the only difference is one has transparency and the other has white background. Definitely I don't mean that I deleted transparency and enlarged the image.
EDIT3 : more explanation about my icons #Hadas

Creating photos to use as ImageButtons in my app - regarding size

When creating images to place as ImageButtons in my app, what is the staple rule to go by in terms of width? I know each phone will resize accordingly with a wrap_content parameter, but what is the universal width I should be using? These are basic titles for each layout I am using, as reference.
Thanks!

Depends on what kind of icon you are creating (menu, app launcher, etc..). Icon sizes also depend on screen density.
Check out Icon Design Guidelines.