There are many online tools which can quickly generate icons & styles for your app. Following are the most useful ones:
Device Art Generator
This tool, developed by Google, enables you to quickly wrap app screenshots in device artwork. This method offers better visual context for your app screenshots on your website or in other promotional materials. It supports all Nexus devices’ resolutions.
Shape Shifter is an online animation editor that allows you to create a vector animation and then export it as an animated vector drawable.
Launchkit is a web-based tool which helps developer focusing more on app developing process. With LaunchKit, you can create screenshots for the app store, createw ebsite for the app, and track your app’s review.
Android Asset Studio
This is a collection of web-based tool which can generates graphics used in Android Studio. The collection consists of
Icon generators and Simple nine-patch generator.
Icon generators has 4 tools Launcher icons, Action bar and tab icons, Notification icons and Generic icons. They can generate icons from existing source images, clipart, or text. The Simple nine-patch generator allows developer to use a source artwork to quickly generate simple nine-patches at different screen densities.
Android Material Icon Generator
This tool is one of the easiest and fastest ways to generate an app’s icon used in Goole Play Store. With Android Material Icon Generator, you can upload a SVG file or choose from hundreds of available material icons and wait for the tool to generate a beautiful icon for your app.
Zeplin is not only a generator but also a good online workspace for any app designers. Its main function is to help collaborate between designers and developers. After completing a design, users can generate all sizes of the assets according to platform needs.
Android Holo Colors Generator
The tool help you create Android widgets such as editext, button, progress bar with a specific color. It will generate all necessary nine-patch assets and associated XML drawables and styles. They can be copied straight into a project.
Android Button Maker
It is a web-based tool to generate buttons code for Android Apps. The buttons are generated based on Drawable Resources which can set a button’s properties such as geometric shape. That’s also the reason why these XML-based buttons can load faster compare to normal png buttons.
Android Layout Binder
This tool can generate all fields used in a class from an input layout XML file. It converts widgets to fields.
For example, it will generate
mItemThumbnail = (ImageView) findViewById(R.id.itemThumbnail);
mItemTitle = (TextView) findViewById(R.id.itemTitle);
SVG to Vector Drawable Converter
It can convert SVG images to Android vector drawable XML resource files. The tools only support Android 5.0+, which is the lowest version that supports VectorDrawable class.
Android Feature Graphic Generator
It will generate a simple yet attractive PNG image file which can be used as your app’s feature graphic. And it follows Google’s guidelines.