Cosmic Brush

Whether you want to doodle on a photo or paint a piece of art from scratch, this is the app you didn't know you were looking for!
Be as creative as you want with inspiring out-of-this-world painting tools like 3D-Shaded Brush, Halo Brush, Plasma Chain Brush, and Translucent Brush.
You will also find more down-to-earth tools, including a standard brush and an eraser.

Full Screen Painting:
Full Screen mode is fully supported.
In addition, you can press the Tab key to hide the toolbar.

Zooming And Panning:
Pinch (trackpad) or use keyboard shortcuts to zoom in/out.
To pan, drag with two fingers (trackpad), slide with one finger (Magic Mouse) or use arrow keys.
Double tap with two fingers (trackpad) or press Space to reset the zoom/pan.

Layers:
The image consists of 2 (3 if you upgrade to Pro) transparent layers on top of each other.
To switch between the different layers, use the button that has what looks like a stack of papers in addition to a small symbol (e.g. a flower) of the currently selected layer.

Color Sets:
Click once on a color to select it. Click a second time to bring up a menu where you can change or adjust the color in a number of ways (this menu also features an Eyedropper tool if you upgrade to Pro).
Adjacent to the colors you will find buttons to switch between the different color sets.
Press a second time if you want to replace the color set with one of the default ones.

Popup Help:
For information on what a specific button does, just hover the mouse pointer above it for a few seconds and a short explanation will appear.

-SOME OF THE FEATURES-
* Pinch to Zoom
* Full Screen Support
* Multiple Undo/Redo Steps
* Layers
* Customizable Color Sets

-OPTIONAL PRO FEATURES-
* Up to 24 Works in Progress
* Change Paper Color
* Seamless Pattern Editing
* Up to 3 Layers
* Merge, Swap, Flip Layers
* Straight Line Mode
* Eyedropper Tool
* Individual Tool Settings
* Scale and Adjust Size

You can upgrade the free app to Pro through a simple in-app purchase.