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Interactive Watch Faces
Similar to the process of designing a traditional watch face, creating one for Wear OS by Google is an exercise in visualizing time clearly. Wear OS devices provide advanced capabilities for watch faces that you can leverage in your designs, such as vibrant colors, dynamic backgrounds, animations, and data integration. However, there are also many design considerations that you must take into account.
For information about designing watch faces for Wear OS, read Interactive Watch Faces.
This lesson shows how to get started implementing a design.
Create an implementation strategy
After you finalize the design for your watch face, you need to determine how to obtain any necessary data and draw the watch face on the wearable device. Most implementations consist of the following components:
- One or more background images
- Application code to retrieve the required data
- Application code to draw text and shapes over the background images
Apps typically show different background images for the interactive and ambient modes. It can be difficult to create a good-looking image for ambient mode. Therefore, ambient mode backgrounds are often completely black or grey with no image.
Background images for Wear OS devices with a screen density of hdpi should be 320 by 320 pixels in size to fit both square and round devices. The corners of the background image are not visible on round devices. In your code, you can detect the size of the device screen and scale down the background image if the device has a lower resolution than your image. To improve performance, you should scale the background image only once and store the resulting bitmap.
You should run the application code to retrieve contextual data only as often as required and store the results to reuse the data every time you draw the watch face. For example, you don't need to fetch weather updates every minute.
To increase battery life, the application code that draws your watch face in ambient mode should be relatively simple. You usually draw outlines of shapes using a limited set of colors in this mode. In interactive mode, you can use full color, complex shapes, gradients, and animations to draw your watch face.
The remaining lessons in this class show you how to implement watch faces in detail.