Implementación de funciones clave en ViewModel para cámara Android

Developing an efficient application that uses the camera on Android requires clarity about the internal management from the ViewModel. Understanding how to handle specific cases, such as displaying the photo taken, cancel previews, and saving images associated with precise locations, allows for optimal user interaction with the application.

What is the role of CancelPreview in the ViewModel?

The CancelPreview function is essential because it allows the user to cancel the preview of the photo taken and return to capture mode. Its implementation follows these basic steps:

• It is defined as aSuspend Function.
• It clearly communicates to the PhotoHandler to stop displaying the current preview.
• It updates the state of the interface to false isPreviewMode, which restores the view to take new pictures.

Because it is a suspended function, it is necessary to launch it from a corrutine in the ViewModel scope. This is achieved by using the launch method of the corroutine constructor.

How to process a photo taken from the camera?

After taking a picture in the camera, the ProcessPhoto function prepares the received data to be displayed in the preview mode. The process includes the following steps:

• It is defined as aPrivate Suspend Function.
• The onPhotoForPreview method of the PhotoHandler is invoked, giving it the bytes of the captured image.
• Finally, it updates the final state of the interface to isPreviewMode equal to true, displaying the captured image.

This function allows a smooth transition from capture mode to display mode.

What steps are involved in saving a photo and associating it with its last location?

The SavePhoto feature ensures that photos are not only stored on the device, but are also associated with relevant location data. Its implementation includes the following practical steps:

Save captured image.

• Capture the current PhotoHandler image from the preview.
• Verify that this image exists and is available for saving.

Assign last available location

• Requests the last known location from the LocationTracker.
• Makes sure that the retrieved location is not empty before proceeding.
• Updates this location with the newly captured photo, adding it to the existing list of images.
• It replaces the previous location segment with the updated one (which includes the new photo).
• Finally, it updates the state UI indicating that it is no longer in preview mode and provides the last saved photo as a reference in the interface.

These technical decisions make it easier for the user to keep a clear and organized record, linking each photo to key location information.

You can apply these practical recommendations to improve the user experience when interacting with essential functionalities in Android apps. Would you like to share with us what other features you consider important in your app?