We will let the user have up to one channel mixing filter, one curve filter, and one convolution filter active at any time. For each filter category, we will provide a menu button that lets the user cycle through the available filters or no filter.
Let's start editing the relevant resource files to define the menu buttons and their text. We should add the following strings to res/values/strings.xml:
<string name="menu_next_curve_filter">Next Curve</string> <string name="menu_next_mixer_filter">Next Mixer</string> <string name="menu_next_convolution_filter">Next Kernel</string>
Then, we should edit res/menu/activity_camera.xml as follows:
<menu xmlns:android="http://schemas.android.com/apk/res/android"> <item android:id="@+id/menu_next_curve_filter" app:showAsAction="ifRoom|withText" android:title="@string/menu_next_curve_filter" /> <item android:id="@+id/menu_next_mixer_filter" app...