Apps development for Android step by step

Lessons related to alpha channel

Lesson 1.5: How to color part of the text and use alpha channel in TextView?

Let’s say that we want to have every word presented in TextView in different color. Any of solutions from previous lesson doesn’t address this issue, but we know how to do it. And there is one more thing related to colors – so called alpha channel that’s responsible for transparency.

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Appendix B: Everything about colors in Android

Android uses standard RGB (red, green and blue) color model. Each primary color value is usually represented by hexadecimal number.  At the beginning of such a color definition you have to put a pound character (#).

The simplest is just #RGB format, where #000 is black and #FFF is white. But in this format we have only 16 values per color so it gives 4096 combinations. That’s why #RRGGBB format is mainly used. In this format we have 256 values per primary color, so 16 777 216 colors in total. Black is #000000 and white is #FFFFFF.

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