Color from rgb android

Класс android.graphics.Color

В графике важную роль играет цвет, который представлен классом Color. Класс Color содержит несколько констант и методов для конвертации и извлечения цветового компонента.

Цвета можно описывать четырьмя числами в формате ARGB, по одному для каждого канала(Alpha, Red, Green, Blue). Каждый из каналов является восьмибитным целым числом и может принимать значения от 0 до 256. Обычно цвет упаковывают в 32-битное целое число. Стоит отметить, что использовать целые числа для цветов эффективнее, чем экземпляры класса Color.

Если все значения RGB-каналов установить равными 0, то получим чёрный цвет, если присвоить значения 255, то получим белый цвет.

Иногда значения указываются не в десятичной форме, а в шестнадцатеричной от 00 до FF, вместо 0 и 255. В этом случае обычно пишут не ARGB, а AARRGGBB. Например, красный цвет в данном формате будет равен FFFF0000 (AA = FF, RR = FF, GG = 00, BB = 00).

Для создания цвета можно использовать статические константы класса Color, например:

Таких констант немного, только для основных цветов.

Получить красную, зелёную и синюю составляющую цвета можно через методы red(), green, blue(). Получить нужный цвет из набора компонентов можно через методы rgb() и argb(), которые вернут вам int-значение цвета.

Метод parseColor() позволяет получить int-значение из шестнадцатеричной формы.

Лучше задавать цвет в ресурсах для большей гибкости. Всегда можно будет поменять в случае необходимости без вмешательства в код программы:

В коде можно обратиться к цвету следующим образом:

Создадим простейший пример для просмотра цветов.

Код для активности:

Запустив проект, вы можете выбирать из выпадающего списка нужный цвет, чтобы закрасить им фон LinearLayout.

Кроме стандартной цветовой модели RGB используется также Цветовая модель HSV

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Tek Eye

How does color work in Android? An Android color is a 32-bit integer value consisting of four eight bit parts (4×8=32). The four parts are tagged ARGB. This is the amount of Red, Green and Blue in the color, plus how opaque (see through) it is, called the Alpha value, the lower the alpha value the more transparent the color appears. (Note that in British English color is spelt colour.) This article shows how to set a color in Android and provides some demo code to try out.

(This Android color tutorial assumes that Android Studio is installed, a basic app can be created and run, and the code in this article can be correctly copied into Android Studio. The example code can be changed to meet your own requirements. When entering code in Studio add import statements when prompted by pressing Alt-Enter.)

Changing Colors in Android and Naming Them for Convenience

The alpha value is the highest (first) byte in the 32-bit value, followed by the red, then green and finally the blue byte. Hence it is referred to as an ARGB value with each letter representing the type and order of the byte. This format allows for easy representation as a hexadecimal number in Java. Add this code to the basic starting app at the bottom of the onCreate in the MainActivity.java (the TextView displaying Hello World! is given the ID of textView):

The three byes representing the color values provide over 16 million color possibilities in Android (256 x 256 x 256 = 16,777,216). A color depth better than the human eye (stated in the Wikipedia article). Plus all these colors can range from transparent (completely see through when alpha is 0), to opaque (completely solid when alpha is 255).

Named Color Resources in Android

To help with handling colors in Android they can be made into a resource for easy reuse. Either open an existing resource file or create a new one. In the Android Studio project there should be a colors.xml file in the res/values folder. In colors.xml add a definition for the required color, Lime is defined here as an example:

(Note: To add a new resource first select the app in the Project explorer file. Then use the File or context menu, usually right-click, then the New option and select Android resource file. A color resource does not need to be stored in colors.xml, other file names can be used.)

Use getColor() to read the color value from the resource:

If the color is solid (full alpha value) then the color resource can leave the alpha value out. Though for clarity and future maintenance it is wise to be explicit and always define all four parts of an Android color:

The use of a named color in a resource file is handy when dealing with common colors (such as the standard HTML named web colors, i.e. CSS colors, or X Window System and SVG color names). A resource file can be created to define the common colors for an app. Here is a resource file to use the HTML/CSS color names in Android code:

Then just use them as required:

Referencing Colors in Android XML Layouts

To reference an Android color resource in an XML layout simple use @color/name_of_color, the same way other resources are referenced, such as strings:

Accessing Android System Color Resources

Are there predefined colors in Android? Yes, there are existing color resources, but not many. Also Google does not recommend using certain system resources as they are not guaranteed to stay the same in future releases, or even be there. You can browse the Android color resources in an app project. Select Packages at the top of the Project explorer in Studio. Expand the Libraries and android, in the R.class view the items in class color. There are resources such as R.color.black and R.color.holo_purple. The full list is also available in the R.color developer documentation. To access these resources you need the package qualifier, as in @android:color/black. In code add android before the R:

Note that the Android color resources starting holo are not available on versions of Android prior to API level 14 (Ice Cream Sandwich).

The Android Color Class

There is a helper class in Android that has functions to ease the generation of color values from individual alpha, red, green and blue components, from strings and from Hue, Saturation and Value (HSV), and back again. The Color class defines a limited range of static colors, e.g. Color.YELLOW, see the Android developer documentation for full information on the Color class:

Android Color class static constants: BLACK, BLUE, CYAN, DKGRAY, GRAY, GREEN, LTGRAY, MAGENTA, RED, TRANSPARENT, WHITE, YELLOW

Color class methods: HSVToColor, RGBToHSV, alpha, argb, blue, colorToHSV, green, parseColor, red, rgb

Android Oreo Introduced ColorSpace

Android Oreo (API 26) introduce advanced color models that go beyond the previous RGB model, e.g. CMYK (the cyan, magenta, and yellow key format). For most apps the RGB colors are fine. However, for specialised applications the new models may be required. See the article Enhancing Graphics with Wide Color Content and the ColorSpace documentation on Android Developers.

For wide color support the Color class was expanded to provide 64 bit color values. Existing methods now come with support for long, and the new methods are: colorspace, convert, getColorSpace, getComponent, getComponentCount, getComponents, getMaxValue, getMinValue, getModel, isInColorSpace, isSrgb, isWideGamut, luminance, pack, toArgb

Changing Text Color in Android

Use the textColor attribute to modify the color of text when it is defined in an XML layout:

Android Color Codes Example Project

To see all the above Android color hexadecimal codes and named colors in action use the color test demo project. Here are examples of the above in action:

Download color-test.zip, extract it to a folder on your development PC and import it into Android Studio. This sample Android colors project is also available from the Tek Eye Android Example Projects page, where further details on importing a sample project into Studio is provided.

Adding a Color Picker to an App

If you need to add the ability to configure a color for a setting in an app it is easily done. The Android SeekBar can be used for a quick and easy color picker, drop four SeekBars onto a layout, one for each component of a color (only three are needed if you do not want to change the transparency). Use the methods from the Color class to combine the SeekBar outputs into the color value. Here’s one in action:

An article on building the above color picker is available in the Android Color Picker Tutorial. That tutorial also covers the color picker available in the original Android API Demos app. The API Demos project was in the pre-Androud Studio versions of the Android Software Development Kit (SDK). In API Demos the color picker is in ColorPickerDialog.java.

There are also plenty of other Android color pickers available, with full source, on GitHub, simply search for Android color picker.

And Finally.

What is the color of the Android Robot? Android green is 0xA4C639.

Summary

Storing ARGB color values in an Android resource files, e.g. #FFFF0000 , makes it easy to remember the color values for Views in Layouts. The names are easier to remember than hex strings. There is a Color helper class available to help with color conversion and value extraction. Several free color picker Views are available to add color selection functionality to apps.

See Also

• Download the code for this example, available in color-test.zip
• An Android Color Picker Tutorial with example source code and project.
• See Color State List Resource for information on changing colors in Views on different states.
• See the Android Studio example projects to learn Android app programming.
• For a full list of all the articles in Tek Eye see the full site Index.

Acknowledgements

Author: Daniel S. Fowler Published: 2013-04-15 Updated: 2017-11-26

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Top 10: Best Android Color Picker Libraries

Carlos Delgado

See our review from 10 of the Best Android Color Picker Libraries.

A color tool, color picker, or color chooser in an application, is a utility that is usually but not necessarily found within graphics apps. They’re used to choose colors or create color schemes. Normally, they allow you to choose a color in its RGB-A, HEX, or HSL-A representation. If you are willing to implement such a feature in your Android Native application, you already know that there are a lot of libraries that allow you to implement this widget in case that you are working on software to colorize photos.

In this top, we’ll share with you 10 of the most imponent libraries to build color pickers in your native android application.

10. ColorSheet

ColorSheet is a color picker fragment from the bottom sheet.

9. Pikolo

Pikolo is an android color picker library. It works as a widget inside your application, so add the HSLColorPicker view to your layout and use it in code as below:

8. ColorPicker by Duanhong

This library allows you to display a ColorPicker for Android. Pick a color using color wheel and slider (HSV & alpha). It can be initialized like this:

7. hsv-alpha ColorPicker android

This library implements a color picker and a color preference for use in Android applications. This plugins features:

• Alpha slider.
• Text field to copy and paste hex color values.
• Old and new colors displayed side by side.
• Optional selection of «no color».
• Proper behavior when orientation changes.
• Up-to-date design.

In addition, the Hue-Saturation picker.

• gives higher hue precision than a square picker of the same size.
• allows easier selection of pure white than a circular picker.

6. AndroidPhotoshopColorPicker

This plugins allows you to implement a full featured Color picker Library for Android! Just like the one in Photoshop! It features:

• Hue bar — Adjust hue using a slider
• Saturation & Value Box — Select the color from the Saturation & Value Box (like in Photoshop)
• Alpha bar — Adjust the alpha using a slider
• Preview — You can see the current selected and previously picked colors side-by-side
• Edit each component individually — You can edit Hue, Saturation, Value, Red, Green and Blue components individually
• Fully customizable — By default, there are two themes(Light and Dark). But you can define your own theme to customize the whole ColorPicker
• Easy to use — All the hardwork is done by us. Just a few lines of code is all you have to do

5. Skydoves ColorPickerPreference

A library that lets you implement ColorPickerView, ColorPickerDialog, ColorPickerPreference. Could get HSV color, RGB values, Html color code from your gallery pictures or custom images just by touching.

4. Android Colorpicker Preference

ColorPickerPreference is a library for android to create color picker in preferences. This template features:

• Color Area
• Hue Slider
• Alpha Slider (disabled by default)
• Old & New Color
• Color Preview in Preferences List

3. Holopicker

Holopicker is an Android Holo themed colorpicker designed by Marie Schweiz. You can now set the Saturation and Value of a color. Also its possible to set the Opacity for a color. You can also set the last selected color and see the difference with the new selected color.

2. ColorPickerView

ColorPickerView is the most standard and powerful colorpicker library. ColorPickerView implements getting HSV colors, ARGB values, Hex color codes from any image drawables or your gallery pictures by tapping on the desired color. Supports alpha & brightness slider bar, dialog, and auto saving & restoring selected data. ColorPickerDialog can be used just like using AlertDialog and provides colors from any drawables. ColorPickerDialog extends AlertDialog . So we can customize themes also. A new dialog that allows you to pick a color can be initialized with the following code:

1. QuadFlask Colorpicker

The colorpicker library by QuadFlask is a pretty simple android color picker with color wheel and lightness bar. The library is not released in Maven Central, but instead you can use JitPack. It can be used easily as a dialog with the following code:

Honorable mentions

Colorpicker

Colorpicker is a simple Android color picker library.

If you know another open source color picker component for Android applications, please share it with the community in the comment box.

Carlos Delgado

Interested in programming since he was 14 years old, Carlos is a self-taught programmer and founder and author of most of the articles at Our Code World.

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