colors

Getting different shades of a particular color is very much useful when setting color to layouts which are just adjacent to each other. It maintains the uniformity of the theme and also creates a distinction between those layouts. In Phimpme Android application we used this method for setting colors for the status bar, navigation bar and few other foreground elements.

Use of different shades of a color

As per the normal theme of the application, we assigned the primary color of the theme to the  background color of the action bar in Phimpme Android application. The status bar will be present just above the action bar. So if we assign the same primary color to the status bar also, then there will be no distinction between both the views and it is not visibly attractive. For getting the distinction between both the views, we created a dark shade of the primary color of the current theme and set it as the background color of the status bar.

In Phimpme Android application we used a bottomnavigationview widget for navigating between activities in the application. It is placed at the bottom of the application window i.e. just above the system navigation bar. So, even here, for creating the distinction between both the views, we used the similar approach of getting the darker shade of the color, assigning it to the system navigation bar and normal shade to the bottomnavigationview of Phimpme Android application.

In the splash screen of the Phimpme Android application, the primary color of the theme is set as the main background. A progress bar also gets displayed on the screen. Its color should match the theme and should also get distinguished from the background. We could’ve used darker shade for this too, but a lighter foreground object would be visibly much better. So, we created a lighter shade of the primary color and used it as the color filter for the progress bar.

Implementation

In Phimpme Android, this is implemented by getting the color coordinates in HSV space corresponding to the given coordinates (here – primary color of theme) in RGB space and changing the luminance in that HSV space and remapping it back to RGB space. By this we get almost any shade of the color.

The implementation for getting darker shade of a color which we used for status bar in Phimpme application is shown below.

public int getDarkerShadeColor(int c){
   float[] hsv = new float[3];
   int color = c;
   Color.colorToHSV(color, hsv);
   hsv[2] *= 0.80f; 
   color = Color.HSVToColor(hsv);
   return color;
}

Generally 20% darker color would be enough for distinguishing from original color. So, we reduced the luminosity to 80% of its previous value and created darker color in the above function.

The implementation for getting lighter color is also almost same. It is given below

public int getLighterShadeColor(int c){
   float[] hsv = new float[3];
   int color = c;
   Color.colorToHSV(color, hsv);
   hsv[2] *= 1.35f; 
   color = Color.HSVToColor(hsv);
   return color;
}

As you can see that both functions are almost same except the multiplier. If the multiplier is less than 1 then the function returns darker shade of the original color and if the multiplier is greater than 1 then the function returns lighter shade of the color. So by using this function, one can produce any shade of a color dynamically without the need hard code in xml files.

Resources:

• A Question on stackoverflow having other methods of implementation https://stackoverflow.com/questions/33072365/how-to-darken-a-given-color-int
• Android color palette https://material.io/guidelines/style/color.html
• Android developer documentation on RGB2HSV conversion https://developer.android.com/reference/android/support/v4/graphics/ColorUtils.html