Setting the Foreground Color Based on the Background Color in Phimpme Android

In the situations where the background color gets changed, the foreground color should also change to some other color. Otherwise the foreground item may not be properly visible on the background.

In Phimpme Android, we came across this situation when dealing with the bottom navigation bar. We have a preference option in our application which enables the user to change the primary color of the application. This change affects the background color of the bottom navigation bar also. We initially had white as selected foreground item’s color and grey as the unselected items’ color. It was fine for darker background colors. But problem arose when we changed the primary color of the application to the lighter shade of any color. The foreground item which was in white color was not clearly visible over the background. So we had to dynamically decide the foreground color when the background color gets changed.

Deciding the foreground color of the bottom navigation bar in Phimpme Android was tough. The foreground item should not only be visible on the background color but it should also be visibly attractive. We needed a minimal look. So we decided to use only two colors – black and white for the selected item’s color. The unselected items’ color can be fixed. A shade of gray with less alpha can be used for it.

The black and white colors are decided based on the lightness of the background color. We used the rgb value of the background color to find the lightness. We fixed a threshold for this lightness by visual judgement and selected the foreground color from the black and white colors based on this threshold lightness. If the lightness of the background color of the bottom navigation color of Phimpme Android application is less than the defined threshold value, we used white as the foreground color and vice-versa.

The lightness can be found out by taking the average of the red, green and blue values of the background color. We considered 100 as the threshold lightness for deciding the foreground color.

void setIconColor(int color){
   if(Color.red(color) + Color.green(color)+ Color.blue(color) < 300)
       colors[0] = Color.WHITE;
   else
       colors[0] = Color.BLACK;
}

For setting the different colors for different states of the foreground items on the bottom navigation bar, we used the setItemIconTintList method which takes ColorStatesList as an argument.

colors[1]  = ContextCompat.getColor(this, R.color.bottom_navigation_tabs);
ColorStateList bottomNavList = new ColorStateList(states, colors);
navigationView.setItemIconTintList(bottomNavList);

This above ColorStateList takes a two dimensional array of states for which we wanted to change the color of item and an array of corresponding colors for those states as arguments. In Phimpme Android we used the following way.

private int[][] states = new int[][] {
       new int[] {android.R.attr.state_checked}, // checked
       new int[] {-android.R.attr.state_checked}, // unchecked
};

private int[] colors = new int[] {
       Color.WHITE, // checked
       0 // unchecked set default in onCreate
};

Resources:

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Implementation of Colour Picker in Phimpme Android Application

In Phimpme Android Project, we have used Color Picker palette which has a various implementation in the project such as changing the theme color of the application, to choose the color for the text while editing an image.

Making XML Layout to choose the specific color from the color palette

The main aim was to provide Line of color, and the user can simply slide through the different colors. A single line should contain all the main colors. I took help of the Open Source project to arrange the layout of the colors. We will display the Color palette in a cardview.

<RelativeLayout
   android:id="@+id/container_edit_text"
   android:layout_width="match_parent"
   android:layout_height="match_parent"
   android:orientation="vertical"
   android:padding="@dimen/big_spacing">
   <uz.shift.colorpicker.LineColorPicker
       xmlns:app="http://schemas.android.com/apk/res-auto"
       android:id="@+id/color_picker_accent"
       android:layout_width="match_parent"
       android:layout_height="60dp"
       app:orientation="horizontal"
       app:selectedColorIndex="0" />
</RelativeLayout>

Inflating the list with the colors

We will inflate the list with all basic colors such as Red, Purple, Blue, Light Blue, Green, Yellow, Orange, Deep orange, Brown, Blue Gray. getAccentColors() function returns the specific color HEXCODE. A color code is six string length long code combination consisting of numbers and alphabets which are stored in the colors.xml resource file. For example, the color code for black is  #000000 and for white #FFFFFF.  

public static int[] getAccentColors(Context context){
   return new int[]{
           ContextCompat.getColor(context, R.color.md_red_500),
           ContextCompat.getColor(context, R.color.md_purple_500),
           ContextCompat.getColor(context, R.color.md_deep_purple_500),
           ContextCompat.getColor(context, R.color.md_blue_500),
           ContextCompat.getColor(context, R.color.md_light_blue_500),
           ContextCompat.getColor(context, R.color.md_cyan_500),
           ContextCompat.getColor(context, R.color.md_teal_500),
           ContextCompat.getColor(context, R.color.md_green_500),
           ContextCompat.getColor(context, R.color.md_yellow_500),
           ContextCompat.getColor(context, R.color.md_orange_500),
           ContextCompat.getColor(context, R.color.md_deep_orange_500),
           ContextCompat.getColor(context, R.color.md_brown_500),
           ContextCompat.getColor(context, R.color.md_blue_grey_500),
   };
}

Implementation of ColorPicker to change the Text color in the Edit Image Activity

Color Palette is implemented the followings steps:

 First,                                                                                                                                        A dialog box is made. This dialog will help to display the color palette.

 Second,                                                                                                                                We need to inflate the dialog box with color_picker_accent XML file we created  in the resource folder.

 Third,                                                                                                                                    We set the dialog box with the line of colors.

 Fourth,                                                                                                                                Get the selected color code. To get the selected color code we used the class  LineColorPicker. The color_picker_accent sends an id for the selected color,  where all the color code is stored.   

final AlertDialog.Builder dialogBuilder = new AlertDialog.Builder(getActivity());
final View dialogLayout = getActivity().getLayoutInflater().inflate(R.layout.color_piker_accent, null);
final LineColorPicker colorPicker = (LineColorPicker) dialogLayout.findViewById(R.id.color_picker_accent);
final TextView dialogTitle = (TextView) dialogLayout.findViewById(R.id.cp_accent_title);
dialogTitle.setText(R.string.text_color_title);
colorPicker.setColors(ColorPalette.getAccentColors(activity.getApplicationContext()));
changeTextColor(WHITE);

In when a user selects a particular color he can either choose OK and CANCEL

When user selects OK

We implemented onClick event to change the color of the text by using the function changeTextColor() which accepts color code as the parameter.

dialogBuilder.setPositiveButton(getString(R.string.ok_action).toUpperCase(), new DialogInterface.OnClickListener() {
   public void onClick(DialogInterface dialog, int which) {
       changeTextColor(colorPicker.getColor());
   }
});

When user selects Cancel

When the user selects cancel, we have set the default color of the text that is White.

dialogBuilder.setNeutralButton(getString(R.string.cancel).toUpperCase(), new DialogInterface.OnClickListener() {
   @Override
   public void onClick(DialogInterface dialog, int which) {
       changeTextColor(WHITE);
       dialog.cancel();
   }
});

changeTextColor function

It accepts the color code. We used this color to change the text color by using the inbuilt function setBackgroundColor() and setTextColor().

private void changeTextColor(int newColor) {
   this.mTextColor = newColor;
   mTextColorSelector.setBackgroundColor(mTextColor);
   mTextStickerView.setTextColor(mTextColor);
}

Conclusion

In this way, it provides a rich user experience. It adds vibrant colors in the application. A quick way to choose the color from the variety of option.

Github

https://github.com/fossasia/phimpme-android

Resources

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