CODEWITHSUNDEEP
androidandroid-viewandroid-resourcesandroid-stylesandroid-color
alexpfx
alexpfx

Reputation: 6680

How to make a shape have solid color that is 50% alpha of an already defined color?

I have a shape defined in a drawable resource file that I use as a background for my TextViews (scrim_background.xml):

<shape xmlns:android="http://schemas.android.com/apk/res/android">
    <solid
        android:color="@color/colorAccent"/>
</shape>

My colors.xml is:

<?xml version="1.0" encoding="utf-8"?>
<resources>


    <color name="white">#fff</color>
    <color name="light_text">#dfff</color>

    <color name="colorPrimary">@color/primary</color>
    <color name="colorPrimaryDark">@color/primary_dark</color>

    <color name="colorAccent">@color/accent</color>


    <color name="primary">#F44336</color>
    <color name="primary_dark">#D32F2F</color>
    <color name="primary_light">#FFCDD2</color>
    <color name="accent">#607D8B</color>

    <color name="accentAlpha">#DD607D8B</color>
    <color name="primary_text">#212121</color>
    <color name="secondary_text">#757575</color>
    <color name="icons">#FFFFFF</color>
    <color name="divider">#BDBDBD</color>

</resources>

The styles for my textviews is:

<style name="BeerItemTextStyleTitle" parent="@android:style/TextAppearance.Medium">
        <item name="android:textColor">@color/light_text</item>
        <item name="android:textStyle">bold</item>
        <item name="android:background">@drawable/scrim_background</item>
        <item name="android:gravity">start|center_vertical</item>
        <item name="android:paddingStart">@dimen/space_small</item>
        <item name="android:paddingEnd">@dimen/space_small</item>
    </style>

I want that the background color to have 50% transparency of the colorAccent.

Something like:

<color name="accent">#88607D8B</color>

But I don't want to fix these values because I'm constantly changing the color scheme.

I tried to add alpha directly to my TextView, like: 

<item name="android:alpha">50</item>

But it was not appropriate as it add the transparency to Text Color as well. I would like that only the background color were transparent.

I would not like to do this programmatically, because this way I would have to find all my textviews and change one by one.

-- EDIT --

I tried to create a meta resource file named bitmap_scrim_background that is: 

<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
    <item>
        <bitmap
            android:src="@drawable/scrim_background">
        </bitmap>
    </item>
</layer-list>


<style name="BeerItemTextStyleTitle" parent="@android:style/TextAppearance.Medium">
    <item name="android:textColor">@color/light_text</item>
    <item name="android:textStyle">bold</item>
    <item name="android:background">@drawable/bitmap_scrim_background</item>
    <item name="android:gravity">start|center_vertical</item>
    <item name="android:paddingStart">@dimen/space_small</item>
    <item name="android:paddingEnd">@dimen/space_small</item>
</style>

But i think things doesn't work this way in Android... It throws:

android.view.InflateException: Binary XML file line #36: Binary XML file line #36: Error inflating class TextView
                                                                                       Caused by: android.view.InflateException: Binary XML file line #36: Error inflating class TextView

Caused by: org.xmlpull.v1.XmlPullParserException: Binary XML file line #5: <bitmap> requires a valid 'src' attribute

Upvotes: 5

Views: 2172

Answers (4)

Oleg Shevchenko
Oleg Shevchenko

Reputation: 181

Using this to create scrollbar thumb 50% transparent with existing non transparent color

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
    android:shape="rectangle"
    android:tint="@color/color_white_alpha_50"   //#80FFFFFF
    android:tintMode="multiply">
    <solid android:color="?colorControlNormal" />
    <corners android:radius="2dp" />
</shape>

Upvotes: 2

Mike
Mike

Reputation: 653

Have you looked at ColorUtils.setAlphaComponent()?

int setAlphaComponent (int color, int alpha)

You could query any color with: 

int x = getColor(R.color.yourColor)

Then create any alpha version of that color with:

int newX = ColorUtils.setAlphaComponent(x, newAlpha);

Upvotes: 1

Alex Covizzi
Alex Covizzi

Reputation: 1171

You can do that programmatically using:

textView.getBackground().setAlpha(50);

Upvotes: 0

Kartik Sharma
Kartik Sharma

Reputation: 723

I am guessing the scrim background is a drawable xml file. You can use the accentColor inside your drawable file.

For example

<shape
    xmlns:android="http://schemas.android.com/apk/res/android">
    <gradient
    android:angle="90"
    android:centerY="0.3"
    android:startColor="@color/accent"
    android:endColor="#00000000"
    android:type="linear"/>
</shape>

Upvotes: 1

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