[android] Set transparent background of an imageview on Android

I am using a web view in which I am adding an image view. How can I set the background of this image view to transparent?

I have tried this:

mImageview.setBackgroundResource(R.color.trans);

Where trans ? <color name="trans">#00000000 </color>.

You could also use View.setAlpha(float) to change the visibility precisely.

0 would be transparent, 1 fully visible. ;)

Or, as an alternate, parse the resource ID with the following code:

  mComponentName.setBackgroundColor(getResources().getColor(android.R.color.transparent));

Color definitions with transparency information may be in the form

#AARRGGBB or #ARGB.

You can use also the shorter value for full transparency: #0000.

Other values are e.g.:

white  grey   black
#FFFF  #F888  #F000 - full color
#EFFF  #E888  #E000
#DFFF  #D888  #D000
#CFFF  #C888  #C000
#BFFF  #B888  #B000
#AFFF  #A888  #A000
#9FFF  #9888  #9000
#8FFF  #8888  #8000
#7FFF  #7888  #7000
#6FFF  #6888  #6000
#5FFF  #5888  #5000
#4FFF  #4888  #4000
#3FFF  #3888  #3000
#2FFF  #2888  #2000
#1FFF  #1888  #1000
#0FFF  #0888  #0000 - full transparency

Try this code :)

Its an fully transparent hexa code - "#00000000"

One more simple way:

mComponentName.setBackgroundResource(android.R.color.transparent);

In your XML file, set an attribute "Alpha"

such as

android:alpha="0.0" // for transparent
android:alpha="1.0" // for opaque

You can give any value between 0.0 to 1.0 in decimal to apply the required transparency. For example, 0.5 transparency is ideal for disabled component

In Android Studio it is very simple to adjust color and opacity using a built-in tool:

There is already a predefined constant. Use Color.TRANSPARENT.

Another working option I came across is to set android:background="@null"

ImageView.setBackground(R.drawable.my_background);

ImageView.setBackgroundResource(R.color.colorPrimary);

ImageView.getImageAlpha();

ImageView.setAlpha(125); // transparency

For those who are still facing this problem, you may try this
element.getBackground().setAlpha(0);

In addition to what Harshad mentioned:

Two hexadecimal characters can be appended to any hexadecimal color code. The first two characters in an 8-digit hex color code represents its opacity in Android.

The two hexadecimal characters can range from 00 to FF. For example,

• Normal opaque black hex- "#000000"
• Fully transparent - "#00000000"
• Fully opaque - "#FF000000"
• 50% transparent - "#7F000000"

This way you can change any color to any level of transparency.

To find the hexadecimal prefix from a percentage:

Divide the percentage number by 100 and multiply by 255 to get the decimal value. Convert the decimal to hexadecimal here.

For example, for 50%, 50/100 * 255 = 127. Using the link we get hexadecimal value 7F.

Source: Android: how to create a transparent or opaque background

In case you want it in code, just:

mComponentName.setBackgroundColor(Color.parseColor("#80000000"));

If you use a drawable XML image you can make it transparent as shown in the picture below, or you can use a color code:

<color name="black">#99000000</color> 

There is already a transparent built into Android: R.color.transparent. http://developer.android.com/reference/android/R.color.html#transparent

But I think you may want to make the background of the image that you are placing into the WebView transparent, for example, with a transparent PNG, rather than the ImageView background. If the actual image is not at all see-through then the ImageView background can't be seen through it.

Try this:

#aa000000

For transparency 000000 = black, you can change these six numbers for the color you want.

use RelativeLayout which has 2 imageViews in . and set transparency code on the top imageView.

transparency code :

<solid android:color="@color/white"/>
<gradient android:startColor="#40000000"   android:endColor="#FFFFFFFF" android:angle="270"/>

If you want to add 20% or 30% transparency, you should pre-pend two more characters to the hexadecimal code, like CC.

Note

android:background="#CCFF0088" in XML

where CC is the alpha value, FF is the red factor, 00 is the green factor, and 88 is the blue factor.

Some opacity code:

Hex Opacity Values

100% — FF
95% — F2
90% — E6
85% — D9
80% — CC
75% — BF
70% — B3
65% — A6
60% — 99
55% — 8C
50% — 80
45% — 73
40% — 66
35% — 59
30% — 4D
25% — 40
20% — 33
15% — 26
10% — 1A
5%  — 0D
0% —  00

You can also set opacity programmatically like:

yourView.getBackground().setAlpha(127);

Set opacity between 0 (fully transparent) to 255 (completely opaque). The 127.5 is exactly 50%.

You can create any level of transparency using the given formula. If you want half transparent:

 16 |128          Where 128 is the half of 256.
    |8 -0         So it means 80 is half transparent.

And for 25% transparency:

16 |64            Where 64 is the quarter of 256.
   |4 -0          So it means 40 is quarter transparent.

Try to use the following code. It will help you in full or more.

1. A .xml file designed to use this code to set background color:

   android:background="#000000"
   

   or

   android:background="#FFFFFF"
   

   

   Or you can set it programmatically as well.

2. Also you can use this code programmatically:

   image.setBackgroundDrawable(getResources().getDrawable(
       R.drawable.llabackground));
   

3. Also this code for setting the background color as well programmatically:

   image.setBackgroundColor(Color.parseColor("#FFFFFF"));
   

4. This code for the same programmatically:

   image.setBackgroundColor(getResources().getColor(Color.WHITE));
   

The color depends on your choice of which color you want to use for transparent. Mostly use a white or #FFFFFF color.

Regarding R.drawable.llabackground: This line of code is for your style of the background, like something special or different for your purpose. You can also use this.

Use the following for complete transparency:

#00000000

When I tried with #80000000 I got a black transparent overlay which I don't want. Try to change the first two digits; it controls the level of transparency, like

#00000000
#10000000
#20000000
#30000000

Use the below code for black:

<color name="black">#000000</color>

Now if you want to use opacity then you can use the below code:

<color name="black">#99000000</color>

And the below for opacity code:

100% — FF
95% — F2
90% — E6
85% — D9
80% — CC
75% — BF
70% — B3
65% — A6
60% — 99
55% — 8C
50% — 80
45% — 73
40% — 66
35% — 59
30% — 4D
25% — 40
20% — 33
15% — 26
10% — 1A
5% — 0D
0% — 00

You can set the background transparent of any layout, any view, or any component by adding this code in XML:

android:background="@android:color/transparent" 

In xml

@android:color/transparent

In code

mComponentName.setBackgroundResource(android.R.color.transparent);