Set transparent background of an imageview on Andr

问题:

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>.

回答1:

In your XML set the Background attribute to any colour, White(#FFFFFF) shade or Black(#000000) shade. If you want transparency, just put 80 before the actual hash code:

#80000000

This will change any colour you want to a transparent one.. :)

回答2:

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\" 

回答3:

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

回答4:

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.

回答5:

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

回答6:

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

回答7:

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.

回答8:

use this code for transparent color

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

回答9:

In case you want it in code, just:

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

回答10:

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

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

回答11:

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

回答12:

One more simple way:

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

回答13:

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

回答14:

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

回答15:

Try this code :)

Its an fully transparent hexa code - \"#00000000\"

回答16:

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

回答17:

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

0 would be transparent, 1 fully visible. ;)

回答18:

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

回答19:

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> 

回答20:

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.

回答21:

ImageView.setBackground(R.drawable.my_background);

ImageView.setBackgroundResource(R.color.colorPrimary);

ImageView.getImageAlpha();

ImageView.setAlpha(125); // transparency

回答22:

Try this:

#aa000000

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