How to Set Opacity Alpha for View in Android

Question

I have a button as in the following    lt Button       android text  Submit        android id    id Button01        android layout width  fill parent        android layout height  wrap content  gt   lt  Button gt    In my onCreate   event  I am calling Button01 like this   setContentView R layout main    View Button01   this findViewById R id Button01   Button01 setOnClickListener this     There is a background in the application  and I want to set an opacity on this submit button  How can I set an opacity for this view  Is it something that I can set on the java side  or can I set in the main xml file   On the java side I tried Button01 mutate   SetAlpha 100   but it gave me an error

User · Answer

What I would suggest you do is create a custom ARGB color in your colors.xml file such as :

<resources>
<color name="translucent_black">#80000000</color>
</resources>

then set your button background to that color :

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

Another thing you can do if you want to play around with the shape of the button is to create a Shape drawable resource where you set up the properties what the button should look like :

file: res/drawable/rounded_corner_box.xml

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
    android:shape="rectangle">
    <gradient
        android:startColor="#80000000"
        android:endColor="#80FFFFFF"
        android:angle="45"/>
    <padding android:left="7dp"
        android:top="7dp"
        android:right="7dp"
        android:bottom="7dp" />
    <corners android:radius="8dp" />
</shape>

Then use that as the button background :

    android:background="@drawable/rounded_corner_box"

User · Answer

Although btnMybutton getBackground   setAlpha 45   is nice idea  it just apply alpha to background and not the whole view   If you want apply alpha to view use btnMybutton setAlpha 0 30f   instead  This apply opacity to View  It accepts a value between 0 and 1   Doc says      Sets the opacity of the view  This is a value from 0 to 1  where 0   means the view is completely transparent and 1 means the view is   completely opaque  If this view overrides onSetAlpha int  to return   true  then this view is responsible for applying the opacity itself    Otherwise  calling this method is equivalent to calling   setLayerType int  android graphics Paint  and setting a hardware   layer  Note that setting alpha to a translucent value  0  lt  alpha  lt  1    may have performance implications  It is generally best to use the   alpha property sparingly and transiently  as in the case of fading   animations

User · Answer

I m amazed by everyone else s MUCH more complicated answers   XML  You can very simply define the alpha in the color definition of the button  or any other view  in your xml   android color   66FF0000        Partially transparent red   In the above example  the color would be a partially transparent red   When defining the color of a view  the format can be either  RRGGBB or  AARRGGBB  where AA is the hex alpha value  FF would be fully opaque and 00 would be full transparent   Dynamically  If you need to dynamically alter the opacity in your code  use  myButton getBackground   setAlpha 128       50  transparent   Where the INT ranges from 0  fully transparent  to 255  fully opaque

User · Answer

I guess you may have already found the answer  but if not  and for other developers   you can do it like this   btnMybutton getBackground   setAlpha 45     Here I have set the opacity to 45  You can basically set it from anything between 0 fully transparent  to 255  completely opaque

User · Answer

I just found your question while having the similar problem with a TextView  I was able to solve it  by extending TextView and overriding onSetAlpha  Maybe you could try something similar with your button   import android content Context  import android util AttributeSet  import android widget TextView   public class AlphaTextView extends TextView      public AlphaTextView Context context        super context          public AlphaTextView Context context  AttributeSet attrs        super context  attrs          public AlphaTextView Context context  AttributeSet attrs  int defStyle        super context  attrs  defStyle           Override   public boolean onSetAlpha int alpha        setTextColor getTextColors   withAlpha alpha        setHintTextColor getHintTextColors   withAlpha alpha        setLinkTextColor getLinkTextColors   withAlpha alpha        return true

User · Answer

Much more easier from the above  Default alpha attribute is there for button  android alpha  0 5    The range is between 0 for complete transparent and 1 for complete opacity

User · Answer

According to the android docs view alpha is a value between 0 and 1   So to set it use something like this   View v  v setAlpha  5f

User · Answer

For a view you can set opacity by the following   view name setAlpha float value     The property view setAlpha int  is deprecated for the API version greater than 11  Henceforth  property like  setAlpha 0 5f  is used

User · Answer

I know this already has a bunch of answers but I found that for buttons it is just easiest to create your own  xml selectors and set that to the background of said button  That way you can also change it state when pressed or enabled and so on  Here is a quick snippet of one that I use  If you want to add a transparency to any of the colors  add a leading hex value   XXcccccc    XX     alpha of color     lt  xml version  1 0  encoding  utf-8   gt   lt selector xmlns android  http   schemas android com apk res android  gt       lt item android state pressed  true   gt           lt shape gt               lt solid                 android color   70c656    gt               lt stroke                 android width  1dp                  android color   53933f    gt               lt corners                 android radius  4dp    gt               lt padding                 android left  10dp                  android top  10dp                  android right  10dp                  android bottom  10dp    gt           lt  shape gt       lt  item gt       lt item gt           lt shape gt               lt gradient                 android startColor   70c656                  android endColor   53933f                  android angle  270    gt               lt stroke                 android width  1dp                  android color   53933f    gt               lt corners                 android radius  4dp    gt               lt padding                 android left  10dp                  android top  10dp                  android right  10dp                  android bottom  10dp    gt           lt  shape gt       lt  item gt   lt  selector gt

User · Answer

For API  lt  11 for textView color I did the following    int textViewColor   textView getTextColors   getDefaultColor     textView setTextColor Color argb 128  Color red textViewColor   Color green textViewColor   Color blue textViewColor       50  transparent   A little cumbersome  but hey  it works  -

User · Answer

I ve run into this problem with ICS JB because the default buttons for the Holo theme consist of images that are slightly transparent  For a background this is especially noticeable   Gingerbread vs  ICS       Copying over all of the drawable states and images for each resolution and making the transparent images solid is a pain  so I ve opted for a dirtier solution  wrap the button in a holder that has a white background  Here s a crude XML drawable  ButtonHolder  which does exactly that   Your XML file   lt  xml version  1 0  encoding  utf-8   gt   lt LinearLayout xmlns android  http   schemas android com apk res android                style   style Content  gt     lt RelativeLayout style   style ButtonHolder  gt         lt Button android id    id myButton                style   style Button                android text   string proceed   gt       lt  RelativeLayout gt   lt  LinearLayout gt    ButtonHolder xml   lt  xml version  1 0  encoding  utf-8   gt   lt layer-list xmlns android  http   schemas android com apk res android  gt     lt item gt       lt shape android shape  rectangle  gt         lt solid android color   color white   gt       lt  shape gt     lt  item gt    lt  layer-list gt    styles xml                 lt style name  ButtonHolder  gt       lt item name  android layout height  gt wrap content lt  item gt       lt item name  android layout width  gt wrap content lt  item gt       lt item name  android background  gt  drawable buttonholder lt  item gt     lt  style gt      lt style name  Button  parent   android style Widget Button  gt       lt item name  android layout height  gt wrap content lt  item gt       lt item name  android layout width  gt wrap content lt  item gt       lt item name  android textStyle  gt bold lt  item gt     lt  style gt          However  this results in a white border because the Holo button images include margins to account for the pressed space      So the solution is to give the white background a margin  4dp worked for me  and rounded corners  2dp  to completely hide the white yet make the button solid   ButtonHolder xml   lt  xml version  1 0  encoding  utf-8   gt   lt layer-list xmlns android  http   schemas android com apk res android  gt      lt item gt       lt shape android shape  rectangle  gt         lt solid android color   android color transparent   gt       lt  shape gt     lt  item gt      lt item android top  4dp  android bottom  4dp  android left  4dp  android right  4dp  gt       lt shape android shape  rectangle  gt         lt solid android color   color white   gt         lt corners android radius  2dp    gt       lt  shape gt     lt  item gt    lt  layer-list gt    The final result looks like this      You should target this style for v14   and tweak or exclude it for Gingerbread Honeycomb because their native button image sizes are different from ICS and JB s  e g  this exact style behind a Gingerbread button results in a small bit of white below the button

User · Answer

android background   android color transparent    The above is something that I know    I think creating a custom button class is the best idea  API Level 11 Recently I came across this android alpha xml attribute which takes a value between 0 and 1  The corresponding method is setAlpha float

[android] How to Set Opacity (Alpha) for View in Android

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