Setting transparency for widget background

Question

I have a homescreen widget, with linear layout. I'm trying to set Alpha for the background during runtime using remote views, but the widget doesn't load.

I'm using this:

remoteView.setFloat(R.id.widget_background, "setAlpha", (float)0.7);

Setting background color or text color the same way, works. How can I set the background transparency using remote views?

score 3 · Answer 1 · answered Jan 29 '16 at 09:22

There is a simple solution using background color in hex. You have a color, for example RED - #ff0000

to set background red to your app widget, you can use:

widget.setInt(R.id.widget_list, "setBackgroundColor", Color.parseColor("#ff0000"));

for color transparency just add in front of your color how much color - transparency rapport you want, for example:

for 20% color will be #20ff0000:

for 85% color #85ff0000 wou'll have:

porlicus · Answer 2 · 2015-01-29T14:08:55.987

I used the following solution:

float opacity = 0.3f;           //opacity = 0: fully transparent, opacity = 1: no transparancy
int backgroundColor = 0x000000; //background color (here black)
remoteView.setInt( R.id.loMain, "setBackgroundColor", (int)(opacity * 0xFF) << 24 | backgroundColor);

loMain is a main layout of my widget

If the main layout of the widget uses shape background (e.g. android:background="@drawable/shape_transparent") which has rounded corner then here is a more complex solution:

        float transparency = 0.5f;  //0...1
        long colorFilter = 0x01000000L * (long)(255f * transparency);   
        try {
            final Method[] declaredMethods = Class.forName("android.widget.RemoteViews").getDeclaredMethods();
            final int len = declaredMethods.length;
            if (len > 0) {
                for (int m=0; m<len; m++ ) {
                    final Method method = declaredMethods[m];
                    if (method.getName().equals("setDrawableParameters")) {
                        method.setAccessible(true);
                        method.invoke(remoteView, R.id.loMain, true, -1, (int)colorFilter, PorterDuff.Mode.DST_OUT, -1);
                        break;
                    }
                }
            }
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (InvocationTargetException e) {
            e.printStackTrace();
        } catch (IllegalAccessException e) {
            e.printStackTrace();
        } catch (IllegalArgumentException e) {
            e.printStackTrace();
        }

You can play with variables alfa and colorFilter to meet your needs.

score 1 · Answer 3 · answered Jun 19 '13 at 10:00

1.You can use Style.xml to make a backgound transparent like below:

<?xml version="1.0" encoding="utf-8"?>
<resources>
  <style name="Theme.Transparent" parent="android:Theme">
    <item name="android:windowIsTranslucent">true</item>
    <item name="android:windowBackground">@android:color/transparent</item>
    <item name="android:windowContentOverlay">@null</item>
    <item name="android:windowNoTitle">true</item>
    <item name="android:windowIsFloating">true</item>
    <item name="android:backgroundDimEnabled">false</item>
  </style>
</resources>

Set this file as a theme of your widget. OR 2.Put 80 after # sign in your color code like this:#80000000 Hope it helps..You can use #80FFFFFF for background without any color.I have not tried it in code but may be its helpful.

But I would like to change the transparency dynamically. When the user selects transparency (from 0 to 1), the widget updates. — domen, Jun 19 '13 at 11:10
For that you can use HashMap of colors where color will be value and 1 to 10 will be your key for that as second option I have given in answer.And set background color from that key of hashmap as per user choice.For that you need different color code as per transparency.From black to white or whatever you like to add. — AndiM, Jun 19 '13 at 11:15

score 1 · Answer 4 · answered Aug 10 '14 at 09:42

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:orientation="vertical"
    android:background="@android:color/transparent">


    <ImageView
        android:id="@+id/widget_image"
        android:layout_width="110sp"
        android:layout_height="110sp"
        android:layout_gravity="center"
        android:src="@drawable/flashlight1" />
</LinearLayout>

Just set background of layout to transparent. Add below code. this worked for me.

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

score 1 · Answer 5 · edited May 23 '17 at 12:10

Set transparent background of an imageview on Android

Above link is the best solution for this type of Background Color.

Below code for black:-

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

Now if u want to use opacity than you can use below code :-

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

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

Setting transparency for widget background

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