How can I make an image transparent on Android?_问答_开发者

I am using a linear layout and frame layout. In the linear layout I keep an image as background and in the frame layout I keep an imageView. In that imageView I give an image.

Now I want to make the second image 开发者_运维知识库(that is in the imageView) transparent. How can I do this?

Try this:

ImageView myImage = (ImageView) findViewById(R.id.myImage);
myImage.setAlpha(127); //value: [0-255]. Where 0 is fully transparent and 255 is fully opaque.

Note: setAlpha(int) is deprecated in favor of setAlpha(float) where 0 is fully transparent and 1 is fully opaque. Use it like: myImage.setAlpha(0.5f)

android:alpha does this in XML:

<ImageView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:src="@drawable/blah"
    android:alpha=".75"/>

Set an id attribute on the ImageView:

<ImageView android:id="@+id/myImage"

In your code where you wish to hide the image, you'll need the following code.

First, you'll need a reference to the ImageView:

ImageView myImage = (ImageView) findViewById(R.id.myImage);

Then, set Visibility to GONE:

myImage.setVisibility(View.GONE);

If you want to have code elsewhere that makes it visible again, just set it to Visible the same way:

myImage.setVisibility(View.VISIBLE);

If you mean "fully transparent", the above code works. If you mean "partially transparent", use the following method:

int alphaAmount = 128; // Some value 0-255 where 0 is fully transparent and 255 is fully opaque
myImage.setAlpha(alphaAmount);

If you are in an XML file, use the following to make your imageview transparent!

 android:background="@null"

On newer versions of Android (post Android 4.2 (Jelly Bean) at least), the setAlpha(int value) method is depreciated. Instead, use the setAlpha(float value) method that takes a float between 0 and 1 where 0 is complete transparency and 1 is no transparency.

Set transparency using setAlpha(float alpha). The below code works for me were I used an alpha value in float, 0 - 1.

0: Full Transparent
0.5 - 50%: Transparent
1: Full Opaque

ImageView imageView = (ImageView) itemView.findViewById(R.id.imageView); imageView.setImageResource(mResources[position]); imageView.setAlpha(.80f);

As setAlpha int has been deprecated, setImageAlpha (int) can be used

ImageView img = (ImageView) findViewById(R.id.img_image);
img.setImageAlpha(127); //value: [0-255]. Where 0 is fully transparent and 255 is fully opaque.

The method setAlpha(int) from the type ImageView is deprecated.

Instead of

image.setImageAlpha(127);
//value: [0-255]. Where 0 is fully transparent and 255 is fully opaque.

In XML, use:

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

Image alpha sets just opacity to ImageView which makes Image blurry, try adding tint attribute in ImageView

 android:tint="#66000000"

It can also be done programatically :

imageView.setColorFilter(R.color.transparent);

where you need to define transparent color in your colors.xml

<color name="transparent">#66000000</color>

For 20% transparency, this worked for me:

Button bu = (Button)findViewById(R.id.button1);
bu.getBackground().setAlpha(204);

Use:

ImageView image = (ImageView) findViewById(R.id.image);
image.setAlpha(150); // Value: [0-255]. Where 0 is fully transparent
                     // and 255 is fully opaque. Set the value according
                     // to your choice, and you can also use seekbar to
                     // maintain the transparency.

You can easily do this in your XML file by this code: