How to apply shadow to ImageView?

问题:

I want to apply shadow to the ImageView. When I'm applying shadow to a TextView I'm getting it but same it's not getting to ImageView. How can I solve this problem?

回答1:

We can also use CardView which provides a rounded corner background and shadow. To use that you need to add the v7 CardView library as a dependency to the project in the build.gradle like below.

dependencies {
    compile 'com.android.support:cardview-v7:23.0.1'
    -------
}

Note: Change 23.0.1 in the above line with the respected version.

So I surrounded the ImageView with CardView to make shadow like below.

<android.support.v7.widget.CardView
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    card_view:cardBackgroundColor="@android:color/white">

    <ImageView
        android:id="@+id/dish_image"
        android:layout_width="match_parent"
        android:layout_height="120dp"
        android:adjustViewBounds="true" />

</android.support.v7.widget.CardView>

It'll add a shadow around the image.

Note: I don't know whether it is a good workaround. I am a beginner. I tried to implement the CardView which gives an idea to implement the same for this. If it is not good please update me with the reason.

回答2:

This is taken from Romain Guy's presentation at Devoxx, pdf found here.

Paint mShadow = new Paint(); 
// radius=10, y-offset=2, color=black 
mShadow.setShadowLayer(10.0f, 0.0f, 2.0f, 0xFF000000); 
// in onDraw(Canvas) 
canvas.drawBitmap(bitmap, 0.0f, 0.0f, mShadow);

Hope this helps.

NOTES

Don't forget for Honeycomb and above you need to invoke setLayerType(LAYER_TYPE_SOFTWARE, mShadow), otherwise you will not see your shadow! (@Dmitriy_Boichenko)

SetShadowLayer does not work with hardware acceleration unfortunately so it greatly reduces performances (@Matt Wear)

Answer Taken from Here

For Api greater than 21. You can try in xml in imageview or Button : Read here at developer site

android:elevation="5dp"

回答3:

You can create a layer list drawable and put your two items (drawables) in it for an image and your shadow.

Your shadow item's position & content might change according to where you want to apply the shadow (top, left, right, both right & left etc) and style of your shadow.

回答4:

Create a file shadow_rect.xml

<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
    <item >
        <shape
            android:shape="rectangle">
            <solid android:color="@android:color/darker_gray" />
            <corners android:radius="0dp"/>
        </shape>
    </item>
    <item android:right="1dp"  android:bottom="2dp">
        <shape
            android:shape="rectangle">
            <solid android:color="@android:color/white"/>
            <corners android:radius="1dp"/>
        </shape>
    </item>

</layer-list>

And the use this as android:background="@drawable/shadow_rect within your Imageview.