Android 中如何给图片添加圆角

在Android开发中，经常需要对图片进行处理，其中一种常见的需求就是给图片添加圆角。给图片添加圆角可以使图片看起来更加美观，增加用户的视觉体验。本文将介绍在Android中如何给图片添加圆角，并提供相应的案例代码。

java
public class RoundedCornerDrawable extends Drawable {
    private final Paint mPaint;
    private final RectF mRectF;
    private final int mCornerRadius;
    public RoundedCornerDrawable(int cornerRadius, int backgroundColor) {
        mPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
        mPaint.setColor(backgroundColor);
        mRectF = new RectF();
        mCornerRadius = cornerRadius;
    }
    @Override
    public void draw(Canvas canvas) {
        canvas.drawRoundRect(mRectF, mCornerRadius, mCornerRadius, mPaint);
    }
    @Override
    public void setAlpha(int alpha) {
        mPaint.setAlpha(alpha);
    }
    @Override
    public void setColorFilter(ColorFilter colorFilter) {
        mPaint.setColorFilter(colorFilter);
    }
    @Override
    public int getOpacity() {
        return PixelFormat.TRANSLUCENT;
    }
    @Override
    protected void onBoundsChange(Rect bounds) {
        super.onBoundsChange(bounds);
        mRectF.set(bounds);
    }
}

xml
    android:id="@+id/imageView"
    android:layout_width="200dp"
    android:layout_height="200dp"
    android:background="@drawable/rounded_corner_drawable"
    android:src="@drawable/image" />

java
public class MainActivity extends AppCompatActivity {
    private ImageView mImageView;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mImageView = findViewById(R.id.imageView);
        mImageView.setBackground(new RoundedCornerDrawable(20, Color.GRAY));
        mImageView.setImageResource(R.drawable.image);
    }
}