Android对LinearLayout设置圆角及透明背景图片

1.布局文件，图片自己选择

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
tools:context=".transparentActivity">
<LinearLayout
android:id="@+id/image"
android:layout_marginTop="20dp"
android:layout_gravity="center"
android:orientation="horizontal"
android:background="@drawable/bg"
android:alpha="10"
android:layout_width="400dp"
android:layout_height="100dp">
</LinearLayout>
</LinearLayout>

2.编写设置画布的工具类Linear_Image_Radius.java

/**
* Linear设置圆角背景图片
*/
public class Linear_Image_Radius {
public static Bitmap toRoundCorner(Bitmap bitmap, int pixels) {
Bitmap output = Bitmap.createBitmap(bitmap.getWidth(), bitmap.getHeight(), Bitmap.Config.ARGB_8888);
Canvas canvas = new Canvas(output);
final int color = 0xff424242;
final Paint paint = new Paint();
//创建和原始照片一样大小的矩形
final Rect rect = new Rect(0, 0, bitmap.getWidth(), bitmap.getHeight());
final RectF rectF = new RectF(rect);
final float roundPx = pixels;
paint.setAntiAlias(true);//抗锯齿
canvas.drawARGB(0, 0, 0, 0);
//paint.setAlpha(1); //这个透明度好像不起作用，可以在主类里再设置
paint.setColor(color);
//画一个基于前面创建的矩形大小的圆角矩形
canvas.drawRoundRect(rectF, roundPx, roundPx, paint);
//设置相交模式
paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SRC_IN));
//图片画到矩形
canvas.drawBitmap(bitmap, rect, rect, paint);
return output;
}
}

3.在Activity内编写setUtils类并调用工具类，给LinearLayout设置背景图片

 private void setUtils(){
Drawable drawable = getResources().getDrawable(R.drawable.linear_bg);
BitmapDrawable bitmapDrawable = (BitmapDrawable) drawable;
Bitmap bitmap = bitmapDrawable.getBitmap();
BitmapDrawable bbb = new BitmapDrawable(Linear_Image_Radius.toRoundCorner(bitmap, 120));
bbb.setAlpha(200); //设置透明度 有效
LinearLayout image_radius_linear = findViewById(R.id.image_radius_linear);
image_radius_linear.setBackgroundDrawable(bbb);
}

设置图片也是同理

ImageView imageView =
findViewById(R.id.imageView);
imageView.setImageBitmap(MyActivity.getRoundedCornerBitmap(bitmap));
imageView.setImageBitmap(MyActivity.toRoundCorner(bitmap, 20));

最后

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