Layout background with SweepGradient

Question

I need to create a multicolor background like in the picture. I know all colors and angles.

I try to do this with SweepGradient, but nothing change, I see only white background.

A piece of my layout

<RelativeLayout
    android:id="@+id/user_info_background"
    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">

Code in fragment:

@Override
public void onActivityCreated(@Nullable Bundle savedInstanceState) {
    super.onActivityCreated(savedInstanceState);
    mRelativeLayout.setBackground(GraphicalUtils.addSweepGradientBackground(getResources().getDisplayMetrics().widthPixels, 
    getResources().getDisplayMetrics().heightPixels,getContext()));}

Method for adding SweepGradient:

 public static Drawable addSweepGradientBackground(int width, int height, Context context){
        Bitmap bitmap = Bitmap.createBitmap(width,height,Bitmap.Config.ARGB_8888);
        Canvas canvas = new Canvas();

        SweepGradient sweepGradient = new SweepGradient(width/2,height/2,Color.RED, Color.BLUE);

        Paint paint = new Paint();
        paint.setShader(sweepGradient);
        paint.setStyle(Paint.Style.FILL);
        paint.setAntiAlias(true);
        canvas.drawBitmap(bitmap,0,0,paint);

        return new BitmapDrawable(context.getResources(), bitmap);

    }

score 1 · Accepted Answer · answered Nov 29 '17 at 09:01

Try this:

public static Drawable addSweepGradientBackground(int width, int height, Context context){
    Bitmap bitmap = Bitmap.createBitmap(width,height,Bitmap.Config.ARGB_8888);
    Canvas canvas = new Canvas(bitmap);

    SweepGradient sweepGradient = new SweepGradient(width/2,height/2,Color.RED, Color.BLUE);

    Paint paint = new Paint();
    paint.setShader(sweepGradient);
    paint.setStyle(Paint.Style.FILL);
    paint.setAntiAlias(true);
    canvas.drawBitmap(bitmap,0,0,null);
    canvas.drawCircle(width/2,height/2, width/2, paint)

    return new BitmapDrawable(context.getResources(), bitmap);

}

the canvas should be bound with bitmap ,and you need draw the circle with the paint which has sweepGradient on the bitmap.

Joe, thank you it works. What do you think I can draw such a background with SweepGradient? — Delphian, Nov 29 '17 at 09:13
Of course , use `SweepGradient(float cx, float cy, int[] colors, float[] positions)` this method to control the color change. — Robbit, Nov 29 '17 at 09:20

Layout background with SweepGradient

1 Answers1