How to change the background colour gradient of view dynamically

Question

I want to make a custom view for my android app which has a functionality to change its background colour "gradient".

Something like this, but the centre handle can be moved left and right using code

The catch is that I want a function something like in the view:

changeBackgroundGradient(ratio, startColour, centreColour, endColour);

ratio (having value between 0 to 1) which is given by formula leftValue/rightValue determining the shape of the gradient

startColour, centreColour and endColour being the colours of which the gradient consists of

How would i make this function?

Regards

Answer 1

You can try below code as this is working for me to change my toolbar color dynamically

private void setGradientColor(View header)
{
    String primaryColor = "#f4f3f2"; // any color code
    String primaryDarkColor = "#000000";

    GradientDrawable gd = new GradientDrawable (
    GradientDrawable.Orientation.BR_TL, // check below link for this you can change this value 
    new int[] { 
        Color.parseColor(primaryColor),
        Color.parseColor(primaryDarkColor)
        }
    );

    gd.setCornerRadius(1f);

    header.setBackground(gd);
}

Update

Check this for more options to apply gradient color in view.

Answer 2

You can try following function. Add these functions in your activity file.

       private Drawable getGradientDrawable()
        {
            GradientDrawable gradient = new GradientDrawable();
            gradient.setGradientType(GradientDrawable.LINEAR_GRADIENT);
            gradient.setColors(new int[]{getRandomHSVColor(), getRandomHSVColor()});
            return gradient;
        }


        protected int getRandomHSVColor(){
            // Generate a random hue value between 0 to 360
            int hue = mRandom.nextInt(361);
            // We make the color depth full
            float saturation = 1.0f;
            // We make a full bright color
            float value = 1.0f;
            // We avoid color transparency
            int alpha = 255;
            // Finally, generate the color
            int color = Color.HSVToColor(alpha, new float[]{hue, saturation, value});
            // Return the color
            return color;
        }
        // Custom method to get a lighter color
        protected int getLighterColor(int color){
            float[] hsv = new float[3];
            Color.colorToHSV(color,hsv);
            hsv[2] = 0.2f + 0.8f * hsv[2];
            return Color.HSVToColor(hsv);
        }

        // Custom method to get reverse color
        protected int getReverseColor(int color){
            float[] hsv = new float[3];
            Color.RGBToHSV(
                    Color.red(color), // Red value
                    Color.green(color), // Green value
                    Color.blue(color), // Blue value
                    hsv
            );
            hsv[0] = (hsv[0] + 180) % 360;
            return Color.HSVToColor(hsv);
        }

Than use this function like below:

your_layout_name..setBackground(getGradientDrawable());