A simple method to set LinearGradient as text color to TextView

GradientTextViewUtil.java

import android.graphics.Color;
import android.graphics.LinearGradient;
import android.graphics.Paint;
import android.graphics.Rect;
import android.graphics.Shader;
import android.text.Layout;
import android.widget.TextView;


public class GradientTextViewUtil {

    public static void setGradientTextColor(TextView textView, float angle, int[] colors) {
        setGradientTextColor(textView, angle, colors, null);
    }

    public static void setGradientTextColor(final TextView textView, final float angle, final int[] colors, final float[] positions) {

        textView.post(new Runnable() {
            @Override
            public void run() {

                final Rect textBound = new Rect(Integer.MAX_VALUE, Integer.MAX_VALUE, Integer.MIN_VALUE, Integer.MIN_VALUE);

                final Layout layout = textView.getLayout();
                for(int i = 0; i < textView.getLineCount(); i++) {
                    float left = layout.getLineLeft(i);
                    float right = layout.getLineRight(i);
                    if(left < textBound.left) textBound.left = (int)left;
                    if(right > textBound.right) textBound.right = (int)right;
                }
                textBound.top = layout.getLineTop(0);
                textBound.bottom = layout.getLineBottom(textView.getLineCount() - 1);
                if(textView.getIncludeFontPadding()) {
                    Paint.FontMetrics fontMetrics = textView.getPaint().getFontMetrics();
                    textBound.top += (fontMetrics.ascent - fontMetrics.top);
                    textBound.bottom -= (fontMetrics.bottom - fontMetrics.descent);
                }

                double angleInRadians = Math.toRadians(angle);

                double r = Math.sqrt(Math.pow(textBound.bottom - textBound.top, 2) +
                        Math.pow(textBound.right - textBound.left, 2)) / 2;

                float centerX = textBound.left + (textBound.right - textBound.left) / 2;
                float centerY = textBound.top + (textBound.bottom - textBound.top) / 2;

                float startX = (float)Math.max(textBound.left, Math.min(textBound.right, centerX - r * Math.cos(angleInRadians)));
                float startY = (float)Math.min(textBound.bottom, Math.max(textBound.top, centerY - r * Math.sin(angleInRadians)));

                float endX = (float)Math.max(textBound.left, Math.min(textBound.right, centerX + r * Math.cos(angleInRadians)));
                float endY = (float)Math.min(textBound.bottom, Math.max(textBound.top, centerY + r * Math.sin(angleInRadians)));

                Shader textShader = new LinearGradient(startX, startY, endX, endY, colors, positions,
                        Shader.TileMode.CLAMP);

                textView.setTextColor(Color.WHITE);
                textView.getPaint().setShader(textShader);
            }
        });
    }
}