get Cubic Gradient - Android Graphics

Android examples for Graphics:Gradient Drawable

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Description

get Cubic Gradient

Demo Code


//package com.java2s;
import android.graphics.Color;
import android.graphics.LinearGradient;
import android.graphics.Shader;
import android.graphics.drawable.Drawable;
import android.graphics.drawable.PaintDrawable;
import android.graphics.drawable.ShapeDrawable;
import android.graphics.drawable.shapes.RectShape;
import android.view.Gravity;

public class Main {
    private static final int GRADIENT_NUM_STOPS = 8;
    private static final int GRADIENT_POWER = 3;

    public static Drawable getCubicGradient(int baseColor, int gravity) {
        PaintDrawable drawable = new PaintDrawable();
        drawable.setShape(new RectShape());
        setCubicGradient(drawable, baseColor, gravity);
        return drawable;
    }/*  w ww .j a  va2  s  .co m*/

    /**
     * Create a cubic gradient by using a compound gradient composed of a series of linear
     * gradients with intermediate color values.
     * adapted from: https://github.com/romannurik/muzei/blob/master/main/src/main/java/com/google/android/apps/muzei/util/ScrimUtil.java
     * @param baseColor The color from which the gradient starts (the ending color is transparent).
     * @param gravity Where the gradient should start from. Note: when making horizontal gradients,
     *                remember to use START/END, instead of LEFT/RIGHT.
     */
    public static void setCubicGradient(PaintDrawable drawable,
            int baseColor, int gravity) {
        final int[] stopColors = new int[GRADIENT_NUM_STOPS];

        int red = Color.red(baseColor);
        int green = Color.green(baseColor);
        int blue = Color.blue(baseColor);
        int alpha = Color.alpha(baseColor);

        for (int i = 0; i < GRADIENT_NUM_STOPS; i++) {
            float x = i * 1f / (GRADIENT_NUM_STOPS - 1);
            float opacity = (float) Math.pow(x, GRADIENT_POWER);
            if (opacity < 0f) {
                opacity = 0f;
            } else if (opacity > 1f) {
                opacity = 1f;
            }
            stopColors[i] = Color.argb((int) (alpha * opacity), red, green,
                    blue);
        }

        final float x0, x1, y0, y1;
        switch (gravity & Gravity.HORIZONTAL_GRAVITY_MASK) {
        case Gravity.START:
            x0 = 1;
            x1 = 0;
            break;
        case Gravity.END:
            x0 = 0;
            x1 = 1;
            break;
        default:
            x0 = 0;
            x1 = 0;
            break;
        }
        switch (gravity & Gravity.VERTICAL_GRAVITY_MASK) {
        case Gravity.TOP:
            y0 = 1;
            y1 = 0;
            break;
        case Gravity.BOTTOM:
            y0 = 0;
            y1 = 1;
            break;
        default:
            y0 = 0;
            y1 = 0;
            break;
        }

        drawable.setShaderFactory(new ShapeDrawable.ShaderFactory() {
            @Override
            public Shader resize(int width, int height) {
                return new LinearGradient(width * x0, height * y0, width
                        * x1, height * y1, stopColors, null,
                        Shader.TileMode.CLAMP);
            }
        });
    }
}

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