activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <Button
        android:id="@+id/button_pick"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="8dp"
        android:layout_marginTop="8dp"
        android:layout_marginEnd="8dp"
        android:layout_marginBottom="16dp"
        android:text="@string/pick_color"
        app:layout_constraintBottom_toTopOf="@+id/picked_color_heading"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintVertical_chainStyle="packed" />

    <TextView
        android:id="@+id/picked_color_heading"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="8dp"
        android:layout_marginLeft="8dp"
        android:layout_marginTop="16dp"
        android:layout_marginEnd="8dp"
        android:layout_marginRight="8dp"
        android:layout_marginBottom="4dp"
        android:text="@string/picked_color"
        app:layout_constraintBottom_toTopOf="@+id/picked_color"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/button_pick" />

    <View
        android:id="@+id/picked_color"
        android:layout_width="40dp"
        android:layout_height="40dp"
        android:layout_marginStart="8dp"
        android:layout_marginTop="4dp"
        android:layout_marginEnd="8dp"
        android:layout_marginBottom="8dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/picked_color_heading" />
</android.support.constraint.ConstraintLayout>

area_picker.xml

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <integer name="thumb_radius">15</integer>
    <color name="thumb_color">@color/colorAccent</color>
</resources>

AreaPicker.java

package com.example.colorpicker.Views;

import android.annotation.SuppressLint;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.drawable.Drawable;
import android.graphics.drawable.GradientDrawable;
import android.graphics.drawable.InsetDrawable;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;

import com.example.colorpicker.R;


public class AreaPicker extends View {
    private OnPickedListener onPickedListener = null;

    private InsetDrawable backgroundDrawable;
    private static int thumbRadius, padding;
    private Paint thumb_paint;

    private float x, y;

    public AreaPicker(Context context) {
        super(context);
        init();
    }

    public AreaPicker(Context context, AttributeSet attrs) {
        super(context, attrs);
        init();
    }

    public AreaPicker(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        init();
    }

    private void init(){
        setFocusable(true);
        setFocusableInTouchMode(true);

        thumb_paint = new Paint();
        thumb_paint.setStyle(Paint.Style.FILL);
        thumb_paint.setColor(getContext().getColor(R.color.thumb_color));

        thumbRadius = getResources().getInteger(R.integer.thumb_radius);
        padding = thumbRadius * 2;

        // On utilise un InsetDrawable comme arrière-plan, pour que, lorsque l'usager fournira son
        // propre Drawable à afficher dans le plan de sélection, celui-ci ne se rendent pas
        // jusqu'au bord du View, mais plutôt laisse une petite marge pour que le le marqueur de
        // sélection puisse déborder du plan de sélection sans déborder du View.
        backgroundDrawable = new InsetDrawable(new GradientDrawable(), padding);
        setBackground(backgroundDrawable);
    }

    public void setInsetDrawable(Drawable dr){
        backgroundDrawable.setDrawable(dr);
    }

    @SuppressLint("ClickableViewAccessibility")
    @Override
    public boolean onTouchEvent(MotionEvent event) {
        if (!isEnabled()) {
            return false;
        }

        x = screen_to_frac_coord(event.getX(), getWidth());
        y = screen_to_frac_coord(event.getY(), getHeight());

        onChange(true);
        return true;
    }

    public void setMaxX(int newMaxX){
        /* IMPLÉMENTER CETTE MÉTHODE */
    }

    public void setMaxY(int newMaxY){
        /* IMPLÉMENTER CETTE MÉTHODE */
    }

    public int getPickedX(){
        /* IMPLÉMENTER CETTE MÉTHODE */
        return 0;
    }

    public int getPickedY(){
        /* IMPLÉMENTER CETTE MÉTHODE */
        return 0;
    }

    public void setPickedX(int newX){
        /* IMPLÉMENTER CETTE MÉTHODE */
    }

    public void setPickedY(int newY){
        /* IMPLÉMENTER CETTE MÉTHODE */
    }

    // Cette fonction doit être appelée immédiatement après que la coordonnée
    // représentée par cet AreaPicker a été mise à jour.
    // (Bref, dès que this.x et/ou this.y a changé, il faut appeler onChange.)
    private void onChange(boolean fromUser){
        if(onPickedListener != null){
            onPickedListener.onPicked(this, getPickedX(), getPickedY(), fromUser);
        }

        invalidate();
    }

    // S'assure que value est entre 0 et 1.
    private float unitClamp(float value){
        return Math.max(0, Math.min(1, value));
    }

    // Convertit une coordonnée exprimée en espace-écran en une coordonée
    // exprimée en fraction de l'étendue (0 à 1).
    private float screen_to_frac_coord(float screen_coord, float screen_range){
        float frac_coord = (screen_coord - padding) / (screen_range - 2 * padding);
        return unitClamp(frac_coord);
    }

    // Convertit une coordonnée exprimée en fraction de l'étendue (0 à 1) en espace-écran.
    private float frac_to_screen_coord(float frac_coord, float screen_range){
        return frac_coord * (screen_range - 2 * padding) + padding;
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);

        float ax = frac_to_screen_coord(x, getWidth());
        float ay = frac_to_screen_coord(y, getHeight());

        canvas.drawCircle(ax, ay, thumbRadius, thumb_paint);
    }

    public void setOnPickedListener(OnPickedListener onPickedListener){
        this.onPickedListener = onPickedListener;
    }

    public interface OnPickedListener{
        void onPicked(AreaPicker areaPicker, int x, int y, boolean fromUser);
    }
}

checker.xml

<?xml version="1.0" encoding="utf-8"?>
<bitmap
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:src="@drawable/checkers"
    android:tileMode="repeat"
    />

ColoredSeekBar.java

package com.example.colorpicker;

import android.content.Context;
import android.graphics.Color;
import android.graphics.drawable.GradientDrawable;
import android.support.annotation.ColorInt;
import android.support.v7.widget.AppCompatSeekBar;
import android.util.AttributeSet;


public class ColoredSeekBar extends AppCompatSeekBar {
    GradientDrawable gd;

    public ColoredSeekBar(Context context) {
        super(context);
        init();
    }

    public ColoredSeekBar(Context context, AttributeSet attrs) {
        super(context, attrs);
        init();
    }

    public ColoredSeekBar(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        init();
    }

    void init(){
        gd = new GradientDrawable();
        setProgressDrawable(gd);
    }

    public void setColor(@ColorInt int leftColor, @ColorInt int rightcolor) {
        gd = new GradientDrawable(GradientDrawable.Orientation.LEFT_RIGHT,
                new int[] {leftColor, rightcolor});
        setProgressDrawable(gd);
    }
}

ColorPickerDialog.java

package com.example.colorpicker;

import android.annotation.SuppressLint;
import android.app.AlertDialog;
import android.content.Context;
import android.graphics.Color;
import android.graphics.drawable.GradientDrawable;
import android.support.annotation.ColorInt;
import android.util.Log; // todo: delete before remise
import android.view.LayoutInflater;
import android.view.View;
import android.widget.SeekBar;

import com.example.colorpicker.Views.AreaPicker;


class ColorPickerDialog extends AlertDialog {
    private static final String TAG = "JTAG"; // todo: delete before remise
    private final static int MAX_RGB_VALUE = 255;
    private final static int MAX_SV_VALUE  = 100;
    private final static int MAX_H_VALUE   = 360;

    private AreaPicker seekSV;
    private SaturationValueGradient saturationValueGradient;
    private OnColorPickedListener onColorPickedListener = null;

    /* Seekbars. */
    private ColoredSeekBar rainbowSeekBar;
    public ColoredSeekBar rSeekBar;
    private ColoredSeekBar gSeekBar;
    private ColoredSeekBar bSeekBar;
    private ColoredSeekBar aSeekBar;

    // Représentation/stockage interne de la couleur présentement sélectionnée par le Dialog.
    private int a, r, g, b;
    // todo: for alpha, see  https://stackoverflow.com/questions/15319635/manipulate-alpha-bytes-of-java-android-color-int



    ColorPickerDialog(Context context) {
        super(context);
        init(context);
    }

    ColorPickerDialog(Context context, int themeResId) {
        super(context, themeResId);
        init(context);
    }

    ColorPickerDialog(Context context, boolean cancelable, OnCancelListener cancelListener) {
        super(context, cancelable, cancelListener);
        init(context);
    }


    private void init(Context context) {
        /* CETTE MÉTHODE DEVRA ÊTRE MODIFIÉE */

        // Initialize dialog
        @SuppressLint("InflateParams")
        View v = LayoutInflater.from(context).inflate(R.layout.dialog_picker, null);
        setView(v);

        /* Set up SeekBar variables. */
        rainbowSeekBar = v.findViewById(R.id.seekH);
        rSeekBar       = v.findViewById(R.id.seekR);
        gSeekBar       = v.findViewById(R.id.seekG);
        bSeekBar       = v.findViewById(R.id.seekB);
        aSeekBar       = v.findViewById(R.id.seekA);

        // Initialize SV gradient
        seekSV = v.findViewById(R.id.seekSV);
        saturationValueGradient = new SaturationValueGradient();
        seekSV.setInsetDrawable(saturationValueGradient);

        /* Setting up Gradients of SeekBars. */
        rSeekBar.setColor(Color.BLACK, Color.RED);
        rSeekBar.setOnSeekBarChangeListener(rListener);
        rSeekBar.setMax(MAX_RGB_VALUE);

        gSeekBar.setColor(Color.BLACK, Color.GREEN);
        gSeekBar.setOnSeekBarChangeListener(gListener);
        gSeekBar.setMax(MAX_RGB_VALUE);

        bSeekBar.setColor(Color.BLACK, Color.BLUE);
        bSeekBar.setOnSeekBarChangeListener(bListener);
        bSeekBar.setMax(MAX_RGB_VALUE);

        aSeekBar.setBackground(context.getDrawable(R.drawable.checker));
        aSeekBar.setColor(Color.parseColor("#00000000"),
                Color.parseColor("#FF000000"));
//        aSeekBar.getProgressDrawable().setColorFilter(Color.RED, PorterDuff.Mode.DST_IN);
//        aSeekBar.setProgressDrawable(context.getDrawable(R.drawable.seekbar_layers));
        aSeekBar.setMax(MAX_RGB_VALUE);

        // adapted from  https://stackoverflow.com/a/32990741/9768291
        GradientDrawable rainbow = new GradientDrawable(
                GradientDrawable.Orientation.RIGHT_LEFT,
                new int[] {Color.RED, Color.MAGENTA, Color.BLUE,
                        Color.CYAN, Color.GREEN, Color.YELLOW, Color.RED});
        rainbowSeekBar.setProgressDrawable(rainbow);
        rainbowSeekBar.setOnSeekBarChangeListener(rainbowListener);
        rainbowSeekBar.setMax(MAX_H_VALUE); // todo: is that it?


        // Exemple pour afficher un gradient SV centré sur du rouge pur.
        saturationValueGradient.setColor(Color.RED);

        // Default color
        setColor(getContext().getColor(R.color.defaultColor));
    }

    @ColorInt int getColor() {
        /* IMPLÉMENTER CETTE MÉTHODE
         * Elle doit retourner la couleur présentement sélectionnée par le dialog.
         * */

        a = aSeekBar.getProgress();
        r = rSeekBar.getProgress();
        g = gSeekBar.getProgress();
        b = bSeekBar.getProgress();

        Log.w(TAG, "getColor() :  rgb=" + Color.rgb(r,g,b));

        return Color.argb(a, r, g, b);
    }

    public void setColor(@ColorInt int newColor) {
        /* IMPLÉMENTER CETTE MÉTHODE
         * Elle doit mettre à jour l'état du dialog pour que la couleur
         * sélectionnée corresponde à "newColor".
         * */

        Log.w(TAG, "from int: " + newColor +
                " | a: " + Color.alpha(newColor) +
                " | r: " + Color.red  (newColor) +
                " | g: " + Color.green(newColor) +
                " | b: " + Color.blue (newColor));
        rSeekBar.setProgress(Color.red  (newColor));
        gSeekBar.setProgress(Color.green(newColor));
        bSeekBar.setProgress(Color.blue (newColor));
//        aSeekBar.setProgress(Color.red(newColor));
    }

    static private int[] HSVtoRGB(int h, int s, int v) {
        /* IMPLÉMENTER CETTE MÉTHODE
         * Elle doit convertir un trio de valeurs HSL à un trio de valeurs RGB
         * */

        return new int[3];
    }

    static private int[] RGBtoHSV(int r, int g, int b) {
        /* IMPLÉMENTER CETTE MÉTHODE
         * Elle doit convertir un trio de valeurs RGB à un trio de valeurs HSL
         * */

        return new int[3];
    }

    public void setOnColorPickedListener(OnColorPickedListener onColorPickedListener) {
        /* IMPLÉMENTER CETTE MÉTHODE
         * Elle doit enregistrer un "OnColorPickedListener", qui sera appelé,
         * éventuellement, lorsque le bouton "ok" du dialog sera cliqué.
         * */
        this.onColorPickedListener = onColorPickedListener;
    }

    public interface OnColorPickedListener {
        void onColorPicked(ColorPickerDialog colorPickerDialog, @ColorInt int color);
    }



    /* SeekBars's Listeners. */

    private SeekBar.OnSeekBarChangeListener rainbowListener = new SeekBar.OnSeekBarChangeListener() {
        @Override
        public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) {
            saturationValueGradient.setColor(Color.rgb(progress, progress, progress)); // todo: fix
        }
        @Override
        public void onStartTrackingTouch(SeekBar seekBar) { }
        @Override
        public void onStopTrackingTouch(SeekBar seekBar) { }
    };

    private SeekBar.OnSeekBarChangeListener rListener = new SeekBar.OnSeekBarChangeListener() {
        @Override
        public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) {
            r = progress;
        }
        @Override
        public void onStartTrackingTouch(SeekBar seekBar) { }
        @Override
        public void onStopTrackingTouch(SeekBar seekBar) { }
    };

    private SeekBar.OnSeekBarChangeListener gListener = new SeekBar.OnSeekBarChangeListener() {
        @Override
        public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) {
            g = progress;
        }
        @Override
        public void onStartTrackingTouch(SeekBar seekBar) { }
        @Override
        public void onStopTrackingTouch(SeekBar seekBar) { }
    };

    private SeekBar.OnSeekBarChangeListener bListener = new SeekBar.OnSeekBarChangeListener() {
        @Override
        public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) {
            b = progress;
        }
        @Override
        public void onStartTrackingTouch(SeekBar seekBar) { }
        @Override
        public void onStopTrackingTouch(SeekBar seekBar) { }
    };
}

dialog_picker.xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <TextView
        android:id="@+id/headerHSV"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginBottom="8dp"
        android:gravity="center_horizontal"
        android:text="@string/hsv"
        app:layout_constraintBottom_toTopOf="@+id/seekSV"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <com.example.colorpicker.Views.AreaPicker
        android:id="@+id/seekSV"
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:layout_marginBottom="8dp"
        app:layout_constraintBottom_toTopOf="@+id/seekH"
        app:layout_constraintDimensionRatio="W,1:1"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/headerHSV"
        app:layout_constraintVertical_weight="1" />

    <com.example.colorpicker.ColoredSeekBar
        android:id="@+id/seekH"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginBottom="8dp"
        android:splitTrack="false"
        app:layout_constraintBottom_toTopOf="@+id/separator1"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/seekSV" />

    <View
        android:id="@+id/separator1"
        android:layout_width="0dp"
        android:layout_height="1dp"
        android:layout_marginBottom="8dp"
        android:background="?android:attr/listDivider"
        app:layout_constraintBottom_toTopOf="@+id/headerRGB"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/seekH" />

    <TextView
        android:id="@+id/headerRGB"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginBottom="8dp"
        android:gravity="center_horizontal"
        android:text="@string/rgb"
        app:layout_constraintBottom_toTopOf="@+id/seekR"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/separator1" />

    <com.example.colorpicker.ColoredSeekBar
        android:id="@+id/seekR"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginBottom="8dp"
        android:splitTrack="false"
        app:layout_constraintBottom_toTopOf="@+id/seekG"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/headerRGB" />

    <com.example.colorpicker.ColoredSeekBar
        android:id="@+id/seekG"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginBottom="8dp"
        android:splitTrack="false"
        app:layout_constraintBottom_toTopOf="@+id/seekB"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/seekR" />

    <com.example.colorpicker.ColoredSeekBar
        android:id="@+id/seekB"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginBottom="8dp"
        android:splitTrack="false"
        app:layout_constraintBottom_toTopOf="@+id/separator2"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/seekG"/>

    <View
        android:id="@+id/separator2"
        android:layout_width="0dp"
        android:layout_height="1dp"
        android:layout_marginBottom="8dp"
        android:background="?android:attr/listDivider"
        app:layout_constraintBottom_toBottomOf="@+id/headerAlpha"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/seekB" />

    <TextView
        android:id="@+id/headerAlpha"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginBottom="8dp"
        android:gravity="center_horizontal"
        android:text="@string/alpha"
        app:layout_constraintBottom_toTopOf="@+id/seekA"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/separator2" />

    <com.example.colorpicker.ColoredSeekBar
        android:id="@+id/seekA"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginBottom="8dp"
        android:splitTrack="false"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/headerAlpha" />

</android.support.constraint.ConstraintLayout>

MainActivity.java

package com.example.colorpicker;

import android.support.annotation.ColorInt;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Toast; // todo: delete before remise

import static android.content.DialogInterface.BUTTON_NEGATIVE;
import static android.content.DialogInterface.BUTTON_POSITIVE;


public class MainActivity extends AppCompatActivity implements ColorPickerDialog.OnColorPickedListener {

    View colorPicked;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        /* CETTE MÉTHODE DEVRA ÊTRE MODIFIÉE */


        /* Set up the ColorPicked square. */
        colorPicked = findViewById(R.id.picked_color);
        colorPicked.setBackground(getDrawable(R.drawable.checker));
        /* todo: initial color of "colorPicked" square (Color.BLACK ?)
        colorPicked.setBack */

        /* Set up the Dialog. */
        ColorPickerDialog dialog = new ColorPickerDialog(this);
        dialog.setTitle(R.string.pick_color);
        dialog.setOnColorPickedListener(this);
        dialog.setButton(BUTTON_POSITIVE,
                getResources().getString(android.R.string.ok),
                (d,which) -> onColorPicked(dialog, dialog.getColor()));
        dialog.setButton(BUTTON_NEGATIVE,
                getResources().getString(android.R.string.cancel),
                (d,which) -> Toast.makeText(this, "dwewd3", Toast.LENGTH_SHORT).show());

        findViewById(R.id.button_pick).setOnClickListener((View v) -> dialog.show());
    }

    @Override
    public void onColorPicked(ColorPickerDialog colorPickerDialog, @ColorInt int color) {
        colorPicked.setBackgroundColor(color);
    }
}

SaturationValueGradient.java

package com.example.colorpicker;

import android.graphics.Color;
import android.graphics.drawable.GradientDrawable;
import android.graphics.drawable.LayerDrawable;
import android.support.annotation.ColorInt;

public class SaturationValueGradient extends LayerDrawable {
    private GradientDrawable saturationGradient;

    private static GradientDrawable[] prepareLayers(){
        // Le dégradé 2D du AreaPicker est créé en superposant 2 dégradés linéaires. Un à
        // l'horizontal, et l'autre vertical. Le dégradé du dessus est dégrade entre noir et
        // transparent, de telle sorte à ce qu'il laisse progressivement transparaître le dégradé
        // en dessous de lui. Seul le dégradé du dessous, qui va de blanc à la couleur
        // pleinement saturée, a besoin d'être modifié. C'est "hacky", mais ça marche!

        // Color layer
        GradientDrawable saturationGradient = new GradientDrawable();
        saturationGradient.setOrientation(GradientDrawable.Orientation.LEFT_RIGHT);

        // Black and white layer
        GradientDrawable valueGradient = new GradientDrawable();
        valueGradient.setOrientation(GradientDrawable.Orientation.TOP_BOTTOM);
        valueGradient.setColors(new int[] {Color.TRANSPARENT, Color.BLACK});
        valueGradient.setStroke(1, Color.BLACK);

        return new GradientDrawable[]{saturationGradient, valueGradient};
    }

    public SaturationValueGradient() {
        super(prepareLayers());
        saturationGradient = (GradientDrawable)this.getDrawable(0);
    }

    public SaturationValueGradient(@ColorInt int color) {
        this();
        setColor(color);
    }

    public void setColor(@ColorInt int color) {
        saturationGradient.setColors(new int[] {Color.WHITE, color});
    }
}