Color picker with usage in android

Question

Can someone provide me some code of a color picker and it's usage in android?

I found some example here Android Color Picker, but I don't know how to use it :(

Please help me, thanks

Answer 1

Color Picker dialog.

public class ColorPickerDialog extends Dialog {

public interface OnColorChangedListener {
    void colorChanged(int color);
}

private OnColorChangedListener mListener;
private int mInitialColor;

private static class ColorPickerView extends View {
    private Paint mPaint;
    private Paint mCenterPaint;
    private final int[] mColors;
    private OnColorChangedListener mListener;

    ColorPickerView(Context c, OnColorChangedListener l, int color) {
        super(c);
        mListener = l;
        mColors = new int[] {
            0xFFFF0000, 0xFFFF00FF, 0xFF0000FF, 0xFF00FFFF, 0xFF00FF00,
            0xFFFFFF00, 0xFFFF0000
        };
        Shader s = new SweepGradient(0, 0, mColors, null);

        mPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
        mPaint.setShader(s);
        mPaint.setStyle(Paint.Style.STROKE);
        mPaint.setStrokeWidth(32);

        mCenterPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
        mCenterPaint.setColor(color);
        mCenterPaint.setStrokeWidth(5);
    }

    private boolean mTrackingCenter;
    private boolean mHighlightCenter;

    @Override
    protected void onDraw(Canvas canvas) {
        float r = CENTER_X - mPaint.getStrokeWidth()*0.5f;

        canvas.translate(CENTER_X, CENTER_X);

        canvas.drawOval(new RectF(-r, -r, r, r), mPaint);
        canvas.drawCircle(0, 0, CENTER_RADIUS, mCenterPaint);

        if (mTrackingCenter) {
            int c = mCenterPaint.getColor();
            mCenterPaint.setStyle(Paint.Style.STROKE);

            if (mHighlightCenter) {
                mCenterPaint.setAlpha(0xFF);
            } else {
                mCenterPaint.setAlpha(0x80);
            }
            canvas.drawCircle(0, 0,
                              CENTER_RADIUS + mCenterPaint.getStrokeWidth(),
                              mCenterPaint);

            mCenterPaint.setStyle(Paint.Style.FILL);
            mCenterPaint.setColor(c);
        }
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        setMeasuredDimension(CENTER_X*2, CENTER_Y*2);
    }

    private static final int CENTER_X = 100;
    private static final int CENTER_Y = 100;
    private static final int CENTER_RADIUS = 32;

    private int floatToByte(float x) {
        int n = java.lang.Math.round(x);
        return n;
    }
    private int pinToByte(int n) {
        if (n < 0) {
            n = 0;
        } else if (n > 255) {
            n = 255;
        }
        return n;
    }

    private int ave(int s, int d, float p) {
        return s + java.lang.Math.round(p * (d - s));
    }

    private int interpColor(int colors[], float unit) {
        if (unit <= 0) {
            return colors[0];
        }
        if (unit >= 1) {
            return colors[colors.length - 1];
        }

        float p = unit * (colors.length - 1);
        int i = (int)p;
        p -= i;

        // now p is just the fractional part [0...1) and i is the index
        int c0 = colors[i];
        int c1 = colors[i+1];
        int a = ave(Color.alpha(c0), Color.alpha(c1), p);
        int r = ave(Color.red(c0), Color.red(c1), p);
        int g = ave(Color.green(c0), Color.green(c1), p);
        int b = ave(Color.blue(c0), Color.blue(c1), p);

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

    private int rotateColor(int color, float rad) {
        float deg = rad * 180 / 3.1415927f;
        int r = Color.red(color);
        int g = Color.green(color);
        int b = Color.blue(color);

        ColorMatrix cm = new ColorMatrix();
        ColorMatrix tmp = new ColorMatrix();

        cm.setRGB2YUV();
        tmp.setRotate(0, deg);
        cm.postConcat(tmp);
        tmp.setYUV2RGB();
        cm.postConcat(tmp);

        final float[] a = cm.getArray();

        int ir = floatToByte(a[0] * r +  a[1] * g +  a[2] * b);
        int ig = floatToByte(a[5] * r +  a[6] * g +  a[7] * b);
        int ib = floatToByte(a[10] * r + a[11] * g + a[12] * b);

        return Color.argb(Color.alpha(color), pinToByte(ir),
                          pinToByte(ig), pinToByte(ib));
    }

    private static final float PI = 3.1415926f;

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        float x = event.getX() - CENTER_X;
        float y = event.getY() - CENTER_Y;
        boolean inCenter = java.lang.Math.sqrt(x*x + y*y) <= CENTER_RADIUS;

        switch (event.getAction()) {
            case MotionEvent.ACTION_DOWN:
                mTrackingCenter = inCenter;
                if (inCenter) {
                    mHighlightCenter = true;
                    invalidate();
                    break;
                }
            case MotionEvent.ACTION_MOVE:
                if (mTrackingCenter) {
                    if (mHighlightCenter != inCenter) {
                        mHighlightCenter = inCenter;
                        invalidate();
                    }
                } else {
                    float angle = (float)java.lang.Math.atan2(y, x);
                    // need to turn angle [-PI ... PI] into unit [0....1]
                    float unit = angle/(2*PI);
                    if (unit < 0) {
                        unit += 1;
                    }
                    mCenterPaint.setColor(interpColor(mColors, unit));
                    invalidate();
                }
                break;
            case MotionEvent.ACTION_UP:
                if (mTrackingCenter) {
                    if (inCenter) {
                        mListener.colorChanged(mCenterPaint.getColor());
                    }
                    mTrackingCenter = false;    // so we draw w/o halo
                    invalidate();
                }
                break;
        }
        return true;
    }
}

public ColorPickerDialog(Context context,
                         OnColorChangedListener listener,
                         int initialColor) {
    super(context);

    mListener = listener;
    mInitialColor = initialColor;
}

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    OnColorChangedListener l = new OnColorChangedListener() {
        public void colorChanged(int color) {
            mListener.colorChanged(color);
            dismiss();
        }
    };

    setContentView(new ColorPickerView(getContext(), l, mInitialColor));
    setTitle("Pick a Color");
 }
}

Usage

new ColorPickerDialog(FingerPaintActivity.this, FingerPaintActivity.this, mPaint.getColor()).show();

FingerPaintActivity.this - is the activity context   mPaint is the paint object. 

Whatever color the user chooses the object will have that color. If user chooses red mPaint will have red color which can be used to draw.

To show a colorpicker

Say on button click you want to display the colorpicker dialog

Button b= (Button) findViewById(R.id.button1);
b.setOnClickListener(new OnClickListener()
{
    public void OnClick(View v)
    {
        new ColorPickerDialog(FingerPaintActivity.this, FingerPaintActivity.this, mPaint.getColor()).show();
    }  
});