ColorPicker in android not working

Question

I have made a simple drawing android program for learning ,I have put a colorDialog which is displayed properly bu after selecting any color ,The pen color is not changing ,

Answer 1

Use the below as a reference. Modify according to your needs. i have used the same color picker that your used.

As you notice the drawing view is a inner class of your activity class and i used a single Paint object so the change in color reflects in the draw.

MainActivity.java

public class MainActivity extends Activity
        implements ColorPickerDialog.OnColorChangedListener {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(new MyView(this));

        mPaint = new Paint();
        mPaint.setAntiAlias(true);
        mPaint.setDither(true);
        mPaint.setColor(0xFFFF0000);
        mPaint.setStyle(Paint.Style.STROKE);
        mPaint.setStrokeJoin(Paint.Join.ROUND);
        mPaint.setStrokeCap(Paint.Cap.ROUND);
        mPaint.setStrokeWidth(12);

        mEmboss = new EmbossMaskFilter(new float[] { 1, 1, 1 },
                                       0.4f, 6, 3.5f);

        mBlur = new BlurMaskFilter(8, BlurMaskFilter.Blur.NORMAL);
    }

    private Paint       mPaint;
    private MaskFilter  mEmboss;
    private MaskFilter  mBlur;

    public void colorChanged(int color) {
        mPaint.setColor(color);
    }

    public class MyView extends View {

        private static final float MINP = 0.25f;
        private static final float MAXP = 0.75f;

        private Bitmap  mBitmap;
        private Canvas  mCanvas;
        private Path    mPath,circlePath;
        private Paint   mBitmapPaint,circlePaint;

        public MyView(Context c) {
            super(c);
            circlePaint = new Paint();
            circlePath = new Path();
            circlePaint.setAntiAlias(true);
            circlePaint.setColor(Color.BLUE);
            circlePaint.setStyle(Paint.Style.STROKE);
            circlePaint.setStrokeJoin(Paint.Join.MITER);
            circlePaint.setStrokeWidth(4f); 

            mPath = new Path();
            mBitmapPaint = new Paint(Paint.DITHER_FLAG);
        }

        @Override
        protected void onSizeChanged(int w, int h, int oldw, int oldh) {
            super.onSizeChanged(w, h, oldw, oldh);
            mBitmap = Bitmap.createBitmap(w, h, Bitmap.Config.ARGB_8888);
            mCanvas = new Canvas(mBitmap);
        }

        @Override
        protected void onDraw(Canvas canvas) {
            canvas.drawColor(0xFFAAAAAA);

            canvas.drawBitmap(mBitmap, 0, 0, mBitmapPaint);

            canvas.drawPath(mPath, mPaint);
            canvas.drawPath(circlePath, circlePaint);
        }

        private float mX, mY;
        private static final float TOUCH_TOLERANCE = 4;

        private void touch_start(float x, float y) {
            mPath.reset();
            mPath.moveTo(x, y);
            mX = x;
            mY = y;
        }
        private void touch_move(float x, float y) {
            float dx = Math.abs(x - mX);
            float dy = Math.abs(y - mY);
            if (dx >= TOUCH_TOLERANCE || dy >= TOUCH_TOLERANCE) {
                mPath.quadTo(mX, mY, (x + mX)/2, (y + mY)/2);
                mX = x;
                mY = y;
            }
            circlePath.reset();
            circlePath.addCircle(mX, mY, 30, Path.Direction.CW);
        }
        private void touch_up() {
            mPath.lineTo(mX, mY);
            // commit the path to our offscreen
            mCanvas.drawPath(mPath, mPaint);
            // kill this so we don't double draw
            circlePath.reset();
            mPath.reset();
        }

        @Override
        public boolean onTouchEvent(MotionEvent event) {
            float x = event.getX();
            float y = event.getY();

            switch (event.getAction()) {
                case MotionEvent.ACTION_DOWN:
                    touch_start(x, y);
                    invalidate();
                    break;
                case MotionEvent.ACTION_MOVE:
                    touch_move(x, y);
                    invalidate();
                    break;
                case MotionEvent.ACTION_UP:
                    touch_up();
                    invalidate();
                    break;
            }
            return true;
        }
    }

    private static final int COLOR_MENU_ID = Menu.FIRST;
    private static final int EMBOSS_MENU_ID = Menu.FIRST + 1;
    private static final int BLUR_MENU_ID = Menu.FIRST + 2;
    private static final int ERASE_MENU_ID = Menu.FIRST + 3;
    private static final int SRCATOP_MENU_ID = Menu.FIRST + 4;

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        super.onCreateOptionsMenu(menu);

        menu.add(0, COLOR_MENU_ID, 0, "Color").setShortcut('3', 'c');
        menu.add(0, EMBOSS_MENU_ID, 0, "Emboss").setShortcut('4', 's');
        menu.add(0, BLUR_MENU_ID, 0, "Blur").setShortcut('5', 'z');
        menu.add(0, ERASE_MENU_ID, 0, "Erase").setShortcut('5', 'z');
        menu.add(0, SRCATOP_MENU_ID, 0, "SrcATop").setShortcut('5', 'z');

        /****   Is this the mechanism to extend with filter effects?
        Intent intent = new Intent(null, getIntent().getData());
        intent.addCategory(Intent.CATEGORY_ALTERNATIVE);
        menu.addIntentOptions(
                              Menu.ALTERNATIVE, 0,
                              new ComponentName(this, NotesList.class),
                              null, intent, 0, null);
        *****/
        return true;
    }

    @Override
    public boolean onPrepareOptionsMenu(Menu menu) {
        super.onPrepareOptionsMenu(menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        mPaint.setXfermode(null);
        mPaint.setAlpha(0xFF);

        switch (item.getItemId()) {
            case COLOR_MENU_ID:
                // color picker
                new ColorPickerDialog(this, this, mPaint.getColor()).show();
                return true;
            case EMBOSS_MENU_ID:
                if (mPaint.getMaskFilter() != mEmboss) {
                    mPaint.setMaskFilter(mEmboss);
                } else {
                    mPaint.setMaskFilter(null);
                }
                return true;
            case BLUR_MENU_ID:
                if (mPaint.getMaskFilter() != mBlur) {
                    mPaint.setMaskFilter(mBlur);
                } else {
                    mPaint.setMaskFilter(null);
                }
                return true;
            case ERASE_MENU_ID:
                mPaint.setXfermode(new PorterDuffXfermode(
                                                        PorterDuff.Mode.CLEAR));
                return true;
            case SRCATOP_MENU_ID:
                mPaint.setXfermode(new PorterDuffXfermode(
                                                    PorterDuff.Mode.SRC_ATOP));
                mPaint.setAlpha(0x80);
                return true;
        }
        return super.onOptionsItemSelected(item);
    }
}

Same color picker you used

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");
    }
}

Snap Shot. Use the menu button to choose options. This is the same as the fingerpaint api in the samples with few minor modifications.

Edit:

You can allow users to change pen thickness using a number picker

how to use number picker with dialog