Develop Reference

Problem with drawing canvas line in scrollView

I'm trying to draw a scrollable timeline. I implement singleLine custom view for drawing a line between circle ImageView's of recycler view:
public class SingleLine extends View {
WeakReference<Context> ctx;
Paint paint;
PointF pointA, pointB;
private int height_custom;
public SingleLine(Context context) {
super(context);
ctx = new WeakReference<>(context);
init();
}
public SingleLine(Context context, #Nullable AttributeSet attrs) {
super(context, attrs);
ctx = new WeakReference<>(context);
init();
}
public void init() {
paint = new Paint();
pointA = new PointF();
pointB = new PointF();
paint.setStrokeWidth(10);
paint.setColor(ctx.get().getResources().getColor(R.color.green));
}
#Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
canvas.drawLine(pointA.x, pointA.y, pointB.x, pointB.y, paint);
invalidate();
}
public PointF getPointA() {return pointA;}
public void setPointA(PointF pointA) {this.pointA = pointA;}
public PointF getPointB() {return pointB;}
public void setPointB(PointF pointB) {this.pointB = pointB;}
}
And in onBindViewHolder() method of my adapter, I use an interface for measuring x/y coordinates of first and last visible view of recyclerview:
#Override
public void onBindViewHolder(#NonNull final TaskViewHolder holder, final int position) {
Tasks tasks = datalist_tasks.get(position);
String hour = "" + tasks.getHour() + ":" + tasks.getMinute();
holder.tv_clock.setText(hour);
holder.tv_title.setText(tasks.getTitle());
holder.tv_comment.setText(tasks.getComment());
holder.itemView.getViewTreeObserver().addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() {
#Override
public void onGlobalLayout() {
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN)
holder.itemView.getViewTreeObserver().removeOnGlobalLayoutListener(this);
else
holder.itemView.getViewTreeObserver().removeGlobalOnLayoutListener(this);
if (iOnMeasureCustomView != null)
iOnMeasureCustomView.onMeasure(holder.iv_status, position);
}
});
}
And I implement that interface in my activity like below:
LinearLayoutManager layoutManager1 = new LinearLayoutManager(_C.get(), RecyclerView.VERTICAL, false);
rv_tasks.setLayoutManager(layoutManager1);
tasksAdapter.setiOnMeasureCustomView(new IOnMeasureCustomView() {
#Override
public void onMeasure(ImageView iv_status, int position) {
int[] screen = new int[2];
iv_status.getLocationOnScreen(screen);
int width = (int) ((iv_status.getWidth() / 2) + convertDpToPixel(8));
if (position == layoutManager1.findFirstCompletelyVisibleItemPosition()) {
pointA.set(iv_status.getX() + width, iv_status.getY() + convertDpToPixel(8));
}
else if (position == layoutManager1.findLastCompletelyVisibleItemPosition()) {
pointB.set(iv_status.getX() + width, screen[1] - convertDpToPixel(40));
singleLine.setPointA(pointA);
singleLine.setPointB(pointB);
singleLine.invalidate();
}
}
});
And also I implement addOnScrollListener() for my recyclerview and write this code snippet (I don't know that if this implementation is correct or no):
rv_tasks.addOnScrollListener(new RecyclerView.OnScrollListener() {
#Override
public void onScrolled(#NonNull RecyclerView recyclerView, int dx, int dy) {
PointF a = singleLine.getPointA();
PointF b = singleLine.getPointB();
if (dy > 0) {
a.y -= dy;
b.y -= dy;
singleLine.setPointA(a);
singleLine.setPointB(b);
singleLine.invalidate();
} else {
a.y += Math.abs(dy);
b.y += Math.abs(dy);
singleLine.setPointA(a);
singleLine.setPointB(b);
singleLine.invalidate();
}
}
});
My problem is when I scroll in activity, like the gif below, my singleLine is something like cutting off imageView and the end x/y of line become the x/y of end of the screen.
Questios
How can I set x/y of the line to prevent this?
And also I need some help with drawing this line with animation. How can I draw this line with animation that starts when the activity started?

How to draw circle according to point array list?

I am creating a test game where a circle will move to a selected position from the point array list when touched. However, it seems that it cannot move to the next position of points when clicked. Can u help me find where is the problem is and what solution I can use?
public class EyeTestActivity extends AppCompatActivity {
private GestureDetectorCompat mDetector;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
WindowManager.LayoutParams.FLAG_FULLSCREEN);
this.requestWindowFeature(Window.FEATURE_NO_TITLE);
setContentView(new TestView(this));
// get the gesture detector
mDetector = new GestureDetectorCompat(EyeTestActivity.this, new SwipeGestureDetector());
}
public boolean onTouchEvent(MotionEvent motionEvent) {
this.mDetector.onTouchEvent(motionEvent);
return super.onTouchEvent(motionEvent);
}
#Override
public boolean dispatchTouchEvent(MotionEvent ev) {
super.dispatchTouchEvent(ev);
return mDetector.onTouchEvent(ev);
}
public class TestView extends View {
public ArrayList<Point> pointlist;
Paint paint;
public TestView(Context context) {
super(context);
init();
setFocusable(true);
setFocusableInTouchMode(true);
createPointList();
}
public void init() {
paint = new Paint();
paint.setColor(Color.WHITE);
paint.setStrokeWidth(5);
paint.setStyle(Paint.Style.STROKE);
}
public void createPointList() {
pointlist = new ArrayList<>();
for (int i = 1; i <= 5; i++) {
float a = 100 * i;
float b = 100 * i;
for (int j = 1; j <= 24; j++) {
float x = (float) (a * Math.sin(Math.toRadians(15 * j)));
float y = (float) (b * Math.cos(Math.toRadians(15 * j)));
for (int k = 0; k < 120; k++) {
pointlist.add(new Point(x, y));
//Add the x and y coordinates to the Point
}
}
}
}
protected void onDraw(Canvas canvas) {
// TODO Auto-generated method stub
super.onDraw(canvas);
paint.setStyle(Paint.Style.FILL);
canvas.drawColor(Color.BLACK);
Point point2 = pointlist.get(z);
canvas.drawCircle(point2.getX() + canvas.getWidth() / 2, point2.getY() + canvas.getHeight()/ 2, 15, paint);
}
}
int z = 0;
public class SwipeGestureDetector implements GestureDetector.OnGestureListener {
#Override
public boolean onDown(MotionEvent e) {
return true;
}
#Override
public void onShowPress(MotionEvent e) {
}
#Override
public boolean onSingleTapUp(MotionEvent e) {
return false;
}
#Override
public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX, float distanceY) {
if (e1.getAction() == MotionEvent.ACTION_MOVE) {
z++;
if (z > 120) {
z = 0;
}
}
return true;
}
#Override
public void onLongPress(MotionEvent e) {
}
public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) {
if(e1 == null || e2 == null)
return false;
if(e1.getPointerCount() > 1 || e2.getPointerCount() > 1)
return false;
else {
try {
float diffX = e2.getX() - e1.getX();
float diffY = e2.getY() - e1.getY();
if(Math.abs(diffX) > Math.abs(diffY)) {
if (Math.abs(diffX) > 100 && Math.abs(velocityX) > 1000) {
if ((diffX > 0) || (diffX < 0)) {
return false;
}
}
}
} catch (Exception e) {
e.printStackTrace();
}
return false;
}
}
}
}
I expect the next circle to be drawn when printed.

First of all, you should have a reference to your TestView layout.
public class EyeTestActivity extends AppCompatActivity {
private GestureDetectorCompat mDetector;
private TestView tv;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
WindowManager.LayoutParams.FLAG_FULLSCREEN);
this.requestWindowFeature(Window.FEATURE_NO_TITLE);
tv = new TestView(this);
setContentView(tv);
// get the gesture detector
mDetector = new GestureDetectorCompat(EyeTestActivity.this, new SwipeGestureDetector());
}
Then, in your onScroll event, you should test e2 instead of e1
#Override
public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX, float distanceY) {
if (e2.getAction() == MotionEvent.ACTION_MOVE) {
z++;
if (z >= 120) { // zero based arraylist, so, >= 120
z = 0;
}
tv.invalidate; // this to redraw the point
}
return true;
}
I think your createPointList is not doing what you want.
You are creating 120 times the same point! Total 120 * 5 * 24 = 14.400 points !
It should be
for (int i = 1; i <= 5; i++) {
float a = 100 * i;
float b = 100 * i;
for (int j = 1; j <= 24; j++) {
float x = (float) (a * Math.sin(Math.toRadians(15 * j)));
float y = (float) (b * Math.cos(Math.toRadians(15 * j)));
pointlist.add(new Point((int)x, (int)y));
}
}

Multiple Sticker Erase Issue

I try to make image editor application. in this application i try to put multiple sticker on image that sticker can move , zoom , rotate, and also selected sticker can erase . can anyone help me ? here is code that i done with sticker move,rotate,zoom but i cant erase selected sticker .
public class MainActivity extends AppCompatActivity {
Bitmap originalBitmap,originalBitmap1;
RelativeLayout rlImageViewContainer;
private ImageView ivRedo;
private ImageView ivUndo;
Button btn_erase;
private ArrayList<Path> paths;
private ArrayList<Path> redoPaths;
Paint destPaint = new Paint();
Path destPath = new Path();
Bitmap destBitmap;
Canvas destCanvas = new Canvas();
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
originalBitmap = BitmapFactory.decodeResource(getResources(), R.drawable.a);
originalBitmap1 = BitmapFactory.decodeResource(getResources(), R.drawable.b);
initView();
}
private void initView() {
ivUndo = (ImageView) findViewById(R.id.iv_undo);
ivRedo = (ImageView) findViewById(R.id.iv_redo);
rlImageViewContainer = findViewById(R.id.rl_image_view_container);
final PhotoSortrView photoSortrView = new PhotoSortrView(this);
rlImageViewContainer.addView(photoSortrView,0);
photoSortrView.setBackgroundColor(getResources().getColor(R.color.tran));
photoSortrView.addImages(this, originalBitmap);
photoSortrView.addImages(this, originalBitmap1);
ivUndo.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
// undo();
}
});
ivRedo.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
// redo();
}
});
btn_erase = (Button) findViewById(R.id.btn_erase);
btn_erase.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
if (photoSortrView.isErase) {
btn_erase.setBackgroundColor(Color.RED);
photoSortrView.isErase = false;
photoSortrView.isMove = true;
} else {
btn_erase.setBackgroundColor(Color.GREEN);
photoSortrView.isErase = true;
photoSortrView.isMove = false;
}
}
});
}
}
PhotoSortrView.java
public class PhotoSortrView extends View implements MultiTouchController.MultiTouchObjectCanvas<MultiTouchEntity> {
private static final String TAG = "PhotoSortr ####### ";
// private static final int[] IMAGES = { R.drawable.m74hubble };
private Path drawPath = new Path();
// drawing and canvas paint
private Paint drawPaint = new Paint(), canvasPaint = new Paint();
// initial color
private int paintColor = Color.TRANSPARENT;
// canvas
private Canvas drawCanvas = new Canvas();
// canvas bitmap
private Bitmap canvasBitmap;
private ArrayList<MultiTouchEntity> imageIDs = new ArrayList<MultiTouchEntity>();
// --
private MultiTouchController<MultiTouchEntity> multiTouchController = new MultiTouchController<MultiTouchEntity>(this);
// --
private MultiTouchController.PointInfo currTouchPoint = new MultiTouchController.PointInfo();
private static final int UI_MODE_ROTATE = 1, UI_MODE_ANISOTROPIC_SCALE = 2;
private int mUIMode = UI_MODE_ROTATE;
// --
private static final float SCREEN_MARGIN = 100;
private int displayWidth, displayHeight;
public boolean isErase = false;
public boolean isMove = true;
Paint destPaint = new Paint();
Path destPath = new Path();
Bitmap destBitmap;
Canvas destCanvas = new Canvas();
int height,width;
// ---------------------------------------------------------------------------------------------------
public PhotoSortrView(Context context) {
this(context, null);
setupPaint();
init(context);
}
private void setupPaint() {
destPaint.setAlpha(0);
destPaint.setAntiAlias(true);
destPaint.setStyle(Paint.Style.STROKE);
destPaint.setStrokeJoin(Paint.Join.ROUND);
destPaint.setStrokeCap(Paint.Cap.ROUND);
destPaint.setStrokeWidth(20);
destPaint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.DST_IN));
}
public PhotoSortrView(Context context, AttributeSet attrs) {
this(context, attrs, 0);
setupDrawing();
}
public PhotoSortrView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
init(context);
}
private void init(Context context) {
Log.e(TAG, "init: " );
Resources res = context.getResources();
setBackgroundColor(Color.TRANSPARENT);
DisplayMetrics metrics = res.getDisplayMetrics();
this.displayWidth = res.getConfiguration().orientation == Configuration.ORIENTATION_LANDSCAPE ? Math
.max(metrics.widthPixels, metrics.heightPixels) : Math.min(
metrics.widthPixels, metrics.heightPixels);
this.displayHeight = res.getConfiguration().orientation == Configuration.ORIENTATION_LANDSCAPE ? Math
.min(metrics.widthPixels, metrics.heightPixels) : Math.max(
metrics.widthPixels, metrics.heightPixels);
}
public void addImages(Context context, Bitmap resourceId) {
Log.e(TAG, "addImages: " );
// setupDrawing();
Resources res = context.getResources();
imageIDs.add(new ImageEntity(resourceId, res));
float cx = SCREEN_MARGIN + (float)
(Math.random() * (displayWidth - 2 * SCREEN_MARGIN));
float cy = SCREEN_MARGIN + (float)
(Math.random() * (displayHeight - 2 * SCREEN_MARGIN));
imageIDs.get(imageIDs.size() - 1).load(context, cx, cy);
invalidate();
}
public void removeAllImages() {
imageIDs.removeAll(imageIDs);
invalidate();
}
public void removeImage() {
if (imageIDs.size() > 0) {
imageIDs.remove(imageIDs.size() - 1);
}
invalidate();
}
public int getCountImage() {
return imageIDs.size();
}
// ---------------------------------------------------------------------------------------------------
#Override
protected void onDraw(Canvas canvas) {
Log.e(TAG, "onDraw: " );
if (isErase){
Log.e(TAG, "onDraw: isErase" );
if (destBitmap != null){
destCanvas.drawPath(destPath,destPaint);
canvas.drawBitmap(destBitmap,0,0,null);
}
}
else if (isMove){
height = imageIDs.get(0).getHeight();
width = imageIDs.get(0).getWidth();
Log.e(TAG, "onDraw: isMove");
canvas.drawBitmap(canvasBitmap, 0, 0, canvasPaint);
canvas.drawPath(drawPath,drawPaint);
int n = imageIDs.size();
for (int i = 0; i < n; i++)
imageIDs.get(i).draw(canvas);
}
super.onDraw(canvas);
}
// ---------------------------------------------------------------------------------------------------
public void trackballClicked() {
mUIMode = (mUIMode + 1) % 3;
invalidate();
}
#Override
public boolean onTouchEvent(MotionEvent event) {
//collegeActivity.set
int action = event.getAction();
Log.e(TAG, "onTouchEvent: " );
float touchX = event.getX();
float touchY = event.getY();
// respond to down, move and up events
if (isErase){
Log.e(TAG, "onTouchEvent: isErase" );
switch (event.getAction()){
case MotionEvent.ACTION_DOWN:
destPath.moveTo(touchX,touchY);
break;
case MotionEvent.ACTION_MOVE:
destPath.lineTo(touchX,touchY);
break;
}
} else if (isMove) {
Log.e(TAG, "onTouchEvent: isMove" );
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
drawPath.moveTo(touchX, touchY);
break;
case MotionEvent.ACTION_MOVE:
drawPath.lineTo(touchX, touchY);
break;
case MotionEvent.ACTION_UP:
drawPath.lineTo(touchX, touchY);
drawCanvas.drawPath(drawPath, drawPaint);
drawPath.reset();
break;
default:
return false;
}
return multiTouchController.onTouchEvent(event);
}
invalidate();
return true;
}
private void setupDrawing() {
Log.e(TAG, "setupDrawing: " );
// prepare for drawing and setup paint stroke properties
drawPath = new Path();
drawPaint.setAlpha(0);
drawPaint.setColor(0);
drawPaint.setAntiAlias(true);
drawPaint.setStrokeWidth(10);
drawPaint.setStyle(Paint.Style.STROKE);
drawPaint.setStrokeJoin(Paint.Join.ROUND);
drawPaint.setStrokeCap(Paint.Cap.ROUND);
canvasPaint = new Paint(Paint.DITHER_FLAG);
}
// size assigned to view
#Override
protected void onSizeChanged(int w, int h, int oldw, int oldh) {
if (w > 0 && h > 0) {
Log.e(TAG, "onSizeChanged: " );
super.onSizeChanged(w, h, oldw, oldh);
width = w;
height = h;
canvasBitmap = Bitmap.createBitmap(w, h, Bitmap.Config.ARGB_8888);
drawCanvas = new Canvas(canvasBitmap);
}
}
// update color
public void setColor(String newColor) {
Log.e(TAG, "setColor: " );
invalidate();
paintColor = Color.parseColor(newColor);
drawPaint.setColor(paintColor);
}
public MultiTouchEntity getDraggableObjectAtPoint(MultiTouchController.PointInfo pt) {
float x = pt.getX(), y = pt.getY();
int n = imageIDs.size();
for (int i = n - 1; i >= 0; i--) {
ImageEntity im = (ImageEntity) imageIDs.get(i);
if (im.containsPoint(x, y))
return im;
}
return null;
}
public void selectObject(MultiTouchEntity img, MultiTouchController.PointInfo touchPoint) {
currTouchPoint.set(touchPoint);
if (img != null) {
// Move image to the top of the stack when selected
drawPaint.setColor(Color.TRANSPARENT);
imageIDs.remove(img);
imageIDs.add(img);
destCanvas = new Canvas();
destBitmap = Bitmap.createBitmap(width,height, Bitmap.Config.ARGB_8888);
destCanvas.setBitmap(destBitmap);
destCanvas.drawBitmap(img.getBitmap(),0,0,null);
} else {
// Called with img == null when drag stops.
}
invalidate();
}
public void getPositionAndScale(MultiTouchEntity img, MultiTouchController.PositionAndScale objPosAndScaleOut) {
// requires averaging the two scale factors)
objPosAndScaleOut.set(img.getCenterX(), img.getCenterY(),
(mUIMode & UI_MODE_ANISOTROPIC_SCALE) == 0,
(img.getScaleX() + img.getScaleY()) / 2,
(mUIMode & UI_MODE_ANISOTROPIC_SCALE) != 0, img.getScaleX(),
img.getScaleY(), (mUIMode & UI_MODE_ROTATE) != 0,
img.getAngle());
}
/**
* Set the position and scale of the dragged/stretched image.
*/
public boolean setPositionAndScale(MultiTouchEntity img,
MultiTouchController.PositionAndScale newImgPosAndScale, MultiTouchController.PointInfo touchPoint) {
currTouchPoint.set(touchPoint);
boolean ok = img.setPos(newImgPosAndScale);
if (ok)
invalidate();
return ok;
}
public boolean pointInObjectGrabArea(MultiTouchController.PointInfo pt, MultiTouchEntity img) {
return false;
}
}

android - animate on swipe

In my new program I need objects that can be swiped to the side. I already have my animation, which is working and I tried to detect the swiping of the user in another class. The problem I have is that I don't know how to connect them. When the swipe gesture is correctly recognized a specific animation should start.
My AnimatedViewClass:
private Runnable r = new Runnable() {
#Override
public void run() {
if(continueAnimation) {
invalidate();
}
}
};
protected void onDraw(Canvas c) {
if (x<0) {
x = this.getWidth()/2-100;
y = this.getHeight()/2-100;
}
else {
x += xVelocity;
if ((x > this.getWidth() - ball.getBitmap().getWidth()) || (x < 0)) {
boolean continueAnimation = false;
}
}
c.drawBitmap(ball.getBitmap(), x, y, null);
if(continueAnimation)
{
h.postDelayed(r, FRAME_RATE);
}
else {
x = this.getWidth()-ball.getBitmap().getWidth();
}
}
My SwipeTouchListener:
public class OnSwipeTouchListener implements OnTouchListener {
private final GestureDetector gestureDetector;
public OnSwipeTouchListener (Context ctx){
gestureDetector = new GestureDetector(ctx, new GestureListener());
}
#Override
public boolean onTouch(View v, MotionEvent event) {
return gestureDetector.onTouchEvent(event);
}
private final class GestureListener extends SimpleOnGestureListener {
private static final int SWIPE_THRESHOLD = 100;
private static final int SWIPE_VELOCITY_THRESHOLD = 100;
#Override
public boolean onDown(MotionEvent e) {
return true;
}
#Override
public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) {
boolean result = false;
try {
float diffY = e2.getY() - e1.getY();
float diffX = e2.getX() - e1.getX();
if (Math.abs(diffX) > Math.abs(diffY)) {
if (Math.abs(diffX) > SWIPE_THRESHOLD && Math.abs(velocityX) > SWIPE_VELOCITY_THRESHOLD) {
if (diffX > 0) {
onSwipeRight();
} else {
onSwipeLeft();
}
}
result = true;
}
else if (Math.abs(diffY) > SWIPE_THRESHOLD && Math.abs(velocityY) > SWIPE_VELOCITY_THRESHOLD) {
if (diffY > 0) {
onSwipeBottom();
} else {
onSwipeTop();
}
}
result = true;
} catch (Exception exception) {
exception.printStackTrace();
}
return result;
}
}
}

You can add GestureDetector to your view class just like this, and replace your code inside onFling()
public class AnimatedViewClass extends View {
GestureDetector gestureDetector;
public AnimatedViewClass(Context context) {
super(context);
gestureDetector = new GestureDetector(getContext(), new GestureDetectorListener());
}
#Override
public boolean onTouchEvent(MotionEvent event) {
gestureDetector.onTouchEvent(event);
return super.onTouchEvent(event);
}
private void onSwipeRight(){
// swipe right detected
// do stuff
invalidate();
}
private void onSwipeLeft(){
// swipe left detected
// do stuff
invalidate();
}
private class GestureDetectorListener extends
GestureDetector.SimpleOnGestureListener {
private static final int SWIPE_THRESHOLD = 100;
private static final int SWIPE_VELOCITY_THRESHOLD = 100;
#Override
public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) {
// onSwipeRight()
// onSwipeLeft()
return super.onFling(e1, e2, velocityX, velocityY);
}
#Override
public boolean onDown(MotionEvent e) {
return super.onDown(e);
}
}
private Runnable r = new Runnable() {
#Override
public void run() {
if(continueAnimation) {
invalidate();
}
}
};
protected void onDraw(Canvas c) {
if (x < 0) {
x = this.getWidth() / 2 - 100;
y = this.getHeight() / 2 - 100;
} else {
x += xVelocity;
if ((x > this.getWidth() - ball.getBitmap().getWidth()) || (x < 0)) {
boolean continueAnimation = false;
}
}
c.drawBitmap(ball.getBitmap(), x, y, null);
if (continueAnimation) {
h.postDelayed(r, FRAME_RATE);
} else {
x = this.getWidth() - ball.getBitmap().getWidth();
}
}
}

Android color picker to be included in the activity

I would like to include a color picker in my paint program. So anyone here has already done something like this please give me some tutorials or piece of code to get me started. I really need to get the whole idea of adding this. I already have set up the canvas for the drawing so I'd like to add the color picker to it. Any ideas are welcome. Thanks.

Your class should implement ColorPickerDialog.OnColorChangedListener
public class MainActivity implements ColorPickerDialog.OnColorChangedListener
{
private Paint mPaint;
mPaint = new Paint();
// on button click
new ColorPickerDialog(this, this, mPaint.getColor()).show();
}
ColorPicker 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");
}
You have to choose the color and click the center circle to pick the color. Set the color to your paint object and use the same to draw.
Snap shot
Edit 2:
Source code can be found at https://code.google.com/p/android-color-picker/
Another ColorPickerDialog
public class ColorPickerDialog extends AlertDialog implements
ColorPickerView.OnColorChangedListener {
private ColorPickerView mColorPicker;
private ColorPanelView mOldColor;
private ColorPanelView mNewColor;
private OnColorChangedListener mListener;
public ColorPickerDialog(Context myDrawingMenuOptionEventsListener, int initialColor) {
super(myDrawingMenuOptionEventsListener);
init(initialColor);
}
private void init(int color) {
// To fight color branding.
getWindow().setFormat(PixelFormat.RGBA_8888);
setUp(color);
}
private void setUp(int color) {
LayoutInflater inflater = (LayoutInflater) getContext()
.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
View layout = inflater.inflate(R.layout.dialog_color_picker, null);
layout.setBackgroundColor(Color.WHITE);
setView(layout);
setTitle("Choose a Color");
// setIcon(android.R.drawable.ic_dialog_info);
mColorPicker = (ColorPickerView) layout
.findViewById(R.id.color_picker_view);
mOldColor = (ColorPanelView) layout.findViewById(R.id.old_color_panel);
mNewColor = (ColorPanelView) layout.findViewById(R.id.new_color_panel);
((LinearLayout) mOldColor.getParent()).setPadding(Math
.round(mColorPicker.getDrawingOffset()), 0, Math
.round(mColorPicker.getDrawingOffset()), 0);
mColorPicker.setOnColorChangedListener(this);
mOldColor.setColor(color);
mColorPicker.setColor(color, true);
}
#Override
public void onColorChanged(int color) {
mNewColor.setColor(color);
if (mListener != null) {
mListener.onColorChanged(color);
}
}
public void setAlphaSliderVisible(boolean visible) {
mColorPicker.setAlphaSliderVisible(visible);
}
public int getColor() {
return mColorPicker.getColor();
}
}
Usage :
final ColorPickerDialog d= new ColorPickerDialog(ActivityName.this,0xffffffff);
d.setAlphaSliderVisible(true);
d.setButton("Ok", new DialogInterface.OnClickListener() {
#Override
public void onClick(DialogInterface dialog, int which) {
mPaint.setColor(d.getColor());
}
});
d.setButton2("Cancel", new DialogInterface.OnClickListener() {
#Override
public void onClick(DialogInterface dialog, int which) {
}
});
d.show();
Snap shot:
In the above choose the color on the right bar. You also make a choice how dark or light the color choosen should be. Click ok to set the paint to your paint object and use the same to draw. Cancel will dismiss the color picker dialog.
Edit 3:
Only change instead of clear function i have added color picker on click of clear button.
public class MainActivity extends Activity implements ColorPickerDialog.OnColorChangedListener {
DrawingView dv ;
RelativeLayout rl;
private Paint mPaint;
private MaskFilter mEmboss;
private MaskFilter mBlur;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
dv = new DrawingView(this);
setContentView(R.layout.activity_main);
mPaint = new Paint();
mPaint.setAntiAlias(true);
mPaint.setDither(true);
mPaint.setColor(Color.GREEN);
mPaint.setStyle(Paint.Style.STROKE);
mPaint.setStrokeJoin(Paint.Join.ROUND);
mPaint.setStrokeCap(Paint.Cap.ROUND);
mPaint.setStrokeWidth(12);
rl = (RelativeLayout) findViewById(R.id.rl);
rl.addView(dv);
Button b = (Button) findViewById(R.id.button1);
//b.setText(R.string.France);
Button b1 = (Button) findViewById(R.id.button2);
rl.setDrawingCacheEnabled(true);
b.setOnClickListener(new OnClickListener()
{
#Override
public void onClick(View v) {
// TODO Auto-generated method stub
// dv.clear();
new ColorPickerDialog(MainActivity.this, MainActivity.this, mPaint.getColor()).show();
}
});
b1.setOnClickListener(new OnClickListener()
{
#Override
public void onClick(View v) {
// TODO Auto-generated method stub
AlertDialog.Builder editalert = new AlertDialog.Builder(MainActivity.this);
editalert.setTitle("Please Enter the name with which you want to Save");
final EditText input = new EditText(MainActivity.this);
LinearLayout.LayoutParams lp = new LinearLayout.LayoutParams(
LinearLayout.LayoutParams.FILL_PARENT,
LinearLayout.LayoutParams.FILL_PARENT);
input.setLayoutParams(lp);
editalert.setView(input);
editalert.setPositiveButton("OK", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int whichButton) {
rl.setDrawingCacheEnabled(true);
String name= input.getText().toString();
Bitmap bitmap =rl.getDrawingCache();
String root = Environment.getExternalStorageDirectory().toString();
File myDir = new File(root + "/MyDraw");
myDir.mkdirs();
File file = new File (myDir, name+".png");
if (file.exists ()) file.delete ();
try
{
if(!file.exists())
{
file.createNewFile();
}
FileOutputStream ostream = new FileOutputStream(file);
bitmap.compress(CompressFormat.PNG, 10, ostream);
// System.out.println("saving......................................................"+path);
ostream.close();
rl.invalidate();
}
catch (Exception e)
{
e.printStackTrace();
}finally
{
rl.setDrawingCacheEnabled(false);
}
}
});
editalert.show();
}
});
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.activity_main, menu);
return true;
}
public class DrawingView 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;
private Paint mBitmapPaint;
Context context;
private Paint circlePaint;
private Path circlePath;
public DrawingView(Context c) {
super(c);
context=c;
mPath = new Path();
mBitmapPaint = new Paint(Paint.DITHER_FLAG);
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);
}
#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) {
super.onDraw(canvas);
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);
invalidate();
}
}
private void touch_up() {
mPath.lineTo(mX, mY);
circlePath.reset();
// commit the path to our offscreen
mCanvas.drawPath(mPath, mPaint);
// kill this so we don't double draw
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;
}
}
#Override
public void colorChanged(int color) {
// TODO Auto-generated method stub
mPaint.setColor(color);
}
}

you have a google code which can help you
http://code.google.com/p/android-color-picker/

I used this link for color picker http://code.google.com/p/android-color-picker/
steps:
I've added some extra file(like:"android-mvn-push.gradle" ) you can skip that file in step 3
and also remove this "apply from: '../android-mvn-push.gradle' " from your bulid.gradle(Module:liabrary) file if your skipping step 3.
Go to the above link and download project as zip file and extract the zip.
Inside Extracted folder you'll see library folder.
Copy that folder into your android Applications main folder where it contains all its gradle n all... and also copy "android-mvn-push.gradle" file to your main project folder.
open bulid.gradle(Module:app) inside that add dependencies like this,
"compile project(':library')"
update Settings.Gradle with include ':app', ':library'
go to Tools>Android>Sync with Gradles and then it will show some error like build gradle not matching bla bla....
Click on that open file error option.
In your bulid.gradle(Module:liabrary) change this,
apply plugin: 'com.android.library'
android {
compileSdkVersion propCompileSdkVersion
buildToolsVersion propBuildToolsVersion
defaultConfig {
minSdkVersion propMinSdkVersion
targetSdkVersion propTargetSdkVersion
versionCode propVersionCode
versionName propVersionName
}
buildTypes {
release {
minifyEnabled false
proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
}
}
}
apply from: '../android-mvn-push.gradle'
To>>>>>>>>>>>
apply plugin: 'com.android.library'
android {
compileSdkVersion 22
buildToolsVersion "22.0.1"
defaultConfig {
minSdkVersion 14
targetSdkVersion 22
versionCode 1
versionName "1.0"
}
buildTypes {
release {
minifyEnabled false
proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
}
}
}
apply from: '../android-mvn-push.gradle'
Finally Tools>Android > Sync with gradle...
and Bingo....It Works ....!!!