@Override
public boolean onTouchEvent(MotionEvent event) {
float x = event.getX() - CENTER_X;
float y = event.getY() - CENTER_Y;
boolean inCenter = 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) 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;
}
private void setCurrentHueSaturation(float x, float y, double distance) {
// get the angle of the point in the color wheel
// note: the (-) is intentional due to the inversion of the y coordinate system (wrt cartesian)
float angle = -(float) Math.atan2(y, x);
// Log.d(TAG, String.format("Angle Rad: %f", angle));
if (angle < 0.0f) {
angle += (float) (2.0 * Math.PI);
}
// change angle to degrees
float hue = (float) (angle * (180.0 / Math.PI));
// Log.d(TAG, String.format("Angle Deg: %f", hue));
// normalize the distance from center
float saturation = (float) (distance / mRadius);
// replace the hue and saturation with the new values
mNewColor[0] = hue;
// only replace the saturation if the value is within range, otherwise the crosshairs will be
// drawn outside of the wheel
if (saturation <= 1.0f) {
mNewColor[1] = saturation;
}
updateListener();
invalidate();
}