In my program I am having it draw a rectangle while the finger is down and moving than erase it after the finger is up. this is to show the user the range of values he/she is using as a "guess" to find the root. however the rectangle never shows up! But, if I remove the call to close the rectangle in the "action_up" part the user can draw the rectangle. Here's the code:
in the on draw function:
if(dataline>1)//if greater than 1, draw rectangle
{
myPaint.setColor(Color.CYAN);
canvas.drawRect(tX1,0, tX2,canvas.getHeight(),myPaint);
}
in the motion event function: public boolean onTouchEvent(MotionEvent ev) { final int action = ev.getAction();
switch (action) {
case MotionEvent.ACTION_DOWN: {
final float x = ev.getX();
final float y = ev.getY();
// Remember where we started
mLastTouchX = x;
mLastTouchY = y;
tX1=(int)ev.getX();
tX2=tX1;
x_1 = ev.getX();
x_1=(x_1-X1)/(zoom_x);
clicks= 1;
tX1=(int) ev.getX();//set first x coord
tX2=tX1;// make second x coord equal to the first
}
case MotionEvent.ACTION_MOVE: {
final float x = ev.getX();
final float y = ev.getY();
// Calculate the distance moved
final float dx = x - mLastTouchX;
final float dy = y - mLastTouchY;
mLastTouchX = x;
mLastTouchY = y;
dataline=2;//let onDraw() draw the rectangle while dragging finger
tX2+= (int)dx;// find new second coordinate
}
case MotionEvent.ACTION_UP: {
dataline=0;//if commented out, rectangle is drawn otherwise, it is never seen.
}
}
return true;
}