RE: Positioning text within a circle
- From: "Ken Perry" <whistler@xxxxxxxxxxxxx>
- To: <programmingblind@xxxxxxxxxxxxx>
- Date: Sun, 8 Feb 2009 12:27:50 -0500
I made a small mistake because you want to know if the points are in the
circle you don't use equals in the if statement you use greater than of
course since the point is the corner of the rectangle you could use greater
than and equals so it would look like this:
If (x-h)**2+(y-k)**2>=r**2:
Now I haven't tested it but that is the idea. If it doesn't work let me
know I know I can make it work but I might have the formula not in the same
form I am sure being that Sina is closer to school than I am he can check it
and make sure it's right.
That or have his friend the one with the strange name check it.
Ken
From: programmingblind-bounce@xxxxxxxxxxxxx
[mailto:programmingblind-bounce@xxxxxxxxxxxxx] On Behalf Of Ken Perry
Sent: Sunday, February 08, 2009 12:24 PM
To: programmingblind@xxxxxxxxxxxxx
Subject: RE: Positioning text within a circle
Ok now that I understand that you don't want it centered what you have to do
is find the formula for a circle then plug the four corner points of the
rectangle in the formula. If they all work then your set.
Suppose you have circle, with diameter endpoints (a,b) and (c,d). The
midpoint of these two endpoints is the center of the circle. Let the center
be (h,k). Then the equation of the circle will be (x-h)^2+(y-k)^2=r^2. In
order to find r, find the diameter and divide it by 2.
Then to plug your values in and test them you would do
If (x-h)^2+(y-k)^2=r^2
That of course depends on what language your using you need to do power
function for example if you're using python it would be
If (x-h)**2+(y-k)**2=r**2:
Then you plug the values in and you know if it works There will be four
tests one for each corner.
Ken
From: programmingblind-bounce@xxxxxxxxxxxxx
[mailto:programmingblind-bounce@xxxxxxxxxxxxx] On Behalf Of Ian D. Nichols
Sent: Sunday, February 08, 2009 12:28 AM
To: programmingblind@xxxxxxxxxxxxx
Subject: Re: Positioning text within a circle
Hi Ken,
Thanks very much for your reply.
Unfortunately I didn't make it clear that I do not want to centre the text
in the circle. I want to place text anywhere in the circle and make sure
that no part of the text accidentally lands outside the circle. What I need
to obtain, or calculate for myself, are the coordinates of a sufficient
number of points on the dircumference so that I can check to see that the
corners of the rectangle containing the text are all within the circle. I
have that logic worked out already. What I am lacking are the numbers to
compare the coordinates of the text with.
I recognize that it is a rather complicated procedure. Windows must know
how to do it because the ellipse function with equal x and y axes draws a
perfect circle.
I've calculated the coordinates of the 4 points where the diagonals
intersect the circumference, and I did it using the theorem of Pythagarus,
as you did in your reply. But only the diagonals of the circle's bounding
square coincide with the hypotenuses of right-angled triangles, so that
method is very limited in what it can do.
Thanks again. I live in hope!
All the best,
Ian
Ian D. Nichols,
Toronto, Canada
----- Original Message -----
From: Ken Perry <mailto:whistler@xxxxxxxxxxxxx>
To: programmingblind@xxxxxxxxxxxxx
Sent: Saturday, February 07, 2009 9:07 PM
Subject: RE: Positioning text within a circle
Ok you can use the formula s1^2+s2^2=h^2 to make sure your rectangles cross
hypotenuse fits as the diameter of the circle. From there you just need to
place the center point of the rectangle in the middle of the circle. So
just Using small numbers I will say that your long side is 4, your short
side is 3 and your circle is 5 diameter. We can find if the rectangle has
the same diameter by doing:
3^2 +4^2 =5^2 Which it does. Most of the circle drawing functions I have
used draw the circle from a midpoint so you
drawCircle(10+l/2,10+s/2))
When you print the text starting at upper left hand corner of the box 10,10
you should get it in the center
So if I am being confusing the thing I am doing is splitting your rectangle
into two right triangles. Finding the hypotenuse which will criss cross the
rectangle right in the middle. That becomes both the center point of the
rectangle and the circle. It also will be the diameter of the circle and
the rectangle. So if your hypotenuse fits as the diameter then it fits.
Then its just simply finding the center and calculating where to place the
first part so the centers of the rectangle and the circle corresponds. If
you need help and I am being too confusing just send me your circle drawing
function and text writing function and I will try and help you out.
Ken
From: programmingblind-bounce@xxxxxxxxxxxxx
[mailto:programmingblind-bounce@xxxxxxxxxxxxx] On Behalf Of Ian D. Nichols
Sent: Saturday, February 07, 2009 6:57 PM
To: program-l@xxxxxxxxxxxxx; programmingblind@xxxxxxxxxxxxx
Subject: Positioning text within a circle
Hi Listers,
I have a circle drawn on the monitor screen. I know its diameter and its
centre point in screen pixels.
I want to make sure that text I draw on the screen is completely within this
circle. I use the TextOut function, which uses a POINT sructure for
positioning the text. I can use GetTextExtentPoint32 to calculate the size
and location of the enclosing rectangle of the text. I need to make sure
that all four of the corners of that rectangle are going to fall within the
circle.
Can some one please tell me how I can determine the location of the
circumference of the circle, so that I can check that my text rectangle will
fall completely within it? I'm more than 50 years out of high school, and
didn't study mathematics or geometry, or whatever it is that I need, at
university.
Thanks in advance.
Ian
Ian D. Nichols,
Toronto, Canada
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