Re: Positioning text within a circle
- From: "Ian D. Nichols" <inich@xxxxxxxxxx>
- To: <programmingblind@xxxxxxxxxxxxx>
- Date: Sun, 8 Feb 2009 00:28:12 -0500
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
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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