Re: [GD-DEVEL] How to calculate the bounding rect for gdImageStringFT when the angle is not zero

On 6/26/07, Andrei Stebakov <[email protected]> wrote:
> Hi
>
> I've been using the function gdImageStringFT for some time and it was fine
> untill I started to think of how to create a text image with non-zero angle.
> It looks like the bounding rect which I calculate setting gdImagePtr to NULL
> doesn't take the angle into account (and it's in the spec too).
> Even if I calculate the rect for zero angle text and then create an image
> with max(rect-width, rect-height) I still need to know the x and y offsets.
>
> Here is some pseudo-code how I do it:
>
> rect = render-no-draw("some text", font, some_angle) //Calc the rect
> int box_width  = rect[2] - rect[0]
> int box_height  = rect[3] - rect[5]
> int horizont_shift  = rect[0]
> int vertical_shift = rect[1]
>
> im = gdImageCreate(box_width, box_height) //Create the image
>
> int x = -horizont_shift
> int y = box_height - vertical_shift
> gdImageStringFT(im, "some text",  ..., x, y) //Draw the text
>
>
> The algorithm above works when the angle is zero, so I need to customize
> somehow for non-zero angle.
> 1) How to calculate the image sizes in this case
> 2) How to calculate x and y for the angled text

gdImageStringFt can tak a bounding rectangle as argument. When you
give it, it will be filled with the bounding rectangle of a given text
at a given angle.

See the example here:
http://www.libgd.org/OldFont#char_.2AgdImageStringFT.28gdImagePtr_im.2C_int_.2Abrect.2C_int_fg.2C_char_.2Afontname.2C_double_ptsize.2C_double_angle.2C_int_x.2C_int_y.2C_char_.2Astring.29_.28FUNCTION.29

Is it what you are looking for?

Cheers,
--Pierre