PHP and MySQL Web Development 4th Ed-tqw-_darksiderg

Drawing Figures and Graphing Data
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$above_line_text = abs($bbox[7]);
$text_y += $above_line_text;
// how far above the baseline?
// add baseline factor
$text_y -= 2; // adjustment factor for shape of our template
These correction factors allow for the baseline and a little adjustment because the image
is a bit “top heavy.”
Writing the Text onto the Button
After that, it’s all smooth sailing.You set up the text color, which will be white:
$white = ImageColorAllocate ($im, 255, 255, 255);
You can then use the imagettftext() function to actually draw the text onto the
button:
imagettftext ($im, $font_size, 0, $text_x, $text_y, $white, $fontname,
$button_text);
This function takes quite a lot of parameters. In order, they are the image identifier, the
font size in points, the angle you want to draw the text at, the starting x and y coordinates
of the text, the text color, the font file, and, finally, the actual text to go on the
button.
Note
The font file needs to be available on the server and is not required on the client’s machine because she will
see it as an image.
Finishing Up
Finally, you can output the button to the browser:
Header (‘Content-type: image/png’);
imagepng ($im);
Then it’s time to clean up resources and end the script:
imagedestroy ($im);
That’s it! If all went well, you should now have a button in the browser window that
looks similar to the one you saw in Figure 22.5.
Drawing Figures and Graphing Data
In the preceding application, we looked at existing images and text.We haven’t yet
looked at an example with drawing, so let’s do that now.