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

Using Text and Fonts to Create Images
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Setting Up the Base Canvas
In Listing 22.2, instead of starting from scratch, you start with an existing image for the
button.You provide a choice of three colors in the basic button: red (red-button.png),
green (green-button.png), and blue (blue-button.png).
The user’s chosen color is stored in the color variable from the form.
You begin by extracting the color from the superglobal $_REQUEST and setting up a
new image identifier based on the appropriate button:
$color = $_REQUEST[‘color’];
...
$im = imagecreatefrompng ($color.’-button.png’);
The function imagecreatefrompng() takes the filename of a PNG as a parameter and
returns a new image identifier for an image containing a copy of that PNG. Note that
this does not modify the base PNG in any way.You can use the imagecreatefromjpeg()
and imagecreatefromgif() functions in the same way if the appropriate
support is installed.
Note
The call to imagecreatefrompng() creates the image in memory only. To save the image to a file or
output it to the browser, you must call the imagepng() function. You’ll come to that discussion shortly,
but you have other work to do with the image first.
Fitting the Text onto the Button
Some text typed in by the user is stored in the $button_text variable.What you need
to do is print that text on the button in the largest font size that will fit.You do this by
iteration, or strictly speaking, by iterative trial and error.
You start by setting up some relevant variables.The first two are the height and width
of the button image:
$width_image = imagesx($im);
$height_image = imagesy($im);
The second two represent a margin in from the edge of the button.The button images
are beveled, so you need to leave room for that around the edges of the text. If you are
using different images, this number will be different! In this case, the margin on each
side is around 18 pixels:
$width_image_wo_margins = $width_image - (2 * 18);
$height_image_wo_margins = $height_image - (2 * 18);