Specifications

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. We can use the ImageCreateFromJPEG() and

ImageCreateFromGIF()functions in the same way if the appropriate support is installed.

Generating Images

HAPTER 19

ENERATING

IMAGES

415

The call to ImageCreateFromPNG() only creates the image in memory. To save the

image to a file or output it to the browser, we must call the

ImagePNG() function.

We’ll come to that in a minute, but we have other work to do with our image first.

NOTE

Fitting the Text onto the Button

We have some text typed in by the user stored in the $button_text variable. What we want to

do is print that on the button in the largest font size that will fit. We do this by iteration, or

strictly speaking, by iterative trial and error.

We 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. Our button images are

beveled, so we’ll need to leave room for that around the edges of the text. If you are using dif-

ferent images, this number will be different! In our 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);

We also need to set up the initial font size. We start with 32 (actually 33, but we’ll decrement

that in a minute) because this is about the biggest font that will fit on the button at all:

$font_size = 33;

Now we loop, decrementing the font size at each iteration, until the submitted text will fit on

the button reasonably:

{

$font_size--;

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