<?php
/* xkcdBookshelf.php
Accepts two post parameters, "book" and "comment," and inserts them into a comic strip.
Requires the GD image manipulation library.
*/

$book = $_POST["book"];
$comment = $_POST["comment"];

$img = imagecreatefrompng("./bookshelf_template.png");

//starting parameters for the text in the first panel
$textColor = imagecolorallocate($img, 0x00, 0x00, 0x00);
$extraInfo = array("linespacing" => .8);
$fontSize = 20;
$maxWidth = 120;
$maxHeight = 35;

if($book) $book = $book . '!';

//wrapper for imageftbbox that only returns the width
function textWidth($text) {
	global $fontSize,$extraInfo;
	$box = imageftbbox($fontSize,0,'/Humor-Sans.ttf',$text,$extraInfo);
	return $box[4];
}

//wrapper for imageftbbox that only returns the height
function textHeight($text) {
	global $fontSize,$extraInfo;
	$box = imageftbbox($fontSize,0,'/Humor-Sans.ttf',$text,$extraInfo);
	return $box[1];
}

//insert linebreaks or shrink text to fit in the horizontal space
while(textWidth($book)>$maxWidth) {
	$lastSpace = strrpos($book,' ');
	if ($lastSpace === false) { //no spaces left
		$fontSize--;
	}
	else {//replace the last space with a linebreak
		$book[$lastSpace] = "\n";
	}
}

//shrink text to fit in the vertical space
//reduces line spacing if possible, then collapses lines, then decreases font
while(textHeight($book)>$maxHeight) {
	$spacing = $extraInfo["linespacing"];
	if ($spacing > .6) {//too much overlap after this.  Values <1 are only okay because this is an all-caps font.
		$extraInfo["linespacing"] = $spacing - .1;
	}
	else {
		$foundUnneededNewline = false;
		$lines = explode("\n",$book);
		for($i=0;($i+1)<count($lines);$i++) {
			if(textWidth($lines[$i] . " " . $lines[$i+1])<$maxWidth) {
				$foundUnneededNewline = true;
				$lines[$i] = $lines[$i] . " ";
				$i++;
				$lines[$i] = $lines[$i] . "\n";
			}
			else {
				$lines[$i] = $lines[$i] . "\n";
			}	
		}
		if ($foundUnneededNewline) {
			$book = implode("",$lines);
		}
		else {
			$fontSize--;
		}
	}
}

imagefttext($img,$fontSize,0,11,16,$textColor,'/Humor-Sans.ttf',$book,$extraInfo);

//starting parameters for the text in the third panel
$extraInfo = array("linespacing" => .8);
$fontSize = 32;
$maxWidth = 55;

//insert linebreaks or shrink text to fit in the horizontal space
while(textWidth($comment)>$maxWidth) {
	$lastSpace = strrpos($comment,' ');
	if ($lastSpace === false) { //no spaces left
		$fontSize--;
	}
	else {//replace the last space with a linebreak
		$comment[$lastSpace] = "\n";
	}
}

$maxHeight = min(100,(substr_count($comment,"\n")+1)*32); //100 pixels or 32 per line

$width = textWidth($comment)+2;
$height = textHeight($comment) + (1.5*$fontSize);

//write to a dummy image
$shortImage = imagecreate($width,$height);
imagecolorallocate($shortImage,0xB2,0xB2,0xB2);
$textColor = imagecolorallocate($shortImage, 0x00, 0x00, 0x00);
imagefttext($shortImage,$fontSize,0,2,$fontSize,$textColor,'/Humor-Sans.ttf',$comment,$extraInfo);

//stretch the dummy image, mostly vertically, then apply filters
$stretchedImage = imagecreate($maxWidth,$maxHeight);
imagecopyresized($stretchedImage,$shortImage,0,0,0,0,$maxWidth,$maxHeight,$width,$height);
imagefilter($stretchedImage,IMG_FILTER_GAUSSIAN_BLUR);

//paste it onto the comic
imagecopy($img,$stretchedImage,436,56,0,0,$maxWidth,$maxHeight);

// Output image to the browser
header('Content-Type: image/png');

imagepng($img);
imagedestroy($img);

?>