<?php

    # Check for non-empty "text" parameter
    #    
    $text = $_GET['text'];
    $huerotation = $_GET['huerotation'];
    $saturation = $_GET['saturation'];
    $text or die("no text parameter given");

    # x and y are the coordinates of the pixel clicked on the image button
    # if the lower button is clicked the specified hue value is used
    # otherwise it's taken from the rainbow button.
    #
    $y = $_GET['y'];
    if ($y<24)     { $huerotation = ($_GET['x']-16)/144*360;}

    $height       = 23;    # how tall is the button
    $cap_width    = 15;    # how wide are the left and right rounded caps
    $cap_overlap  = 5;     # how many pixels should the text intrude into each cap
    $center_width = 20;    # how wide is the stretchable center part
    
    $left_name   = "button_left.png";
    $center_name = "button_center.png";
    $right_name  = "button_right.png";

    # What font face and size to use
    #
    $ttfont = "/System/Library/Frameworks/JavaVM.framework/Versions/1.3.1/Home/lib/fonts/LucidaSansRegular.ttf";
    $ttsize = 8;

    # Calculate the bounding box of the given string with
    # the above font parameters
    #
    $ttbbox = imagettfbbox($ttsize, 0, $ttfont, $text);

    # array index 2 contains lower right X, 0 contains lower left X,
    # difference is our text width
    #
    $ttwidth = $ttbbox[2] - $ttbbox[0];

    # The image width is the text width plus the
    # space needed for the two caps on each side
    # minus the intrusion amount
    #
    $img_width = $ttwidth + 2 * ($cap_width - $cap_overlap);
    
    $img_out = ImageCreate($img_width, $height) or die("Unable to create new image");

    # Load in the three images needed to create the button
    #
    $img_button_left   = ImageCreateFromPNG($left_name) or die("Unable to open $left_name");
    $img_button_center = ImageCreateFromPNG($center_name) or die("Unable to open $center_name");
    $img_button_right  = ImageCreateFromPNG($right_name) or die("Unable to open $right_name");

    # Fill the empty image canvas by tiling the center image
    #
    for ($i =0; $i < $img_width / $center_width; $i++) {
        ImageCopy($img_out, $img_button_center, $i * $center_width, 0, 0, 0, $center_width, $height);
    }
    
    # Now add the left and right cap, this finishes the button
    #
    ImageCopy($img_out, $img_button_left, 0, 0, 0, 0, $cap_width, $height);
    ImageCopy($img_out, $img_button_right, $img_width - $cap_width, 0, 0, 0, $cap_width, $height);

    # Rotate the color hue value by the parameter given
    #
    for($i = 0; $i < imagecolorstotal($img_out); $i++) {

        $colors = ImageColorsForIndex($img_out, $i);
        $hsv = rgb2hsv($colors['red'], $colors['green'], $colors['blue']);
        $hue = $hsv[0];
        $sat = $saturation ? $saturation : $hsv[1];
        $val = $hsv[2];

        $hue += $huerotation;

        $rgb = hsv2rgb($hue, $sat, $val);

        $red   = $rgb[0];
        $green = $rgb[1];
        $blue  = $rgb[2];

        ImageColorSet($img_out, $i, $red, $green, $blue);

    }


    # Define text color black and render the text onto the button image
    #
    $text_color = ImageColorAllocate($img_out, 0, 0, 0);
    ImageTTFText($img_out, $ttsize, 0, $cap_width - $cap_overlap, 15, $text_color, $ttfont, $text);

    # That's it, output the result
    #
    header("Content-Type: image/png");
    ImagePng($img_out);
    
?>

<?php

    function hsv2rgb($h, $s, $v) {
    
        # Adapted from C source code found here:
        # http://www.cs.rit.edu/~ncs/color/t_convert.html
    
        if ($s == 0) {        # achromatic
            $r = $g = $b = $v;
            return array($r * 255, $g * 255, $b * 255);
        }

        $h %= 360;

        $h /= 60;
        $i = floor($h);
        $f = $h - $i;
        $p = $v * (1 - $s);
        $q = $v * (1 - $s * $f);
        $t = $v * (1 - $s * (1 - $f));
    
        switch($i) {
            case 0:
                $r = $v;
                $g = $t;
                $b = $p;
                break;
            case 1:
                $r = $q;
                $g = $v;
                $b = $p;
                break;
            case 2:
                $r = $p;
                $g = $v;
                $b = $t;
                break;
            case 3:
                $r = $p;
                $g = $q;
                $b = $v;
                break;
            case 4:
                $r = $t;
                $g = $p;
                $b = $v;
                break;
            default:        # and case 5:
                $r = $v;
                $g = $p;
                $b = $q;
                break;
        }
    
        return array($r * 255, $g * 255, $b * 255);
    
    
    }
    
    
    function rgb2hsv($red, $green, $blue) {
    
        # Adapted from C source code found here:
        # http://www.cs.rit.edu/~ncs/color/t_convert.html
    
    
        # Need values from 0 - 1 instead of 0 - 255
        #
        $r = $red   / 255;
        $g = $green / 255;
        $b = $blue  / 255;
    
        $min = min($r, $g, $b);    
        $max = max($r, $g, $b);    
    
        $v = $max;
    
        $delta = $max - $min;
    
        if ($max != 0) {
            $s = $delta / $max;
        } else {
            $s = 0;
            $h = -1;
            return array($h, $s, $v);
        }
    
    
        if ($delta) {
    
            if ($r == $max) {
                $h = ($g - $b) / $delta;
            } else if ($g == $max) {
                $h = 2 + ($b - $r) / $delta;
            } else {
                $h = 4 + ($r - $g) / $delta;
            }
    
        } else {
            $h = 0;
        }
    
        $h *= 60;
    
        if ($h < 0) {
            $h += 360;
        }
    
        return array($h, $s, $v);
    
    }

?>