有没有人有脚本使用PHP创建水平渐变（从左到右）？

Here's the current code I am using.

<? header("Content-type: image/png");
// example: <img src="gradient.php?height=600&width=100&start=00FF00&end=ff0000" />
$height=100;
$width=1;
$start='000000';
$end='FFFFFF';
extract($_REQUEST); // overwrite using vars from url
$start_r = hexdec(substr($start,0,2));
$start_g = hexdec(substr($start,2,2));
$start_b = hexdec(substr($start,4,2));
$end_r = hexdec(substr($end,0,2));
$end_g = hexdec(substr($end,2,2));
$end_b = hexdec(substr($end,4,2));
$image = @imagecreate($width,$height);
for($y=0;$y<$height;$y++){
    for($x=0;$x<$width;$x++){
        if($start_r==$end_r) $new_r = $start_r;

        $difference = $start_r-$end_r;
        $new_r = $start_r-intval(($difference/$height)*$y); 

        if($start_g==$end_g) $new_g = $start_g;

        $difference = $start_g-$end_g;
        $new_g = $start_g-intval(($difference/$height)*$y);     

        if($start_b==$end_b) $new_b = $start_b;

        $difference = $start_b - $end_b;
        $new_b = $start_b-intval(($difference/$height)*$y);

        $row_color = imagecolorresolve($image,$new_r,$new_g,$new_b);
        imagesetpixel($image,$x,$y,$row_color);
    }    
}
imagepng($image);
imagedestroy($image);
?>

The above code works perfect in making vertical (top to bottom) gradients but I'd like to be able to make horizontal ones as well. I have a very good understanding for PHP, but I don't deal with PHP image functions very often. If someone can help me and figure this out I'd really appreciate it!

This code will work for vertical gradient and make it faster as well.

I have commented out useless code so you know what to delete.

for($x=0;$x<$width;$x++){
    /*if($start_r==$end_r) $new_r = $start_r;*/
    // ^^ the line above is useless, $new_r will be set below either way

    $difference = $start_r-$end_r;
    $new_r = $start_r-intval(($difference/$width)*$x); 

    /*if($start_g==$end_g) $new_g = $start_g;*/
    // ^^ the line above is useless, $new_g will be set below either way

    $difference = $start_g-$end_g;
    $new_g = $start_g-intval(($difference/$width)*$x);     

    /*if($start_b==$end_b) $new_b = $start_b;*/
    // ^^ the line above is useless, $new_b will be set below either way

    $difference = $start_b - $end_b;
    $new_b = $start_b-intval(($difference/$width)*$x);

    $new_color = imagecolorresolve($image,$new_r,$new_g,$new_b);
    // ^^ used to be $row_color

    for($y=0;$y<$height;$y++){
        imagesetpixel($image,$x,$y,$new_color);
    }    
}

should just be able to swap your width and height loops/values.

Thanks go out to Gert!

Here is the final code I came up with, it's efficient, the images cache, and the file sizes are very friendly.

<? header("Content-type: image/png"); // example: <img src="gradient.php?width=100&start=00FF00&end=ff0000&type=x" />
$width = 1; $height=1; $start='000000'; $end='FFFFFF'; $type='x'; extract($_REQUEST);
$path = "gradients/".$start."-".$end."_".$width."x".$height."_".$type.".png";
if(file_exists($path)) echo file_get_contents($path);
else{
    $r1 = hexdec(substr($start,0,2)); $g1 = hexdec(substr($start,2,2)); $b1 = hexdec(substr($start,4,2));
    $r2 = hexdec(substr($end,0,2));   $g2 = hexdec(substr($end,2,2));   $b2 = hexdec(substr($end,4,2));
    $image = @imagecreate($width,$height);
    switch($type){
        case 'x': $d1 = 'height'; $d2 = 'width'; $v1 = 'y'; $v2 = 'x'; break;
        case 'y': $d1 = 'width'; $d2 = 'height'; $v1 = 'x'; $v2 = 'y'; break;
    }
    for($$v1=0;$$v1<$$d1;$$v1++){
        $r = $r1-intval((($r1-$r2)/$$d1)*$$v1); $g = $g1-intval((($g1-$g2)/$$d1)*$$v1); $b = $b1-intval((($b1-$b2)/$$d1)*$$v1);
        $color = imagecolorresolve($image,$r,$g,$b); for($$v2=0;$$v2<$$d2;$$v2++) imagesetpixel($image,$x,$y,$color);
    } imagepng($image,$path,1); imagepng($image,NULL,1); imagedestroy($image);
}?>

Variable $type can be x or y, and it would be in relation to your CSS sheet and what coordinate is repeating... Here are some examples:

<style type="text/css">
body{
        background:url(gradient.php?height=123&start=ABBABB&end=FFF000&type=x) repeat-x scroll top left; /* the &type=x' so the repeat is 'repeat-x'. height needs set. */
}
</style>

<style type="text/css">
body{
        background:url(gradient.php?width=345&start=111222&end=999888&type=y) repeat-y scroll top left; /* the &type=y' so the repeat is 'repeat-y'. width needs set. */
}
</style>