newbie question - variable data types?

Nerd Monster

I'm sure the solution to this is very simple and I'm just overlooking
something. I'm using the following code to color an image:

$thishex= 0xFF0000;
$red = imagecolorallocate($im, 0, 0, $thishex);

That works perfect. The problem is, the hex color is coming in the URL
string, without the preceding "0x". To remedy this, I tried:

$hex1 = "0x";
$hex2 = "FF0000";
$thishex = $hex1 . $hex2;
$red = imagecolorallocate($im, 0, 0, $thishex);

This does not work, despite the fact that it echos 0xFF0000. As a flash
developer, I have run up against this problem before when I don't use strict
data types. As a php newbie, I am not sure that there is a similar
phenomenon in PHP.

Anybody got the answer to this one? I'm sure it's very simple.

Norman Peelman

Nerd Monster wrote:
> I'm sure the solution to this is very simple and I'm just overlooking
> something. I'm using the following code to color an image:
>
> $thishex= 0xFF0000;
> $red = imagecolorallocate($im, 0, 0, $thishex);
>
> That works perfect. The problem is, the hex color is coming in the URL
> string, without the preceding "0x". To remedy this, I tried:
>
> $hex1 = "0x";
> $hex2 = "FF0000";
> $thishex = $hex1 . $hex2;
> $red = imagecolorallocate($im, 0, 0, $thishex);
>
> This does not work, despite the fact that it echos 0xFF0000. As a flash
> developer, I have run up against this problem before when I don't use strict
> data types. As a php newbie, I am not sure that there is a similar
> phenomenon in PHP.
>
> Anybody got the answer to this one? I'm sure it's very simple.
>
>
>
>
>

Two problems:

1) 0xFF0000 = 16711680 (not 255 like you want)
2) Your second example is using a string (which equates to 0), not a
hexadecimal value.

As long as $hex is a string (as it should be coming in as GET/POST/REQUEST:

This will work with or without adding '0x',

$red = imagecolorallocate($im, 0, 0, base_convert($hex, 16, 10)/512/128))

This will only work if you add '0x' to it:

$red = imagecolorallocate($im, 0, 0, ($hex/512/128))


Norm

Nerd Monster

> Two problems:
>
> 1) 0xFF0000 = 16711680 (not 255 like you want)
> 2) Your second example is using a string (which equates to 0), not a
> hexadecimal value.
>
> As long as $hex is a string (as it should be coming in as
> GET/POST/REQUEST:
>
> This will work with or without adding '0x',
>
> $red = imagecolorallocate($im, 0, 0, base_convert($hex, 16, 10)/512/128))
>
> This will only work if you add '0x' to it:
>
> $red = imagecolorallocate($im, 0, 0, ($hex/512/128))
>
>
> Norm

Thanks Norm! Here's the problem, and you can test these complete examples on
your own machine to verify.
The following works correctly:
-----
<?php
$im = imagecreatetruecolor(100, 100);

$fillcolor = imagecolorallocate($im, 0, 0, 0x00FF00);
imagefill($im, 0, 0, $fillcolor);

header('Content-type: image/png');
imagepng($im);
imagedestroy($im);
?>
-----

Using your example, the following does not work (assuming you pass $urlcolor
in the url):

------
<?php
$im = imagecreatetruecolor(100, 100);

$fillcolor = imagecolorallocate($im, 0, 0, base_convert($_GET["urlcolor"],
16, 10)/512/128);
imagefill($im, 0, 0, $fillcolor);

header('Content-type: image/png');
imagepng($im);
imagedestroy($im);
?>
------

Any clues?

Norman Peelman

Nerd Monster wrote:
>> Two problems:
>>
>> 1) 0xFF0000 = 16711680 (not 255 like you want)
>> 2) Your second example is using a string (which equates to 0), not a
>> hexadecimal value.
>>
>> As long as $hex is a string (as it should be coming in as
>> GET/POST/REQUEST:
>>
>> This will work with or without adding '0x',
>>
>> $red = imagecolorallocate($im, 0, 0, base_convert($hex, 16, 10)/512/128))
>>
>> This will only work if you add '0x' to it:
>>
>> $red = imagecolorallocate($im, 0, 0, ($hex/512/128))
>>
>>
>> Norm
>
> Thanks Norm! Here's the problem, and you can test these complete examples on
> your own machine to verify.
> The following works correctly:
> -----
> <?php
> $im = imagecreatetruecolor(100, 100);
>
> $fillcolor = imagecolorallocate($im, 0, 0, 0x00FF00);
> imagefill($im, 0, 0, $fillcolor);
>
> header('Content-type: image/png');
> imagepng($im);
> imagedestroy($im);
> ?>
> -----
>
> Using your example, the following does not work (assuming you pass $urlcolor
> in the url):
>
> ------
> <?php
> $im = imagecreatetruecolor(100, 100);
>
> $fillcolor = imagecolorallocate($im, 0, 0, base_convert($_GET["urlcolor"],
> 16, 10)/512/128);
> imagefill($im, 0, 0, $fillcolor);
>
> header('Content-type: image/png');
> imagepng($im);
> imagedestroy($im);
> ?>
> ------
>
> Any clues?
>
>
>
>

Ok, you switched your variable on me.

You need to:

if (baseconvert(...) > 512)
{
divide by 512;
}
if (new value > 128)
{
divide again by 128
)

something like that...

The hex numbers your passing in are too big. Must be 0-255 (0x00 - 0xFF)

Norm

Michael Fesser

..oO(Nerd Monster)

>Thanks Norm! Here's the problem, and you can test these complete examples on
>your own machine to verify.
>The following works correctly:

But it is not correct!

>-----
><?php
>$im = imagecreatetruecolor(100, 100);
>
>$fillcolor = imagecolorallocate($im, 0, 0, 0x00FF00);

As said, the numbers passed to imagecolorallocate() have to be 0..255.

To split a given hex string into its color parts, you could use string
functions or something like this:

function imageColorAllocateHex($im, $color) {
$c = hexdec($color);
return imageColorAllocate($im,
0xFF & $c >> 0x10,
0xFF & $c >> 0x8,
0xFF & $c
);
}

Usage:

$color = imageColorAllocateHex($im, '00FF00');

Micha

Norman Peelman

Michael Fesser wrote:
> .oO(Nerd Monster)
>
>> Thanks Norm! Here's the problem, and you can test these complete examples on
>> your own machine to verify.
>> The following works correctly:
>
> But it is not correct!
>
>> -----
>> <?php
>> $im = imagecreatetruecolor(100, 100);
>>
>> $fillcolor = imagecolorallocate($im, 0, 0, 0x00FF00);
>
> As said, the numbers passed to imagecolorallocate() have to be 0..255.
>
> To split a given hex string into its color parts, you could use string
> functions or something like this:
>
> function imageColorAllocateHex($im, $color) {
> $c = hexdec($color);
> return imageColorAllocate($im,
> 0xFF & $c >> 0x10,
> 0xFF & $c >> 0x8,
> 0xFF & $c
> );
> }
>
> Usage:
>
> $color = imageColorAllocateHex($im, '00FF00');
>
> Micha

Thanks Micha, I can't believe what a horrible post I gave... yuck! I was
five minutes to work when I realized how bad it was.

Norm

Nerd Monster

"Norman Peelman" <.com> wrote in message
news:46dd7b2b$0$15366$...
> Michael Fesser wrote:
>> .oO(Nerd Monster)
>>
>>> Thanks Norm! Here's the problem, and you can test these complete
>>> examples on your own machine to verify.
>>> The following works correctly:
>>
>> But it is not correct!
>>
>>> -----
>>> <?php
>>> $im = imagecreatetruecolor(100, 100);
>>>
>>> $fillcolor = imagecolorallocate($im, 0, 0, 0x00FF00);
>>
>> As said, the numbers passed to imagecolorallocate() have to be 0..255.
>>
>> To split a given hex string into its color parts, you could use string
>> functions or something like this:
>>
>> function imageColorAllocateHex($im, $color) {
>> $c = hexdec($color);
>> return imageColorAllocate($im,
>> 0xFF & $c >> 0x10,
>> 0xFF & $c >> 0x8,
>> 0xFF & $c
>> );
>> }
>>
>> Usage:
>>
>> $color = imageColorAllocateHex($im, '00FF00');
>>
>> Micha
>
> Thanks Micha, I can't believe what a horrible post I gave... yuck! I was
> five minutes to work when I realized how bad it was.
>
> Norm

Thanks to both of you for the help! I've been working on a colorpicker
wysiwyg using Flash with remoting to choose the colors and then php to
process the resulting images. I plan to post my source files here and on
sourceforge when I'm done. Thanks again!