There and Back Again

I gave a presentation at yesterdays azPHP Meeting.

The slides from this are now available.

Also there should be another HTML_AJAX release today fixing and annoying bug.

This release is a mix of bug fixes and new features.

There shouldn’t be any reference bugs left so those of you running on php 4.4 or 5.1 should be fine now.

The only item that should cause you problems is that php 4 exports method and class names to JavaScript lowercase while php5 does it in the specified case. So if you want php4 and 5 compatability you’ll need to specify the methods to export. A lowercase all option is on the list of things to do.

Changes:
There is now a append util function on HTML_AJAX
New HTML_AJAX_Debug and HTML_AJAX_Helper classes, look at the examples to see there basic use
HTML_AJAX_Server::registerJSLibrary added to allow you to use the same server class to export you own js libs
multiple client libs can be combined into a single request server.php?client=main,httpclient,customlibname (see helper_usage.php in examples for details)

The default loading implementation has been moved to its own javascript file. If you don’t want the default implementation just don’t include this lib. The implementation has also had a half second timer added so it only shows on slower calls, so if your using it on intranets, you won’t see if for your really fast calls.

Start on a serializer built on php’s serialize call. Be aware this hasn’t had much testing and that it has security issues in older versions of php (bug in unserialize call) and may never work correctly with multibyte characters until php6, but it may be faster and like any serializer its optional.

I’m sure there was some other stuff too. Also like any OpenSource project were looking for more help, including people willing to work on docs, do core development, and auxilary classes for items like template or framework integration. Some widgets may also find there way into HTML_AJAX as optional components so if your interested in writing any let me know.

The meeting is tomorrow 7:00pm at Walt’s TV in Tempe be sure to invite anyone you know that might be interested.

The meeting will have two two presentations each around 45 minutes long and then will finish things up with a open QA Session answering questions about the presentations or about anything else that is PHP releated.

The Presentations are:

Beginning Presentation: Smarty Presentation by Chris Cowan
Advanced Presentation: Getting started with HTML_AJAX by Joshua Eichorn

Meeting Timeline –
Tuesday October 25
  7:00 – PHP News
  7:15 – Smarty Presentation by Chris Cowan
  8:00 – Getting started with HTML_AJAX by Joshua Eichorn
  8:45 – QA Session
  9:30ish – Social Hour(s) at Old Chicago

In a recent project, I had the joy (make that pain) of using GD a lot. The project was an update to the a facial composite tool for Identikit. The new code isn’t live yet, its still in final testing, but its all done for me except for a bit of final bug fixing.

Anyway the app is written in Flash and integrates with PHP for things like saving files to the database or creating a jpeg for the user to save. So what I have is a bunch of transparent pngs that I composite together to make the final sketch. Just like you would do by hand if you had an old school version of this from little paper cutouts.

The problem I ran into with GD is it doesn’t repect an images transparency. So my basic test of this is, open an transparent Image and resize then output the image.

You take the starting Image (shown on and off a colored background so you can see the transparency)

Next we resize it, some code for this is shown below:

<?php

// load in the source image
$im = imagecreatefrompng('sample1.png');
imagesavealpha($target,true);

// get its width and height
$imageWidth = imagesx($im);
$imageHeight = imagesy($im);

// were doubling in size
$targetWidth = $imageWidth*2;
$targetHeight = $imageHeight*2;

// create a target im
$target = imagecreatetruecolor($targetWidth,$targetHeight);
imagesavealpha($target,true);

// fill the image with transparency
$trans = imagecolorallocatealpha($target,255,255,255,127);
imagefill($target,0,0,$trans);

// copy with resize to the target
if (isset($_GET['resample'])) {
        imagecopyresampled($target,$im,0,0,0,0,$targetWidth,$targetHeight,$imageWidth,$imageHeight);
}
else {
        imagecopyresized($target,$im,0,0,0,0,$targetWidth,$targetHeight,$imageWidth,$imageHeight);
}

// output the image as a png
header('Content-Type: image/png');
imagepng($target);

?>

Output from this is shown below, first using resize then using resample

As you can see the background is still alpha transparent but the lenses are now black. I hope im just missing some flag, but in that case someone should really add a makeBrokenGDWorkLikeIWouldExpect flag so I don’t have to find the right combination of them to make things work. After all if I shelled out to ImageMagick convert to do the resize it would just do the right thing.

Anyhow feedback on what im doing wrong here would be nice, or if this just doesn’t work what I need to make this a good bug report.

Any how this example doesn’t have the problems I had before, that just had a simple bug in it from me filling in the wrong order.

Anyhow I did have similar problems when working with the compositing code for this app, im guessing it was caused by a similar mistake, but i’d have to read through commit logs to be sure, and that doesn’t sound like much fun. Suffice it too say, the equivalent code using Imagemagick on the command line is a lot easier to understand though not much easier to debug.

Anyhow the second part item after resizing an image is adjusting its properties. Shading the image, playing with gamma works pretty well, flipping it if needed (this would be nice to have as part of the GD api but its quite easy to write, This manual comment has one), and then adjusting the transparency of the image (Imagecopymerge works well for that).

A sample output would be:

And for a quality comparison, the same thing done shelling out to composite

The main things I would take out of this is that the API for GD is way to low of a level for normal use, so you’ll want to look into a wrapper (there are some options in PEAR but none with a stable release). There are also quality issues with GD when making images larger, but I don’t want to see new features like cubic interpolation added until the api to use them is reasonable.

Code for GD Compositing

<?php

// create a target im
$target = imagecreatetruecolor(500,200);
imagesavealpha($target,true);
imagealphablending($target,true);

// fill the image with transparency
$trans = imagecolorallocatealpha($target,255,255,255,127);
imagefill($target,0,0,$trans);

// copy the eyes in place first
// load in the source image
$im = imagecreatefrompng('sample2.png');
imagesavealpha($im,true);
imagealphablending($im,true);

// get its width and height
$imageWidth = imagesx($im);
$imageHeight = imagesy($im);

// were doubling in size
$targetWidth = $imageWidth*2;
$targetHeight = $imageHeight*2;

imagecopyresampled($target,$im,2,26,0,0,$targetWidth,$targetHeight,$imageWidth,$imageHeight);
imagedestroy($im);

// copy the glasses on top of that
// load in the source image
$im = imagecreatefrompng('sample1.png');
imagesavealpha($im,true);
imagealphablending($im,true);

// get its width and height
$imageWidth = imagesx($im);
$imageHeight = imagesy($im);

// were doubling in size
$targetWidth = $imageWidth*2.2;
$targetHeight = $imageHeight*2.2;

imagecopyresampled($target,$im,0,0,0,0,$targetWidth,$targetHeight,$imageWidth,$imageHeight);
imagedestroy($im);

// output the image as a png
header('Content-Type: image/png');
imagepng($target);

?>

Code for ImageMagick compositing

<?php

header('Content-type: image/png');
passthru('composite -geometry +2+26 sample2.png -resize 200%  back.png - | composite sample1.png -resize 220% - - ');

?>

Blog spam has started to find its way into my moderation queue again. To help cut down on the amount of junk I have to delete by hand I added ringtone to my kill list. So if you want to make sure your comment is never seen, toss ringtone in it and it will be gone.