February, 2015

How to call some Pixastic functions

21st February, 2015 - Posted by david

I was doing a bit of work with Canvas recently, manipulating images in the browser and writing the results out to files. I was looking for a package that could do various effects on the images, such as sharpen, blur etc. and came across the Pixastic package used in similar applications. However, unfortunately, the website for the package is currently down and I couldn’t find much documentation on it anywhere. So, I had to look at the source code to figure out how to call the various functions. Not the end of the world, but I just thought I’d stick some simple examples here, to maybe help get others started with the package and to direct them to the source code for more information!

I got the source code from JSdeilvr.net, which is minified, but there is unminified source on GitHub.

The 3 functions I was looking to use were sharpen, brighten/darken and blur. I’ll go through each individually. Firstly though, I’ll mention that the first parameter to each function is a Javascript Image object, which obviously has a src attribute with your image’s contents. The whole point of this was that I was building a tool with buttons which, when clicked, would perform each of the functions above on the current Image. When applying a filter, it’s best track the current level of e.g. brightness, increase/decrease this value, reset the image to how it originally looked and then apply the filter with the new value. This is better than say brightening it by 10%, then brightening the result by 10% again.

Seeing as I used brightness for the example above, I’ll start with that. Also, to darken an image, you simply reduce the brightness value, obviously.

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// initial code setup
var img = new Image();
img.src = 'whatever';
img.original_src = img.src; // for doing the resets
// add the current value of each filter to the Image
$.extend(img, {brightness: 0, sharpen: 0, blur: 0});

// ...

// 'Brighten' button click handler
$('#brighten').click(function() {
img.brightness += 2; // brighten by 2 (for darken, reduce by an amount, will work with negative values)
// max brightness of 255
if (img.brightness > 255) img.brightness = 255;

// now we reset the image by creating a copy
img.src = img.original_src;
// now, apply the filter
img = Pixastic.process(img, "brightness", {
brightness : img.brightness
});
});

For sharpen, I found it best not to sharpen by the same amount each time, it just didn’t lead to nice results.

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$('#sharpen').click(function() {
if (img.sharpen < 0.5){
img.sharpen += 0.1;
}
else if (img.sharpen > 0.75){
img.sharpen += 0.01;
}
else {
img.sharpen += 0.02;
}
if (img.sharpen < 0.88) {
img.sharpen = 0.88;
}

// now we reset the image by creating a copy
img.src = img.original_src;
// now, apply the filter
img = Pixastic.process(img, "sharpen", {
amount : img.sharpen
});
});

Lastly, blur was a bit more straightforward, increasing by 1 every time:

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$('#blur').click(function() {
img.blur++;

// now we reset the image by creating a copy
img.src = img.original_src;
// now, apply the filter
img = Pixastic.process(imageObjs[selected_image].image, "blur", {
amount : img.blur
});
});

As I’m sure you’ve spotted, there’s a certain amount of repetition in the code above, starting with the line “// now we reset…”. What I did was to write a function called applyFilters, which you call once you’ve calculated your new value for brightness/sharpen/blur. This will then reset the image and apply all 3 filters. With the code above, if you were to say brighten, then blur, only the blur would be applied, as the image is reset each time. Doing it this way removes that problem.

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So, that should be enough to get you working with Pixastic. As for working with Canvas, that’s another blog post!

Homepage takeover with existing skyscraper ads

14th February, 2015 - Posted by david

Sometimes in work we can be asked to do things we don’t like and recently I was asked to look into implementing one of those homepage takovers. Personally, I think these are awful and would like to think I wouldn’t degrade my site by implementing one, but they do make money and have a high click rate, so I can see why sites like to use them.

Normally they’re done using a fixed background wallpaper that’s clickable all the way to the edge of the page. However, I was asked to simulate this look using 2 existing skyscraper ads, 170px in width, to be positioned either side of the main content and fixed to the top of the page. Since it wasn’t entirely straightforward, I thought I’d block about it here, to help anyone else in a similar situation. I’m not going to go into the specifics of displaying the ads, simply the CSS and Javascript involved in positioning them where you want them.

I should point out, this might be possible with just CSS, but changing a site’s fundamental structure to accomodate the new columns isn’t always possible. Also, you might only want the takeover on the homepage and not other pages. This solution should have minimal impact, as it simply adds 2 divs, that can go anywhere in the HTML.

So, to describe the set-up, let’s say our main content is 1000px in width, centred in the page and we want 2 170px x 1068px divs to contain our ads and line up on the right and left of that content, as well as for the 2 ads to remain fixed at the top of the page, no matter how far we scroll down. We’ll give each of these divs a class of side-banner, with left-banner and right-banner IDs. Since these are going to be positioned explicitly, it doesn’t really matter where in the HTML you put them, maybe just inside your main content div. Initially, we’re simply going to position them in the extreme top corners of each side. I’m also going to give them different background colours, so we can know they’re positioned correctly without having to worry about loading the ads (which can come later).

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.side-banner {
width: 170px;
height: 1068px;
position: fixed;
top: 0;
}
#right-banner {
right: 0;
background: red;
}
#left-banner {
left: 0;
background: green;
}

To align these alongside the content, I needed to write a Javascript function (position_banners()) to position them correctly. This function is called when the page finishes loading, as well as when the window is resized. It simply gets the body’s width, subtracts the width of our main content (remember 1000px), divides the result by 2 (as we’ve 2 sides), then further subtracts the width of our banners. This fairly basic formula works out the amount to move each div in from their corresponding edge, to line up with our main content. Then, we just use CSS left and right to position them nicely.

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$(document).ready(function() {
position_banners();
$(window).resize(position_banners);
});

function position_banners() {
var margin = ($('body').width() - 1000) / 2 - $('#left-banner').width(),
left = Math.floor(margin),
right = Math.ceil(margin);
$('#left-banner').css({left: left + 'px'});
$('#right-banner').css({right: left + 'px'});
}

I know this code isn’t the tidiest, but should be enough to get the idea of what you need to do.

To further enhance the ‘takeover’ effect, you could display a 970px x 250px ‘billboard’ right at the top of your main content.

Opening hours done right, in PHP and MySQL

7th February, 2015 - Posted by david

I often see different ways of storing and displaying opening hours for various businesses when browsing the web. Some seem to simply store them as an unstructured blob of plaintext and spit that back to the user. Others will store the exact times for each day and display all 7 days on 7 separate rows.

I think neither of these options are great and I’ve come up with what I think is the ideal solution. Basically, we want to store the exact time for each day, but group similar days together. So, you could have lines like ‘Mon – Thurs: 9 – 5’, but if it’s say Tuesday at 10am, you’d also know that the business is currently open. I also think you could have alternative text to display when the business is closed (indicated by open and closed being NULL), so you could have something like ‘Sat – Sun: Open by appointment’.

So, let’s start with our table layout, see below. The primary key is id, which is just your standard auto_increment value. business_id is if you have multiple businesses, each with their own opening hours, as was the case for me. You might want to build an index on this field too. If you’re just storing your own opening hours, dow could be the primary key and you could drop those last 2 fields. open and closed are just simple strings, to store the time in 24-hour ‘HH:MM’ format. Doing it this way, you can still to comparisons like WHERE open > '09:00' and get the result you were expecting.

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+---------------+-----------------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+---------------+-----------------------+------+-----+---------+----------------+
| id | mediumint(9) unsigned | NO | PRI | NULL | auto_increment |
| business_id | mediumint(8) unsigned | NO | MUL | NULL | |
| dow | tinyint(1) unsigned | NO | | NULL | |
| open | char(5) | YES | | 09:00 | |
| closed | char(5) | YES | | 17:30 | |
| optional_text | char(100) | YES | | NULL | |
+---------------+-----------------------+------+-----+---------+----------------+

Next up, I want to show you a quick function to format the time. Being a programmer, the time ’13:30′ is easily translated to ‘1.30pm’, but for the general public it might not be so simple, so this function will display your time in a more human readable format, such as the example given above. Basically, we want to drop any leading 0s, any 0-value minutes, convert the time to a 12-hour version with ‘am’ and ‘pm’ and change the ‘:’ to a ‘.’ (this last bit is probably a bit region-specific). For midnight, we’ll store that as ’24:00′ (which I know is technically the start of the next day!) and display that to the user as ‘midnight’, instead of the slightly confusing ‘0am’.

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/**
* Function to change an opening hour to a more human readable version,
* e.g., 09:00 to 9am or 13:30 to 1.30pm
*
* @param String $time Time to format, in HH:MM format
*
* @return String Formatted time
*
*/
function format_opening_hour($time) {
if ($time == '24:00') {
$new_time = 'midnight';
}
else {
list($hours, $minutes) = explode(':', $time);
$hours = ltrim($hours, '0');
$am_pm = ($hours >= 12) ? 'pm' : 'am';
if ($hours > 12) $hours -= 12;
$new_time = $hours;
if ($minutes != '00') {
$new_time .= '.'.$minutes;
}
$new_time .= $am_pm;
}
return $new_time;
}

OK, so displaying the data in a nice table, with similar days grouped together, is the next bit. We’ll have 2 columns, one for the day/days, the other for the time. If a day has a value for optional_text, then that value will be displayed and the times are ignored. I’m also going to add another block of optional text ($extra_text below) that will be displayed at the end of the table and is applied for all days, to be used for something like ‘phone anytime’. Finally, there’s a $short_day_names option, so you can choose between say ‘Mon’ and ‘Monday’.

I should also mention at this point: I’m returning a block of HTML here from a function, as well as mixing business logic with display logic; I realise this is generally a bad idea and some of this could be split into a function and a template, but seeing as it’s a simple 2-column table, I just kept it all together.

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/**
* Function to generate a simple html table for a business' opening hours
*
* @param Array $opening_hours Array of rows from opening_hours table, sorted by dow (0-indexed, starting with Monday)
* @param String $extra_text Extra block of generic text that applies to all days, goes at end of table
* @param String $short_day_names Whether to use e.g. 'Mon' or 'Monday'
*
* @return String HTML <table> output
*
*/
function opening_hours_table($opening_hours, $extra_text='', $short_day_names=false) {
$dow = array(
array('long' => 'Monday', 'short' => 'Mon'),
array('long' => 'Tuesday', 'short' => 'Tue'),
array('long' => 'Wednesday', 'short' => 'Wed'),
array('long' => 'Thursday', 'short' => 'Thu'),
array('long' => 'Friday', 'short' => 'Fri'),
array('long' => 'Saturday', 'short' => 'Sat'),
array('long' => 'Sunday', 'short' => 'Sun')
);
$key = ($short_day_names) ? 'short' : 'long';

// first, find similar days and group them together
if (!empty($opening_hours)) {
$opening_short = array();
// start with current day
for ($i=0; $i<7; $i++) {
$temp = array($i);
// try to find matching adjacent days
for ($j=$i+1;$j<7;$j++) {
if (empty($opening_hours[$i]['optional_text']) &&
empty($opening_hours[$j]['optional_text']) &&
$opening_hours[$i]['open'] == $opening_hours[$j]['open'] &&
$opening_hours[$i]['closed'] == $opening_hours[$j]['closed'] ||
!empty($opening_hours[$i]['optional_text']) &&
!empty($opening_hours[$j]['optional_text']) &&
strtolower($opening_hours[$i]['optional_text']) == strtolower($opening_hours[$j]['optional_text']) ) {
// we have a match, store the day
$temp[] = $j;
if ($j == 6) $i = 6; // edge case
}
else {
// otherwise, move on to the next day
$i = $j-1;
$j = 7; // break
}
}
$opening_short[] = $temp; // $temp will be an array of matching days (possibly only 1 day)
}
}

$html = '<table>';
$colspan = '';

if (!empty($opening_short)) {
$colspan = ' colspan="2"';
foreach ($opening_short as $os) {
$day_text = $dow[$os[0]][$key];
if (count($os) > 1) { // if there's another, adjacent day with the same time
$end = array_pop($os); // get the last one
$end = $dow[$end][$key];
$day_text = $day_text . ' - ' . $end; // append the day to the string
}
// at this point, $day_text will be something like 'Monday' or 'Monday - Thursday'
if (!empty($opening_hours[$os[0]]['optional_text'])) {
// optional string takes precedent over any opening hours that may be set
$hours_text = htmlentities($opening_hours[$os[0]]['optional_text']);
}
elseif (!empty($opening_hours[$os[0]]['open'])) {
// otherwise generate something like '9am - 5.30pm'
$hours_text = format_opening_hour($opening_hours[$os[0]]['open']) . ' - ' .format_opening_hour($opening_hours[$os[0]]['closed']);
}
else {
// if nothing, it must be closed on that day/days
$hours_text = 'Closed';
}
// new row for our table
$html .= '<tr>
<td>'.$day_text.':</td>
<td>'.$hours_text.'</td>
</tr>';
}
}

// append the extra block of text at the end of the table
if (!empty($extra_text)) {
$html .= '<tr>
<td'.$colspan.'>'.htmlentities($extra_text).'</td>
</tr>';
}

$html .= '</table>';
return $html;
}

So, with the following data…

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+-----+-------+--------+----------------+
| dow | open | closed | extra |
+-----+-------+--------+----------------+
| 0 | 09:00 | 17:30 | NULL |
| 1 | 09:00 | 17:30 | NULL |
| 2 | 09:00 | 17:30 | NULL |
| 3 | 09:30 | 19:00 | NULL |
| 4 | 09:30 | 19:00 | NULL |
| 5 | 09:30 | 16:00 | NULL |
| 6 | NULL | NULL | By appointment |
+-----+-------+--------+----------------+

you should end up with the following table:

Monday – Wednesday	9am – 5.30pm
Thursday – Friday	9.30am – 7pm
Saturday	9.30am – 4pm
Sunday	By appointment
Phone anytime before 11pm