PHP

Posts about the server side scripting language PHP

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Drawling A Circle With Pixels In PHP

30th October 2019 - 9 minutes read time

Since my last post, where I talked about drawling a line with pixels in PHP, I have been looking at drawing circles. As it turns out, there are a few different ways to draw a circle, so I'll go through a few options here.

To start with, there are some built in functions in PHP that can be used to draw an arc, circle or ellipse as a filled in shape or a line. The built in function in PHP called imageellipse() that can be used to draw a circle. This is part of the GD library.

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Too Many Open Files Error In PHP SoapClient

21st September 2019 - 4 minutes read time

Whilst working on a project recently I hit upon a PHP error that I've never seen before. During a process where a soap service was calling an API the connection would fail and the program would fatal error and stop.

I had protection mechanisms in place to catch this kind of connection error, but the fatal error was caused when the program tried to throw the exception I had put in place to indicate a failed connection.

Here is the error message (with some of the detail removed). This is a Drupal site but that detail is irrelevant to the problem.

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PHP:CSI - Random Increment Insert

26th January 2019 - 7 minutes read time

A while ago I was working on some changes to a website and came across a block of code that made me stare blankly at my screen. The website I was working on was a custom build website, created by another developer at the company I was working with at the time. I have never done a PHP:CSI on this site before but remember being so amazed at what I found at the time that I made a note of it for future reference. I have pondered recently how to approach the analysis of the code.

The code I found was in a method that inserted an item into a database table. For some reason that I can't fathom the developer had opted to not use auto increment ID's and has instead developed a method that essentially randomly decided on an ID number for the item.

I can't paste the entire block of code here, but I can include the region of code that made me scratch my head in bewilderment.

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Drawling A Line With Pixels In PHP

13th January 2019 - 8 minutes read time

From the drawers of "I didn't realise how complicated that was" I was wondering the other day how to draw a line using just pixels. This turned out to be more complicated than I thought.

Normally in PHP you would use the imageline() function to draw a line between two points. The following block of code creates and image and draws a white line from the coordinates 50x,50y to 200x,150y.

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Color Sorting In PHP: Part 4

2nd January 2019 - 6 minutes read time

Following on from by previous post about sorting colors I decided to take another step towards sorting colors by segmenting the data to create a further dimension to the multi-dimensional array.

The array is already split into segments based on the hue of the color, but we can further split this by separating out saturation and value into separate arrays within hue. To do this we set the saturation or value to be a constant and push them into separate arrays.

The new code looks like this. Please excuse the duplication of code here. This is just a simple example to show how the array is put together.

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Color Sorting In PHP: Part 3

1st January 2019 - 8 minutes read time

The last time I looked at sorting colors I had produced a nice band or sorted colors, but to do so I had essentially removed a third of the data from the color information. This meant that there was no white or black colors in the band of sorted colors.

After a bit of thinking on how to solve this I hit upon a way of using a two dimensional array of colors to filter the colors into blocks. This would allow the missing color information to be rendered correctly, and would only mean a small amount of work to allow it to work with the rendering function used in the previous examples.

Generating The Data

I could easily just generate every color available and use that as the data. What I wanted to generate was a random assortment of colors that would represent the sort of data being produced by a system or other input.

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SOLID Principles In PHP

20th August 2018 - 14 minutes read time
SOLID is a set of object oriented design principles aimed at making code more maintainable and flexible. They were coined by Robert "Uncle Bob" Martin in the year 2000 in his paper Design Principles and Design Patterns. The SOLID principles apply to any object oriented language, but I'm going to concentrate on what they mean in a PHP application in this post.
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Best Practice With Return Types In PHP

23rd July 2018 - 9 minutes read time

I've been using PHP for a number of years and have seen the same things being done with return values from functions over and over again. I have always thought of this as pretty standard, but the more I think about it the less it makes sense. Looking back over my career I am quite sure that a few serious bugs could have been avoided if I had not mixed return types.

As PHP is a loosely typed language this gives the developers the ability to change the type of value that is returned from a function. This happens quite often within the PHP codebase itself as many built in functions will return false if an error happened.

A common practice in userland code is to return false from a function if something went wrong. This might be because it is encouraged in PHP itself.

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Don't Validate And Format In A Single Function

30th June 2018 - 5 minutes read time

I wanted to impart a piece of advice to do with validation and formatting of user input, although I've never seen anyone suggest it. I guess it would come under the single responsibility principle so it might seem obvious to some people. There can be reasons why this might at least seem like a good idea at the time.

Essentially, if you want to validate that something is correct, don't format it at the same time. These two actions should be done in separate functions or even classes. I hope to demonstrate that using a single function validate and format anything is a bad idea. I'll mainly be using PHP to demonstrate this, but the principle should be pretty much the same in any language.

Take the following function called isValid(). This is an arbitrary and simple example but shows validation and formatting in use in a single function.

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Color Sorting In PHP: Part 2

23rd June 2018 - 4 minutes read time

Following on from my last post about sorting colors I have been thinking about different ways of sorting colors. I have been looking at interfaces that allow people to select colors and they will quite normally have a band of colors that does look nicely sorted. As it turns out this is perfectly possible to do if the colors are normalised to remove light and dark variations of different colors.

The easiest way to remove different amounts of lightness and darkness from a color is to convert it to the HSV color space. This way we can just set the value (brightness) and saturation (amount of grey) to be 1. This will change the color by simply removing any information that does not pertain to the actual color. For example, a color that is a very light shade of blue will be changed to be simply blue.