PATCH: 1.4.2 Gradient Graph Lines

[nelsonab]

Topka posted a question about having gradient lines in Zabbix. It sounded like a fun hack and a few hours later it was done.

It's a fairly straightforward hack. When you create a graph you have the ability to add an item with it's line type of "Gradient Line". It will then take the color of the line you chose and create a gradient from that color to white/opaque below that line. The gradient goes from the line to the bottom of the graph. When there are jagged nearly vertical lines in the graph the gradient graph does not look very good. The was most often observed in testing with Processor load with a resolution of 5 seconds. Changing that to 15 or 30 improved quality on a 1hr graph.

The patch will work with any color and with multiple items. No Changes are needed to the database.

NOTE:
If your php version does not use true-color images gradient graphs will not work. I added some code to detect the use of true-color image functions. If your php does not use true-color you will only see a normal line. This is due to the need for an alpha channel and the way php handles color variables.

To apply the patch.
1) Save the patch to your system
2) Change into your Zabbix directory
eg "cd /srv/www/htdocs"
3) Apply the patch
patch -p1 < /path/to/your/patch/gradient.patch

Please post any problems encountered.

[Alexei]

Thank you for the patch. I will try to integrate it into 1.4.3, it is registered as ZBX-125 in our support system.

[Palmertree]

Great Patch. Another cool thing would be able to change the background color of the graph to black or any other color.

[nelsonab]

That's pretty easy however it will involve a change to the database making it nonstandard and complicating the upgrade path. Perhaps for 1.5? Alexei??

[topkoa]

Slight tweak-

Hey- your patch works great..

I was wondering if you would mind adding one small tweak to it?

I have been using it with my temperature gages and I think a specific color gradient would be preferrable-

Check the following link for an example of what I mean:

http://oss.oetiker.ch/rrdtool/gallery/temp-poprs..png

Thanks again, and please forgive me for being a pain..

[nelsonab]

Hmm A shaded gradient. It would be pretty easy to hack overall. I'll give it some thought, there are some limitations right now with graphs and items.

Alexi what are your thoughts to having a general field for specific item/graph related options in the gitems table? As an example you could use the field to store a start/end color or other options. I'm thinking a varchar(255). Your thoughts?

[Alexei]

Alexi what are your thoughts to having a general field for specific item/graph related options in the gitems table? As an example you could use the field to store a start/end color or other options. I'm thinking a varchar(255). Your thoughts?

I am not happy about "universal" fields in the database structure. Anyway feel free to implement it in your way, I will review the changes and adjust the code and database changes as well.

[Palmertree]

Graph Background Colors

I was going to try and take a hack at the background color in the graphs but can not locate the code for the default background colors. Does anyone know where I should start looking? I was looking around in the file graphs.inc.php. If anyone else wants to take a hack at this too, please feel free to do so.

[nelsonab]

The background is drawn in the drawWorkPeriod() method located in includes/classes/graph.inc.php

There are two sections to the method. The first draws the normal work period in white and the second will draw the non-work period in grey. After that drawGrid() gets called in the Draw() method.