PiggZ Blog

Tradeoffs

Sat, 14 Mar 2009 08:11:18 GMT

So i tried several things to speed up my grid drawing.

1. As suggested by ZRusing, instead of multiple calls to drawLine and drawPoint, I instead created a vector of each and used a single call to drawLines and drawPoints. This made no difference.

2. Draw lines only. This was super fast.

3. Draw points only. This was still slow.

4. Anholt on #intel-gfx suggested grid-aligning my points to screen pixels. I wasnt 100% sure what this meant, so i changed the drawing code to use integer maths instead of floating point to ensure all drawing of points would be on an actual pixel, but this made no difference.

5. Turned off antialiasing in QPainter. Instant 200x speedup!

So the options seem to be use antialiasing with the raster graphics system, or dont use antialiasing, and have a slightly different look, which I dont mind, and is what im doing at the moment.

Drawing Performance (or not)

Thu, 12 Mar 2009 07:01:15 GMT

In my app, I draw a background grid. Its nothing fancy, just some lines and dots but it was quite slow, and would get slower the larger the area obviously. I'm by no means an expert in drawing graphics optimally, but I had a few hacks in there to speed it up, like caching the background and only redrawing the affected rect. But still it wasn't great, it felt sluggish. 'Feeling' sluggish isn't very scientific, so I ripped out he drawing code and put it in a test app which timed it, that app is here. On my system, which isn't a 6GHz oct-core with the latest nvidia sli gfx, its just a run-of-the-mill core2duo with intel x3100, it takes roughly 200ms to draw the grid. Running under Qt4.5 with the raster graphics system, it takes 1ms. Yes, 1. 200x faster using software rendering than using x11. Restarting X using the VESA driver also had great improvements. Even running KDE4 with the VESA driver 'felt' more responsive. So, is it just my system? I have no idea if 200ms is a respectable time for this code, so how about you run it and post the results?

Kexi Data Access

Fri, 16 Jan 2009 23:55:52 GMT

While its been possible to generate great looking reports in Kexi for quite some time, even containing user supplied scripts to enhance the core functionality, one thing that wasn't possible was the ability to access data from the database from within a script.

Well, now that has changed :)

If your familiar with the likes of DAO/ADO on windows/ms access then this should be a breeze to you.
Imaging having a report that contains the data from a table, but then for each record, while the report is being rendered, executing arbitrary queries based on that data to populate other fields....this should now be possible in Kexi.

The following snippet is a small example of opening a query when the report is opened, and getting the first 10 records to populate fields on the report:

function test_kexi_object_report()
{
this.OnOpen = function()
{
debug.message("On open", "open");
test_kexi_object.detail.setBackgroundColor("#dddddd");

var conn = Kexi.getConnection();

var cur = conn.executeQueryString("select msre_desc from weight");
for(i=0;i<10;i++) {
test_kexi_object.objectByName("Field" + (i + 10)).setSource("=" + cur.value(0));
test_kexi_object.objectByName("Field" + (i + 10)).setBackgroundOpacity(0);
cur.moveNext();
}

}
}

Nice, even if I do say so myself ;)

Charts with child/master fields

Sat, 18 Oct 2008 14:29:19 GMT

I guess most database reporting apps can do this, and now Kexi can be added to the list. We could already embed a chart in a report, and assign it a set of data, but what if you want the chart to change depending on the data in the main report? The way to do that is with master->child field links. You specify a field (or fields) in the report (the master) which will be used as an expression on a field (or fields) in the chart (the child). If you're used to msa, its the same as you get with sub forms/reports/charts. This lets you do something like this. The example is a bit boring, but its the first thing I could think of after getting the implementation working :)

Kexi to ODS

Tue, 08 Jul 2008 14:56:07 GMT

After reading the headers for kspread which showed me where I was going wrong, I now have Kexi reports able to output to an ODS (Opendocument Spreadsheet) file by utilising the excellent KSpread libraries. Fields in a report are ordered based on horizontal position, and the text saved into a Cell based on the order. As a test I generated a 20000 row sheet, and openened it up in OO.o, see it here, and download it here.

HTML Reports in Kexi

Thu, 19 Jun 2008 09:44:25 GMT

After some initial work, a re-think and re-design, and a re-implementation you can now get quite nicely formatted reports from Kexi in HTML form using some CSS magic.

Only text is implemented atm, so images, charts, barcodes are still to come, but the output is pretty close to the original page based version, as you can see at http://www.piggz.co.uk/kexi/htmlcss3.png and http://www.piggz.co.uk/kexi/htmlcss4.png.

There will also be a simplified table based version as an option.

Some samples are at http://www.piggz.co.uk/kexi/product_list.html (its 1.9mb representing 10000 records, so be warned ;) and http://www.piggz.co.uk/kexi/rainfall.html.

Enjoy.

Now i remember why I dont use Windows

Wed, 23 Apr 2008 12:56:33 GMT

My mum pops round last night with her laptop. Earlier it had displayed a message saying the battery was going to run out, and then turned off. It wouldnt turn back on.

I tested the power supply with a multi-meter and it seemd OK. I asked if it had been dropped...'No' was the reply, shortly followed by 'Well, it did fall off the little table but was still working OK'

I decided it was best to get a new laptop, as this one clearly wasnt getting power from the mains. But this particular machine is the one with the entire shop inventory and sales history in it and it would be handy to get it off and onto another machine.

No problem, I whipped out the HD, and installed it in my own laptop.

Windows proceeded to boot and got the the 'Activation' screen. No problem I thought, a quick call to Microsoft will have us running in no time, and I can transfer all the data/documents to a USB stick.

I entered the 60! digit number, and was told to change the license key, which I did, and then entered a new 60 digit number, I must have done it too fast because I got transferred to an operator.

I explained the situation and that i was temporarily using my mums HD in my laptop to recover some data from it. I was quite shocked when I was told that because Windows had been pre-installed on the original laptop, the license couldnt be transferred to another machine. After a short agrument where I told him I thought it unfair as we needed the data and it was clearly a temporary situation as I run Linux he gave me the activation key, and all seemed good.

In went the USB disk......and.......nothing.

Device manager suggested drivers needed re-installed, fair enough as it was another machine (though im sure a linux kernel would have reconfigured itself a bit better), so I reinstalled the usb drivers which got rid of the exclamation marks, rebooted and was sure it would work this time.

The screen resolution was even right now......but shortly after starting up it all went horribly wrong.....BSOD, for no aparent reason.

A cycle of rebootss commenced, along with disk checking...nothing would work, not even safe mode.

'Ah' I though.....i'm being stupid, why not boot off a Linux live CD and copy the files?

In went Ubuntu, the USB drive worked OK and I went to mount the NTFS drive.

Catastrophe!! the drive wouldnt mount....errors suggesting a bad/missing MFT, and I should run chkdsk.

I rebooted again, but this time Windows wouldnt even attempt to load, the partition seems totally corrupt. I eventually got a 'Windows Recovery Console CD' and attempted to run chkdsk from it, but it told me the drive had unrecovereable errors :(

As a last resort I left 'photorec' running over night scanning for .mdb files, and it managed to find some which may reduce the strain of re-entering all orders and transactions for the last year from paper copies.

Ive also left 'testdisk' running to see if it can find an MFT, but I dont hold much hope.

Motto? BACKUP BACKUP BACKUP.... she had even bought a USB stick to backup the shop database to, but she clearly hasnt got the hang of it.....I bet she does it tonight though!

Look out Microsoft, here we come ;)

Thu, 17 Apr 2008 19:30:57 GMT

Ok, so we're maybe not quite there yet,but our own office DB app kexi is slowly gaining features. You will shortly be able to create charts directly within a reports. You can already see what it will look like from the designer, it just isnt saved or rendered yet, but because it looks quite cool, i think its worth showing off (atleast the others in #kexi think so). Check it out here. To get an idea on how it evolved, have a look at the 6 prior snaps also.

Script your reports

Fri, 14 Mar 2008 12:34:47 GMT

So you have a report to produce, no problem for kexi these days, but your asked to highlight certain conditions...what do you do?

Script it!

Write something like this. And get results like this.

I would have made those text boxes transparent, if it didnt crash when i selected them...but thats something to fix tonight ;)

Kexi Reporting - progress++

Sat, 02 Feb 2008 15:30:34 GMT

Im sure if I had milestones, one of them would be printing, which i've just got working so I may aswell show it off :)

print.pdf

The designer is coming on quite nicely too.

As is the on screen rendering.

Ive also prepared another version for Kexi1 that adds a couple of requested features from ppl on #kexi. That version does basically work, but ive got to admit ive neglected it to work on the Kexi2 but if anyone needs something i'll do my best to add it.

Dear Lazy Web

Mon, 31 Dec 2007 17:59:04 GMT

I have a subclass of QGraphicsLineItem that i want to interact with on a scene. Suppose the line is 1px wide, 20px long and horizontal starting at 0,0 local coordinates. I can click on the line and drag it around, but i have to click right on it. I'd like to have say, +-5 pixels either side that will select the line, and send hover events to it. I tried reimplementing boundingRect to return QRectF(-5,-5, x2() +10, y2()+10) but to no avail.

Any suggestions?

Cheers

Reports in Kexi 2

Mon, 31 Dec 2007 17:50:59 GMT

Ive been working quite hard to bring my report part for Kexi to the upcoming Kexi2. Finally its starting to look useful. The port has been quite long and boring. I started by re-basing on openrpt 2.2 which is now lgpl, removing the dependencies on Qt3Support and moved the build system to CMake. Then came the long and boring task of basing the designer on QGraphicsView instead of QCanvas. While doing this i also changed the way coordinates are stored and re-used code from koffice where possible (though i'm sure more can be done).

I also did quite a lot of re-factoring to share more code between the designer and renderer components(i don;t need to methods of parsing the same xml).

Anyway, the fruits of my labour (so far) are here and here.

Preview Kexi Report Part 0.0.5

Thu, 05 Jul 2007 22:03:33 GMT

Here is a quick preview if the next version of the report part for Kexi. What you see here is Group Headers/Footers working (they didnt work at all in <= 0.0.4). Unfortunately, to get this to work I had to fix a crash in KexiDB's sqlite driver which affects 'buffered' cursors. Kexi itself doesn't actually use buffered cursors, so im the first to stumble on this problem. The fix is simple, but do I:
a. require users to use an svn version of kexi with the fix
b. code a workaround in the report part (ie, do my own buffering)

Feel free to post other suggestions. To go the svn way, it would also be nice to add buffering to atleast the pqxx driver (it wouldnt be difficult) so reporting (with headers) would also work with databases on Postgres.

linuxbabe

Tue, 19 Jun 2007 10:27:01 GMT

Not exactly kde related, so sorry to planetkde readers.

In the early hours of saturday morning, my wife gave birth to a little girl called Megan. So we're pretty tired at the moment, its been an action packed few days.

From this photo, it looks like she may be joining linuxchix in a few years :)

Kexi Report Part 0.0.3

Thu, 07 Jun 2007 21:51:17 GMT

After a few nights work, I proudly present Kexi Report Part version 0.0.3. Pick it up on kde-apps at http://www.kde-apps.org/content/show.php/Kexi+Report+Part?content=58208. I had to get this out quickly, as its probably the last version i'll get out before my good wife gives birth again :).
New features are:
*Double Buffered for HUGE speed improvement when scrolling
*Labels and Field can have foreground/background colour
*And the editor gets an icon and menu entry

Enjoy

Images in a kexi report

Tue, 15 May 2007 22:34:08 GMT

As the initial version of my kexi report part seems to be going quite well on kde-apps ( http://kde-apps.org/content/show.php/Kexi+Report+Part?content=58208 ) the current development version just got images. Both static and dynamic (stored in the database) are supported, as can be seen by this screenshot http://www.piggz.co.uk/KexiReportImages1.png. The logo at the top is static and stored in the report, all characters are stored in the database, and returned by the query, sweet.

Another Sceenshot

Mon, 30 Apr 2007 15:15:05 GMT

This time just a report.

http://www.piggz.co.uk/3rdKexiReport.png

Kexi Reports

Mon, 30 Apr 2007 15:13:45 GMT

Kexi 1.6 is a great program....it can do many things...that is, apart from generate reports.

Until now that is.

Ive been (slowly) working on modifying openrpt (www.openrpt.com) which is a postgresql/odbc reporting engine, so that it works with kexi.

Currently, ive only tried very simple things....the designer works pretty well...it opens a connection to a kexi database, using the kexi dialogs, and saves the report definitions as kexi database objects.

Ive created a KexiPart, which displays the rendered report within kexi, when a report is selected from the database tree.

Theoretically, printing shouldnt be difficult....and now that I can actually see something that looks like a report rendered on screen, i'll have more motiviation to work on it.

Im sure Kexi 2 will have something much greater, but for now, im quite happy that Kexi 1.6 can have reporting.

Obligatory Screenshot: http://www.piggz.co.uk/2ndKexiReport.png

Only on linux...

Tue, 27 Mar 2007 08:09:15 GMT

(and probably other free os's) can you have a piece of hardware with no driver, talk it over with a developer who gets you to generate a log file from windows, give him access to your machine, and watch while in a few hours he writes a driver for your DVB-T USB adapter, on your laptop from the other side of the world.

How cool is that?

Sign This Petition

Mon, 19 Feb 2007 22:52:41 GMT

Hi Just found this petition for the use of linux in the UK government. It closes TODAY so please sign it.

http://petitions.pm.gov.uk/Use-LINUX/

KDE3 apps on Windows

Sun, 04 Feb 2007 12:47:46 GMT

Ive been writing a little application to allow the management of my mums website database from a desktop app. It uses kde3, soap (using gsoap2) and some xml parsing. I was hoping I'd be allowed to wipe Windows from the machine, but that's a no-no (atm, I may push a bit more).

So i basically have 3 options:
1. Rewrite using QT4 and port to windows. Probably the best long term solution, especially when kde4 comes out, but I needed something quicker.

2. Use cygwin. An ok solution, but the kde in cygwin is quite old, and i wanted quanta to run aswell.

So i went with 3. colinux. It was quite simple to set up, in no time i had a very minimal fc6 + kdebase + kdewebdev + gcc. Networking worked so I copied my app from an smb share on my laptop, compiled and installed.

By hacking rc.local, I had kicker run on startup, positioned in the top-centre of the screen, with some buttons for quanta, konqueror and my app.

It works pretty well, takes a while to boot up, but you cant expect much from a laptop with 256mb ram, running both windows xp and linux!!

Amusingly, konqueror starts up faster than ie7

Sleep Deprivation

Thu, 04 Jan 2007 11:30:00 GMT

I'm sure lots of you have suffered from this......you know how it goes, you get to bed, your lying there and your mind is working overtime. A sudden surge of inspiration hits you for a little project to work on, and you cant help but start designing it in your head. Before you know it, you've missed several hours of sleep.

:)

Comments Section

Sun, 24 Dec 2006 10:16:13 GMT

Finally got round to adding a comments section to my blog (the downside of writing your own instead of using something off-the-shelf). Decided to use a captcha to prevent spam as it seems to have worked a treat in the guestbook.

So feel free to leave as many or as few comments as you like.

LINUX Road Show

Sat, 16 Dec 2006 09:23:55 GMT

I just got confirmation of a place at the free UK Linux Roadshow. Its at HP's Bristol labs on the 11th January and being run by the HP User Group. Anyone else out there going?

See http://www.hpug.org.uk/index.php?option=com_events&task=view_detail&Itemid=45&agid=24&year=2007&month=01&day=11
for the details.

A Tip

Wed, 22 Nov 2006 22:01:40 GMT

When you in the psql command line, and you press 'up arrow' for the last command, make sure its the command you want before hitting [Enter], otherwise you may realise that youve just deleted your entire blog and it needs recreating, which will surely cause it to spam the planets. So, im sorry for reposting things you may have already read :).

YardsOfYarn, Amarok, Koffice

Wed, 22 Nov 2006 21:59:36 GMT

Its been a year in the making, but i finally got the e-commerce system i've been writing for my mums website into a state where it actually works, infact, a random woman bought 6 balls of wool, and paid smoothly via paypal, before the site was technically ready. I know there are things like this pre-packaged, but i wanted the experience in building a medium(ish) scale website by hand. The main tool I used? Quanta, i'd be lost without it. Now just have to wait for all the money to roll in and take a percentage :).

So if anyone needs wool/yarn/needlwork/xstitch etc, just visit www.yardsofyarn.co.uk.

In other news, the Amarok guys accepted my shoutcast browser, so expect to see that in 1.4.5 (or now if your using svn).

Done a bit more coding in koffice, nothing too substantial, mainly porting, and learning the neq qt4 ways of doing things.

Amarok - Shoutcast

Wed, 22 Nov 2006 21:57:31 GMT

Hacked together shoutcast support for the amarok playlist browser. You get a folder view containing all the genres, when you double click a genre, it downloads the station list. All you do then is double click a station and it gets added to the playlist. Still a few bugs to work out, but when its ready i'll try and get it into amarok, its the only feature i miss from XBMC on the xbox.

Porting started

Wed, 22 Nov 2006 21:56:53 GMT

Managed to get a workable development environment set up for KDE4 (thanks jstaniek). This seems to work well....
1. Add both your main user and development user to the 'users' group
2. Change the group ownership of the source files to 'users'
3. Change the permissions to 664 (or 660)
4. Edit the files from your main users account using kate (or preferred editor)
5. Compile the files using the development user So, doing this has allowed me to quickly port the kspread-kexi import filter to koffice2 without much trouble (by not much i mean i cant get cmake to create the .moc files so i'm doing it by hand). Next job to start porting kexi drivers/migration.