Delphi histogram component? - delphi

Does it happen that no one ever needs histogram in Delphi ?
Google gave me a bunch of half-baked code snippets. But it means that each time you need one - you have to invent one more ad hoc bycicle.
Torry mostly told me about some very expensive closed source Math Statistics or Financial packages, that as a subproduct have histograms. But they are very expensive and since you have no source code, each time you install update onto IDE/RTL/VCL you're probably screwed, until the vendor would make (soon ? ever?) updated packages. Given thatvendor is still does exists.
S.O. told me nothing, nil.
For what i found...
Mitov.com provides some histograms in PlotLab. which told to be free for non-commercial. Alas, it is again closed-source, and if the Histogram - quite fancy let's admit -is the onlything i need from it - why pay the whole price ?
One more example http://DSpatial.sf.net
Just few years ago i used it in Delphi 5, but even then i felt the author is loosing interest in the project. I made few enhancement, fixed some bugs, he merged them and that's all. The component was not very useful and lacked upon features, yet better than nothing. Now the project seems to be completely dead. Good old days, etc. But i do not want them back :-)
And Stack Overflow seemingly carries no single question about it. But maybe just no one bothered to create topic, after search found nothing ? I mean, Delphi was created for database access, histograms are one of basic ways to visualize data, and no one crosses them ? Something with nice style, with rich mouse tooltip like in HTML/CSS/JS on http://www.moskva.fm/stations/FM_95.2 ?
Or is this too domain-related and not ever possible to have good abstraction ?

TChart is a control that ships with most versions of Delphi. TChart can be used to make histograms (bar charts) in style. The following give you some ideas about how to use it: http://www.digitalcoding.com/tutorials/delphi/Simple-steps-to-create-Delphi-chart.html and http://delphi.about.com/od/adptips2006/qt/chart_selectbar.htm .
If you need something with code, google the pages at delphiforfun.org/programs/oscilloscope.htm . These are not controls. The oscilloscope article has a histogram with source. Some of the other projects at the site have other histogram graphs with source..not elegant but useful and free. Use them as a template to make your own control.
The link at http://delphiforfun.org/programs/Math_Topics/probability_distributions.htm shows how to make your own statistics displays with "histograms." This example makes use of TChart.
Here is some more stuff to try I found looking at my resource file:
http://wiki.lazarus.freepascal.org/TAChart, http://members.home.nl/mvanwesten/en_lazarus.html , http://www.martinole.org/TAChart.html ...some of these are GPU components that supposedly work with some versions of Delphi. Perhaps this is your lucky day as there is some source code. The first and third listed probably will work reasonably for histograms. You may have to write your own statistics algorithms.

Found this thread while doing some searching. The ImageEn component suite has a THistogramBox component. It's the NOT prettiest thing in the world, but it's the only one I've found so far.
http://www.imageen.com

I came across a histogram example in a gdiplus package available for download from code central. I don't know if it will do what you need but when I saw it I remembered your SO question.
HTH.

If you were using firemonkey, you could just created a series of TRectangles in series. They can be made unclickable by turning hittest off. Or is that too easy and straightforward?

Related

F# Priority Queue

I have tried to use this snippet of code
https://code.msdn.microsoft.com/windowsdesktop/Net-Implementation-of-a-d3ac7b9d
to implement a heap-based implementation of Prim's algorithm to solve the Minimum Spanning Tree (MST) problem in a non-directed connected graph.
after a few iterations, i find that the heap/priority queue is not well maintained anymore.
that is the head of the PriorityQueue doesn't have the lowest Key in the Heap.
PQ 0 [-7230, 309]
...
PQ 146 [-7277, 308]
Has anyone use this code and experienced similar problems ?
I can post a link on GitHub if anyone would be looking at it
My needs are for a heap datastructure which supports deletion of an element in the middle. It looks like Fsharpx.collections doesnt have such a data structure.
does anybody know a good implementation available somewhere ?
thanks
Recently, I ported a MaxHeap from PLINQ to F# here and made it MinHeap. It is array-based and performs much better than any "pure functional" alternative.
However, after a lot of benchmarking, I found that SortedDeque based on just a simple sorted circular buffer performs significantly better on most use cases even when I need to add or delete in the middle.
My answer is inspired by V.B. but here it is in full
I have used another library than FSharpx.collections, it is called
Spreads
read that page for details and instructions.
SortedDeque is the data structure i need for this problem.
I used the same code, just changing from the microsoft blog page code to the library functions and found the good result, so it is indeed some bug in the microsoft blog page code
PS. this spreads library has been designed to format financial data for quantitative analysis and i'm happy i found it !!! IT looks like this library is rather recent and thats why its not on top of Google's search or referenced in any other SO question (or if it is i didn't see it)
FSharpx.Collections is of no use for that problem as you can see from that discussion heap issue in FSharpx.Collections

Any Delphi trending controls available

I need a control to add data trending to my application. Is anything available or do I need to use a graphing control and add my own trending features?
Trending is typically an included feature in 3rd party charting components (at least the ones i've seen) but it might be called something else such as linear regression or possiblly something like "least squares*." You should definitely not need to roll your own, unless you think it would be fun. ;-)
Google-ing for "Delphi Chart Regression" will turn up some interesting links.
(* Least squares is typically the method used to establish a trend line from a data set.)
In your shoes, I'd use the stats and charting tools from http://www.lohninger.com/delfcomp.html. It may be a bit more low-level than you want, but I've been very happy with this guys tools (which are reasonably priced, IMO, and, as I recall, can be downloaded for free on a trial basis...)
Check out the curvefit example (comes with an exe demo so no compiling or installing is necessary) here: http://www.lohninger.com/examples_part1.html It'll show you the kinds of charting as well as curve fitting. It's very instructive.
Try JvChart from the JEDI JVCL. If you don't like it, let me know, because I wrote most of it, and I always like to know what people think. It can do static and scrolling displays, and it is very easy to add a few lines and plot some data. A demo app is included in the JVCL\examples\JvChart folder.
There is also TJvSimScope, which is like an oscilloscope and is optimal for fast-scrolling charts showing data which changes on a per-second basis.
JVCL is open source and free
Look for TChart component on your component palette. If your Delphi version has it, then look for demo that uses it.

Draw and manipulate shapes at run time

What's the best way to draw shapes interactively at run time using Delphi? I need to be able to select, drag and resize the shapes. This will be used to mark up existing images and documents.
This looks like a good starting point, but I'm wondering if there's a more complete library (preferably free) available that will save some time.
Update:
If you're going with a custom solution from scratch, I've seen another example on Delphi Central that might be an even better starting point.
I will recommend you, read some links on my site. Are explained and all the source code is available; You can see and get some usefull for you.
Plugin system in Delphi - Part 2
Not directly what you need, is a plugin system for Delphi. But all the samples are based on a drawing tool that uses Shapes (Creating, selecting, resizing). You can review the code and extract what you need.
Sample manipulating of "Maps and Figures"
Sample of how to create, select and move components at runtime (in this case with TImage).
- Select shapes visually: Shows different ways to select shapes visually.
The web is in Spanish, but you can generate an authomatic translation on the web itself.
Anyway the code is commented.
Regards.
Excuse-me for my bad english.
One freeware option would be TssControlSizer. Just change the "control" property to the control you want to manipulate resize/move.
Not sure if you've moved on now with this Bruce but if you haven't, it might be worth looking at TMS Components Diagram Studio - it's certainly cheap, and looks quite powerful from the demo.
I would use Flex Graphics (commercial, $499 for one developer, with sources, $1500 for site-license, with source code). When I bought it, it was a lot less than that. So I guess, I wouldn't pay that now. It's a lightweight 'drawing/cad' package.
But as I already own it, I could import a page from the original document as an image, perhaps rendered in PNG or WMF, and then mark it up with lines, etc.
You could think of it as a light "cad" package. It has most primitive shapes, and you can easily create your own new objects or shapes in Delphi classes, that could be "smart shapes" like the ones in Visio.
http://www.flex-graphics.com/
Another commercial component set that I have heard only good things about is TRichView. They have a TRichViewEdit that looks like you could emulate a document markup environment easily with it.
Please check here:
TCAD -2d graphics component for delphi
http://www.codeidea.com
wish can help you.

Where should I begin when building a component?

I am looking to build my own component and have no idea where to begin. I have some Delphi books but they are old and outdated, and am looking for some recommendations on tutorials/books to help me do this. The component will be pretty simple, basically 2 labels and an image. I need hundreds of these in an array, so I thought a component would be the best route. The text will adjust based on width etc, and have some mouseover events. So basically, where do I begin?
I am using Delphi 2009, this will be a win32 app.
Thanks!
You can order Ray Konopka's book Dev. Custom Delphi 3 Components - PDF for 25$. It's a specialized book on the subject and very good for a beginner too.
The main principles behind developing components is:
Whether the component is visual or
not (Does it need a Canvas to paint on)
Does it need a window handle or not (visual or non-visual)
Once you answered those questions you can look at Delphi's source code for examples.
As far as I know, Delphi Component Design, by Danny Thorpe, is still the best book on the subject. Component design hasn't changed significantly in the last 15 years, so whatever books you have probably aren't as outdated as you think. There are three things to keep in mind while reading older references:
Names of certain units have changed. There's no DsgnIDE anymore, for example. It's DesignIDE instead.
Design-time code is strictly separated from run-time code now. This means you can't use DesignIDE in your component's unit, or else you're barred from using run-time packages. Older Delphi versions didn't have this technical restriction (although it's always been a legal restriction), so old code examples you find might need to change a little bit.
Strings are Unicode now, so as with all old code examples you find, there might be some invalid assumptions about character sizes that you'll need to recognize.
The biggest obstacle to writing components is that you're expected to use various protected members of the classes you descend from, but those frequently aren't documented, so you'll have to be much more willing to go read the VCL source code for examples of how various methods are used.
The easiest way to do what you want is to create a new form. Drop the labels and image and arrange them the way you want; if it suits your need, put them on a panel so they can be moved around as a unit.
Select all the components you want included (and including the panel if you chose to use one), and then click the Component item on the IDE's main menu, and select the "Create Component Template". (It's only enabled if you have selected components on the current form.) A dialog will appear asking you for a name for the new component, and the Component Palette page on which you want it to appear.
Take a look at this article, which describes how to build new components made up of a group of existing components.
Don't worry about your books being old.
Just about everything from the old days still works fine and what little doesn't is generally due to name conflicts or the addition of Unicode in the 2009 version.
They aren't Microsoft, they don't go breaking old code without good reason. In fact, take some code from the old DOS days--assuming it doesn't try to manipulate the screen it's likely to run with minimal fixup.
Don't worry about your old books! Since v3, Delphi hasn't changed much. This is why most of the programs compiled with D3 still compiles in D7 or even newer versions. And if it doesn't compile, probably you need to change a line or two, here and then.
I would recommend you to search other VERY simple components on Internet and see how they are made. Then make your own and post it here. Let other take a look at it and suggest improvements or spot bugs.
About your control's design:
1) maybe you DON'T need those two labels. You can just paint the text directly on the image. If you have lots of those components as you say, you may save a little bit of memory.
2) you may NOT want to have lots and lots and lots of images loading in one form. The overhead may be significant. What you can do is to load the pictures ONLY in images that are visible on screen - and you will put on screen ONLY 5-10 images (or whatever number of images you can show on the form without going out of screen). As the user scrolls down, you keep the same same TImage controls on screen but you load new (next) images in them.
3) You may not want to store labels and TImage in an array (I suppose it is an TImage because it seems you want to show them on the screen else you won't need labels - you need to explain your problem in more details if I got it wrong). But you can store a TBitmap and the text (that you want to display in labels) instead.
So, you may need to calculate how much CPU/disk overhead your hundreds of controls will create and how much memory they need. If you stay well under 1GB and the loading time is under 10 seconds, then it is relatively ok. IF not, you may want to think about your control's design before starting to actually implement it.
Hope this was helpful.
See ya.

Delphi printing primer

I need to add printing capabilities to an app and I have been looking around for information about printing. Logical/physical sizes, dpi, font scaling, etc, lots to digest since I never programmed printing into any app before.
Are there any sites that would offer a primer on the topics of page sizes, margins and all the other elements required to understand printing on Windows? I've been looking around for a while but what I find is either cryptic or years old...
I've been playing around with TPrinter, but I would like to build solid printing functionalities and understand what I'm doing better.
Using a report solution is not an option, even though I'm sure it would provide better results much sooner.
Two links to get you started:
Printing with TPrinter
Printing via the TPrinter Canvas
I think that you are looking too lowlevel.
Try looking at the build reporting tools (Rave or whatever is in your product).
Personally i am using a product called Report Builder from Digital Metaphors.
But if you want to do the lowlevel stuff lot og good information can be found at efg's computer lab - printing
Well, I have done things a variety of ways in the past, including the "hard way" with TPrinter. In fact, I recently had to do that again to run a special inventory label printer.
On the other hand, sometimes you are better off taking work others have done and using it for your benefit. I agree that ReportSmith isn't so great, and also it's Delphi (and Windows) specific. Using Excel or Word has those limitations, plus the fact that the user has to actually have them installed.
One thing I have done to make printing easy for some simple applications is just to generate an HTML file and call the user's web browser, then they can print it. HTML tables can be created relatively easily for numerical data, and you can include photos, etc. as well. This works well for some applications, and works on every platform where a web browser is installed. The downside, of course, is that HTML isn't the most precise layout language.
The version of Delphi you´re using is important. A number of Delphis came with print engines like ReportSmith (ugh). Another option thinking laterally is to use MS Word as a print engine. I´ve hooked into instances of Word & Excel before & utilised their functionality. As to raw printing using TPrinter or the print method of TForm you´d have to be pretty desperate. I seem to recall the Pacheo / Texeira Delphi books coming with a pretty good overview so you might want to see if you can find a copy of that somewhere.

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