Dropdownlist - number of display element - asp.net

I have dropdownlist on my webpage.
When I click it the list with all items is expanded. But this list is very long.
How can I change it to achievie a list with (e.g.) 5 displayed items and with a scrollbar next to them.
If it is not possible, how can I do it with ListBox? I know it is Rows property there but can I declare how many rows is display all the time not after expanding the list.

This control, will, of course be rendered on the page as a standard <select> control.
With these, the height of the list once its dropped down is determined by the browser, and you have no control over this. You'll notice when the list approaches the foot of the page, the browser will implement the scrollbar as you suggested, but not with the number of items you maybe want.
My only suggestion would be to investigate the options offered by some client-side drop down add-ins. You may be able to find some jQuery ones that will help.
A simple google search for "jquery dropdowns" yielded this article as the top result: 38 jQuery And CSS Drop Down Multi Level Menu Solutions. If you can't find something here then there are also plenty similar sites in the search results.

I think this post provides you with a couple of different solutions to your problem.
http://blogs.msdn.com/b/rakkimk/archive/2011/05/02/dropdownlist-html-select-vertical-scrollbar-number-of-items.aspx

Related

Designing Custom Drop Down with mulitple rows and columns

I have a requirement like for the drop down as shown. Could any one help me in achieving this.
Briefing:
On click of the button a pane should be opened which contains rows and columns containing text, on click of it appropriate action need to take place. The source can be dynamic too....
There are many techniques for acheiving this design. You could do it purely with html and css by having an image that looks like a dropdown popup an absolutely positioned div underneath. Or you could use the asp.net ajax control toolkit control called "PopupControl" that essentially abstracts all the html/css away allowing you to just specify a target panel. There are also various jquery plugins, here is one from abeatifulsite.

how to increase Drop Down List capacity in asp.net

How can you increase Drop Down List capacity in asp.net? I have to display 20,000 items in a single DropDownList but it not showing all items after binding. Some items are missing.
How can I achieve this?
I'm not aware of any direct limitation applied by the .NET framework; there may be a limit applied by the client, but I'm not sure. 20,000 is a lot of items and a lot of HTML to render, and HTML rendering is one of the bigger performance problems. You may want to instead consider an alternative approach like an AutoComplete feature, such as this.
There is no reason the dropdown list selection would be missing items.
Check your data source before binding to make sure all the items are there, it could be an issue with the query filling the data source rather than the dropdown list missing items.
Though as people have pointed out, replace this with either a search function or a autocomplete function dropdown lists should not be a place for 20,000 items.

How to show only 30 rows and hide the remaining rows of QTableWidget

I'm having a QTableWidget with 10,000 records. I need to show only 30 rows at a time and hide the remaining rows. While dragining/clicking vertical scrollbar it should show corresponding rows and hide the other rows.
ie, if one clicks on upper scroll button it should show one more upper item and hide one lower item and vice versa. It should happen while scrolling as well.
Can anyone help me in doing this?
I think you can trap the events of up/down buttons as Nicholas said, for the tracking of slider/scroll bar u need use 'setTracking(true)'followed by the handling of signal either 'valueChanged(int)' or 'sliderMoved(int)'.
Thanks,
Pradeep
Qt unfortunately won't make this easy for you, there is ways and means of doing it however. Depending on how you're populating your widget I'd recommend setting it up so you initially populate your 30 rows, you then need to trap the signals coming from the scroll buttons being clicked and tell the table widget to remove the upper/lower item and add the next one, there's trade off's to this method, but it'll make it easier than trying to maintain a large list of hidden rows.
I don't know if explicitly showing/hiding things is the way you want to go. Instead, take a look at Qt's model and view classes. If you are using a database, have a look at QSqlTableModel, which should handle these things for you. Otherwise, have a look at the Model-View programming document, their related examples, and especially the portion about optimizing for performance (although in a model, 10,000 records isn't really all that many for most uses).
There is a way to change table scrolling from pixels to items. In Designer Property Editor for the table, in the QAbstractItemView section, there is a VerticalScrollMode selection. This can either be ScrollPerPixel or what you probably want, ScrollPerItem.
That may change the behavior of the signal from pixels to items which would make your calculations easier.
I'm using 4.4.3.

showing top n options in a dropdownlist

Consider an ASP.NET server control DropDownList (or <input type='select'>) with a large number of options (e.g. 100 options). When clicking on the list, the full list of 100 options are shown. They're all displayed, and run off the screen.
How can the control's picklist size be resized or limited to the first n options?
Frédéric Hamidi has already given the short answer, however he has also referred you to a perfect alternative. Explore this and that is similar to what I had done when I faced similar situation.
Idea is that you don't populate your list. This way your drop down will be empty and in place of that you show a div with scrollbar and whatever you wish. Align this div in such a way that user thinks, "it is the dropdown".

Flex collapsible field group control

I am trying to make a side panel in a Flex application that would hold a bunch of properties of a selected object. The number of properties may become huge, but they all fall into some certain categories.
For that, I am looking for a flex control that would be like a collapsible field group. Or like an accordion that can have multiple open panels at a time. Do you know, where can I get one?
UPDATE: I want something like the second example on the following page: http://extjs.com/deploy/dev/examples/form/dynamic.html
Thanks,
Artem.
http://www.flexdownloads.com/#view=detail;vstr1=19
is what you are looking for.
It sounds to me like you are looking for some sort of tree component. Flex actually has one of those and you should probably take a look at it.
This is a good link to see what controls are included in flex http://examples.adobe.com/flex3/componentexplorer/explorer.html

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