there is a search View ( app is a MVP - PRISM WPF ) which had some issue with scrolling. it took hell of a long time to scroll when you click the scroll bar buttons. Click and dragging the scroll bar was even worse!!
considering i like anomalies, i picked it and started looking into what was going wrong. I suspected many things, but evidently the issue with the datagrid scroll was due to "ScrollViewer.CanContentScroll=True" i removed it and the scrolling was a pleasant experience compared with earlier.
Now i was wondering why my developers had put that property as true, with in couple of mins i found Doing a Page down was scrolling more than a page with out the CanContentScroll property marked true!
Now i need the scrolling to be faster AND i also need page down and page up to scroll as expected! Can some one tell me What I am missing here?? thanks!
I had similar issues with my datagrid : slow scrolling, and also randomly size changing scrollbar.
I did the following:
simplify the templates of the cells (no more nested borders and multiple colors, ToggleButtons instead of CheckBoxes)
in code use frozen colors.
this helped speed things up but did not solve the issue.
Then i set the row / cells templates height and also the RowHeight property, and then it was ok : i had both smooth scrolling and normal scrollbar. So i guess that the DataGrid was unable to compute the size of what remained to be displayed that made both the scroll slow and the scrollbar having changing size.
(Yet the rows / cells were all having same actual height in their templates since they were defined with same controls but Height property was not set...)
Hope that can help.
Related
Here is the problem. If you dynamically place controls in a panel, it works fine, but only until the vertical scrollbar appears. Once there is enough content for this to happen, it starts positioning controls nonsensically.
In my window, you can click a button to add another row of controls inside the panel, which represent options for an item in a list. If you scroll the vertical scrollbar on the panel all the way down and click the button again, the new row of controls will be positioned below the bottom edge of the panel out of view. If you scroll down, there is a huge gap between the new row and the previous row of controls. This should not happen. The positioning code is working flawlessly, as proven by debug output. As far as I can tell, the problem is the stupid anchoring system, however disabling anchoring on these controls does not fix the problem as one might expect. Instead, it just makes it position them wrong in a different manner. This makes no sense at all, and is super annoying!
I tried disabling Autoscroll in code before controls are added to the panel. No change. So I modified that code to disable both the vertical scroll bar and Autoscroll and set the scrollbar to not visible before controls are added. No change again, except that the now disabled vertical scrollbar still manages to appear usable when there is enough content in the panel in spite of it being disabled and set not visible!? That's not supposed to happen when I disabled and made it invisible! With anchoring disabled on the controls being added to the panel and once the vertical scrollbar has appeared, clicking the button to add a few more rows of controls now causes them to be indented a bit for no reason and positioned overlapping each other a bit vertically! It's as if the coordinate system in the panel has somehow arbitrarily changed, because of the presence of a vertical scrollbar and anchoring being disabled on the controls? The debug code shows that the controls are all being placed at correct coordinates, yet they appear positioned very wrongly. So my code is working perfectly, and therefore something else is the problem here.
Everything behaves exactly as expected up until the vertical scrollbar appears. This is so bizarre. Does anyone have any idea what on earth is going on with this stuff? Apparently it is far easier to make it do stupid stuff than to get it working properly.
Thanks again! I got it working. I went with TaW's solution first since it seemed like the simplest solution. Incidentally, I already tried TaW's approach days ago when I was fighting with it, but I had naturally subtracted the AutoScrollPosition value rather than add it, because I didn't expect it to be a negative value!
It seems very odd that control positioning is relative to the current AutoScrollPosition, as absolute coordinates seems like a much more natural, intuitive approach than having negative numbers. I guess that would make it slightly harder to place a control in the currently visible area, but I suppose that's not a big deal as most scrollable interfaces are probably initialized ahead of time and don't need to do that anyway.
I use a RadGridView (a GridView from telerik libraries) and I resize the rows height for simulate a zoom.
The issue is that the scrollbar values become wrong after a zoom. I receive the values ExtentHeight (total virtual height of my RadGridView) and a VerticalOffset (my position), and both are false.
As I know the individual height of every cells, I can manually calculate the ExtentHeight, but not the VerticalOffset. And the concern is that I have synchronized my grid with a scrollbar which gives a render of the RadGridView, and it can’t be synchronized with these bad values. The only solution is to scroll all the RadGridView, and the scrollbar will be updated with the new heights of its children.
You can see an example in this video, where I scroll after a zoom, and it’s not working. Then I scroll all the grid (with the down arrow), and it works after.
https://youtu.be/QqvTnYK5A6o
So how my scrollbar can automatically updates the values of its content ?
The method scrollBar.UpdateLayout(); doesn't work unfortunaly.
Thanks !
The solution is to set the property EnableRowVirtualization of the RadGridView to false, but it causes a big performance problem unfortunately.
I've been tasked at work with creating a UserControl containing a ListView and ComboBox's for sorting the ListView data. Sorting with the Combobox's s the easy part; the part with which I'm having difficulty is implementing a method of scrolling. In the end, the control should have an Excel-like feel to it. However, sometimes the ListView is too tall or wide for where it is placed. Therefore, there two be two scrollbars somewhere on the control. One vertically moves of the ListView only, and the other moves both the ListView and ComboBox filters horizontally.
Please note in the image above that the ComboBox's do adjust themselves according to column width, but the code for that is not enabled at the moment.
What I've tried: In the control, the filter boxes are in their own panel, and the ListView has had its own panel at times. I've tried using various combinations of the HScroll/VScroll and HorizontalScroll/VerticalScroll properties and the native function ShowScrollBar() for all the controls, but nothing has worked. The only way I've gotten scrollbars to appear is by settings AutoScroll (Scrollable for the ListView) to true. Of course, the scroll bars come in pairs and work only on the same control. I also attempted to programmatically move the scroll bars, but I haven't been able to accomplish that, either.
I've got to be doing something wrong, but I'm not sure what it is. Any help is appreciated!
I think I'd go for a different solution.
If you put the ComboBoxes in a AutoSrcoll panel with the same Anchors as the ListView you would give your users the freedom to scroll the two independently.
Yes, a ScrollBar would appear and take space but I would still happily sell that as a feature, not a bug ;-)
As for handling the Scroll event of a ListView: It is hidden and you'll have to subclass it to get access to it. See here
I need to create an app for TV guide. Requirement is that UI must be a copy of one you can see here: raspored.bnet.hr. As you can see, there's a lot of data. So, basically it would be a large scrollable table. Since there is no such UI control as table on Windows Phone, I found out that the best approach would be to create one vertical listbox with horizontal listboxes as its items. This is all ok and I'm able to create it. But, to make it behave like a table I also need to make these horizontal listboxes scroll in sync, not to scroll one row at a time. Then I disabled horizontal scroll on horizontal listboxes, and enabled it on the parent (vertical) listbox and while it gave the result I wanted to achieve one big problem came up - UI virtualization. I know ListBox has UI virtualization enabled by default and I can see it while scrolling on vertical listbox, but when I disable horizontal scroll on horizontal listboxes, performance is really bad, and sometimes there's an OutOfMemoryException. I understand why this happens because when I disabled horizontal scroll, those listboxes didn't know which items are on screen anymore, so the loaded all of them into memory.
What I also tried is to leave scroll on every listbox so they have UI virtualization, and then place ScrollViewer above them. Then I tried to listen on Manipulation events on scrollviewer and progamatically scroll all of the listboxes as needed. This didn't work good, first of all ManipulationDelta event doesn't appear to fire frequently enough to make scrolling smooth, and I think there could be a performance problem with calling ScrollToHorizontalOffset on ~180 listboxes.
I also tried the LongListSelector from WP8 as I read that it has much better UI virtualization and should be used instead of ListBox. The problem with this is that I couldn't make it scroll horizontally. Is it possible at all? I tried to wrap it into ScrollViewer which can scroll horizontally and it's working, but only if I set fixed width on LLS.
I also tried Telerik's RadDataBoundListBox and the problem was similar, I can't get both horizontal and vertical scrolls on the same listbox. So I could only get that each list scrolls on its own.
Can someone tell me if they had similar situation and what would be the best approach to solve this? I believe I'm not the only one that has this requirement to implement large scrollable table.
Thanks
UPDATE:
I'll just inform you that I didn't find a proper way to implement this, instead I've done it in HTML with WebBrowser control. Seems like IE already has UI virtualization implemented so it can work with large pages very well.
May be in your listbox there are images? and Out of memory Execption will occur you can do 2 things:
Don't load data in one time use BackgroundWorker
Have one local image in the App of the image you are downloading and set it as default image & when you scroll to some 50 values in forward clean the image Url to local and when it comes back give again the image url you want to show .
Because i have used it to scroll around 20k values.
I've got a Checkedlistbox, which is 3 rows high, and large enough to display about 5 elements.
As long as I've got less than 15 elements, everything runs fine.
However, if I add a sixteenth element, the checkedlistbox displays an horizontal scrollbar which takes 2 item rows, which means all the Items are now on only one row.
Worse, if I remove the extra item, the horizontal scrollbar stays in place.
I've tried using :
mycheckedlistbox.HorizontalScrollbar = false;
mycheckedlistbox.ScrollAlwaysVisible = false;
but this doesn't seem to have any effect.
I use the multicolumn=true mode, which seems to cause this misbehaviour
Is there a way to prevent the control from displaying an horizontal scrollbar, and use a vertical scrollbar instead?
I've found someone with a similar question on msdn forums, but it seems he didn't get an anwser.
Well, judging from the answers there, and from the few test I ran, this does seem sort of impossible, but at the same time, I think you're trying to defeat the purpose. If I were in you're shoes, I'd use a DataGridView with no grid lines and one that can't be editable. You have much more control over what's going on in the grid, and you can customize it MUCH more than a CheckedListBox. You can have the same effect as you can have DataGridViewCheckBoxColumns there as well.
(If you need a code sample, post in the comments, and I'll whip up a quick sample.)
The scrollbar makes the layout of the items bi-stable. You can get the scrollbar to disappear by whacking it on the head:
checkedListBox1.MultiColumn = false;
checkedListBox1.MultiColumn = true;
That forces WF to recreate the control handle, the flicker might be barely noticeable. Yes, a vertical scrollbar is possible but you'll have to give up on MultiColumn.