I have a custom control that inherits from Panel. I end up putting several DataGrids and Labels on this panel. When it gets too long it auto scrolls for me.
I really need the scrolling because it is a list of scanned in objects that will grow larger than the space on the screen will allow.
But when I scroll it flickers quite a lot. I would love to have it give me some smooth scrolling.
I have seen several "Compact Framework" double buffer examples out there, but they all are double buffering draw methods (ie graphics.DrawString). My custom control does not do any painting by itself. It just puts normal grids and labels on the panel and lets the panel paint them.
Is there a way to double buffer normal controls (again NOT custom painting)?
The Compact Framework Controls do not have the DoubleBuffered property or the underlying double-buffering mechanism. There's no way to add it either.
The only way to get double-buffering is to override the painting of the control and do your own.
Related
So I am making a dark mode option for my application and I want the scrollbar back color to also change color so that it doesn't look out of place. I have tried to search for a solution but so far I have only found code for a scrollbar as in the control. but I need to change the scrollbar of a panel. Does someone happen to know how to do this? Thanks a lot in advance.
I faced the same challenge when I started to work on custom controls that should support the Dark Mode. The problem with Panel control as well as other controls is that their ScrollBars are managed internally by those controls and there is no way to customize them.
My Idea was to create a custom ScrollBar control that supports custom colors and themes, see my answer https://stackoverflow.com/a/73613059/5514131
And in our custom Panel control, we create the custom ScrollBars internally and use the various Panel properties and events to link the custom ScrollBars to our Panel.
With the help of the Panel VerticalScroll and HorizontalScroll properties, we can know whether the default Panel scrollbars are visible or not and their properties to copy to our custom ScrollBars.
With the help of LocationChanged, SizeChanged, and other Panel events and properties we should bind the custom ScrollBars to our Panel and place them on top of the default ones to completely cover them.
I used the OnMouseWheel and OnScroll to update our custom ScrollBars when the Panel is scrolled using the code or mouse wheel.
We should dispose the custom ScrollBars when the Panel is disposed, or its handle is destroyed.
I know this isn't the best approach, but it should work to prevent the default ugly scrollbars from ruining your beautiful Dark Mode.
This workaround can be applied to other controls, I actually used it with TabControls, however, it will be more complex to implement.
Windows Forms Panel control with custom ScrollBars based on the Flat ScrollBar control https://gist.github.com/ahmedosama007/39f8b76e65300e5969110b753fe0a654
I have an ordinary Panel control with a bunch of user controls contained within. At the moment, I do the following:
panel.Controls.Clear();
but this has the effect that I see (albeit quickly) each control disappearing individually.
Using SuspendLayout and ResumeLayout does not have any noticeable effect.
Question: Is there a way I can remove ALL controls, and have the container update only when all child controls have been removed?
Edit: the controls I am removing are derived from UserControl, so I have some control over their drawing behaviour. Is there some function I could possibly override in order to prevent the updating as they are removed?
Thank you Hans for your suggestion - yes, it turns out I was leaking controls.
Here's what I ended up doing:
panel.Visible = false;
while (panel.Controls.Count > 0)
{
panel.Controls[0].Dispose();
}
panel.Visible = true;
Basically, I hide the entire panel (which is border-less) before I dispose of each control. Disposing of each control automatically removes said control from the parent container, which is nice. Finally, I make the container visible once more.
What I think you need is Double Buffering.
There are several answers concerning this already on SO like
Winforms Double Buffering,
Enabling Double Buffering
and
How do I enable double-buffering of a control using C# (Windows forms)?
SuspendLayout stops the control redrawing as the children are removed but those actions are still processed in order when you call ResumeLayout. Double Buffering will stop the control painting at all until the offscreen buffer is updated. The update won't happen any quicker but it will be rendered to screen all at once from the buffer. If your machine is very slow you might still get a flicker when the buffer is rendered to the screen, like you would when loading a picture.
How can I speed up the scrolling of UserControls in a WinForms app.?
My main form has trouble scrolling quickly on slow machines--painting for each of the small scroll increments is CPU intensive.
My form has roughly fifty UserControls (with multiple fields) positioned one below the other.
I’ve tried intercepting OnScroll and UserPaint in order to eliminate some of the unnecessary re-paints for very small scroll events, but the underlying Paint gets called anyway.
How can I streamline scrolling on slower machines?
The tried-and-true method is to use an offscreen bitmap which is updated only when the data represented by your control actually changes; then, all OnPaint needs to do is render that bitmap to the screen.
If your paint process is intensive, and since you have so many controls, you'll find this makes a massive difference to the performance of your application.
Note that using the DoubleBuffering control property won't help in your case--it does tell WinForms to render to an offscreen bitmap before rendering to the screen, but that still happens at every paint cycle since WinForms doesn't keep track of when the representation has changed.
So, you'd have to roll your own. It's not that difficult. Here's what looks like a reasonably good article on the subject.
You can also increase the size of the scroll step. For example
panel1.VerticalScroll.SmallChange = 100;
Will cause the panel to scroll it's content 100 units vertically per click of the scrollbar button. So you take bigger steps each time, that might make the experience feel better at least. And you can do the same for the horizontal scroll bar of course.
I have used tabs to eliminate scrolling.
I have a panel that has lots of labels and checkboxes. I want to grab all these controls and resize them?
How would I do this? Would this be like going through the panel for all the controls then resizing them?
Or do you think it would be better to re render the whole form again with the new sizes. However this would require me to do another request to the webservice to get the information.
I need to resize the controls because I want allow user to switch from portrait mode to landscape.
Use Dock, or for more precise control use the Anchor property. By setting Anchor to Left, Right, Top, Bottom the control will scale with the window. By setting Anchor to Right the control will move with the right border. By setting Anchor to Top and Bottom the control will scale vertically, but have a fixed width.
you can also use tablelayoutpanel and flowlayoutpanel controls.
For mobile, I think these controls are not available.
First of all, you should not just store the values from the web service in controls. They should be safely tucked away in one or more objects somewhere, to be easily accessed from your form.
I'm afraid you ahve to resize and/or change location of your controls depending on which mode you are in.
For developing resolution aware applications for .NET CF, see here:
http://msdn.microsoft.com/en-us/library/ms838174.aspx
I have a user control that has:
a) a buttons panel at the top (it always has to be visible)
b) a panel with controls that are dynamically added and re-sized at run-time. The controls can be many, so the panel has to be scrollable.
This user control will be hosted in a form, with the following requirements:
a) The initial size of the form will try to fit in maximum part of the dynamic content.
b) On changing the form size, the control has to be re-sized accordingly.
I had played with various anchoring, docking, and auto-sizing and I don't quite get it working in the way I want to. Sometimes, it is the scrolling that messes up, sometimes it is something else.
What combination of anchoring, docking, and auto-sizing of the panels, usercontrol, form should work best to achieve the desired outcome?
I succeeded to meet the requirements. Here is my solution:
The dynamic panel is anchored to the top and the bottom of the control. It does not AutoSize, it manually changes its MaximumSize and PreferredSize after change in the contents.
The form hosts the form using:
cntrl.AutoSize = true;
cntrl.AutoSizeMode = System.Windows.Forms.AutoSizeMode.GrowAndShrink;
cntrl.Dock = System.Windows.Forms.DockStyle.Fill;
The form subscribes to a custom control's event that notifies for the preferredHeight and it changes its own Height accordingly.
I'd go with a table layout panel. You can specify two rows by one column with the exact size for the buttons at the top and fill the rest with the bottom. Then put put either a normal panel or a flowlayoutpanel for the dynamic content in that area.
Without knowing the specifics of your problem I find multiple fill docked split containers with one fixed panel and/or a fixed slider usually creates a really handy resizing experience. You can also collapse panels very effectively too.