WinForm ComboBox Drawing Bug - c#

I have a WinForm with TableLayoutPanel and ComboBoxes inside. Combo boxes expand by percantage size. And always after start application, left combobox has artifacts like these:
but the disappear as soon as I put a mouse on them. I have already tried different options, and the only thing that helps, is to set a constant size for all comboboxes, but that's not good for me.
That's how sizes looks like:
And how looks like typical scheme of my form:
Red squares - TableLayoutPanel with content;
Green squares - TableLayoutPanel without content, with margin 0, and single border.
Maybe somebody has ideas on how to fix this bug? Thanks.

So it's really a bug, but I found a simple solution.
Just subscribe to SizeChanged Event of parrent control/form and call Refresh() method in event handler. Control will be redrawn to the required size.

Related

C# Windows Forms, painting combobox borders

We need to show our disabled comboboxes as an image. The image has the same height as the standard combobox, but for some reason it cannot override the borders of the combobox.
Instead, it end up looking like this:
We would like them look like this image, i.e. that the image is shown on top of everything - including the combobox borders:
Any ideas?
Thanks.
First of all, what you are trying sounds really dirty - the best way would be, if your ComboBox would just look like your image as soon as you disable it!
If there is really no other way:
Create a PictureBox in front of your ComboBox. Set the image as the PictureBox's image, make it Visible whenever you want to "disable" your ComboBox.
But again, using controls to simulate behaviour you would expect to be part of another control is dirty.
Get the location of you textbox, set it invisible, then a the same location place an imagebox

Control proportions different between runtime and designer

i'm currently modifying an existing C# WinForm project. I try to arrange some controls inside a GroupBox. However on runtime, they seem to be aligned differently and the Groupbox has a lot more space. Is there some option checked or is this the standard behavior? Any hints are highly appreciated! Thanks!
Here is what it looks like, as you can see there is no way except trial and error to arrange the checkboxes. On runtime there is easily enough space to have four colums in one row, in designer i can hardly fit three without having them overlap.
To prevent the groupbox to resize according to its content, you should make GroupBox.AutoSize to false.
GroupBox groupBox = new GroupBox();
groupBox.AutoSize= false;
check to Size property, and check if someone change it, for the checkbox Location to stay the same in different sizes of the form use anchor property and set it to left or left top.
it's basically must be the size, if the autoSize is off. check what's the starting size, and the size after the form is shown. it shouldn't be the same, but if it is, you can set it to smaller
Check the Anchor property on the checkboxes. Looks like some of them might be anchored to the right.
Not sure it applies to these checkboxes, but AutoScaleMode can impact the scaling of a form. Set to None to ensure it doens't get scaled.

Strange white area in panel c#

I have a problem with panel and weird area on it. I fill my panel with many PictureBoxes 32x32px, and a small area of this panel is filled with white area.
Here is how it looks like:
You can see that the first PictureBox has specified grass image, which is 32x32px, but the PictureBox below has only half of it's image. It's very strange.
I have also an onClick event specified for PictureBoxes to change it's background to other image. If I click on 'working' PictureBox it's background changes, but when I click on 'corrupted' one, it doesn't.
So basically, my question is - what could be the reason for such effect? Is it possible to find it out without analysing a code? I would like to avoid putting a code here, because it's very complicated and long.
EDIT
I used WinSpy++ and it is the result (red point is a place where i hover cursor)
so we can see that PictureBox is partly hidden behind this white area.
I don't know if the question is still active, but I'll try to respond anyway. It is more a comment on it, but since I'm not allowed to make comments yet I'll just answer.
I had encountered a similar issue when implementing some picutreBox drawing using onPaint event handler. The problem was that I called pictureBox.Invalidate() during onPaint and it caused displaying of the unwanted white color box. You might want to avoid using Invalidate() or Refresh() in your onPaint event if there is one.
If this is not the case it might also help to refresh the form or pictureBoxes that are corrupted. Try to call this.Refresh() after the form initialization, preferably in onLoad or onShown event handler.
If it still doesn't help then the problem is somewhere else, I'd guess there is a control hidden somewhere that causes that. But we'll need to see some code in order to suggest any other advice.

width of the dropdown arrow

So in winforms, every dropdown combobox has this little arrow thingy to the right that tells the user it's a dropdown, kinda like this:
Now how do I figure out how wide that is in pixels? Reason is, I'm using ControlDrawToBitmap, this doesn't draw the text properly for the combo boxes, and I can redraw the contents, I just whack some of the arrows (which are drawn properly).
First idea that comes to mind: Check to see if the combobox button width tracks with the scrollbar width. The scrollbar width can be modified in user preferences. Use GetSystemMetrics() API to get the width of the various scrollbar pieces. If you change your system scrollbar width and it does not affect the size of a normal combobox, then ignore this.
Second idea: use the edit control's formatting rect to find out what the edit control thinks is the usable display area (minus the combo box). See EM_GETRECT in MSDN.
However, it sounds like this is just a hack workaround for your real problem: If you could get the controls to draw correctly to bitmap, then you wouldn't need this hackery.
I calculated it to be 9 pixels wide in photoshop

Docking and Anchoring on a Windows Form application

I'm developing an app for Windows Mobile 5.0 and above, with C# and .NET Compact Framework 2.0 SP2.
I have a WinForm with two panels inside (upperPanel and bottomPanel). I want that upperPanel always fill 2/3 of form's height, and bottomPanel fills 1/3 of form's height. Both panels will fill completly form's width.
I've used this:
upperPanel.Dock = Fill;
bottomPanel.Dock = Bottom;
But upperPanel fills the form completly.
How can I do this? I want, more o less, the same gui on differents form factors and on landscape or protrait mode.
Thank you.
What you need to do is to put the bottom panel on first and set its Dock property to Bottom. Then set the panel's height to be 1/3 of the form's height. Finally, add a second panel and set its Dock property to Fill. The key here is that you want to add the control that will fill the remaining area to be added last. Alternatively, you can play around with the Bring to Front and Send to Back commands in Visual Studio to get the designer to cooperate.
You may also need to hook the OnSizeChanged event for the form and re-set the height of the bottom panel to account for layout changes. It's been a little while since I did compact framework programming, so I'm not sure.
Right click on the upperPanel and select Bring To Front. However, I don't think this will give you the result you want. When you resize, the bottom panel will remain the same height, while the upper panel will stretch to fill the form.
Using your docking settings, with this code might do the trick:
protected override void OnSizeChanged(EventArgs e)
{
base.OnSizeChanged(e);
this.bottomPanel.Height = Convert.ToInt32((double)this.Height / 3.0);
}
Set both panels to "not anchored". That is: Remove Dock-Value and clear the Anchor property. Then, move the controls so they are sized the way you'd like them to be sized.
After that, upon resizing the form, they should resize relatively.
EDIT
Oops, just tried it and sure it doesn't work. I mixed this up with a solution that automatically keeps controls centered within the window...
Well, I'd guess you then have to create a handler for the form's Resize event and manually align the controls after the form has been resized.
Go to Tools, Other Windows, Document Outline. Find the two panels, and swap the order of them. The control that has DockStyle.Fill has to come first for it to be docked correctly. (or last.. never sure which one it is, but it is one of them :p)
This won't solve the always 1/3 and 2/3 issue though... cause the bottom panel will have a fixed height (unless I am mistaken). I think maybe the TableLayoutPanel supports this though...
Update: As noted in the comments, that panel doesn't exist in the compact framework. So, I suppose the easiest solution to this problem would then try to use the docking, but update the height of the bottom panel whenever the size of the form changes.
If you want this to work perfectly you'll need to add some code to the Resize event of the Form which then specifically works out the relative sizes and places the controls in the correct place after a resize.
If you're not worried about losing precision and the forms aren't going to move much you can avoid this by using some relatively smart anchoring. Essentially you're going to have to select a "grower" (the part of the form that gets bigger, the bigger the form gets). In this scenario I would probably anchor the top part to Top | Left | Right and the bottom part to Top | Left | Right | Bottom. This would mean that the lower part of the form will get bigger if the form is expanded. In most cases this is acceptable. If it isn't use the Resize event and some code.
The easiest way to do this is to nest panels. Just set up panels for top bottom and fill. Then use panels within those panels to do the same. The only issues I've had therein are datagrid resizing, which is always a pain anyway. in that case, you have to use some code to resize the datagrid control on the form resize event.
I would like to add a point to #jasonh answer.
For the panel that occupies 2/3 of the form, you will have to set the AutoScroll property of the panel to true.
This will enable the panel to display scroll when the control size exceed the visibility to the user and also ensure the visibility of the smaller panel which is 1/3 of the forms height.
You can get the required design by using nested panels along with few setting with Anchoring and Docking Properties.Follow the following steps:
1) Add the Form and put a Panel1 on it. Set its Dock Property as 'Fill' and ResizeMode as 'Grow&Shrink'.
2) Add Second panel2 and set its Dock Property to 'Bottom', Set the Height and set the Anchor property to 'Top,Left'.
3)Add Third panel and set its Dock Property to 'None', Set the Height and set the Anchor property to 'Top,Bottom,Left,Right'.
Save and Compile. Now all the panels Would maintain their relative Positioning With resizing.

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