I am sure many developers are frustrated by the flickering when resize events happens faster than onPaint event.
I have created many user objects that is shown on the main form.
When I try to set the location and size of each controls at the resize event of the main form, I get the flickering.
To resolve this I wanted to do a new approach as mentioned below.
When resizeBegin event is triggered, show a borderline of current frame
When resize event is triggered, only the borderline will be resized leaving the controls in the main frame untouched.
The tricky part is when the borderline is larger than original size, I want it to show the background of the window as it self.
Click for Enlarge image
On the contrary if the borderline is smaller then, I still want the original objects to be shown
Click for Reduce image
When resizeEnd then the borderline will be hidden and the controls in the frame will be resized.
Does anybody know how to implement the tricky part mentioned at resize?
Related
I have a WinForms form containing many controls. On resizing the form, I need to place and resize the components and redrawing pictures in PictureBoxes.
I had problems with flickering, so now I call SuspendLayout at the beginning of the SizeChanged event (and ResumeLayout at the end).
But it was not enough, so I use a boolean variable indicating, if the form should be repainted. I set it to true at SizeChanged event and false after the Paint event. This solved the problem, because for some mysterious reason the Paint event was raised incredibly often.
The form still did not repaint correctly sometimes. I solved that by calling SizeChanged method in ResizeEnd event (and I don't know why it worked).
Now almost everything works, but after maximizing/unmaximizing the form, the pictures in the PictureBoxes are not repainted. Everything is sized and placed right, except for the pictures, which have the same size (but the PictureBoxes are resized). I have no idea why or what else I can do (except for disabling maximizing).
I would appreciate any advice.
I have a PictureBox control on my form for which I have written two events for MouseEnter and MouseLeave. On MouseEnter anther PictureBox enters the form and stands beside the original and with MouseLeave the second PictureBox goes way.
All works fine. Except when the cursor is on the original PictureBox’s border area the MouseEnter and MouseLeave events are repeatedly run. So the second image enters and leaves the form until the cursor is taken away. This makes a strange sight.
How can I avoid this situation?
The border area can be tricky, especially when you want to trigger something the might influence it even if it is only by a few pixels..
One classic situation is when you want to resize or move a control by clicking an dragging it at its border. Unless you use the internal calls and simply code mouseenter, -leave, -move, -down and -up you may well end up with e.g. moving the control away from the mouse and thereby triggering another leave event.
This often occurs only at one set of borders, like left&top or right&bottom.
You need to check you code for any such influences, like the new PictureBox pushing the old one away by a few pixels or a resize that makes it smaller; even one pixel can lead to the effect you see..
If the MouseEnter event is triggering a border to be drawn, or the size of the first PictureBox to change in any way, that can cause the effect you describe.
You could add a check against the mouse coordinates in MouseEnter to ensure that the mouse pointer gets far enough into the control's interior before the event fires. That would prevent an instant firing of the Leave event.
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.
I have a simple System.Windows.Forms.Form.
Based on business requirements, once certain functionality becomes available as a result of some background processing, I am increasing the form's size and opening up a previously hidden area with additional controls (buttons etc). The changes to the form's size are done by a background thread, using BeginInvoke.
All this works fine. However, if the user is dragging around the form on the screen, and coincidentally during this time the method that changes form's size is called, the size change does not become effective (technically, the form changes size, but instantaneously reverts to the previous size).
I am changing the form size by setting the Form.Size property, but have tried other ways like setting Form.ClientSize, and calling Form.SetBounds(). Have also tried out Form.SuspendLayout()/Form.ResumeLayout() and forcing Form.PerformLayout().
Nothing I have tried so far works, and when it is being moved around, the form refuses to change size.
Put code in the Form_LocationChanged event to detect if the previously hidden area is visible (or should be via a bool variable) and resize the form accordingly. Otherwise the ResizeEnd event fires after a move ends, try that.
I have a Control that can overlay multiple C# user controls in my GUI. This control has a semi-transparent background in order to 'grey-out' portions of the GUI and the class looks somethink like this:
public greyOutControl: UserControl
{
// Usual stuff here
protected overide OnPaint()
{
paintBackround();
base.OnPaint();
}
}
Currently the control sometimes gets caught in a loop and constantly re-draws the background, making the semi-transparent color appear less and less transparent.
My idea to combat this is the following (in broad terms):
1) Determine what controls the greyOutControl is on top of
2) call Refresh() on those controls to update the display
3) continue drawing the greyOutControl.
My question is: How can I determine which controls the greyOutControl overlaps?, or is there a way that I can refresh only the part of the GUI that greyOutControl covers?
Why don't you keep track of your transparent controls and paint them after all the other controls are drawn?. Painting anything at the top of the Z-order shouldn't cause the other controls to be repainted.
I don't see a direct way of finding the overlapping controls. I think you might need to check the whole control tree to find out that. About refreshing, you can use Control.Invalidate(Rectangle) method to specify which part to refresh.
The solution to this problem I found was to programmatically take a screen shot of the area being overlayed and then use that image as the background for the control being overlayed. This then allows you to put the alpha overlay into the image within the OnPaint() method and the control to draw itself correctly.
This does have the disadvantage that the background isn't updated in the overlapping control, but unless there was a number of event handlers watching if something changes and then update the overlayed control I cant see any way around the issue. Sometimes I regret not trying to use WPF!