Project: I have a parent panel which holds a ComboBox and FlowLayoutPanel. The FlowLayoutPanel holds a variable number of child panels (a custom control that inherits from UserControl). Each child panel contains some labels, two ComboBoxes, a button, and a DataGridView with 3 ComboBox columns and a button column. The DataGridView may have 1-6 rows. The FlowLayoutPanel is populated with child panels when an item is selected from the ComboBox on the parent panel.
Problem: Populating the FlowLayoutPanel with about 50 child panels takes about 2.5 seconds. Specifically, I've determined that the call to FlowLayoutPanel.Controls.AddRange() is the culprit.
Relevant Code: I can't post all of my code here (too much code plus parts of it are confidential), but I'll do my best to explain what is happening.
Parent Panel:
private void displayInformation(Suite suite)
{
this.SuspendLayout();
// Get dependencies.
List<SuiteRange> dependents = new List<SuiteRange>(suite.dependencies.Keys);
dependents.Sort(SuiteRange.Compare);
// Create a ChildPanel for each dependent.
List<ChildPanel> rangePanels = new List<ChildPanel>();
foreach (SuiteRange dependent in dependents)
{
ChildPanel sdp = new ChildPanel();
sdp.initialize(initialSuite.name, dataAccess);
sdp.displayInformation(dependent, suite.dependencies[dependent]);
rangePanels.Add(sdp);
}
// Put the child panels in the FlowLayoutPanel.
flpDependencyGroups.SuspendLayout();
// Takes ~2.5 seconds
flpDependencyGroups.Controls.AddRange(rangePanels.ToArray());
flpDependencyGroups.ResumeLayout();
// Takes ~0.5 seconds
updateChildPanelSizes();
this.ResumeLayout();
}
Things I've tried:
- Call SuspendLayout() / ResumeLayout() on the parent panel and/or FlowLayoutPanel. Minimal performance increase (~0.2 seconds).
- Use Control.FlatStyle.Flat on ComboBoxes, Buttons, and DataGridView columns. Minimal performance increase (~0.1 seconds).
- Verified that none of my controls use a transparent background color.
- Set ChildPanel.DoubleBuffered and ParentPanel.DoubleBuffered to true.
- Remove the FlowLayoutPanel from its parent before calling AddRange() and re-adding it after.
Things that might be relevant:
- The panels and controls use anchors (as opposed to autosize or dock).
- My controls are manually populated and do not use the DataSource property.
EDIT: Solution:
@HighCore's answer is the correct solution. Unfortunately I won't be implementing it at this time (it could happen down the road) because I found a workaround. The workaround doesn't really solve the problem, just masks it, hence why I'm not posting this as an answer. I discovered that the form loads in half the time if the Dependencies tab isn't on top (i.e. the Product Lists tab is selected). This reduces loading time to about 1 second, which is acceptable. When data is being loaded and the Dependencies tab is on top, I switch to the Product Lists tab, throw up a dark grey box over the tab control that says "Loading..." in the middle, load the data, and then switch back to the Dependencies tab.
Thanks all for your comments and suggestions, it was greatly appreciated.
ElementHost
. Let me know if that is an option for you and I'll post an answer with full source code. – Mila[.net-2.0]
, my proposed solution would only work in .Net 3.0 and above, and will probably work much better in 4.0 and above. – Mila