Develop Reference

Container UserControl - Handle and Modify Added Controls

I'm trying to create a custom container as UserControl.
My Goal: I want to be able to drag controls inside the designer and handle incoming controls inside the code of my usercontrol.
Example: I place my container somewhere and then add a button. In this momemt I want my usercontrol to automatically adjust the width and position of this button. Thats the point where Im stuck.
My code:
[Designer("System.Windows.Forms.Design.ParentControlDesigner, System.Design", typeof(IDesigner))]
public partial class ContactList : UserControl
{
public ContactList()
{
InitializeComponent();
}
private void ContactList_ControlAdded(object sender, ControlEventArgs e)
{
e.Control.Width = 200; // Nothing happens
e.Control.Height = 100; // Nothing happens
MessageBox.Show("Test"); // Firing when adding a control
}
}
The MessageBox is working well. The set width and height is ignored.
The question is just "why?".
EDIT
I've just noticed, when placing the button and recompiling with F6 the button gets resized to 200x100. Why isnt this working when placing?
I mean... the FlowLayoutPanel handles added controls right when you place it. Thats the exact behaviour im looking for.

Using OnControlAdded
To fix your code, when you drop a control on container and you want to set some properties in OnControlAdded you should set properties using BeginInvoke, this way the size of control will change but the size handles don't update. Then to update the designer, you should notify the designer about changing size of the control, using IComponentChangeService.OnComponentChanged.
Following code executes only when you add a control to the container. After that, it respects to the size which you set for the control using size grab handles. It's suitable for initialization at design-time.
protected override void OnControlAdded(ControlEventArgs e)
{
base.OnControlAdded(e);
if (this.IsHandleCreated)
{
base.BeginInvoke(new Action(() =>
{
e.Control.Size = new Size(100, 100);
var svc = this.GetService(typeof(IComponentChangeService))
as IComponentChangeService;
if (svc != null)
svc.OnComponentChanged(e.Control,
TypeDescriptor.GetProperties(e.Control)["Size"], null, null);
}));
}
}

How To Set TabPage on start?

I have a TabControl with three TabPages. The initial start of the app opens always the first TabPage on the left side. For me it's necessary to set the starting TabPage (for example the second one).
Of course, I know about possibilities to change the tab on start like these:
tabControl.SelectedTab = tabPage;
tabControl.SelectTab(tabPage);
...
But this code would also activate additional events to fire like TabControl.Selecting, TabControl.Deselecting, TabControl.SelectedIndexChanged etc. — I would really like to prevent this in advance.
What I am looking for is some kind of property in the TabControl like "StartingTabPageIndex" - setting it to 1 would open the second TabPage on start without invoking any unnecessary events.

Another option. Go into the Form Designer, change the SelectedIndex property from 0 to 1:
//
// tabControl1
//
this.tabControl1.Controls.Add(this.tabPage1);
this.tabControl1.Controls.Add(this.tabPage2);
this.tabControl1.Controls.Add(this.tabPage3);
this.tabControl1.Location = new System.Drawing.Point(223, 21);
this.tabControl1.Name = "tabControl1";
this.tabControl1.SelectedIndex = 1; // <-- This Line
this.tabControl1.Size = new System.Drawing.Size(300, 143);
this.tabControl1.TabIndex = 3;
The event handlers aren't connected yet, and making any modifications to the TabControl in the designer doesn't seem to affect that property. It seems safe to change it this way.

You should remove the binding with the event handlers from the designer and add them after you have set the initial tabpage
After removing them in the designer (this doesn't delete the event handler code) rebind the event handler in the form load event after setting the required tabpage
tabControl.SelectedTab = tabPage;
tabControl.Selected += tabControl_Selected;
.... and so on for the other events to handle....

Update
I just made a simple test, and SelectedTab does not work because it expects the handle to be created on set.
However this seems to work:
public class MyTabControl : TabControl
{
[DesignerSerializationVisibility(DesignerSerializationVisibility.Visible)]
[Browsable(true)]
public new int SelectedIndex
{
get { return base.SelectedIndex; }
set { base.SelectedIndex = value; }
}
}
You'll now be able to see SelectedIndex in the designer and can set it. It won't change the visible tab in the designer, but it will store the "initial tab index" (zero-based).
It does change SelectedIndex, but it does not call the events since events are assigned last in the designer's serialization, so they are never assigned before the change.
Old
One option would be having SelectedTab serialized. You'd only need to derive your own custom TabControl from TabControl and have something like this:
public class MyTabControl : TabControl
{
[DesignerSerializationVisibility(DesignerSerializationVisibility.Visible)]
public new TabPage SelectedTab {
get { return base.SelectedTab; }
set { base.SelectedTab = value; }
}
}
That way you'll get your designer selected SelectedTab as initial.
I haven't tested this, but theory says it should work :-)

Winforms Control Layout at Runtime

I've been working on developing a custom control which will be used in our CRM frontend. The control itself is nothing special, it simply wraps two labels, text edits, and a button into a single control. (The control is only acting as a wrapper, a bit long winded, but unfortunately our only option due to various restrictions)
I though it would be nice to give the control a Font and ForeColor property, that would change the Font and Color of the labels. Changing the font size means that the relative position of the text boxes be changed to keep everything in line. No problem.
I encapsulated the layout logic in an UpdateLayout method, which is called on the set accessor of the Font property and everything works beautifully at design time, however, at runtime, the Font of the labels is correct, but the layout of the text boxes and button are still in the default positions, hence, the labels overlap.
What am I missing in for updating the position of controls at the init stage in runtime? I've tried calling the UpdateLayout() method from both Initialize and the constructor of the control, alas to no avail.
Am i missing something obvious here?
EDIT:
As requested, I whipped up a quick test. My test control looks like so (Not including Designer code):
public partial class TestControl : UserControl
{
private Font _font;
[Browsable(true)]
public override Font Font
{
get
{
return this._font ?? SystemFonts.DefaultFont;
}
set
{
this._font = value;
this.DoLayout();
}
}
private void DoLayout()
{
this.label1.Font = this._font;
this.Size = new Size(label1.Width + textBox1.Width + 10,
label1.Height >= textBox1.Height ? label1.Height : textBox1.Height);
this.textBox1.Location = new Point(label1.Location.X + 5 + label1.Width, 1);
this.Update();
}
public TestControl()
{
InitializeComponent();
}
protected override void OnLayout(LayoutEventArgs e)
{
base.OnLayout(e);
DoLayout();
}
}
That works great at design time, but runtime, less so...
EDIT2:
So the above code doesn't entirely reflect the problem accurately, however, I have tried Jogy's suggestion of overriding the OnLayout method, and lo and behold, it works!
I'm relatively new to Custom Controls, so a rookie mistake on my part. This will definitely be committed to the long term memory.

Override OnLayout() method and call your UpdateLayout() there.

Thanks for supplying the code, I would provide the properties by reusing already available controls.
public override Font Font
{
get { return this.label1.Font; }
set
{
this.label1.Font = value;
// Additional code to update related controls.
}
}
Also be aware that the declaration of
private Font _font;
Delivers a non-initialized variable, and by using it in the "Do_Layout" might use a null value. Maybe change it to the following when using your code.
this.label1.Font = this.Font;

DesignerHost fails to create control with Visible = false

Good day!
I'm writing a .vsix to replace old controls to new ones. I have designerHost which is the current designer instance. Then I start converting like this:
foreach (OldCombo oldCmbx in OldCmbxs())
{
...
NewCombo newCmbx = designerHost.CreateComponent(NewComboType, oldcmbx.Name) as NewCmbx;
...
newCmbx.Visible = oldCmbx.Visible;
...
designerHost.DestroyComponent(oldCmbx);
}
The thing is -oldCmbx is always Visible=true, no matter how it's written in the designer.cs file. I'm always creating Visible=true newCmbx's. If I force newCmbx to be Visible=false, then designer doesn't show newCmbx after the conversion, but the visible property is still true, so Visible property is definitely not what I'm searching for. So how can I force newCmbx's to be Visible=false in designer.cs?

After digging through .NET source code I've found that ControlDesigner is shadowing Visible property of the Control, so what is going to be serialized/deserialized in InitializeComponent is far related from actual Visible property of Control.
Designer.Visible property is initialized like this:
public override void Initialize(IComponent component)
{
PropertyDescriptorCollection properties = TypeDescriptor.GetProperties(component.GetType());
PropertyDescriptor descriptor = properties["Visible"];
if (((descriptor == null) || (descriptor.PropertyType != typeof(bool))) || !descriptor.ShouldSerializeValue(component))
{
this.Visible = true;
}
else
{
this.Visible = (bool) descriptor.GetValue(component);
}
...
}
descriptor.ShouldSerializeValue(component) for Control.Visible is always false in case of newly created control.
Designer.Visible property:
private bool Visible
{
get
{
return (bool) base.ShadowProperties["Visible"];
}
set
{
base.ShadowProperties["Visible"] = value;
}
}
In the Designer.PreFilterProperties() actual Visible property of the Control is shadowed by Visible property of the designer.
Now, when the designer is initialized(in my code that's happening when I'm creating component designerHost.CreateComponent) newCmbx.Visible is always true.
Why it is so? Because Visible property of the Control is used in painting of the control(on the designer surface as well). If I set newCmbx.Visible = false it just disappears from the design surface (but still serializes from the Visible property of the designer) - that's bad, so by design of the Control class, when Control is instantiated, it is always Visible so that it could be visible on the design surface. Any subsequent changes in Visible property influence Visible property of the designer, not Control itself (in the context of working in Designer mode).
So, what I need in order to solve that problem is Visible property of the designer.
Correct code looks like this:
foreach (OldCombo oldCmbx in OldCmbxs())
{
bool _visible = GetVisiblePropThroughReflection(designerHost.GetDesigner(oldCmbx));
...
NewCombo newCmbx = designerHost.CreateComponent(NewComboType, oldcmbx.Name) as NewCmbx;
...
SetVisiblePropThroughReflection(designerHost.GetDesigner(newCmbx), _visible);
...
designerHost.DestroyComponent(oldCmbx);
}

UserControl not rendering within FlowLayoutPanel when dock changed

When I add my UserControls to a FlowLayoutPanel, they display properly. When I change the Dock or Anchor properties on the UserControls before adding them, they are still added but do not render.
According to "How to: Anchor and Dock Child Controls" this should be possible.
I can tell that the controls are added (despite not drawing) because adding enough of them causes a vertical scrollbar to appear.
Setting the "Dock" property of the UserControls to "Left" or "None" will cause them to render, but none of the other options.
Setting the "Anchor" property on the UserControls to anything but Top | Left does not render.
Setting the dock before or after adding the control makes no difference (Add, Dock vs. Dock, Add).
The FlowLayoutPanel is itself is docked (Fill), has FlowDirection set to TopDown, has WrapContents set to false, has AutoScroll set to true, and is otherwise default.
I am using .NET 3.5.
In answer to a comment, the two commented lines are the locations I tried to change the dock. The second spot definitely makes more sense, but I tried the other because it couldn't hurt.
public void CreateObjectControl( object o )
{
ObjectControl oc = new ObjectControl();
oc.MyObject = o;
//This was a spot I mentioned:
//oc.Dock = DockStyle.Fill;
ObjectDictionary.Add( o, oc );
flowLayoutPanel1.Controls.Add( oc );
//This is the other spot I mentioned:
oc.Dock = DockStyle.Fill;
}

try using SuspendLayout and Resumelayout function for the controls before making any amendments which need rendering for proper viewing.
You could see the code from Designer.cs for that particular control
Syntax
control.SuspendLayout();
{Your code for designer amendments}
control.resumeaLayout();

I think I may have found a workaround (read: dirty trick) ... this answer helped to point me in the right direction. Here's an excerpt from the MS article that you also linked to:
For vertical flow directions, the FlowLayoutPanel control calculates the width of an implied column from the widest child control in the column. All other controls in this column with Anchor or Dock properties are aligned or stretched to fit this implied column.
The behavior works in a similar way for horizontal flow directions. The FlowLayoutPanel control calculates the height of an implied row from the tallest child control in the row, and all docked or anchored child controls in this row are aligned or sized to fit the implied row.
This page does not specifically mention that you can't Dock/Anchor the tallest/widest control. But as this control defines the layout behaviour of the FlowLayoutPanel, and thus influences the way all other sibling controls are displayed, it is well possible that Dock and Anchor don't work properly for that 'master control'. Even though I can't find any official documentation regarding that, I believe it to be the case.
So, which options do we have? At runtime, we could add a panel control of height 0 and width of the FlowLayoutPanel client area before you add your usercontrol. You can even set that panel's visibility to false. Subscribing to some Resize/Layout events of the FlowLayoutPanel to keep that panel's size will to the trick. But this does not play nicely at design time. The events won't fire and thus you can't really design the surface the way you want it to look.
I'd prefer a solution that "just works" at design time as well. So, here's an attempt at an "invisible" control that I put together, to fix the controls resizing to zero width if no other control is present. Dropping this as first control onto the FlowLayoutPanel at design time seems to provide the desired effect, and any control subsequently placed on the FlowLayoutPanel is anchorable to the right without shrinking to zero width. The only problem is that, once this invisible control is there, it seems I can't remove it anymore via the IDE. It probably needs some special treatment using a ControlDesigner to achieve that. It can still be removed in the form's designer code though.
This control, once placed onto the FlowLayoutPanel, will listen for resize events of it's parent control, and resize itself according to the ClientSize of the parent control. Use with caution, as this may contain pitfalls that didn't occur to me during the few hours I played with this. For example, I didn't try placing controls that were wider than the FlowLayoutPanel's client area.
As a side note, what will still fail is trying to anchor to the bottom, but that wasn't part of the question ;-)
using System;
using System.Collections;
using System.ComponentModel;
using System.ComponentModel.Design;
using System.Drawing;
using System.Windows.Forms;
namespace ControlTest
{
public sealed class InvisibleControl : Control
{
public InvisibleControl()
{
TabStop = false;
}
#region public interface
// Reduce the temptation ...
public new AnchorStyles Anchor
{
get { return base.Anchor; }
set { base.Anchor = AnchorStyles.None; }
}
public new DockStyle Dock
{
get { return base.Dock; }
set { base.Dock = DockStyle.None; }
}
// We don't ever want to move away from (0,0)
public new Point Location
{
get { return base.Location; }
set { base.Location = Point.Empty; }
}
// Horizontal or vertical orientation?
private Orientation _orientation = Orientation.Horizontal;
[DefaultValue(typeof(Orientation), "Horizontal")]
public Orientation Orientation
{
get { return _orientation; }
set
{
if (_orientation == value) return;
_orientation = value;
ChangeSize();
}
}
#endregion
#region overrides of default behaviour
// We don't want any margin around us
protected override Padding DefaultMargin => Padding.Empty;
// Clean up parent references
protected override void Dispose(bool disposing)
{
if (disposing)
SetParent(null);
base.Dispose(disposing);
}
// This seems to be needed for IDE support, as OnParentChanged does not seem
// to fire if the control is dropped onto a surface for the first time
protected override void OnHandleCreated(EventArgs e)
{
base.OnHandleCreated(e);
ChangeSize();
}
// Make sure we don't inadvertantly paint anything
protected override void OnPaint(PaintEventArgs e) { }
protected override void OnPaintBackground(PaintEventArgs pevent) { }
// If the parent changes, we need to:
// A) Unsubscribe from the previous parent's Resize event, if applicable
// B) Subscribe to the new parent's Resize event
// C) Resize our control according to the new parent dimensions
protected override void OnParentChanged(EventArgs e)
{
base.OnParentChanged(e);
// Perform A+B
SetParent(Parent);
// Perform C
ChangeSize();
}
// We don't really want to be resized, so deal with it
protected override void OnResize(EventArgs e)
{
base.OnResize(e);
ChangeSize();
}
#endregion
#region private stuff
// Make this a default handler signature with optional params, so that this can
// directly subscribe to the parent resize event, but also be called without parameters
private void ChangeSize(object sender = null, EventArgs e = null)
{
Rectangle client = Parent?.ClientRectangle ?? new Rectangle(0, 0, 10, 10);
Size proposedSize = _orientation == Orientation.Horizontal
? new Size(client.Width, 0)
: new Size(0, client.Height);
if (!Size.Equals(proposedSize)) Size = proposedSize;
}
// Handles reparenting
private Control boundParent;
private void SetParent(Control parent)
{
if (boundParent != null)
boundParent.Resize -= ChangeSize;
boundParent = parent;
if (boundParent != null)
boundParent.Resize += ChangeSize;
}
#endregion
}
}