CODEWITHSUNDEEP
c#wpfmargin
Oztaco
Oztaco

Reputation: 3459

Why can I not change the Margin?

enter image description here On the top it says, "Gets or sets...", so then why is it not letting me change it?

Upvotes: 3

Views: 1723

Answers (3)

Luke Woodward
Luke Woodward

Reputation: 65054

The point here is that it makes no sense to assign to a property within a temporary struct value, as it has no lasting effect.

System.Windows.Thickness is a struct, and label1.Margin is a copy of the Thickness value for the margin of label1. It's a copy because structs are passed by value. There's no point assigning to label1.Margin.Left as you will only change the value of Left in a copy of label1.Margin.

What you can do instead is the following:

Thickness t = label1.Margin;
t.Left = ......; // assign your value here
label1.Margin = t;

See also the MSDN page for the CS1612 error.

The tooltip is saying 'Gets or sets...' because you can get or set the Margin property of label1, but in your specific case there's no point assigning to the Left property of label1.Margin.

Upvotes: 0

Picrofo Software
Picrofo Software

Reputation: 5571

You can't do this because although Margin.Left gets or sets, it's not used like a variable. Just like Padding.

As you may notice, Margin (as for Padding) is a property and Thickness is its value. So, when you say

label1.Margin.Left = MainGrid.ActualHeight / 2 - label1.ActualHeight / 2;

you are only editing a copy (Margin) because Margin returns a struct (Thickness) . That's why you receive an error. The changes are not saved because it's a copy!

Basically, although you can change the value of Object.Margin.Left to a specific value yet it wouldn't save/change the object Margin property and that's why you get an error.

For example

We can NOT say 

label1.Margin.Left = MainGrid.ActualHeight / 2 - label1.ActualHeight /2;

but we can say

Thickness NewThickness = new Thickness(); //Initialize a new Thicnkess
NewThickness.Left = MainGrid.ActualHeight / 2 - label1.ActualHeight /2; //Set the left property of NewThickness
label1.Margin = NewThickness; //Apply the changes to label1

This means that, because Margin is a property, you are not allowed to change its Thickness directly.

Alternatively, you can use the following which I believe to be easier to set a Margin of an object

label1.Margin = new Thickness(double left, double top, double right, double bottom);

Thanks,
I hope you find this helpful :)

Upvotes: 4

bonCodigo
bonCodigo

Reputation: 14361

Seems like all arguments are mandatory for the WPF Margin property, although you may want change just one or two property values a time...

with Google search I saw in Java as well as ASP.net using margin property with all 4 values set.

However this example allows user to retrieve Label.Margin.Left value though... http://forums.asp.net/t/1834713.aspx/1

Upvotes: 0

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