Setting WPF background Opacity programmatically

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I'm working on application which creates a new wpf border component for each row in a database. This means I've got to style the border component in C# rather than XAML (as far as I'm aware). The styling is all good so far apart from trying to set the background opacity.

motherboards.Add(new Border());

Border moboBorder = motherboards[i];

moboBorder.Width = 150;

moboBorder.Height = 150;

moboBorder.BorderBrush = Brushes.Black;

moboBorder.Background = Brushes.White;

moboBorder.CornerRadius = new CornerRadius(10);

moboBorder.Margin = new Thickness(5);

moboBorder.BorderThickness = new Thickness(1);

You can adjust the background opacity in XAML like so

<Border BorderThickness="1" Height="100" Width="100">

    <Border.BorderBrush>

        <SolidColorBrush Color="Black" Opacity="0.7"/>

    </Border.BorderBrush>

</Border>

But as I've said I'm creating the component in C# rather than XAML. I guess this is how you set the value in c#

moboBorder.Background.Opacity = //Value

However, I can't figure out what kind of value it takes, not just a straight up number, nothing from brushes than I can see and nothing like = new Opacity()

I've tried googling around but everything is about setting the opacity for the whole element rather than just the background of it.

edited Jan 3 at 5:56

Cœur

19.3k10116155

asked Dec 4 '17 at 20:43

nomicron

3210

Doesn't it take a double, between 0.0 and 1.0?

– Geoff James
Dec 4 '17 at 20:50

@GeoffJames that's what I thought but no it says that it's read only: i.imgur.com/VEkaW9I.png

– nomicron
Dec 4 '17 at 20:52

2

@nomicron You can't set the opacity property on a brush once it's in use. You can create a new Brush though: Background = new SolidColorBrush(((SolidColorBrush)Background).Color) { Opacity = 0.5 };

– Ed Plunkett
Dec 4 '17 at 20:54

So you can't set it because it's readonly. That's because you're trying to set the Opacity of a Brush. You need to set the Background` itself with a Brush with an Opacity of your desire

– Geoff James
Dec 4 '17 at 20:54

For any future reader (and potential comment upvoter), please note that it's wrong to say that you "can't set the opacity property on a brush once it's in use". You can very well do that, provided that the Brush is not frozen. The members of the Brushes class are frozen, and can therefore not be changed (regardless whether they are in use or not).

– Clemens
Dec 5 '17 at 10:16

add a comment |

motherboards.Add(new Border());

Border moboBorder = motherboards[i];

moboBorder.Width = 150;

moboBorder.Height = 150;

moboBorder.BorderBrush = Brushes.Black;

moboBorder.Background = Brushes.White;

moboBorder.CornerRadius = new CornerRadius(10);

moboBorder.Margin = new Thickness(5);

moboBorder.BorderThickness = new Thickness(1);

You can adjust the background opacity in XAML like so

<Border BorderThickness="1" Height="100" Width="100">

    <Border.BorderBrush>

        <SolidColorBrush Color="Black" Opacity="0.7"/>

    </Border.BorderBrush>

</Border>

But as I've said I'm creating the component in C# rather than XAML. I guess this is how you set the value in c#

moboBorder.Background.Opacity = //Value

However, I can't figure out what kind of value it takes, not just a straight up number, nothing from brushes than I can see and nothing like = new Opacity()

I've tried googling around but everything is about setting the opacity for the whole element rather than just the background of it.

edited Jan 3 at 5:56

Cœur

19.3k10116155

asked Dec 4 '17 at 20:43

nomicron

3210

Doesn't it take a double, between 0.0 and 1.0?

– Geoff James
Dec 4 '17 at 20:50

@GeoffJames that's what I thought but no it says that it's read only: i.imgur.com/VEkaW9I.png

– nomicron
Dec 4 '17 at 20:52

2

@nomicron You can't set the opacity property on a brush once it's in use. You can create a new Brush though: Background = new SolidColorBrush(((SolidColorBrush)Background).Color) { Opacity = 0.5 };

– Ed Plunkett
Dec 4 '17 at 20:54

So you can't set it because it's readonly. That's because you're trying to set the Opacity of a Brush. You need to set the Background` itself with a Brush with an Opacity of your desire

– Geoff James
Dec 4 '17 at 20:54

For any future reader (and potential comment upvoter), please note that it's wrong to say that you "can't set the opacity property on a brush once it's in use". You can very well do that, provided that the Brush is not frozen. The members of the Brushes class are frozen, and can therefore not be changed (regardless whether they are in use or not).

– Clemens
Dec 5 '17 at 10:16

add a comment |

motherboards.Add(new Border());

Border moboBorder = motherboards[i];

moboBorder.Width = 150;

moboBorder.Height = 150;

moboBorder.BorderBrush = Brushes.Black;

moboBorder.Background = Brushes.White;

moboBorder.CornerRadius = new CornerRadius(10);

moboBorder.Margin = new Thickness(5);

moboBorder.BorderThickness = new Thickness(1);

You can adjust the background opacity in XAML like so

<Border BorderThickness="1" Height="100" Width="100">

    <Border.BorderBrush>

        <SolidColorBrush Color="Black" Opacity="0.7"/>

    </Border.BorderBrush>

</Border>

But as I've said I'm creating the component in C# rather than XAML. I guess this is how you set the value in c#

moboBorder.Background.Opacity = //Value

However, I can't figure out what kind of value it takes, not just a straight up number, nothing from brushes than I can see and nothing like = new Opacity()

I've tried googling around but everything is about setting the opacity for the whole element rather than just the background of it.

edited Jan 3 at 5:56

Cœur

19.3k10116155

asked Dec 4 '17 at 20:43

nomicron

3210

motherboards.Add(new Border());

Border moboBorder = motherboards[i];

moboBorder.Width = 150;

moboBorder.Height = 150;

moboBorder.BorderBrush = Brushes.Black;

moboBorder.Background = Brushes.White;

moboBorder.CornerRadius = new CornerRadius(10);

moboBorder.Margin = new Thickness(5);

moboBorder.BorderThickness = new Thickness(1);

You can adjust the background opacity in XAML like so

<Border BorderThickness="1" Height="100" Width="100">

    <Border.BorderBrush>

        <SolidColorBrush Color="Black" Opacity="0.7"/>

    </Border.BorderBrush>

</Border>

But as I've said I'm creating the component in C# rather than XAML. I guess this is how you set the value in c#

moboBorder.Background.Opacity = //Value

However, I can't figure out what kind of value it takes, not just a straight up number, nothing from brushes than I can see and nothing like = new Opacity()

I've tried googling around but everything is about setting the opacity for the whole element rather than just the background of it.

c# wpf opacity

edited Jan 3 at 5:56

Cœur

19.3k10116155

asked Dec 4 '17 at 20:43

nomicron

3210

edited Jan 3 at 5:56

Cœur

19.3k10116155

asked Dec 4 '17 at 20:43

nomicron

3210

edited Jan 3 at 5:56

Cœur

19.3k10116155

edited Jan 3 at 5:56

Cœur

19.3k10116155

edited Jan 3 at 5:56

Cœur

19.3k10116155

asked Dec 4 '17 at 20:43

nomicron

3210

asked Dec 4 '17 at 20:43

nomicron

3210

asked Dec 4 '17 at 20:43

nomicron

3210

Doesn't it take a double, between 0.0 and 1.0?

– Geoff James
Dec 4 '17 at 20:50

@GeoffJames that's what I thought but no it says that it's read only: i.imgur.com/VEkaW9I.png

– nomicron
Dec 4 '17 at 20:52

2

@nomicron You can't set the opacity property on a brush once it's in use. You can create a new Brush though: Background = new SolidColorBrush(((SolidColorBrush)Background).Color) { Opacity = 0.5 };

– Ed Plunkett
Dec 4 '17 at 20:54

So you can't set it because it's readonly. That's because you're trying to set the Opacity of a Brush. You need to set the Background` itself with a Brush with an Opacity of your desire

– Geoff James
Dec 4 '17 at 20:54

For any future reader (and potential comment upvoter), please note that it's wrong to say that you "can't set the opacity property on a brush once it's in use". You can very well do that, provided that the Brush is not frozen. The members of the Brushes class are frozen, and can therefore not be changed (regardless whether they are in use or not).

– Clemens
Dec 5 '17 at 10:16

add a comment |

Doesn't it take a double, between 0.0 and 1.0?

– Geoff James
Dec 4 '17 at 20:50

@GeoffJames that's what I thought but no it says that it's read only: i.imgur.com/VEkaW9I.png

– nomicron
Dec 4 '17 at 20:52

2

@nomicron You can't set the opacity property on a brush once it's in use. You can create a new Brush though: Background = new SolidColorBrush(((SolidColorBrush)Background).Color) { Opacity = 0.5 };

– Ed Plunkett
Dec 4 '17 at 20:54

So you can't set it because it's readonly. That's because you're trying to set the Opacity of a Brush. You need to set the Background` itself with a Brush with an Opacity of your desire

– Geoff James
Dec 4 '17 at 20:54

For any future reader (and potential comment upvoter), please note that it's wrong to say that you "can't set the opacity property on a brush once it's in use". You can very well do that, provided that the Brush is not frozen. The members of the Brushes class are frozen, and can therefore not be changed (regardless whether they are in use or not).

– Clemens
Dec 5 '17 at 10:16

Doesn't it take a double, between 0.0 and 1.0?

– Geoff James
Dec 4 '17 at 20:50

@GeoffJames that's what I thought but no it says that it's read only: i.imgur.com/VEkaW9I.png

– nomicron
Dec 4 '17 at 20:52

@nomicron You can't set the opacity property on a brush once it's in use. You can create a new Brush though: Background = new SolidColorBrush(((SolidColorBrush)Background).Color) { Opacity = 0.5 };

– Ed Plunkett
Dec 4 '17 at 20:54

So you can't set it because it's readonly. That's because you're trying to set the Opacity of a Brush. You need to set the Background` itself with a Brush with an Opacity of your desire

– Geoff James
Dec 4 '17 at 20:54

For any future reader (and potential comment upvoter), please note that it's wrong to say that you "can't set the opacity property on a brush once it's in use". You can very well do that, provided that the Brush is not frozen. The members of the Brushes class are frozen, and can therefore not be changed (regardless whether they are in use or not).

– Clemens
Dec 5 '17 at 10:16

add a comment |

3 Answers
3

active

oldest

votes

A double is certainly a "straight up number"; hover the mouse over the property to see the data type.

The problem (thanks, Clemens) is that you're trying to set the opacity of Brushes.Black, which is a system object and you've got no business doing that.

But you can set the Opacity of a SolidColorBrush that you create yourself.

To create a new semi-opaque white brush:

x.Background = new SolidColorBrush(Colors.White) { Opacity = 0.5 };

See Geoff's answer for how to create a color from an RGB triplet (or ARGB quad) instead of named colors.

Or just keep the existing brush, if you're confident that you didn't get it from Brushes.

Background.Opacity = 0.5;

If you did this, you got it from System.Brushes:

<Window

    Background="DeepSkyBlue"

    ...

If you did this, you didn't:

<Window.Background><SolidColorBrush Color="DeepSkyBlue" /></Window.Background>

That DeepSkyBlue is Colors.DeepSkyBlue; you're creating a new brush with that color.

You should be doing all of this in XAML with bindings instead of creating WPF controls in C#. You'll shoot your eye out, kid.

But it's your eye.

edited Dec 4 '17 at 22:53

answered Dec 4 '17 at 20:58

Ed Plunkett

30.2k53679

1

Totally agree with your suggestion of using bindings. MVVM all the way :o)

– Geoff James
Dec 4 '17 at 20:59

Exactly what I needed, great thank you

– nomicron
Dec 4 '17 at 21:00

1

It's not true that "you can't set the Opacity of a Brush once it's in use". You just can't change the Opacity of the members of the Brushes class (as these are readonly). However, if you assign Background = new SolidColorBrush(Colors.Black) to an element, you can easily later set Background.Opacity = 0.5. Both answers should be edited.

– Clemens
Dec 4 '17 at 22:24

@Clemens Whoops, thanks. Updated.

– Ed Plunkett
Dec 4 '17 at 22:30

2

@Clemens - I've probably taken your comment out of context and been a bit subjective, sorry. Far too often I see members of SO trolling all over others' answers for "see my answer" comments. I agree it's very constructive and adds good value to point these things out. I've deleted my stupid-ass comment, now, so as not to draw away from the point of the answers.

– Geoff James
Dec 4 '17 at 22:56

|
show 5 more comments

As @Clemens kindly pointed out in the comments:

You can't set the Opacity of the system's shared brushes directly.

You will need to use a non-shared SolidColorBrush, and then you will be able to set the Opacity of that.

You will be able to change the Opacity from any point in the code, from thereon-in.

E.g.:

moboBorder.Background = new SolidColorBrush(Color.FromRgb(255, 0, 0))

                        {

                            Opacity = 0.5 // or whatever opacity between

                                          //  0.0 (0%) and 1.0 (100%)

                        };

moboBorder.Background = new SolidColorBrush(Color.FromRgb(255, 0, 0));

moboBorder.Background.Opacity = 0.5;

Similar the above example, you could also set the alpha (the opacity) if you're using RGB.

You can use the Color.FromArgb() static method, instead:

moboBorder.Background = new SolidColorBrush(Color.FromArgb(0.5, 255, 0, 0));

Just use a double between 0.0 and 1.0 (as before), as your first argument to the method.

Hope this helps.

edited Dec 4 '17 at 23:04

answered Dec 4 '17 at 20:58

Geoff James

2,3371725

1

It's not true that "you can't set the Opacity of a Brush once it's in use". You just can't change the Opacity of the members of the Brushes class (as these are readonly). However, if you assign Background = new SolidColorBrush(Colors.Black) to an element, you can easily later set Background.Opacity = 0.5. Both answers should be edited.

– Clemens
Dec 4 '17 at 22:26

Good point, @Clemens - absolutely right! Updated my answer to clarify this to do with the shared brushes. Thanks!

– Geoff James
Dec 4 '17 at 22:32

add a comment |

The equivalent of the XAML

<Border.BorderBrush>

    <SolidColorBrush Color="Black" Opacity="0.7"/>

</Border.BorderBrush>

in code behind would be

moboBorder.Background = new SolidColorBrush

{

    Color = Colors.Black,

    Opacity = 0.7

};

In contrast to the predefined Brushes in the Brushes class (which are frozen), the above SolidColorBrush can be changed at any time later, like

moboBorder.Background.Opacity = 0.5;

edited Dec 5 '17 at 6:39

answered Dec 4 '17 at 22:30

Clemens

90.2k894186

add a comment |

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3 Answers
3

active

oldest

votes

3 Answers
3

active

oldest

votes

A double is certainly a "straight up number"; hover the mouse over the property to see the data type.

The problem (thanks, Clemens) is that you're trying to set the opacity of Brushes.Black, which is a system object and you've got no business doing that.

But you can set the Opacity of a SolidColorBrush that you create yourself.

To create a new semi-opaque white brush:

x.Background = new SolidColorBrush(Colors.White) { Opacity = 0.5 };

See Geoff's answer for how to create a color from an RGB triplet (or ARGB quad) instead of named colors.

Or just keep the existing brush, if you're confident that you didn't get it from Brushes.

Background.Opacity = 0.5;

If you did this, you got it from System.Brushes:

<Window

    Background="DeepSkyBlue"

    ...

If you did this, you didn't:

<Window.Background><SolidColorBrush Color="DeepSkyBlue" /></Window.Background>

That DeepSkyBlue is Colors.DeepSkyBlue; you're creating a new brush with that color.

You should be doing all of this in XAML with bindings instead of creating WPF controls in C#. You'll shoot your eye out, kid.

But it's your eye.

edited Dec 4 '17 at 22:53

answered Dec 4 '17 at 20:58

Ed Plunkett

30.2k53679

1

Totally agree with your suggestion of using bindings. MVVM all the way :o)

– Geoff James
Dec 4 '17 at 20:59

Exactly what I needed, great thank you

– nomicron
Dec 4 '17 at 21:00

1

It's not true that "you can't set the Opacity of a Brush once it's in use". You just can't change the Opacity of the members of the Brushes class (as these are readonly). However, if you assign Background = new SolidColorBrush(Colors.Black) to an element, you can easily later set Background.Opacity = 0.5. Both answers should be edited.

– Clemens
Dec 4 '17 at 22:24

@Clemens Whoops, thanks. Updated.

– Ed Plunkett
Dec 4 '17 at 22:30

2

@Clemens - I've probably taken your comment out of context and been a bit subjective, sorry. Far too often I see members of SO trolling all over others' answers for "see my answer" comments. I agree it's very constructive and adds good value to point these things out. I've deleted my stupid-ass comment, now, so as not to draw away from the point of the answers.

– Geoff James
Dec 4 '17 at 22:56

|
show 5 more comments

A double is certainly a "straight up number"; hover the mouse over the property to see the data type.

The problem (thanks, Clemens) is that you're trying to set the opacity of Brushes.Black, which is a system object and you've got no business doing that.

But you can set the Opacity of a SolidColorBrush that you create yourself.

To create a new semi-opaque white brush:

x.Background = new SolidColorBrush(Colors.White) { Opacity = 0.5 };

See Geoff's answer for how to create a color from an RGB triplet (or ARGB quad) instead of named colors.

Or just keep the existing brush, if you're confident that you didn't get it from Brushes.

Background.Opacity = 0.5;

If you did this, you got it from System.Brushes:

<Window

    Background="DeepSkyBlue"

    ...

If you did this, you didn't:

<Window.Background><SolidColorBrush Color="DeepSkyBlue" /></Window.Background>

That DeepSkyBlue is Colors.DeepSkyBlue; you're creating a new brush with that color.

You should be doing all of this in XAML with bindings instead of creating WPF controls in C#. You'll shoot your eye out, kid.

But it's your eye.

edited Dec 4 '17 at 22:53

answered Dec 4 '17 at 20:58

Ed Plunkett

30.2k53679

1

Totally agree with your suggestion of using bindings. MVVM all the way :o)

– Geoff James
Dec 4 '17 at 20:59

Exactly what I needed, great thank you

– nomicron
Dec 4 '17 at 21:00

1

It's not true that "you can't set the Opacity of a Brush once it's in use". You just can't change the Opacity of the members of the Brushes class (as these are readonly). However, if you assign Background = new SolidColorBrush(Colors.Black) to an element, you can easily later set Background.Opacity = 0.5. Both answers should be edited.

– Clemens
Dec 4 '17 at 22:24

@Clemens Whoops, thanks. Updated.

– Ed Plunkett
Dec 4 '17 at 22:30

2

@Clemens - I've probably taken your comment out of context and been a bit subjective, sorry. Far too often I see members of SO trolling all over others' answers for "see my answer" comments. I agree it's very constructive and adds good value to point these things out. I've deleted my stupid-ass comment, now, so as not to draw away from the point of the answers.

– Geoff James
Dec 4 '17 at 22:56

|
show 5 more comments

A double is certainly a "straight up number"; hover the mouse over the property to see the data type.

The problem (thanks, Clemens) is that you're trying to set the opacity of Brushes.Black, which is a system object and you've got no business doing that.

But you can set the Opacity of a SolidColorBrush that you create yourself.

To create a new semi-opaque white brush:

x.Background = new SolidColorBrush(Colors.White) { Opacity = 0.5 };

See Geoff's answer for how to create a color from an RGB triplet (or ARGB quad) instead of named colors.

Or just keep the existing brush, if you're confident that you didn't get it from Brushes.

Background.Opacity = 0.5;

If you did this, you got it from System.Brushes:

<Window

    Background="DeepSkyBlue"

    ...

If you did this, you didn't:

<Window.Background><SolidColorBrush Color="DeepSkyBlue" /></Window.Background>

That DeepSkyBlue is Colors.DeepSkyBlue; you're creating a new brush with that color.

You should be doing all of this in XAML with bindings instead of creating WPF controls in C#. You'll shoot your eye out, kid.

But it's your eye.

edited Dec 4 '17 at 22:53

answered Dec 4 '17 at 20:58

Ed Plunkett

30.2k53679

A double is certainly a "straight up number"; hover the mouse over the property to see the data type.

The problem (thanks, Clemens) is that you're trying to set the opacity of Brushes.Black, which is a system object and you've got no business doing that.

But you can set the Opacity of a SolidColorBrush that you create yourself.

To create a new semi-opaque white brush:

x.Background = new SolidColorBrush(Colors.White) { Opacity = 0.5 };

See Geoff's answer for how to create a color from an RGB triplet (or ARGB quad) instead of named colors.

Or just keep the existing brush, if you're confident that you didn't get it from Brushes.

Background.Opacity = 0.5;

If you did this, you got it from System.Brushes:

<Window

    Background="DeepSkyBlue"

    ...

If you did this, you didn't:

<Window.Background><SolidColorBrush Color="DeepSkyBlue" /></Window.Background>

That DeepSkyBlue is Colors.DeepSkyBlue; you're creating a new brush with that color.

You should be doing all of this in XAML with bindings instead of creating WPF controls in C#. You'll shoot your eye out, kid.

But it's your eye.

edited Dec 4 '17 at 22:53

answered Dec 4 '17 at 20:58

Ed Plunkett

30.2k53679

edited Dec 4 '17 at 22:53

answered Dec 4 '17 at 20:58

Ed Plunkett

30.2k53679

answered Dec 4 '17 at 20:58

Ed Plunkett

30.2k53679

answered Dec 4 '17 at 20:58

Ed Plunkett

30.2k53679

1

Totally agree with your suggestion of using bindings. MVVM all the way :o)

– Geoff James
Dec 4 '17 at 20:59

Exactly what I needed, great thank you

– nomicron
Dec 4 '17 at 21:00

1

It's not true that "you can't set the Opacity of a Brush once it's in use". You just can't change the Opacity of the members of the Brushes class (as these are readonly). However, if you assign Background = new SolidColorBrush(Colors.Black) to an element, you can easily later set Background.Opacity = 0.5. Both answers should be edited.

– Clemens
Dec 4 '17 at 22:24

@Clemens Whoops, thanks. Updated.

– Ed Plunkett
Dec 4 '17 at 22:30

2

@Clemens - I've probably taken your comment out of context and been a bit subjective, sorry. Far too often I see members of SO trolling all over others' answers for "see my answer" comments. I agree it's very constructive and adds good value to point these things out. I've deleted my stupid-ass comment, now, so as not to draw away from the point of the answers.

– Geoff James
Dec 4 '17 at 22:56

|
show 5 more comments

1

Totally agree with your suggestion of using bindings. MVVM all the way :o)

– Geoff James
Dec 4 '17 at 20:59

Exactly what I needed, great thank you

– nomicron
Dec 4 '17 at 21:00

1

It's not true that "you can't set the Opacity of a Brush once it's in use". You just can't change the Opacity of the members of the Brushes class (as these are readonly). However, if you assign Background = new SolidColorBrush(Colors.Black) to an element, you can easily later set Background.Opacity = 0.5. Both answers should be edited.

– Clemens
Dec 4 '17 at 22:24

@Clemens Whoops, thanks. Updated.

– Ed Plunkett
Dec 4 '17 at 22:30

2

@Clemens - I've probably taken your comment out of context and been a bit subjective, sorry. Far too often I see members of SO trolling all over others' answers for "see my answer" comments. I agree it's very constructive and adds good value to point these things out. I've deleted my stupid-ass comment, now, so as not to draw away from the point of the answers.

– Geoff James
Dec 4 '17 at 22:56

Totally agree with your suggestion of using bindings. MVVM all the way :o)

– Geoff James
Dec 4 '17 at 20:59

Exactly what I needed, great thank you

– nomicron
Dec 4 '17 at 21:00

It's not true that "you can't set the Opacity of a Brush once it's in use". You just can't change the Opacity of the members of the Brushes class (as these are readonly). However, if you assign Background = new SolidColorBrush(Colors.Black) to an element, you can easily later set Background.Opacity = 0.5. Both answers should be edited.

– Clemens
Dec 4 '17 at 22:24

@Clemens Whoops, thanks. Updated.

– Ed Plunkett
Dec 4 '17 at 22:30

@Clemens - I've probably taken your comment out of context and been a bit subjective, sorry. Far too often I see members of SO trolling all over others' answers for "see my answer" comments. I agree it's very constructive and adds good value to point these things out. I've deleted my stupid-ass comment, now, so as not to draw away from the point of the answers.

– Geoff James
Dec 4 '17 at 22:56

|
show 5 more comments

As @Clemens kindly pointed out in the comments:

You can't set the Opacity of the system's shared brushes directly.

You will need to use a non-shared SolidColorBrush, and then you will be able to set the Opacity of that.

You will be able to change the Opacity from any point in the code, from thereon-in.

E.g.:

moboBorder.Background = new SolidColorBrush(Color.FromRgb(255, 0, 0))

                        {

                            Opacity = 0.5 // or whatever opacity between

                                          //  0.0 (0%) and 1.0 (100%)

                        };

moboBorder.Background = new SolidColorBrush(Color.FromRgb(255, 0, 0));

moboBorder.Background.Opacity = 0.5;

Similar the above example, you could also set the alpha (the opacity) if you're using RGB.

You can use the Color.FromArgb() static method, instead:

moboBorder.Background = new SolidColorBrush(Color.FromArgb(0.5, 255, 0, 0));

Just use a double between 0.0 and 1.0 (as before), as your first argument to the method.

Hope this helps.

edited Dec 4 '17 at 23:04

answered Dec 4 '17 at 20:58

Geoff James

2,3371725

1

It's not true that "you can't set the Opacity of a Brush once it's in use". You just can't change the Opacity of the members of the Brushes class (as these are readonly). However, if you assign Background = new SolidColorBrush(Colors.Black) to an element, you can easily later set Background.Opacity = 0.5. Both answers should be edited.

– Clemens
Dec 4 '17 at 22:26

Good point, @Clemens - absolutely right! Updated my answer to clarify this to do with the shared brushes. Thanks!

– Geoff James
Dec 4 '17 at 22:32

add a comment |

As @Clemens kindly pointed out in the comments:

You can't set the Opacity of the system's shared brushes directly.

You will need to use a non-shared SolidColorBrush, and then you will be able to set the Opacity of that.

You will be able to change the Opacity from any point in the code, from thereon-in.

E.g.:

moboBorder.Background = new SolidColorBrush(Color.FromRgb(255, 0, 0))

                        {

                            Opacity = 0.5 // or whatever opacity between

                                          //  0.0 (0%) and 1.0 (100%)

                        };

moboBorder.Background = new SolidColorBrush(Color.FromRgb(255, 0, 0));

moboBorder.Background.Opacity = 0.5;

Similar the above example, you could also set the alpha (the opacity) if you're using RGB.

You can use the Color.FromArgb() static method, instead:

moboBorder.Background = new SolidColorBrush(Color.FromArgb(0.5, 255, 0, 0));

Just use a double between 0.0 and 1.0 (as before), as your first argument to the method.

Hope this helps.

edited Dec 4 '17 at 23:04

answered Dec 4 '17 at 20:58

Geoff James

2,3371725

1

It's not true that "you can't set the Opacity of a Brush once it's in use". You just can't change the Opacity of the members of the Brushes class (as these are readonly). However, if you assign Background = new SolidColorBrush(Colors.Black) to an element, you can easily later set Background.Opacity = 0.5. Both answers should be edited.

– Clemens
Dec 4 '17 at 22:26

Good point, @Clemens - absolutely right! Updated my answer to clarify this to do with the shared brushes. Thanks!

– Geoff James
Dec 4 '17 at 22:32

add a comment |

As @Clemens kindly pointed out in the comments:

You can't set the Opacity of the system's shared brushes directly.

You will need to use a non-shared SolidColorBrush, and then you will be able to set the Opacity of that.

You will be able to change the Opacity from any point in the code, from thereon-in.

E.g.:

moboBorder.Background = new SolidColorBrush(Color.FromRgb(255, 0, 0))

                        {

                            Opacity = 0.5 // or whatever opacity between

                                          //  0.0 (0%) and 1.0 (100%)

                        };

moboBorder.Background = new SolidColorBrush(Color.FromRgb(255, 0, 0));

moboBorder.Background.Opacity = 0.5;

Similar the above example, you could also set the alpha (the opacity) if you're using RGB.

You can use the Color.FromArgb() static method, instead:

moboBorder.Background = new SolidColorBrush(Color.FromArgb(0.5, 255, 0, 0));

Just use a double between 0.0 and 1.0 (as before), as your first argument to the method.

Hope this helps.

edited Dec 4 '17 at 23:04

answered Dec 4 '17 at 20:58

Geoff James

2,3371725

As @Clemens kindly pointed out in the comments:

You can't set the Opacity of the system's shared brushes directly.

You will need to use a non-shared SolidColorBrush, and then you will be able to set the Opacity of that.

You will be able to change the Opacity from any point in the code, from thereon-in.

E.g.:

moboBorder.Background = new SolidColorBrush(Color.FromRgb(255, 0, 0))

                        {

                            Opacity = 0.5 // or whatever opacity between

                                          //  0.0 (0%) and 1.0 (100%)

                        };

moboBorder.Background = new SolidColorBrush(Color.FromRgb(255, 0, 0));

moboBorder.Background.Opacity = 0.5;

Similar the above example, you could also set the alpha (the opacity) if you're using RGB.

You can use the Color.FromArgb() static method, instead:

moboBorder.Background = new SolidColorBrush(Color.FromArgb(0.5, 255, 0, 0));

Just use a double between 0.0 and 1.0 (as before), as your first argument to the method.

Hope this helps.

edited Dec 4 '17 at 23:04

answered Dec 4 '17 at 20:58

Geoff James

2,3371725

edited Dec 4 '17 at 23:04

answered Dec 4 '17 at 20:58

Geoff James

2,3371725

answered Dec 4 '17 at 20:58

Geoff James

2,3371725

answered Dec 4 '17 at 20:58

Geoff James

2,3371725

1

It's not true that "you can't set the Opacity of a Brush once it's in use". You just can't change the Opacity of the members of the Brushes class (as these are readonly). However, if you assign Background = new SolidColorBrush(Colors.Black) to an element, you can easily later set Background.Opacity = 0.5. Both answers should be edited.

– Clemens
Dec 4 '17 at 22:26

Good point, @Clemens - absolutely right! Updated my answer to clarify this to do with the shared brushes. Thanks!

– Geoff James
Dec 4 '17 at 22:32

add a comment |

1

It's not true that "you can't set the Opacity of a Brush once it's in use". You just can't change the Opacity of the members of the Brushes class (as these are readonly). However, if you assign Background = new SolidColorBrush(Colors.Black) to an element, you can easily later set Background.Opacity = 0.5. Both answers should be edited.

– Clemens
Dec 4 '17 at 22:26

Good point, @Clemens - absolutely right! Updated my answer to clarify this to do with the shared brushes. Thanks!

– Geoff James
Dec 4 '17 at 22:32

Good point, @Clemens - absolutely right! Updated my answer to clarify this to do with the shared brushes. Thanks!

– Geoff James
Dec 4 '17 at 22:32

add a comment |

The equivalent of the XAML

<Border.BorderBrush>

    <SolidColorBrush Color="Black" Opacity="0.7"/>

</Border.BorderBrush>

in code behind would be

moboBorder.Background = new SolidColorBrush

{

    Color = Colors.Black,

    Opacity = 0.7

};

In contrast to the predefined Brushes in the Brushes class (which are frozen), the above SolidColorBrush can be changed at any time later, like

moboBorder.Background.Opacity = 0.5;

edited Dec 5 '17 at 6:39

answered Dec 4 '17 at 22:30

Clemens

90.2k894186

add a comment |

The equivalent of the XAML

<Border.BorderBrush>

    <SolidColorBrush Color="Black" Opacity="0.7"/>

</Border.BorderBrush>

in code behind would be

moboBorder.Background = new SolidColorBrush

{

    Color = Colors.Black,

    Opacity = 0.7

};

In contrast to the predefined Brushes in the Brushes class (which are frozen), the above SolidColorBrush can be changed at any time later, like

moboBorder.Background.Opacity = 0.5;

edited Dec 5 '17 at 6:39

answered Dec 4 '17 at 22:30

Clemens

90.2k894186

add a comment |

The equivalent of the XAML

<Border.BorderBrush>

    <SolidColorBrush Color="Black" Opacity="0.7"/>

</Border.BorderBrush>

in code behind would be

moboBorder.Background = new SolidColorBrush

{

    Color = Colors.Black,

    Opacity = 0.7

};

In contrast to the predefined Brushes in the Brushes class (which are frozen), the above SolidColorBrush can be changed at any time later, like

moboBorder.Background.Opacity = 0.5;

edited Dec 5 '17 at 6:39

answered Dec 4 '17 at 22:30

Clemens

90.2k894186

The equivalent of the XAML

<Border.BorderBrush>

    <SolidColorBrush Color="Black" Opacity="0.7"/>

</Border.BorderBrush>

in code behind would be

moboBorder.Background = new SolidColorBrush

{

    Color = Colors.Black,

    Opacity = 0.7

};

In contrast to the predefined Brushes in the Brushes class (which are frozen), the above SolidColorBrush can be changed at any time later, like

moboBorder.Background.Opacity = 0.5;

edited Dec 5 '17 at 6:39

answered Dec 4 '17 at 22:30

Clemens

90.2k894186

edited Dec 5 '17 at 6:39

answered Dec 4 '17 at 22:30

Clemens

90.2k894186

answered Dec 4 '17 at 22:30

Clemens

90.2k894186

answered Dec 4 '17 at 22:30

Clemens

90.2k894186

add a comment |

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