We Keep Coding

How to change the font size in a mahapps project?

So I am trying to change the default font family and the font size in my project. I decided to start with buttons.
I do it like this (I am gonna create a separated file for my style, but now I just want to make it work somehow):
<Controls:MetroWindow.Resources>
<ResourceDictionary>
<ResourceDictionary.MergedDictionaries>
<ResourceDictionary Source="/Templates/MyTemplateSelector.xaml"/>
<ResourceDictionary Source="/Templates/FullMenu.xaml"/>
</ResourceDictionary.MergedDictionaries>
<Style BasedOn="{StaticResource MetroButton}" TargetType="Button">
<Setter Property="FontFamily" Value="Calibri" />
</Style>
</ResourceDictionary>
</Controls:MetroWindow.Resources>
and nothing changes. What is wrong?
I guess it's because program can't find "{StaticResource MetroButton}".
App.xaml
<Application x:Class="WpfApp2.App"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="clr-namespace:WpfApp2"
xmlns:dialogYesNo="clr-namespace:WpfApp2.DialogYesNo"
StartupUri="Views/MainWindow.xaml">
<Application.Resources>
<ResourceDictionary>
<ResourceDictionary.MergedDictionaries>
<!-- MahApps.Metro resource dictionaries. Make sure that all file names are Case Sensitive! -->
<ResourceDictionary Source="pack://application:,,,/MahApps.Metro;component/Styles/Controls.xaml" />
<ResourceDictionary Source="pack://application:,,,/MahApps.Metro;component/Styles/Fonts.xaml" />
<ResourceDictionary Source="pack://application:,,,/MahApps.Metro;component/Styles/Colors.xaml" />
<!-- Accent and AppTheme setting -->
<ResourceDictionary Source="pack://application:,,,/MahApps.Metro;component/Styles/Accents/Blue.xaml" />
<ResourceDictionary Source="pack://application:,,,/MahApps.Metro;component/Styles/Accents/BaseLight.xaml" />
<ResourceDictionary Source="ViewModels.xaml" />
<ResourceDictionary Source="Dialogs.xaml" />
</ResourceDictionary.MergedDictionaries>
</ResourceDictionary>
</Application.Resources>

So, you just need to use it in App.xaml after declaring metro references:
<Style TargetType="Label">
<Setter Property="FontFamily" Value="Segoe UI Light"/>
</Style>
<Style TargetType="TextBlock">
<Setter Property="FontFamily" Value="Segoe UI Light"/>
</Style>
<Style TargetType="TextBox">
<Setter Property="FontFamily" Value="Segoe UI "/>
</Style>
Button uses TextBox, so button will be changed automatically.

Instead of define a style just to set fontfamily/weight you can just define in your resource directly the fontfamily and weight with a key(an example with a font that i use)
<Controls:MetroWindow.Resources>
<FontFamily x:Key="FontAwesome">/tuseradm;component/assets/fontawesome-webfont.ttf#FontAwesome</FontFamily>
</Controls:Flyout.Resources>
then in your button just set the font family
<Button FontFamily="{StaticResource FontAwesome}" Content="" />
EDIT adding another answer:
by default mahapps override the default wpf style. If you want to modify a style for let's say buttons in all your view you don't need to use based on
<Style BasedOn="{StaticResource {x:Type Button}}" TargetType="Button">
<Setter Property="FontFamily" Value="Calibri" />
<Setter Property="FontWeight" Value="ExtraLight"/>
</Style>
EDIT 2
At least for me, even if i see the change at design time using the approach exposed in the first edit, at run time the problem persist. So in my opinion, is much better to stick with my first answer. Maybe it could be annoying to set fontfamily and fontweight for each button, but it is the safest way to deal with mahapps styles. The only way to solve this 100% for sure is to find (no clue where) the template of mahapps buttons and modify it

Setup for ResourceDictionary [duplicate]

I have resource dictionary files (MenuTemplate.xaml, ButtonTemplate.xaml, etc) that I want to use in multiple separate applications. I could add them to the applications' assemblies, but it's better if I compile these resources in one single assembly and have my applications reference it, right?
After the resource assembly is built, how can I reference it in the App.xaml of my applications? Currently I use ResourceDictionary.MergedDictionaries to merge the individual dictionary files. If I have them in an assembly, how can I reference them in xaml?

Check out the pack URI syntax. You want something like this:
<ResourceDictionary Source="pack://application:,,,/YourAssembly;component/Subfolder/YourResourceFile.xaml"/>

An example, just to make this a 15 seconds answer -
Say you have "styles.xaml" in a WPF library named "common" and you want to use it from your main application project:
Add a reference from the main project to "common" project
Your app.xaml should contain:
<Application.Resources>
<ResourceDictionary>
<ResourceDictionary.MergedDictionaries>
<ResourceDictionary Source="pack://application:,,,/Common;component/styles.xaml"/>
</ResourceDictionary.MergedDictionaries>
</ResourceDictionary>
</Application.Resources>

I'm working with .NET 4.5 and couldn't get this working... I was using WPF Custom Control Library. This worked for me in the end...
<ResourceDictionary Source="/MyAssembly;component/mytheme.xaml" />
source: http://social.msdn.microsoft.com/Forums/en-US/wpf/thread/11a42336-8d87-4656-91a3-275413d3cc19

Resource-Only DLL is an option for you. But it is not required necessarily unless you want to modify resources without recompiling applications. Have just one common ResourceDictionary file is also an option. It depends how often you change resources and etc.
<ResourceDictionary Source="pack://application:,,,/
<MyAssembly>;component/<FolderStructureInAssembly>/<ResourceFile.xaml>"/>
MyAssembly - Just assembly name without extension
FolderStructureInAssembly - If your resources are in a folde, specify folder structure
When you are doing this it's better to aware of siteOfOrigin as well.
WPF supports two authorities: application:/// and siteoforigin:///.
The application:/// authority identifies application data files that
are known at compile time, including resource and content files. The
siteoforigin:/// authority identifies site of origin files. The scope
of each authority is shown in the following figure.

For UWP:
<ResourceDictionary Source="ms-appx:///##Namespace.External.Assembly##/##FOLDER##/##FILE##.xaml" />

Using XAML:
If you know the other assembly structure and want the resources in c# code, then use below code:
ResourceDictionary dictionary = new ResourceDictionary();
dictionary.Source = new Uri("pack://application:,,,/WpfControlLibrary1;Component/RD1.xaml", UriKind.Absolute);
foreach (var item in dictionary.Values)
{
//operations
}
Output: If we want to use ResourceDictionary RD1.xaml of Project WpfControlLibrary1 into StackOverflowApp project.
Structure of Projects:
Resource Dictionary:
Code Output:
PS: All ResourceDictionary Files should have Build Action as 'Resource' or 'Page'.
Using C#:
If anyone wants the solution in purely c# code then see my this
solution.

I know I will probably go to WPF hell but I like to keep it simple.
In my "external" WPF project named MyCorp.Wpf.Dll where I have a folder called assets with my resource dictionaries
MyCorp.Wpf.Dll
|- Assets
|- TextStyles.xaml
|- Colours.axml
Let's assume I have this TextStyles.xaml with the UI font styles that I need to apply because I need windows 10/ 11 style compliance
<Style x:Key="Header" TargetType="TextBlock">
<Setter Property="FontFamily" Value="Sego UI Light"/>
<Setter Property="FontSize" Value="46" />
</Style>
<Style x:Key="Subheader" TargetType="TextBlock">
<Setter Property="FontFamily" Value="Sego UI Light"/>
<Setter Property="FontSize" Value="32" />
</Style>
<Style x:Key="Title" TargetType="TextBlock">
<Setter Property="FontFamily" Value="Sego UI SemiLight"/>
<Setter Property="FontSize" Value="24" />
</Style>
<Style x:Key="SubTitle" TargetType="TextBlock">
<Setter Property="FontFamily" Value="Sego UI Normal"/>
<Setter Property="FontSize" Value="20" />
</Style>
<Style x:Key="Base" TargetType="TextBlock">
<Setter Property="FontFamily" Value="Sego Semibold"/>
<Setter Property="FontSize" Value="15" />
</Style>
<Style x:Key="Body" TargetType="TextBlock">
<Setter Property="FontFamily" Value="Sego Normal"/>
<Setter Property="FontSize" Value="15" />
</Style>
<Style x:Key="Caption" TargetType="TextBlock">
<Setter Property="FontFamily" Value="Sego Normal"/>
<Setter Property="FontSize" Value="12" />
</Style>
</ResourceDictionary>
These styles are in my corporate style guide and I am re-sing them al over the place
now in my brand new application I can use the corporate style DLL from an internal NuGet package feed or I link it because It happens to be in my solution using the following resource dictionary
<ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
>
<ResourceDictionary.MergedDictionaries>
<ResourceDictionary Source="/MyCorp.Wpf;component/Assets/TextStyles.xaml"/>
<ResourceDictionary Source="/MyCorp.Wpf;component/Assets/Styles.xaml"/>
<ResourceDictionary Source="/MyCorp.Wpf;component/Assets/Brushes.xaml"/>
<ResourceDictionary Source="/MyCorp.Wpf;component/Assets/ColorStyles.xaml"/>
</ResourceDictionary.MergedDictionaries>
</ResourceDictionary>
I have no clue where the extra component come from, I just know I needed. then in my new application I just link it like so:
<Application x:Class="MyNew.App"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
StartupUri="MainWindow.xaml">
<Application.Resources>
<ResourceDictionary>
<ResourceDictionary.MergedDictionaries>
<ResourceDictionary Source="ExternalResources.xaml"/>
</ResourceDictionary.MergedDictionaries>
<BooleanToVisibilityConverter x:Key="VisibilityConverter"/>
</ResourceDictionary>
</Application.Resources>
</Application>
This way I have all external links in the ExternalResources.xaml where everyone understands where they came from and updating them is easy
I can then use the external resource definitions like any other in my windows, page and controls
<syncfusion:ChromelessWindow x:Class="IDPS.ChromelessWindow1"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:local="clr-namespace:IDPS"
xmlns:r="clr-namespace:IDPS.Wpf.Properties;assembly=IDPS.Wpf"
xmlns:syncfusion="http://schemas.syncfusion.com/wpf"
syncfusion:SfSkinManager.Theme="{syncfusion:SkinManagerExtension ThemeName=FluentDark}"
mc:Ignorable="d"
MinHeight="450" MinWidth="800">
<Grid>
<TextBlock Text="Hello world" Style="{StaticResource Title}"/>
</Grid>
</syncfusion:ChromelessWindow>

Metro Styles in resource dictionary

I am trying to style my WPF application with Mahapps Metro. I have added the all the needed .xaml files in my MergedDictionary in the App.xaml. If I write the following in a view file,
<Button DockPanel.Dock="Left" VerticalAlignment="Top" Style="{DynamicResource SquareButtonStyle}"/>
it works, i.e., the button is styled in the SquareButtonStyle style. But if I instead add the following in my own resource dictionary,
<Style TargetType="Button">
<Setter Property="Style" Value="{DynamicResource SquareButtonStyle}"/>
</Style>
I get an error message,
Setting of the property
"System.Windows.ResourceDictionary.DeferrableContent" has caused an
exception.
(my transation of the German error message). So how can I style all buttons, e.g., with SquareButtonStyle without having to do that on each button individually?
EDIT: Here is my app.xaml (the last dictionary, ResourceDic.xaml, is my own one where the above code is):
<Application xmlns:local="clr-namespace:MGM8" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation">
<Application.Resources>
<ResourceDictionary>
<ResourceDictionary.MergedDictionaries>
<ResourceDictionary>
<local:MGM8_BootStrapper p7:Key="bootstrapper" xmlns:p7="http://schemas.microsoft.com/winfx/2006/xaml" />
</ResourceDictionary>
<ResourceDictionary Source="pack://application:,,,/MahApps.Metro;component/Styles/Controls.xaml" />
<ResourceDictionary Source="pack://application:,,,/MahApps.Metro;component/Styles/Fonts.xaml" />
<ResourceDictionary Source="pack://application:,,,/MahApps.Metro;component/Styles/Colors.xaml" />
<ResourceDictionary Source="pack://application:,,,/MahApps.Metro;component/Styles/Accents/Blue.xaml" />
<ResourceDictionary Source="pack://application:,,,/MahApps.Metro;component/Styles/Accents/BaseLight.xaml" />
<ResourceDictionary Source="ResourceDic.xaml" />
</ResourceDictionary.MergedDictionaries>
</ResourceDictionary>
</Application.Resources>

Style property can't be set inside Style of any element.
Just declare your style at root level(a root resource Dictionary or App.xmal resources). Just create the style with TargetType Button don't give any key to it. it will be applied to all the buttons in the app.
for ex:
<Style TargetType="Button" BasedOn="{StaticResource SquareButtonStyle}" >
<Setter Property="Height" Value="50"/>
<Setter Property="BorderThickness" Value="2,1" />
</Style>
So above is extending your SquareButtonStyle for your application for all buttons(only if defined at root level).
Update:
You have to use following in your own Resource Dictionary:
<ResourceDictionary.MergedDictionaries>
<ResourceDictionary Source="SquareButtonStyle dictionary"/>
</ResourceDictionary.MergedDictionaries>
Then only you can create a button style based on SquareButtonStyle in your ResourceDictionary.

Using style defined in merged dictionary from another merged dictionary

Below you can see how I am trying to segregate styles by merging dictionaries (I'm skipping namespaces for the sake of cleanliness)
App.xaml:
<Application.Resources>
<ResourceDictionary>
<ResourceDictionary.MergedDictionaries>
<ResourceDictionary Source="Style/Colors.xaml" />
<ResourceDictionary Source="Style/HeaderStyle.xaml"/>
</ResourceDictionary.MergedDictionaries>
</ResourceDictionary>
</Application.Resources>
Colors.xaml:
<SolidColorBrush x:Key="DarkTextForeground" Color="#7471b9"/>
HeaderStyle.xaml:
<Style x:Key="HeaderTextBlockStyle" TargetType="TextBlock">
<Setter Property="Foreground" Value="{StaticResource DarkTextForeground}"/>
<Setter Property="FontWeight" Value="Black"/>
</Style>
During compilation I get a following error:
Cannot find a Resource with the Name/Key DarkTextForeground
To make It work we have to merge Colors.xaml inside HeaderStyle.xaml like this:
<ResourceDictionary.MergedDictionaries>
<ResourceDictionary Source="Colors.xaml"/>
</ResourceDictionary.MergedDictionaries>
<Style x:Key="HeaderTextBlockStyle" TargetType="TextBlock">
<Setter Property="Foreground" Value="{StaticResource DarkTextForeground}"/>
<Setter Property="FontWeight" Value="Black"/>
</Style>
Can anyone explain to me, why I have to reference Colors.xaml in HeaderStyle.xaml? Can't I just reference styles defined in different merged dictionary?I assume that Colors.xaml is loaded before HeaderStyle.xaml so it should be visible for dictionaries defined later.

This is a response to my question from Erick Fleck at msdn forums:
In your first example each file is parsed independently and then added to the merged dictionary so they don't know anything about each other...similarly, the XAML in a merged dictionary cannot reference names in the 'parent' ResourceDictionary. In other words, you should think of a MergedDictionaries as a one-way reference.
It's the way It works I guess...

VS2012 The resource "X" could not be resolved

I have a Resources.xaml file in my project that contains a resource dictionary like so:
<ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
<Style x:Key="GPHeaderFontSize" TargetType="TextBlock">
<Setter Property="FontWeight" Value="Bold" />
<Setter Property="FontSize" Value="24" />
<Setter Property="Text" Value="BLAHHHHH"/>
</Style>
</ResourceDictionary>
I have included this dictionary in App.xaml like so:
<Application x:Class="GoldenPlains.App"
xmlns="schemas.microsoft.com/winfx/2006/xaml/presentation";
xmlns:x="schemas.microsoft.com/winfx/2006/xaml";
xmlns:phone="clr-namespace:Microsoft.Phone.Controls;assembly=Microsoft.Phone"
xmlns:shell="clr-namespace:Microsoft.Phone.Shell;assembly=Microsoft.Phone">
<Application.Resources>
<local:LocalizedStrings xmlns:local="clr-namespace:GoldenPlains" x:Key="LocalizedStrings"/>
<ResourceDictionary x:Key="GPResources">
<ResourceDictionary.MergedDictionaries>
<!-- Sometimes VS2012 complaining about path with blue line, please ignore it as path is correct -->
<ResourceDictionary Source="Styles/GPResources.xaml"/>
</ResourceDictionary.MergedDictionaries>
<Style x:Key="GPRootOverlayBarStyle" TargetType="Image">
<Setter Property="Source" Value="Assets/Images/root_brown_horizontal_bar.png"/>
<Setter Property="Width" Value="729"/>
<Setter Property="HorizontalAlignment" Value="Left"/>
<Setter Property="Stretch" Value="Uniform"/>
</style>
</Application.Resources>
...
...
</Application>
However when I try to reference an element in the resource dictionary from another Page.xaml file it cannot seem to resolve the resource....
eg:
I have tried using a binding like so:
<TextBlock Style="{Binding Path=LocalizedResources.MyTextBlockStyle, Source= {StaticResource GPResources}}"/>
it does not indicate that something is wrong but nothing shows up on the UI.
A point in the right direction would be great, cheers.

Resource Dictionary definition in the App.xaml should be about like following example :
<Application.Resources>
<ResourceDictionary>
<local:LocalizedStrings xmlns:local="clr-namespace:GoldenPlains" x:Key="LocalizedStrings"/>
<ResourceDictionary.MergedDictionaries>
<ResourceDictionary Source="Styles/GPResources.xaml"/>
</ResourceDictionary.MergedDictionaries>
<!-- Other resources if you have -->
</ResourceDictionary>
</Application.Resources>
Then, when you need to apply style defined in Resources.xaml to a UI control, simply refer to the style's key/name :
<TextBlock Style="{StaticResource GPHeaderFontSize}" />
Notes: All resources need to be inside ResourceDictionary tag, including LocalizedStrings.