为什么使用 ResourceDictionary 时不显示颜色/画笔？

Question

I have some application wide resources in my programm:

<Application.Resources>
    <ResourceDictionary>

        <!--Colors-->
        <Color x:Key="PaleRed" R="255" G="127" B="127" />
        <Color x:Key="PaleGreen" R="222" G="255" B="209" />
        <Color x:Key="PaleBlue" R="112" G="200" B="255" />
        <Color x:Key="LightGray" R="155" G="155" B="155" />
        <Color x:Key="DarkGray" R="100" G="100" B="100" />

    </ResourceDictionary>
</Application.Resources>

In my ViewModel I get the Background

public Brush Background
    {
        get
        {
            Color paleRed = (Color)Application.Current.Resources["PaleRed"];
            Color paleGreen = (Color)Application.Current.Resources["PaleGreen"];
            Color paleBlue = (Color)Application.Current.Resources["PaleBlue"];
            Color lightGray = (Color)Application.Current.Resources["LightGray"]; 

            #region comment
            paleRed = Color.FromRgb(255, 127, 127);
            paleGreen = Color.FromRgb(222, 255, 209);
            paleBlue = Color.FromRgb(112, 200, 255);
            lightGray= Color.FromRgb(112, 112, 112);
            #endregion

            if (ComponentType == ComponentType.test)
            {
                return new SolidColorBrush(paleBlue);
            }

            var color = Percentage > 0.0 ? paleGreen : paleRed;
            Brush solidBack = new SolidColorBrush(color);
            Brush gradientBack = new LinearGradientBrush(lightGray, color, 0);

            return Amount-AmountSold > 0 ? solidBack : gradientBack;
        }
    }

When setting the Background like it is in the example above (region not commented), it shows the colors in the right way. If I comment the reassignment, the colors are not shown (only white background). But when I set a breakpoint with the region commented, the colors(and brushes) are not null and have the right ARGB values.

Can anyone tell me why this happens?

Answer 1

The way you're defining the colours, you need to also provide A.

EG:

    <Application.Resources>
        <ResourceDictionary>
            <!--Colors-->
            <Color x:Key="PaleRed" R="255" G="127" B="127" A="255" />
            <Color x:Key="PaleGreen" R="222" G="255" B="209" />
            <Color x:Key="PaleBlue" R="112" G="200" B="255" />
            <Color x:Key="LightGray" R="155" G="155" B="155" />
            <Color x:Key="DarkGray" R="100" G="100" B="100" />
            <SolidColorBrush x:Key="PaleRedBrush" Color="{StaticResource PaleRed}"/>
        </ResourceDictionary>
    </Application.Resources>

Set the background of my mainwindow to PaleRedBrush

<Grid Background="{StaticResource PaleRedBrush}">

That works

If I remove that A setting or use a different colour then it's white - the background of my window.