My question is similar to this one.
However, the answer in that thread does not work for me, because I'm using the LinearGradientBrush for an opacity mask.
I've got a grid with three rows:
<Grid.RowDefinitions>
<RowDefinition Height="50" />
<RowDefinition Height="*" />
<RowDefinition Height="50" />
</Grid.RowDefinitions>
The content of the grid should be semi-transparent at the top and the bottom of the grid (the first and third row).
I understand I can't use clipping, because that does not allow for adjustable opacity. So I guess I have to go with opacity masks. They take images or brushes as content, the latter of which makes more sense for this problem, but raises the question of how to set the offset of the GradientBrush to the absolute value of the gridrow's height.
Also, I'm using the MVVM pattern. Binding the offset does not work because it doesn't derive from FrameworkElement. The only solution I can see right now would be to bind the complete brush to my viewmodel, and adjust it every time the grid's size changes. Not too nice, is there a more elegant solution?
What I'd like to do is something like this (RowDefinitions and content skipped)
pseudo code:
<Grid>
<Grid.OpacityMask>
<LinearGradientBrush StartPoint="0.5,1" EndPoint="0.5,0">
<LinearGradientBrush.GradientStops>
<GradientStop AbsoluteOffset="50" Color="#7F000000" />
<GradientStop AbsoluteOffset="*" Color="#00000000" />
<GradientStop AbsoluteOffset="50" Color="#7F000000" />
</LinearGradientBrush.GradientStops>
</Grid.OpacityMask>
</Grid>
I can't split the grid or anything like that, because the content spans the three rows. DrawingBrush would solve it nicely I guess, but that's not living in the SL house.
I'm using Silverlight 3.
Related
I would like to create a custom border around a content, that the upper and lower side of the border is not continuous, it should have a style like bracket as below. (inside the "bracket border" the content should be placed e.g. grid, stackpanel, etc.)
Note that the height of the right and the left border can be changed depending on the content's height, whereas the top and the bottom should have a standard width.
[ sample content ]
In order to achieve this, I separated the view in a 3 columns grid:
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="22px"></ColumnDefinition>
<ColumnDefinition Width="*"></ColumnDefinition>
<ColumnDefinition Width="22px"></ColumnDefinition>
</Grid.ColumnDefinitions>
<Border Grid.Column="0" BorderBrush="Blue" BorderThickness="6px 6px 0px 6px"></Border>
<Border Grid.Column="1" BorderBrush="Transparent" BorderThickness="6px">
<!--Place for the actual content of the border-->
<TextBlock Text="Test" FontSize="15"></TextBlock>
</Border>
<Border Grid.Column="2" BorderBrush="Blue" BorderThickness="0px 6px 6px 6px"></Border>
</Grid>
Is there another approach for achieving this style?
One possible solution is to write your own Border based on a Decorator.
An implementation (for a different border) can be found in How can I draw a border with squared corners in wpf?
One simple trick is try setting some LinearGradientBrush for the BorderBrush. If your text has a fixed width, it will look best at all time. However when the text's width may change, the horizontal lines (at 2 ends) will shrink/extend at some ratio. That's because we set some Offset for the GradientStop and it's pity that this Offset can only be set based on some ratio (from 0 to 1) with the width of the whole Brush (which is exactly the width of the Border when the background is stretched). Note that the MappingMode cannot change this behavior, it just works for StartPoint and EndPoint.
Here is the pure XAML code:
<Border VerticalAlignment="Center" HorizontalAlignment="Center"
BorderThickness="3" Padding="5,0,5,0">
<TextBlock Text="Square bracket border here" FontSize="30"
HorizontalAlignment="Center"/>
<Border.BorderBrush>
<LinearGradientBrush StartPoint="0,1" EndPoint="1,1">
<GradientStop Offset="0.03" Color="Blue"/>
<GradientStop Offset="0.03" Color="Transparent"/>
<GradientStop Offset="0.97" Color="Transparent"/>
<GradientStop Offset="0.97" Color="Blue"/>
</LinearGradientBrush>
</Border.BorderBrush>
</Border>
You can change the Offset of the first 2 GradientStops to what you want, the Offset of the remaining GradentStops should be the subtraction of the first's Offset from 1.
If using some code behind, you can pinpoint exactly the length of the horizontal lines (at the 2 ends). That way we need some Binding between the Offset and the ActualWidth of the Border. Next we need some Converter here, this Converter will convert the ActualWidth and the desired exact length to the correct ratio. So when the text width changes, the length of the horizontal lines will always be some fixed value.
You can try the following XAML code:
<Grid>
<Border BorderBrush="Black" BorderThickness="1"/>
<TextBlock Text="sample content"/>
<Border BorderBrush="White" BorderThickness="0,1,0,1" Margin="8,0,8,0"/>
</Grid>
Second border's color "White" can be replaced with the actual background color. "Transparent" color will not help.
Thanks,
RDV
I'm working on a custom control and I have a VisualBrush with the Visual property as such:
<VisualBrush.Visual>
<Grid>
<Ellipse Stretch="Uniform" Stroke="OrangeRed" StrokeThickness="1">
<Ellipse.Fill>
<RadialGradientBrush GradientOrigin="0.5,0.5">
<GradientStop Color="Yellow" Offset="0" />
<GradientStop Color="Orange" Offset="1" />
</RadialGradientBrush>
</Ellipse.Fill>
</Ellipse>
<Ellipse Stretch="Uniform">
<Ellipse.Fill>
<RadialGradientBrush GradientOrigin="0.5, 0.05" RadiusX=".7" RadiusY=".5" >
<GradientStop Color="White" Offset=".10" />
<GradientStop Color="Transparent" Offset="1" />
</RadialGradientBrush>
</Ellipse.Fill>
</Ellipse>
</Grid>
</VisualBrush.Visual>
When the Stretch property is set to Uniform instead of using the RadialGradientBrush I created, it somehow creates a SolidColorBrush using the Stroke color. However, when I explicitly set the Width and Height properties of the Ellipse instead of using the Stretch property, I get the gradient I expected.
Any ideas of what's going weird here?
EDIT: I just observed the behavior occurs when I enclose the Ellipse inside of a ViewBox.
I'm not sure what you're using the ViewBox for in your above example, but I think some of the strange behaviour you're seeing is a result of not setting the size on the root element for your VisualBrush.
In the documentation for VisualBrush.Visual, there's a paragraph that mentions sizing (added emphasis):
When you define a new Visual for a VisualBrush and that Visual is a
UIElement (such as a panel or control), the layout system runs on the
UIElement and its child elements when the AutoLayoutContent property
is set to true. However, the root UIElement is essentially isolated
from the rest of the system; styles, storyboards, and external layout
dictated by the parent where the brush is applied cannot permeate this
boundary. Therefore, you should explicitly specify the size of the
root UIElement, because its only parent is the VisualBrush and
therefore it cannot automatically size itself to the area being
painted. For more information about layout in Windows Presentation
Foundation (WPF), see the Layout.
If I run your code above, my ellipse is completely filled with the stroke colour, presumably because the the layout is calculated with the smallest value for the ellipse, so the stroke is large enough to cover ellipse content/fill (which is then upscaled to the fill the viewport so it looks like the stroke is the fill colour).
If I give the root element some arbitrary size on which to base the layout <Grid Width="100" Height="100">...</grid> I start to see the stroke and fill colours, rendered with relative sizes.
Suppose there is an element with irregular shape composed of other elements with arbitrary nesting:
<Window.Resources>
<RadialGradientBrush x:Key="brush">
<GradientStop Color="Black" Offset="0" />
<GradientStop Color="White" Offset="1" />
</RadialGradientBrush>
</Window.Resources>
<StackPanel Name="element">
<StackPanel.Effect>
<DropShadowEffect ShadowDepth="0" BlurRadius="10" />
</StackPanel.Effect>
<Rectangle Name="child1" Height="100" Margin="10" Stroke="Black" Fill="{StaticResource brush}" />
<Grid>
<Rectangle Name="child2" Height="100" Margin="10" Stroke="Black" Fill="{StaticResource brush}" />
</Grid>
</StackPanel>
All parts are interactive (i.e a child can be a real control).
How can I fill backgrounds of children with a single radial gradient that spans all of them (should look like as if it is sized to element).
UPDATE: StackPanel has a shadow which should be drawn around children.
One possible solution is to generate gradients with Radius and Origin/Center bound to element's and child's properties with appropriate conversions, but such approach would be rather complex and expensive.
Finally, I went with transformed gradients route except instead of bindings and converters I was able to elegantly solve it by creating background Transformation in ArrangeOverride of child elements and exposing it via dependency property.
Actual RadialGradientBrush binds its Transform to BackgroundTransform by searching for ancestor with matching type.
This assumes that one can modify/wrap child classes which is true in my case. It can be made more flexible with attached properties and a bit more work.
Actual code is in this gist.
I'm styling a simple graphical object in Silverlight, which is shown as a red rectangle with some white text on it; when the mouse hovers the rectangle, I want to show an overlay rectangle which fades from red to transparent, so that the text is only partially visible. My problem is, the LinearGradientBrush I'm using does not go from red to transparent but from red to some kind of semi-transparent white! I've reproduced the problem as follows:
<Grid x:Name="LayoutRoot" Background="Red">
<Grid.RowDefinitions>
<RowDefinition/>
<RowDefinition/>
</Grid.RowDefinitions>
<Grid>
<Grid.Background>
<LinearGradientBrush>
<GradientStop Color="Transparent" Offset="0"/>
<GradientStop Color="Red" Offset="1"/>
</LinearGradientBrush>
</Grid.Background>
</Grid>
In this case, you can easily see that the upper part of the grid is slightly lighter than the lower part, even though I've used the Transparent color constant. The result is identical if I use #00FFFFFF, while if I use #00xxxxxx, where xxxxxx is the RGB code of any color, the hue of the upper rectangle changes according to the color! Shouldn't the first two digits of the code represent the alpha channel? Why doesn't "00" mean full transparency? Any hint is appreciated.
I'd like to apply a Brush (LinearGradientBrush in this case) to two or more objects (TextBlocks) at once. The effect that I'd like is something like this:
Edit
I cannot simply apply the same brush to both objects, as this will make both of them start red and go to blue (instead of the second one starting at a shade of purple).
I'm sure I'm overlooking something quick-n-easy...
Thanks,
wTs
I did it like this:
<Border Height="100" Width="600" >
<Border.OpacityMask>
<VisualBrush>
<VisualBrush.Visual>
<StackPanel>
<TextBlock FontSize="85.333" FontFamily="Calibri" TextAlignment="Right">
The big first line
</TextBlock>
<TextBlock TextWrapping="Wrap" Margin="0,0,8,0" FontSize="32" FontFamily="Calibri" Text="The small second line" TextAlignment="Right" />
</StackPanel>
</VisualBrush.Visual>
</VisualBrush>
</Border.OpacityMask>
<Border.Background>
<LinearGradientBrush EndPoint="0.974,0.49" StartPoint="0,0.457">
<GradientStop Color="#FFFD0202"/>
<GradientStop Color="#FF0234FD" Offset="1"/>
</LinearGradientBrush>
</Border.Background>
</Border>
So, a border whose background is filled with the gradient from blue to red. The only visible part of the gradient is the text in the opacity mask.
Maybe some simpler control than the border would be even better.
The remaining issue is that one has to size the container control explicitly, as it has no content.
What about using an ObjectDataProvider that exposes a method that returns the brush you want based on 3 integers, the starting x position of the brush, the current x position of the brush, and the ending x position of the brush (I could see use cases where you might want four parameters, x start, x end, x current start, x current end, but the 3 parameter will work for the case you have asked for). You can either statically assign these integers based on the layout of your control or use databinding for the parameters.
If you are unfamiliar with ObjectDataProvider and binding to method parameters for this class, i suggest going here and here
Declare the brush into the window (or application) resources and bind the Foreground property of the two textblocks with the brush.