Develop Reference

WPF - Setting corner radius in code behind

I want to bring a some rectangles to my WPF-Pages, these Rectangles should have rounded corners. To bring a few of the rectangles to the page without having to write every single one in xaml I decided to do it with a loop in the code.
I tried this one:
for (int i = 0; i < 5; i++)
{
Rectangle rect = new Rectangle();
rect.Fill = System.Windows.Media.Brushes.Green;
var style = new Style(typeof(Border));
style.Setters.Add(new Setter(Border.CornerRadiusProperty, new CornerRadius(12.0, 0, 0 , 0)));
rect.Resources.Add(typeof(Border), style);
Grid.SetColumn(rect, 1);
Grid.SetRow(rect, 1);
mainGrid.Children.Add(rect);
}
but the corner radius of my rectangles won´t change. Do you have any suggestion?
Thanks for your help in advance!

To bring a few of the rectangles to the page without having to write every single one in xaml
Good problem to solve.
I decided to do it with a loop in the code
Absolutely bad solution. Use proper MVVM with an <ItemsControl> bound to your list of objects you're trying to display, stored in your view model. And then create a global style sheet and apply it to this either automatically or manually.
Anyway to answer your question, you're creating an unnamed style on Border and applying it to a Rectangle. That will never auto-apply, and good thing, because you reference Border.CornerRadiusProperty which doesn't exist on a Rectangle.
You want to either make your style override the Rectangle's template and add a Border around it, then set its corner border radius, or manually add the border above the rectangle and set its corner radius in your setter (only add the style to the Border's resources).
Your code doesn't really make sense to me though, Rectangle also has corner radius properties, RadiusX and RadiusY, you could just set those if that's what you want.

The rectangle is overflowing. If you do the same thing with a border it will work. When you add the rectangle inside the border you can see what its doing
Rectangle rect = new Rectangle();
rect.Fill = System.Windows.Media.Brushes.Green;
Border b = new Border();
b.Width = 100;
b.Height = 100;
b.Background = Brushes.White;
b.CornerRadius= new CornerRadius(12, 0, 0, 0);
b.BorderThickness = new Thickness(2);
b.BorderBrush = Brushes.Red;
b.Child = rect;//adding this rectangle will show you how the corner is overflowing
grid_Main.Children.Add(b);

UWP Composition - Grid with rounded corners DropShadow

I have a UWP app, which I should start by pointing out that it uses very little XAML. The views are built from JSON object recieved from an API. This means that the vast majority of everything is done in C#, and therefore adds a little complexity to my problem.
I basically want to have a panel (e.g. Grid) that can have rounded corners and have a drop shadow applied to it. The drop shadow should also have the rounded corners, this can be seen in the sample below.
I have looked at the DropShadowPanel as part of the Windows Community Toolkit, but this from what I can tell doesn't do the rounded corners unless I change the content to be a rectangle or some other shape.
To use this as a solution would mean the XAML equivalent of something like:
<Grid>
<toolkit:DropShadowPanel>
<Rectangle />
<toolkit:DropShadowPanel>
<Grid CornerRadius="30">
<!-- My Content -->
</Grid>
</Grid>
To me, this seems like an inefficient use of XAML!
I have also discovered the Composition Pro Toolkit, which to me looks bery interesting as it is all code behind. In particular the ImageFrame control looks to achieve the basis of what I require - although far more advanced than my needs.
The below has been based on the ImageFrame, but doesn't work (content is my grid):
protected FrameworkElement AddDropShadow(FrameworkElement content)
{
var container = new Grid { HorizontalAlignment = content.HorizontalAlignment, VerticalAlignment = content.VerticalAlignment, Width = content.Width, Height = content.Height };
var canvas = new Canvas { HorizontalAlignment = HorizontalAlignment.Stretch, VerticalAlignment = VerticalAlignment.Stretch };
content.Loaded += (s, e) =>
{
var compositor = ElementCompositionPreview.GetElementVisual(canvas).Compositor;
var root = compositor.CreateContainerVisual();
ElementCompositionPreview.SetElementChildVisual(canvas, root);
var shadowLayer = compositor.CreateSpriteVisual();
var frameLayer = compositor.CreateLayerVisual();
var frameContent = compositor.CreateShapeVisual();
root.Children.InsertAtBottom(shadowLayer);
root.Children.InsertAtTop(frameLayer);
frameLayer.Children.InsertAtTop(frameContent);
var rectangle = root.Compositor.CreateRoundedRectangleGeometry();
rectangle.Size = new Vector2((float)content.ActualWidth, (float)content.ActualHeight);
rectangle.CornerRadius = new Vector2(30f);
var shape = root.Compositor.CreateSpriteShape(rectangle);
shape.FillBrush = root.Compositor.CreateColorBrush(Colors.Blue);
//var visual = root.Compositor.CreateShapeVisual();
frameContent.Size = rectangle.Size;
frameContent.Shapes.Add(shape);
//create mask layer
var layerEffect = new CompositeEffect
{
Mode = Microsoft.Graphics.Canvas.CanvasComposite.DestinationIn,
Sources = { new CompositionEffectSourceParameter("source"), new CompositionEffectSourceParameter("mask") }
};
var layerEffectFactory = compositor.CreateEffectFactory(layerEffect);
var layerEffectBrush = layerEffectFactory.CreateBrush();
//CompositionDrawingSurface
var graphicsDevice = CanvasComposition.CreateCompositionGraphicsDevice(compositor, new Microsoft.Graphics.Canvas.CanvasDevice(forceSoftwareRenderer: false));
var frameLayerMask = graphicsDevice.CreateDrawingSurface(new Size(0, 0), Windows.Graphics.DirectX.DirectXPixelFormat.B8G8R8A8UIntNormalized, Windows.Graphics.DirectX.DirectXAlphaMode.Premultiplied);
layerEffectBrush.SetSourceParameter("mask", compositor.CreateSurfaceBrush(frameLayerMask));
frameLayer.Effect = layerEffectBrush;
var shadow = root.Compositor.CreateDropShadow();
//shadow.SourcePolicy = CompositionDropShadowSourcePolicy.InheritFromVisualContent;
shadow.Mask = layerEffectBrush.GetSourceParameter("mask");
shadow.Color = Colors.Black;
shadow.BlurRadius = 25f;
shadow.Opacity = 0.75f;
shadow.Offset = new Vector3(0, 0, 0);
shadowLayer.Shadow = shadow;
content.Opacity = 0; //hiding my actual content to see the results of this
};
container.Children.Add(canvas);
container.Children.Add(content);
return container;
}
In these tests, I am doing the same inefficient use of object, creating another container that has both the composition canvas, and also the grid. If possible, I'd like to apply the composition directly to the original content grid.
I am completely new to composition, so any thoughts, pointers, glaring errors or solutions would be most welcomed.
A Hack Solution?
I have changed my method to the following, visually it works - but is it right?
protected FrameworkElement AddDropShadow(FrameworkElement content)
{
var container = new Grid { HorizontalAlignment = content.HorizontalAlignment, VerticalAlignment = content.VerticalAlignment };
var rectangle = new Rectangle { Fill = new SolidColorBrush(Colors.Transparent) };
content.Loaded += (s, e) =>
{
rectangle.Fill = new SolidColorBrush(Colors.Black);
rectangle.Width = content.ActualWidth;
rectangle.Height = content.ActualHeight;
rectangle.RadiusX = 30;
rectangle.RadiusY = 30;
var compositor = ElementCompositionPreview.GetElementVisual(rectangle).Compositor;
var visual = compositor.CreateSpriteVisual();
visual.Size = new Vector2((float)content.ActualWidth, (float)content.ActualHeight);
var shadow = compositor.CreateDropShadow();
shadow.BlurRadius = 30f;
shadow.Mask = rectangle.GetAlphaMask();
shadow.Opacity = 0.75f;
visual.Shadow = shadow;
ElementCompositionPreview.SetElementChildVisual(rectangle, visual);
};
container.Children.Add(rectangle);
container.Children.Add(content);
return container;
}
The concept here is that my container grid holds a rectangle and my content grid (or other element).
The first error of this method is that is assumes my input FrameworkElement will be rectangular. I imagine that this could be improved upon by creating a bitmap render of the content as highlighted in this blog - but this will likely be quite costly. I also have to ensure that the rectangle size and shape exactly matches that of my main content!
It feels very wrong that there is a rectangle drawn on the screen (even though hidden by my main content). The rectangle is purely there to create the alpha mask so I guess it could be scrapped if the mask is created from the renderof the content.
I've tried setting the visibility of the rectangle to collapsed to remove it from the visual tree. This means that I can attach the visual to the container instead:
ElementCompositionPreview.SetElementChildVisual(container, visual)
However, doing this means that the shadow displays in front of the main content, which means I need some other ui element to attach it too - may as well be the rectangle!

Your solution to use Rectangle is my current workaround everywhere I need rounded shadow under Grid or Border. It's simple and it's plain, why should I complain :)
But if it's not your choice you can draw a rounded rectangle and blur it:
GraphicsDevice = CanvasComposition.CreateCompositionGraphicsDevice(Compositor, CanvasDevice.GetSharedDevice());
var roudRectMaskSurface = GraphicsDevice.CreateDrawingSurface(new Size(SurfaceWidth + BlurMargin * 2, SurfaceHeight + BlurMargin * 2), DirectXPixelFormat.B8G8R8A8UIntNormalized, DirectXAlphaMode.Premultiplied);
using (var ds = CanvasComposition.CreateDrawingSession(roudRectMaskSurface))
{
ds.Clear(Colors.Transparent);
ds.FillRoundedRectangle(new Rect(BlurMargin, BlurMargin, roudRectMaskSurface.Size.Width + BlurMargin, roudRectMaskSurface.Size.Height + BlurMargin), YourRadius, YourRadius, Colors.Black);
}
var rectangleMask = Compositor.CreateSurfaceBrush(roudRectMaskSurface);
Now you can apply this surface in the EffectBrush with blur effect to obtain custom shadow.
BlurMargin - corresponds to the blur amount, you need it because your blurred surface will be bigger than initial source rectangle (to avoid blur clip).

uwp Expression node fade in animation

I am using the sample on Windows UI dev labs sample gallery. And I used ShyHeader example to put in my app, but I am not using exactly the same code but I actually edited the example according to own needs.
My question is how can I use expression node to fade in a specific XAML element in correspondence to the scroll viewer, I am able to fade out an element with the scroll viewer. but I am not being able to fade in an element from opacity 0 -> opacity 1.
here is my code.
<ScrollViewer x:Name="MyScrollViewer">
<Grid>
<local:MyAdaptiveView Margin="0,300,0,0"
x:Name="AllVideosGridView"/>
<Grid x:Name="Header" Height="300" VerticalAlignment="Top">
<FlipView x:Name="MainFlipView"
</FlipView>
<Grid Background="Blue" Height="150" VerticalAlignment="Bottom" Opacity="0.5" Name="FrontGrid">
</Grid>
</Grid>
</Grid>
</ScrollViewer>
page loaded method
the only important piece of code is only at the very end of this method, the last 4, 5 lines, you can see I am able to fade out element by doing 1- progresNode but my attempt to fade in another element ( frontVisual ) by doing 0+ progressNode doesn't work and frontVisual actually remains at 0 opacity even after I scroll.
private void ShyView_Loaded(object sender, RoutedEventArgs e)
{
// Get the PropertySet that contains the scroll values from MyScrollViewer
_scrollerPropertySet = ElementCompositionPreview.GetScrollViewerManipulationPropertySet(MyScrollViewer);
_compositor = _scrollerPropertySet.Compositor;
// Create a PropertySet that has values to be referenced in the ExpressionAnimations below
_props = _compositor.CreatePropertySet();
_props.InsertScalar("progress", 0);
_props.InsertScalar("clampSize", 150);
_props.InsertScalar("scaleFactor", 0.7f);
// Get references to our property sets for use with ExpressionNodes
var scrollingProperties = _scrollerPropertySet.GetSpecializedReference<ManipulationPropertySetReferenceNode>();
var props = _props.GetReference();
var progressNode = props.GetScalarProperty("progress");
var clampSizeNode = props.GetScalarProperty("clampSize");
var scaleFactorNode = props.GetScalarProperty("scaleFactor");
// Create a blur effect to be animated based on scroll position
var blurEffect = new GaussianBlurEffect()
{
Name = "blur",
BlurAmount = 0.0f,
BorderMode = EffectBorderMode.Hard,
Optimization = EffectOptimization.Balanced,
Source = new CompositionEffectSourceParameter("source")
};
var blurBrush = _compositor.CreateEffectFactory(
blurEffect,
new[] { "blur.BlurAmount" })
.CreateBrush();
blurBrush.SetSourceParameter("source", _compositor.CreateBackdropBrush());
// Create a Visual for applying the blur effect
_blurredBackgroundImageVisual = _compositor.CreateSpriteVisual();
_blurredBackgroundImageVisual.Brush = blurBrush;
_blurredBackgroundImageVisual.Size = new Vector2((float)Header.ActualWidth, (float)Header.ActualHeight);
// Insert the blur visual at the right point in the Visual Tree
ElementCompositionPreview.SetElementChildVisual(Header, _blurredBackgroundImageVisual);
// Create and start an ExpressionAnimation to track scroll progress over the desired distance
ExpressionNode progressAnimation = EF.Clamp(-scrollingProperties.Translation.Y / clampSizeNode, 0, 1);
_props.StartAnimation("progress", progressAnimation);
// Create and start an ExpressionAnimation to animate blur radius between 0 and 15 based on progress
ExpressionNode blurAnimation = EF.Lerp(0, 15, progressNode);
_blurredBackgroundImageVisual.Brush.Properties.StartAnimation("blur.BlurAmount", blurAnimation);
// Get the backing visual for the header so that its properties can be animated
Visual headerVisual = ElementCompositionPreview.GetElementVisual(Header);
// Create and start an ExpressionAnimation to clamp the header's offset to keep it onscreen
ExpressionNode headerTranslationAnimation = EF.Conditional(progressNode < 1, 0, -scrollingProperties.Translation.Y - clampSizeNode);
headerVisual.StartAnimation("Offset.Y", headerTranslationAnimation);
// Create and start an ExpressionAnimation to scale the header during overpan
ExpressionNode headerScaleAnimation = EF.Lerp(1, 1.25f, EF.Clamp(scrollingProperties.Translation.Y / 50, 0, 1));
headerVisual.StartAnimation("Scale.X", headerScaleAnimation);
headerVisual.StartAnimation("Scale.Y", headerScaleAnimation);
//Set the header's CenterPoint to ensure the overpan scale looks as desired
headerVisual.CenterPoint = new Vector3((float)(Header.ActualWidth / 2), (float)Header.ActualHeight, 0);
// Get the backing visual for the photo in the header so that its properties can be animated
Visual photoVisual = ElementCompositionPreview.GetElementVisual(MainFlipView);
// Create and start an ExpressionAnimation to opacity fade out the image behind the header
ExpressionNode imageOpacityAnimation = 1 - progressNode;
photoVisual.StartAnimation("opacity", imageOpacityAnimation);
// Get the front visual for the photo in the header so that its properties can be animated
Visual frontVisual = ElementCompositionPreview.GetElementVisual(FrontGrid);
// Create and start an ExpressionAnimation to opacity fade out the image behind the header
ExpressionNode imageOpacityAnimation2 = 0 + progressNode;
frontVisual.StartAnimation("opacity", imageOpacityAnimation2);
}
Note the behavior I actually want is that when I scroll down then FlipView should fade out and when I scroll up to the top it should fade in, which is working perfectly, but along with it I want FrontGrid to be exactly opposite, i.e: fade in on scroll down and fade out on scroll up.
Thanks in advance

Your expression looks OK.
Note the Opacity you are animating with Composition is the Opacity of Visual. However, the Opacity of 0.5 you are setting on FrontGrid XAML is from UIElement. Doing so will break the Composition opacity expression animation.
The fix is simple - Try getting the Visual of your FrontGrid right after InitializeComponent and set its Opacity to 0.5 there (i.e. frontVisual.Opacity = 0.5) instead of setting it in XAML.
You will see this kind of "weird" behaviors starting from the Anniversary Update, due to a XAML-Composition Interop Behavior change.
For a full explanation, please read this official document.
In short, XAML doesn't know if Composition has changed the Opacity, it still thinks it should be 0.5 as it was last set. So it will try to override and cause the animation to fail. This happens to a few more properties like Offset and Size too.
My advice is if you go Composition, try going Composition all the way. :)

Redrawing and custom shaped windows question

I'm using C#2.0 and I want to create a facebook style tooltip window. I currently made it with 2 windows and transparent key. One for the triangle arrow pointer and one for the square. The whole picture looks like that:
I have problem with the redrawing (as shown in the picture).
Is there a way to use whole shaped window on that? (While I need to make it sizeable)
If no, is this the proper way to make that? Or I need to 'glue' the triangle to the rectangle

Two ways to solve --
Using transparency: Irregular shaped Windows Form (C#)
Or using Control.Region which is the actual shaping of the window. Plenty of samples or:
How do I make a genuinely transparent Control?
protected override void OnSizeChanged(EventArgs e)
{
base.OnSizeChanged(e);
const int ArrowSize = 25;
Point[] points = new[] {
new Point(ArrowSize, 0),
new Point(this.Width, 0),
new Point(this.Width, this.Height),
new Point(ArrowSize, this.Height),
new Point(ArrowSize, ArrowSize),
new Point(0, ArrowSize/2)
// don't need - autocloses
// ,new Point(ArrowSize, 0)
};
GraphicsPath path = new GraphicsPath();
path.AddLines(points);
this.Region = new Region(path);
}

Merging Shapes and Attaching Partial Drag/Drop in WPF

I would like to draw two shapes in WPF and merge them together. Then, I'd like to attach a drag/drop event to ONE of the original shapes.
So basically, you can only drag if you click on a certain part of the shape, but it will drag the entire shape with you.
Here is some code:
// Set up some basic properties for the two ellipses
Point centerPoint = new Point(100, 100);
SolidColorBrush ellipseColor_1 = new SolidColorBrush(Color.FromArgb(255, 0, 0, 255));
double width_1 = 10; double height_1 = 10;
SolidColorBrush ellipseColor_2 = new SolidColorBrush(Color.FromArgb(50, 255, 0, 0));
double width_2 = 200; double height_2 = 200;
// Create the first ellipse: A small blue dot
// Then position it in the correct location (centerPoint)
Ellipse ellipse_1 = new Ellipse() { Fill = ellipseColor_1, Width = width_1, Height = height_1 };
ellipse_1.RenderTransform = new TranslateTransform(point.X - width_1 / 2, point.Y - height_1 / 2);
// Create the second ellipse: A large red, semi-transparent circle
// Then position it in the correct location (centerPoint)
Ellipse ellipse_2 = new Ellipse() { Fill = ellipseColor_2, Width = width_2, Height = height_2 };
ellipse_2.RenderTransform = new TranslateTransform(point.X - width_2 / 2, point.Y - height_2 / 2);
// ???
// How should I merge these?
// ???
// Now apply drag drop behavior to ONLY ellipse_1
MouseDragElementBehavior dragBehavior = new MouseDragElementBehavior();
dragBehavior.Attach(ellipse_1); // This may change depending on the above
// ...
// Add new element to canvas
This code creates two circles (a big one and a small one). I would like to only be able to drag if the small one is clicked, but I'd like to have them attached so they'll move together without having to manually add code that will take care of this.

If you put them both in a Grid (or Canvas, StackPanel, etc.), and set the drag behavior on the panel, they will be "merged". If you set IsHitTestVisible to false on ellipse_2, it won't respond to any mouse events, so effectively it won't be draggable.