I currently have an Adorner inside a ScrollViewer. Objects at the bottom of the scrollviewer can sometimes display a large adorner below them. Unfortunately, that adorner is not included in the ExtentHeight of the scrollviewer, so the lower portion of the adorner is clipped by the bottom of the scrollviewer's viewport.
Is there a way to get the adorner layer's contents to be included in the scrollable region of the scrollviewer?
I'm afraid the consensus from other sources and hours of investigation seems to be that what I mentioned simply isn't possible. My solution has been simply to detect the last item in my ListBox and automatically add a margin to its bottom when my Adorner is being displayed. It's a bit of a hack, but it achieves the desired behavior mentioned above.
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I am trying to do something a little bit specific, and I can't seem to find if it is even possible. So I thought I would lay down the question here.
What I'm looking for is a way to change the anchor point of the scrollviewer from the top to the bottom (however you look at it). I'll explain what I mean.
By default when the control contained in your scrollviewer gets taller, so will your vertical scrollbar scollableheight.
But what happens is, the vertical scrollbar will stay at the same scrolloffset from the top, while what I want is that the vertical scrollbar keeps it's position relative to the bottom. The reason I want this behaviour is because I am creating a list that the user can expand more of by scrolling to the top. but then when I add the new items it looks like the scrollviewer scrolls up to the newly added items. (although it is actually the content the is pushed down) So if the scrollviewer would have the vertical scrollbar anchored to the bottom, the visible part of the content would stays at the same position to the user because the distance from that part to the bottom didn't change.
I hope you can understand what I'm trying to do.
I allready found one way of doing this, but it is not the desired option to me.
Option 1) Apply a Scaletransform of -1 in the Y-axis to the scrollviewer to flip it upside down. Then apply another ScaleTransform of -1 in the Y-axis to the content of the scrollviewer to make the content right side up.
But the problem with this technique is that for one, when you scroll using your mousewheel the scrollviewer scrolls inverted as normal. And second, I'm using 2 scaletransformations just to change the behaviour of the scrollviewer, and not even for eye candy. So that seems a bit excessive to me.
Option 2) anyone?
I have the following UI element hierarchy: UserControl>ScrollViewer>Canvas. I am drawing lots of stuff on the canvas, and it becomes larger than the UserControl, at which point the ScrollViewer displays the scrollbars. So far, so good. Now I apply a ScaleTransform to the Canvas (say, 2.0, making everything twice as large). However, my scrollbars to not adjust, so I can now only scroll half-way across my enlarged canvas. How do I get my ScrollViewer scrollbars to adjust when I apply a scaletransform to the canvas being displayed within the ScrollViewer?
Your problem is that the ScaleTransform is a RenderTransform and not a LayoutTransform. The size it reports to the ScrollViewer is the same size regardless of what the scale is.
One solution I've used in the past to get around this is to nest the Canvas in another Canvas. You can then in code change the size of the outer Canvas to reflect the actual dimensions of the inner Canvas. The ScrollViewer will then update to reflect the correct dimensions. You don't actually change the size of the inner Canvas, you just change the scale.
This answer should answer your question:
XAML: make a ScrollViewer show scrollbars when the ScaleTransform of a child object gets big
I am building a control, where the user can "draw" resizable rectangles that are laid over the content. To resize those rectangles, I use an Adorner on top of them which contains 4 Thumbs to change the size of the rectangle.
The problem is, that this control is is "zoomable", meaning a ScaleTransform is applied to the whole control depending on a zoom factor. The Thumbs in the Adorner are affected by this ScaleTransform as well.
But I need them to keep their size, independent of the zoom factor.
I tried putting the Adorners in a Layer of another non-transformed control instead of the rectangle-layer, but this didn't work.
How can I achieve this?
Thanks,
Andrej
Have you checked this post: Transformations on AdornedElement are also applied to Adorner?! ? Does it work?
I also find this question on MSDN: How to exclude scaleTransform from GeneralTransform in Adorner GetDesiredTransform method., this is good because also there is some example code.
I have an ItemsControl in a ScrollViewer. The items in the ItemsControl are expanded to a DataTemplate which basically consists of an Adorner.
Now the problem is, when scrolling, the Visual Children of the Adorner are visible outside the ScrollViewer. Lets say I scroll from the Horizontal Offset 0 to 100, the Visual Children of the Adorner move to the left and are visible next to the ScrollViewer, although they should be hidden. Setting ClipToBounds on the ItemsControl or the ScrollViewer does not work.
I understand, that Adorner are rendered above all elements z-order wise, but they really shouldn't be visible in such cases as with the ScrollViewer. The adorned Element by the way behaves like expected and is not visible through the ScrollViewer.
Is there any easy way to "clip" the Adorners, so that they are only visible in the visible scroll area?
Thanks,
Andrej
Setting ClipToBounds on the containing control is not enough. You must set the adorner's IsClipEnabled property too.
I've encountered the same problem when subclassing the WPFToolkit DataGrid to draw an adorner around the current cell.
The content of the ScrollViewer is rendered by a ScrollContentPresenter instance. ScrollContentPresenter has its own adorner layer, which is accessible through the ScrollContentPresenter.AdornerLayer property.
I found that my adorner correctly clips if I add it to that layer.
My solution was to push a clip region onto the drawing context, render whatever I needed, and pop the clipping at the end, like this:
drawingContext.PushClip(new RectangleGeometry(new Rect(0, 0, this.AdornedElement.RenderSize.Width, this.AdornedElement.RenderSize.Height)));
// continue drawing
drawingContext.Pop();
You can plug this in into any Adorner, the bounds are already available as part of the element.
Been checking the web and this site, but couldn't come up with any descent results.
Is there a way to make a canvas in WPF show scrollbars on overflow ? Been trying the scrollviewer, but can't get it to work :(
Thanks in advance..
The problem you're running into is that Canvas, unlike many WPF panels and containers, does not size to contents. That means if you add an element which goes outside the canvas boundaries it will not update it's size. Hence embedding a Canvas in a ScrollViewer will do no good unless you manually update the size of the Canvas.
It sounds like what you want is a Canvas which supports size to contents. This blog entry has exactly that control.
http://themechanicalbride.blogspot.com/2008/11/auto-sizing-canvas-for-silverlight-and.html
I took a different approach and abandoned the Canvas for Grid. The Canvas is more performant but for my purposes at least I haven't noticed a difference. The grid can mimic the behavior of canvas by doing the following.
Create a single row,single column grid.
Set the HorizontalAlignment to Left
Set the VerticalAlignment to Top
Use Margin "x,y,0,0" to set the position.
Bam..works just like canvas and it works great in a Scrollviewer.