I have some problems with zooming wpf canvas control. I zoom canvas using ScaleTransform operation which is provieded by WPF. The problem is that canvas location is changing during zooming. Is there any efficient (and simple) way to keep the scroll position intact during zooming operation ?? I konow I could set a scroll position myself every time but it will be unefficient
How about using LayoutTransform instead of RenderTransform? You didn't mention which one you were using, but because LayoutTransform is not changing the position i guess you used the later.
I think you are looking for something that maintains scroll position while zooming, have a look at > http://www.codeproject.com/KB/docview/WpfZoomAndDragPanel.aspx
You need to set the CenterX and CenterY of the ScaleTransform. That is what controls what's in the middle of the display and it's how you can keep your zoom centered.
Related
I have a WPF scrollViewer that I use for panning (MouseDown, MouseMove, MouseUp) and I would like to include an acceleration effect that incorporates inertia. So, if the mouse moves beyond a threshold speed and I release the mouse, it continues to pan but slows down as a function of the initial speed. Any ideas, thoughts or examples?
I've done basically this before and started by looking at ScrollViewer but in the end threw it away and used a Viewbox with a Canvas as the child for absolute positioning of content (I was supporting zoom aswel as scroll, it was basically DeepZoom without the scaled images for zooming so there was pixelation when zoomed right in). I wrote code for determining the gesture direction and the speed of the gesture from the mouse events and converted this to a scroll direction and speed and then animated the Canvas.Left and Canvas.Top properties of the scrollable content (which was in the Children collection of the Viewbox's child Canvas) with DoubleAnimation. It worked well, however there may be a better way...heres a thread suggesting hosting DeepZoom in WPF via a Frame control (although I wouldn't do it that way).
EDIT: Basically the ScrollViewer was just too restricting. Even if you get into the ControlTemplate and get references to the ScrollBars directly, it is the position of the Thumb of these scrollbars that you would need to animate and I'm pretty sure this is what I found I couldn't do (it was almost 3 years ago :)
I have a UserControl which has a quadratic Image as a Child. This Image is at the bottom of the UserControl, and half of it is clipped (e.g. the Control's Height is 400, Image's height is 200 and it is set to y=300).
Now, When I rotate the Image, it is still clipped like the way it was first. Like when rotating around 90 degrees, I suddenly have an Image which is only 100px wide.
It seems like the original clipping which was made because of the bounds of the UserControl, are applied forever.
How do I solve this problem? I hope I explained my problem understandable ;)
How are you rotating the image? If you are rotating using a RenderTransform, then WPF does not re-render what was already displayed on the screen - it simply rotates the pixels.
Instead, rotate the image using a LayoutTransform; this forces WPF to re-render the control given the new area it occupies, which should eliminate the clipping you see.
You can also call InvalidateMeasure() after applying render transform.
I have a StackPanel inside of a ScrollViewer.
I have a slider that does a scale transform on the stackpanel to allow zoom-in and zoom-out functionality. The problem is that when I zoom in, the scrollviewer doesn't treat the content as being 'bigger'.
So, if I scroll in a little and scroll as far right as I can go - it stops me before I get to the end of the content. If I zoom back out to the untransformed level, I see that it's stopping exactly at that point. If I zoom in a lot, I can only see a small fraction of my total content when I scroll all the way over.
I can change the TransformOrigin to control which side loses the most content; but I figure there should be some way for the scrollviewer (or another control?) to take care of it for me.
Are you doing render transform, or layout transform? You should be doing the latter.
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.
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.