I have a WPF application with many tabs..
in one tab.. i make a verycomplex vector drawing consisting of thousands of drawing visuals.. (this represents a machine and all elements need to be interactable..)
It takes 3/4 seconds for drawing this for the first time..After the first draw it should be done..
The problem is if i switch to another tab and comeback, it takes atlease 2,3 seconds to show the tabpage with drawing again.. Since there is no redraw, why should it take so much time..?
If the component is not going to change, you could call Freeze() on it to mark it as done. Without trying it out I don't know if that would help, but you could give it a shot.
Not all objects are Freezable. Check out the MSDN documentation for more info:
http://msdn.microsoft.com/en-us/library/ms750509.aspx
Another thing you could try would be rendering the vector art to a bitmap, and displaying that. Maybe it makes you feel icky to lose the vector precision, but if you know it's not going to change and it will look the same, what's the harm? (If you support printing or something that will require a hi-res version, you could always switch back for that operation.) For info on how to convert a UIElement to a bitmap, check out:
http://msdn.microsoft.com/en-us/library/system.windows.media.imaging.rendertargetbitmap.aspx
Another possible solution: You don't really explain what kind of interaction you are doing with the elements, but if all you want to do is zoom and pan, a RenderTransform may be good enough (which is more efficient than a LayoutTransform and/or moving all the elements individually). I haven't played around with combining Freeze() and a RenderTransform, but you may be able to get the desired zooming while reducing the amount of layout WPF has to do.
Related
I made an app that detects objects occupying the smartphone camera and now I want to draw the bounding boxes.
I've seen more than one way to do it and so far I'm planning to use the react-native-canvas library or to create a button in form of a bounding box located in the corresponding coordinates, but I'm wondering what the least resource-intensive solution would be.
This is because object detection already takes up a lot of resources and now I am going to add a function that draws bounding boxes several times per second, so I will surely have to lower the detections per second, but the ideal would be to lower them as little as possible. This is one of those situations where a few fractions of a second will be significant in performance.
I'm pretty new to react native so I need some help finding the optimal solution.
For example plotting buttons without installing an external library and that might work faster, I'm not sure if that makes sense.
Hopefully somebody can point me in the right direction.
Thanks.
I have a set of pages that look like this:
I have the content in grids with * Heights and Widths so the grid correctly scales when the entire window resizes. I would like the text to resize with the grid. Basically I would like the user to resize from this:
To this:
(preserving white space)
One way to do this would be to wrap the TextBlock in a ViewBox with margins on the right and bottom (for Grid.Row="3") to account for white space. But because I have several pages with different lengths and line counts I would have to set the margin specifically for each page otherwise the text sizes would differ on each page. Is there a better way to do this??
I don't think there is a better way to do this. There are different ways. But, I think it isn't just a matter of opinion that they would not be better.
Ways I can think of.
Render your text offscreen, rendertargetbitmap that so you've got a picture. Change your textblocks on screen to images and stretch them.
Or
Work out the size your text wants to be. Then do some calculation comes up with a different fontsize which is "better". This is a lot easier to write a description of than do.
In my opinion.
A viewbox is easier to implement. Way less error prone than calculations. Will give at least as good results as rendering to a picture.
I just want to add one more solution to the ones suggested by Andy, which is more of a scientific approach and takes a bit of practice to master.
Suppose you have to find a function F, which maps one or more variables to a desired single value. In your case that would be a function F, which takes aspect ratio of the window as input and outputs an appropriate font size.
How can you find such a function?
Well... you don't need to do any math yourself!
First, you need some data to begin with:
1. Resize the window randomly
2. Calculate aspect ration (X)
3. Pick an appropriate font size that looks good enough (Y)
4. Repeat the measurement 7 to 10 times (sorry data scientists)
5. Enter the data in Excel - one column for X and another one for Y
6. Insert a scatter chart
7. Choose the best trendline for your data, but avoid the polynomial one
8. Display the trendline equation and use the expression in your code
Now I should mention the pros and cons of this regression technique.
Pros:
1. It can solve a wide range of tricky problems:
"I use this 3rd party control, but when the text is too long it overlaps the title bar. How to trim it so it doesn't go beyond the top border?. Deadline is coming!"
2. Even if it doesn't solve the problem perfectly, the results are often acceptable
3. It takes minutes to try out unlike spending a day refreshing your math skills
Cons:
1. The biggest problem is that to keep it simple, you often lower the number of
variables by assuming some of them to be constant. In this post I've assumed that
the font family won't change for example, neither the font weight.
2. If any of the assumptions does not hold the final result could be even worse
This technique is fragile, but powerful. Use it as your last weapon and never leave magic expression like
fontSize = (int)(0.76 + 1.2 * aspectRation) without documenting how it came to be.
I'm trying to write an CAD-like application in WPF(.NET 4.0) that needs to be able to display a lot of 2D points/lines. It will be used to display CAD-plans of entire cities with zoom, pan, rotate and point snapping on mouseover.
Right now I purely use WPF. I read the objects from the CAD file draw them into a StreamGeometry, use it as stroke of a new Path and add it to a Canvas, with several transforms.
My problem is that this solution doesn't scale well enough. It works fine with small CAD-files, but when I want to display like half a city(with houses and land boundaries) it is very very delayed.
I also tried to convert my CAD-file to an image, but
- a resolution a 32000x32000 is sometimes not enough
- when zooming out the lines are too thin.
In the end I need to be able to place this on a Canvas(2D/3D) as background.
What are my best options here?
Thanks,
Niklas
wpf is not good for a large 3d models. im afraid it is too slow. Your best bet is direct 3d or openGL
However, even with the speed of direct3d,openGL you will still need to work out how to cull as many polygons/vertices as possible before the rendering of the scene if you are trying to show an entire city.
there is a large amount of information on this (generally under game development)
there are a few techniques including frustrum culling, near and far plane culling.
also, since you probably have a static scene you may be able to use binary spacial partitioning.
As I understand the subject is 2D CAD system within WPF.
Great! I use it...
OpenGL and DirectX are in infinite loop OnDraw always. The CPU works all the time.
WPF/Silverlight 2D is smart model.
Yes, total amount of elements (for example, primitives inherited from Shape) must be not so much. But how many?
I tested own app (Silverlight). WPF will be a bit faster I hope...
Here my 2D CAD results. Performance is still great. Each beam consists of multiple primitives.
Use a VirtualCanvas like this one from Chris Lovett.
I've written a simple game-like app in WPF. The number of objects drawn is well within WPF capabilities - something like a few hundred ellipses and lines with simple fills. I have a DispatcherTimer to adjust the positions of the objects from time to time (1/60th of a second).
The code to compute the new positions can be quite intensive when there are lots of objects, and can fully load a processor. Whenever this occurs, WPF starts skipping frames, presumably trying to compensate for the "slowness" of my application.
What I would much rather happen is for all the frames to be drawn anyway, only slower. The dropped frames do not add any speed - because visual updates were pretty quick anyway.
Can I somehow force WPF to have my changes to the visuals be reflected on the screen regardless of whether WPF thinks it's a good idea?
Unfortunately I don't think there's anything you can do about this, although I will happily be corrected! WPF is designed to be an application creation framework, not a games library, so it priortises application performance and "usability" over framerate. This actually works very well when producing applications as it allows you to use quite rich animations and effects while maintaining perceived performance on lower end systems.
The only thing I think you might be able to try is push your movement code's Dispatcher priority down slightly to below Render (Loaded is the next one down) using something like:
this.Dispatcher.BeginInvoke(DispatcherPriority.Loaded, MoveMyStuff);
I don't have any kind of test harness to verify if that will help though.
This issue was fixed by using a Canvas with an OnRender override instead of creating and moving UIElements. This does mean that everything needs to be drawn by hand in OnRender, but it can now run at any FPS consistently, without skipping any frames.
I need to write a gauge control in WPF for a project at work. By gauge control, I mean something akin to a traditional car speedometer: a circular face with numbers and ticks around the circumference, and a needle pointing to the current value. Although I could get my employer to purchase a third-party control, or even find a free one somewhere, I’d still like to write it myself, for curiosity’s sake more than anything else.
My first thought was to ‘skin’ an existing control using a template, something like a ProgressBar for example as it has Minimum, Maximum and Value properties. However, I don’t think this will offer me the flexibility that I need.
I’d like to animate the needle that points to the current value, so that when the gauge’s value changes the needle moves from the old value to the new value. I figured the easiest way to do this would be to have some kind of shape or geometry representing the needle, and then apply a RotateTransform of the relevant number of degrees to get the needle to point to the correct value. The animation’s To property would be set to the ‘value degrees’ property via binding.
It seems to me that there are three basic approaches I could take:
Use one custom FrameworkElement to represent the entire gauge
I could derive from FrameworkElement, override its OnRender method, then use the DrawingContext to draw both the gauge face and the needle. This would mean that I could no longer animate the needle directly using a RotateTransform, but would instead have to redraw the entire gauge every time the value changes. This seems inefficient to me, as the gauge face represents the bulk of the drawing code but would change very rarely. However, this approach is the most lightweight in terms of the number of elements used.
Use two custom FrameworkElements, one for the face and one for the needle
I’m currently leaning towards this approach. One element would represent the face, the other the needle. This would allow me to target the needle element with the RotateTransform. The gauge control would then consist of three elements: the face, the needle, and a Panel container to hold both of them (ie. Canvas, Grid, whatever). So three elements instead of one, hence not as lightweight as the first approach.
Use DrawingVisuals to draw the face and needle
I’ve also read about the DrawingVisual class, but I’m a bit confused as to why anyone would use this as opposed to deriving from FrameworkElement and overriding OnRender, given that DrawingVisual must be hosted in a custom FrameworkElement anyway. It would seem that this approach doesn’t offer any advantages over the second approach, and would require more code, but maybe I’m missing something.
Any thoughts or advice regarding which approach people think is best and why would be most welcome!
Personally I'd recommend making a CustomControl using the second approach. Unless you are going to be showing more than 1000 of the gauges in view at the same time you aren't going to notice the extra element in your visual tree and I think you'll find it's much easier to make and maintain.
You could just style a slider control and feed values into it. You should be able to make a slider look like any kind of gauge you need.