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Direct X and WPF integration

THis might be a very vague questions and apologies if posted in the wrong forum.
But I am starting out on a project involving C# and WPF. This project requires some really serious heavy graphics, want the final result to be as smooth as an iPad graphics. So, now my question is, is WPF upto the task? if not can I do something about it? Hardware boost? or if not is there anyway to leverage on Direct X? or third party libraries?

As everything reagarding to 2D graphics in WPF is based on DirectX calls, you will probably not find any faster way except using DirectX directly.
To my understanding everything regarding graphics on an IPad/IPhone seems faster compared to other devices is based on the fact that the rendering on those devices is done in a dedicated thread.
As long as you are not going to use Windows Forms (where everything is rendered using the CPU) you should be fine ;-)

Which one has a faster runtime performance: WPF or Winforms?

I know WPF is more complex an flexible so could be thought to do more calculations. But since the rendering is done on the GPU, wouldn't it be faster than Winforms for the same application (functionally and visually)?
I mean when you are not running any games or heavy 3d rendering, the GPU isn't doing heavy work, right? Whereas the CPU is always busy.
Is this a valid assumption or is the GPU utilization of WPF a very minor operation in its pipeline?
EDIT: The application that I am interested is a 3d modeling and animation software, where you have 3d viewports to navigate and edit the scene, and objects inside the scene. But I want to use WPF because of its modern architecture, and it's from scratch.
EDIT2: Also for my purposes I will use DirectX hands down for the app itself because of the high end requirements of the software. As for people using lower end or computers without a dedicated GPU, that's OK since they aren't not in my primary customer area. Just like other high end 3d software for film and games, it will be understandable to require a powerful computer to fully benefit from the application.

Provided the machine has a GPU, you'll get better rendering performance in WPF.
We have a large desktop application that we wrote in WinForms, and are now porting to WPF. We've witnessed much better rendering performance, particularly when resizing windows or redrawing controls.
We've also found that WPF "controls" are more lightweight than WinForm controls. If I recall right, WPF controls do not necessarily require an operating system handle, and don't register for Windows window messages via WndProc, at least not independently.
For your case, since you're building a 3d modeling app, which kind of assumes some 3d hardware on the machine, you should absolutely use WPF over WinForms.

For the app scenario you describe, I would expect WPF to outperform WinForms for 3D work on a full featured GPU by a wide margin.
The difference between the application types is more than just the rendering the 3D vector pipeline. WPF's internal architecture is radically different than WinForms, specifically designed to overcome the caveats learned from years of prior experience with the Windows GDI and WinForms apps.
(WinForms is a relatively thin wrapper around Windows GDI and User model that was originally created in the late 1980's. The Windows User control model has evolved over the past 25 years, but the core architectural patterns are largely unchanged.)
For example, WPF always separates UI rendering from application logic. When the WPF window goes to draw something, the actual rendering happens on a background thread. The refreshed visuals are flipped to the display during the video retrace interval, so you don't get partial blits or "tearing" artifacts on screen.
WinForms does none of this. If you render to DirectX or OpenGL surfaces in a WinForms app, you have to do the work of flipping the video page and making sure it happens at the right time to avoid screen tearing artifacts.
Wpf's default controls are GPU aware and can be custom styled with glows and transparency and whatnot all GPU accelerated. WinForms controls do not benefit significantly from GPU features, since about the only things WinForms (Windows User controls) uses for rendering are 2D bitblit and rectangle fill. Glows, transparency, animations are all possible with WinForms, but you have to do all the work to implement them.
In WPF, UI slickness is mostly a matter of designing and styling to get WPF to do it for you. In WinForms, you have to push the pixels yourself.

This is a really tough question to answer.
A huge portion of WPF performance is your GPU. A good GPU works wonders for making WPF perform well. WPF can be very performant. If your requirements are to have a decent GPU, since it's a 3D modeling program, you'll probably find WPF performance to be as good or better than Windows Forms - though this really depends on what you're using.
That being said, it's usually difficult to compare - mostly because WPF allows you to add a lot of visual effects that people tend to never even attempt in Windows Forms. Many WPF applications "seem" faster even though they're actually slower in some instances because of extra visual clues.
That being said, if you have a LOT of controls, WPF can actually outperform Windows Forms by a fair amount. In Windows Forms, each control requires a separate window handle, and receives its own message sets. With a lot of controls, this can actually slow things down pretty dramatically.
The real question here should be is WPF perf. "good enough" for your application. If you're doing a 3D modeling application, chances are WPF will not be your bottleneck- it should be fine.

For 3D modeling, WPF is clearly a lot better choice than WinForms -- but it's still a long ways from ideal. Winforms has no (direct) support for 3D rendering at all, and WPF has some. For a program that's aimed primarily toward 3D rendering, however, you might be better off with something dedicated more specifically to 3D rendering tasks, such as OpenGL or Direct3D.
On their own, neither of those provides a huge advantage over WPF, but unless what you're doing is fairly specialized, I wouldn't use those directly though. I'd use something like OpenSceneGraph or Ogre3D, that can use either of those for its rendering, but provides a much higher-level interface and does more to manage rendering your scene.
Either or both of these probably could use WPF for the actual drawing -- but I'm pretty sure neither one does, at least currently. I don't know whether they ever will either -- they might, but I doubt it's a real priority, since they already support OpenGL and Direct3D. For their purposes WPF provides little advantage.

Seeing as WPF actually uses DirectX under the hood and the fact that you use XAML to specify DirectX objects, WPF is by far the easiest solution.
Example coding a camera in xaml:
<PerspectiveCamera x:Key="Camera"
Position="0, 0, 4"
LookDirection="0, 0, -4"
UpDirection="0, 1, 0"
FieldOfView="30"/>

Is WPF the reason my application is slow?

I am developing an application using WPF. The app runs full screen, and I need it to resize nicely no matter the monitor resolution. The graphic designer has designed beautiful images for the UI buttons, backgrounds, etc. Using an Illustrator plug-in, all the images have been converted to xaml files. I've added all these images into the application, and they look great. I am also using a lot of Grid layouts so that the screen can resize while still maintain the layout. All of this is displaying as desired, nothing looks stretched when run at a different resolution. However, screen transitions and UI interaction are slow.
I am wondering, is this is due to the heavy use of graphics? Am I using too many Grid layouts? But, I need the Grids so that I can have resolution independence.
The application runs fine on my development machine, but is very noticeably slower on machine with lower performance capabilities. Yeah, this is to be expected, but not to the degree that I'm seeing. My employer insists the application runs smoothly on these lower performance machines.
I've done some profiling of the application and it seem that what takes the most time is the display stuff (though I'm not sure I fully understand how effectively to use a profiler).
If it is the WPF that is causing the slowdown, what can I do to improve this?

You can drill into which WPF activities are using up time using the Performance Profiling Tools for WPF. Assuming a heavy graphical load is causing the slowdown, this should give you some help as to what might need to be simplified (e.g. layouts) or removed (e.g. bitmap effects (these are a classic perf killer, though I don't want to prejudice your profiling!)).

If it is the WPF that is causing the slowdown
Probably not ;)
It is much more likely that it is your code that causes the slowdown. WPF is powerful, but you have to understand the core concepts to make it work well... You should have a look at this video from a PDC session, it provides lots of advice on how to make your WPF application faster

Convert your XAML Vector Images of buttons into Transparent PNG Images. Path and Shapes are very heavy to render, calculate and resize. Mostly after deployment, the images never change its better to have them as raster then vector, unless you want to perform smooth animation of changing shape, size or other attributes.
Grids are very costly layout managers as compared to Canvas, DockPanel. You can certainly think of replacing certain grids with DockPanel sometimes, but yes its not an easy fix it requires lot of brainstorming.
Avoid Panel with Single Child. Try to reduce Visual Hierarchy.
Use more of fixed size for buttons and such small elements, if you specify fixed sizes of children, it becomes easy for Panels to do layout processing.

In general, WPF is perfoming much worse in drawing performance than Windows Forms, and native GDI or DirectX.
Yes, WPF is powerful in the sense you might make some neat stuff that is not supported in GDI, but it is more sluggish.
If you are having much drawing to do, and you want to support it on slow hardware, then WPF is not a good choice.

WPF performance depends heavily on the quality of the video card in the machine more that the processor/memory. Bad video card = bad WPF performance.

Well, this is a long shot: when I installed VSTS 2010 (and it uses WPF) it was very slow on a Windows 2008 server with enough CPU/memory, and very fast in a more modest notebook. We managed to disable hardware acceleration and it became notably fast into that machine.
Maybe you do want to try this configuration, as it is very simple: Visual Studio 2010 Beta 2 editor performance fix running on a virtual machine

Is it smart building an OpenGL C# application to replace GDI

I have developed a quite large application using MFC. Naturaly, I used GDI for drawing, CCmdTarget for event routing, and the document-view architecture.
It was a convenient development path.
Now, the client is interested in converting this application to .Net.
I would prefer (and they too) writing the new product in C#.
The application displays and interacts with thousands of graphic objects, so
I figured going with GDI+, although seems natuaral, can cause performance issues,
So I am thinking of using OpenGL, specifically - OpenTK - as the graphics library (it's 2D).
I know that OpenGL works differently that these Windows APIs, which rely on Invalidation of portion of the screen. OpenGL has a rendering loop which constantly draws to the screen.
My question is:
Is this an acceptable way to go, thinking of:
performance - will the users need special graphics cards (hardware?). It is graphics intensive, but it's not a high-end game
printing and print preview - are these things complex to achienve?
multiple selection and context menus
Is this library goes well inside windows forms?

I don't think so. Use WPF if you can or DirectX if you can't.
I know it might not be fair but if I'm programming on .NET (microsoft) on windows (microsoft) I'd rather use DirectX ... which is also from microsoft.
As a side note: don't reinvent the wheel. Recoding user controls in open-gl can be very time consuming, if you do make sure you have a good reason.

In my experience developing CAD-like software, the benefits of OpenGL and DirectX are fast depth testing, smooth rotation and panning, lighting and powerful texture capabilities. Obviously there are other benefits but, despite what most tutorials would lead you to believe, implementing a rendering system using either of these APIs is a significant undertaking and should not be taken lightly.
Specifically:
If it is a 2D app and you already have it implemented in GDI then switching to GDI+ will be much easier. Additionally, on modern hardware, 2D GDI or GDI+ can be about as fast as 2D OpenGL or DirectX. And ultimately, the end-user probably won't notice the difference, especially with double buffered support in GDI+.
You do not need (and probably don't want) a continuous rendering loop for your app. In OpenGL and DirectX you can explicitly invalidate the window when your scene changes.
If you go with OpenGL or DirectX you will need to consider putting your objects into display lists or vertex arrays (buffers) for fast drawing. This is not difficult but managing objects in this way adds complexity to the system and will most likely significantly change the architecture of your rendering system.
Printing in either OpenGL or DirectX can also be tedious. On the one hand you can render to a bitmap and print that out. However, for high quality images you may want vectorized images instead, which are difficult to produce with either of these rendering frameworks.
I would also stay away from writing GUIs in OpenGL or DirectX...unless you're really looking for a challenge ;~)
Finally, and this is just an annoyance from an install perspective, the Managed DirectX run-time library that must be installed on the user's machine is around 100 MB.

I have no experience with C#, but I have once built a layer system for a drawing program that used openGL for rendering.
To make this layer I asked openGL for the current framebuffer and converted it to an image to use as a texture under the current canvas. So I guess from there its pretty easy to go to printing and print preview.

Direct X and Open GL much faster than GDI+.

You can also use an TAO framework as an alternative to OpenTK.

Rendering graphics in C#

Is there another way to render graphics in C# beyond GDI+ and XNA?
(For the development of a tile map editor.)

SDL.NET is the solution I've come to love. If you need 3D on top of it, you can use Tao.OpenGL to render inside it. It's fast, industry standard (SDL, that is), and cross-platform.

Yes, I have written a Windows Forms control that wraps DirectX 9.0 and provides direct pixel level manipulation of the video surface.
I actually wrote another post on Stack Overflow asking if there are other better approaches: Unsafe C# and pointers for 2D rendering, good or bad?
While it is relatively high performance, it requires the unsafe compiler option as it uses pointers to access the memory efficiently. Hence the reason for this earlier post.
This is a high level of the required steps:
Download the DirectX SDK.
Create a new C# Windows Forms project and reference the installed
Microsoft DirectX assembly.
Initialize a new DirectX Device object with Presentation Parameters
(windowed, back buffering, etc.) you require.
Create the Device, taking care to record the surface "Pitch" and
current display mode (bits per pixel).
When you need to display something, Lock the backbuffer
surface and store the returned pointer to the start of surface
memory.
Use pointer arithmetic, calculate the actual pixel position in the
data based on the surface pitch,
bits per pixel and the actual x/y pixel coordinate.
In my case for simplicity I am sticking to 32 bpp, meaning setting a pixel is as simple as: *(surfacePointer + (y * pitch + x))=Color.FromARGB(255,0,0);
When finished drawing, Unlock the back buffer surface. Present the surface.
Repeat from step 5 as required.
Be aware that taking this approach you need to be very careful about checking the current display mode (pitch and bits per pxiel) of the target surface. Also you will need to have a strategy in place to deal with window resizing or changes of screen format while your program is running.

Managed DirectX (Microsoft.DirectX namespace) for faster 3D graphics. It's a solid .NET wrapper over DirectX API, which comes with a bit of performance hit for creating .NET objects and marshalling. Unless you are writing a full featured modern 3D engine, it will work fine.
Window Presentation Foundation (WPF) (Windows.Media namespace) - best choice for 2D graphics. Also has limited 3D abilities. Aimed to replace Windows Forms with vector, hardware accelerated resolution-independent framework. Very convenient, supports several flavours of custom controls, resources, data binding, events and commands... also has a few WTFs. Speed is usually faster than GDI and slower than DirectX, and depends greatly on how you do things (seen something to work 60 times faster after rewriting in a sensible way). We had a success implementing 3 1280x1024 screens full of real-time indicators, graphs and plots on a single (and not the best) PC.

You could try looking into WPF, using Visual Studio and/or Expression Blend. I'm not sure how sophisticated you're trying to get, but it should be able to handle a simple editor. Check out this MSDN Article for more info.

You might look into the Cairo graphics library. The Mono project has bindings for C#.

Cairo is an option. I'm currently rewriting my mapping software using both GDI+ and Cairo. It has a tile map generator, among other features.