Why do I see pixels when zooming WPF application in Windows? - wpf

I have developed a GUI for a random application using WPF. I have a bunch of out of box WPF controls laid on the application window. I haven't customized anything, didn't use bitmaps, etc.
When running my application and zooming using Magnifier application in Windows 7 (Win key + Plus key, the magnified GUI is showing pixels.I am probably wrong, because I can't explain it otherwise, but isn't WPF supposed to provide vector like control rendering?
Thanks for participating in the discussion.
Bonus Reading
Tim Sneath: Magnifier: An Interesting Discovery (archive)
WPF Vector based interface *(screenshot of WPF being vector scaled by Magnifier)
MSDN Blogs: Greg Schechter explains why it longer happens (archive)

Back when Vista first shipped, and when WPF was on version 3.0, zooming with the built-in magnifier would actually do vector-based scaling.
This stopped working when WPF 3.5 service pack 1 shipped. (It worked in 3.5 before sp1.) The reason it worked before then is that the DWM (Desktop Window Manager) - the part of Windows responsible for presenting everything you see on screen - uses MILCORE.DLL to do its rendering. Version 3.0 and 3.5 of WPF also used this same component to render - this meant that all WPF content was native content, so to speak. (In fact, on Windows XP, which doesn't have the DWM, MILCORE.DLL is something that WPF puts on your system for its own benefit. But it's built into Vista and Windows 7.) When WPF was using MILCORE.DLL to render on Vista, any effects applied by the DWM such as scaling would also apply in the way you want to WPF - it really did scale without pixelating.
Unfortunately, this is no longer the case. And the reason is that WPF started adding new rendering features. In 3.5 sp1, the new feature in question was support for custom pixel shaders. To enable that, Microsoft had to release an update to the MIL. (The Media Integration Layer - the bit that does the actual rendering.) However, they weren't really in a position to update MILCORE.DLL, because that's part of Windows - it's how everything you see on screen gets to be on screen. Releasing a new version of MILCORE.DLL effectively means pushing out an update to Windows. The release schedule for Windows is independent of that for .NET, and so the only way the WPF team could reasonably add new features was to ship a new MIL. (In theory they could have done it via Windows Update, but since WPF is now owned by a different division of Microsoft than Windows, that sort of thing doesn't seem to happen in practice.)
As of .NET 3.5 sp1, the MIL is in a different DLL called wpf_gfx_vXXXX.dll where vXXXX is the version number. In .NET 4.0, it's wpf_gfx_v0400.dll.
The upside is that WPF gets to add new rendering features with each new version, without needing Windows itself to be updated. The downside is that WPF's rendering is no longer as tightly integrated with Windows as it was briefly back when Vista shipped. And the upshot is, as you've seen, that magnifying is not as much fun as it used to be.

The magnifier application implements its own zoomed image rendering, so that's why you are seeing pixels. WPF does use vector graphics, but in this situation it's not the WPF application itself that is rendering the zoomed image.
If you use something like Snoop you can see zoomed and scaled WPF vector graphics rendering in action.

I suppose, Windows 7 magnifier takes a snapshot of actual application on-screen UI, and then magnifies it itself (not making a special case for WPF applications). Of course what it can access is just the pixels, not the vector graphics which works behind the scene.

The Windows-7-Magnifier is pixel based, but there is a difference in magnifier mode depending on wether an Aero-theme is active or not.
with Areo theme the zoom is pixelated.
without Areo theme the zoom is smoothed (blurry).
Only with Areo theme other Views (except "Docked") are selectable.

Related

How can I make a stack panel with a transparent background and blur effect in WPF without an image?

I have only found solutions to this question that work with images, but I want to be able to overlook a stack panel with this "effect", for example. I actually want it to look something like the one in Windows, for example, like here:
so that you can see a slight transparency in the background.
This kind of translucent texture is called Acrylic and is a Fluent Design System component on Windows 10.
If you want to bring this kind of brush to your app, I would recommend you to look into using the WinUI library. This is the modern and native user experience (UX) framework for Windows desktop applications going forward.
WinUI 2.x controls be used WPF applications using XAML Islands.
WinUI 3 is the next version of WinUI that includes a full native UI platform that can be used on top of the latest version of .NET and be seen as a replacement for WPF and WinForms GUIs.
There is no native support for Acrylic in WPF.

What renders WinForm controls that are hosted in a WPF application?

From MSDN article I found out that WinForm controls can be hosted in a WPF application using HwndHost.
Also, from other internet resources, I found that WPF is rendered using DirectX and WinForm is rendered using GDI+.
My question is, what renders a WinForm control when the WinForm control is drawn in a WPF application; DirectX, GDI+, or both?
I have very little experience with both technologies and making baby steps.
Thank you
You are incorrect about requiring a HwndHost to display a Windows Forms control in a WPF Application. The article that you were reading is for Win32 Interoperation, not for Windows Forms. To use a Windows Forms control in a WPF Application, you should use the WindowsFormsHost Class.
As for what will render the Windows Forms control, you need to understand something. WPF uses a totally different graphics system to Windows Forms. From the WPF Graphics Rendering Overview page on MSDN:
One of the keys to understanding the role of the Visual object is to understand the difference between immediate mode and retained mode graphics systems. A standard Win32 application based on GDI or GDI+ uses an immediate mode graphics system. This means that the application is responsible for repainting the portion of the client area that is invalidated, due to an action such as a window being resized, or an object changing its visual appearance.
In contrast, WPF uses a retained mode system. This means application objects that have a visual appearance define a set of serialized drawing data. Once the drawing data is defined, the system is responsible thereafter for responding to all repaint requests for rendering the application objects. Even at run time, you can modify or create application objects, and still rely on the system for responding to paint requests. The power in a retained mode graphics system is that drawing information is always persisted in a serialized state by the application, but rendering responsibility left to the system.
Therefore in general, the WPF Rendering system will render the WindowsFormsHost, although you may find that Windows Forms does actually perform some rendering of its own on the Windows Forms control.
You need to understand WPF and Win32 Interoperation, it show how controls are plotted.
On the other hand Technology Regions Overview explains the relationship between Wind32, WPF and DirectX.
Hope it will make you more clear about this..!!!

Difference in display of WPF and Windows Forms applications

Actually, I have started learning WPF. I have few months of experience in developing Windows Forms applications. Though, I am getting the meaning of a WPF application, but still I am not able to differentiate the difference between two, on the basis of their output.
With reference to this Link: Device Independent Pixel (DPI), I have learnt that whenever the operating system render a WPF application it manages its size itself according to its resolution.
So to check this difference, I created two demo applications in both frameworks and changed the resolutions as well.. but I didn't find any satisfactory difference. Which could explain it is a WPF application and this one is a Windows Forms application.
It does not create any scroll bar on maximizing and doesn't make the button big or small on changing the resolution.
I have read somewhere that Visual Studio 2010 has been rewritten in WPF. But in my experimentation I saw that, (on changing the resolution of desktop) it makes text and graphics unreadable/blurry. On re-sizing its window, everything was getting hidden except the menu-bar. And the menu-bar content was shifting its positioning, e.g. far right one menu items were shifting down. Why?
Kindly make me correct & explain a little more bit (this display issue) too.
To answer this question properly I should write a whole chapter, but I keep it short:
There are three major differences between a WPF application and a Windows Forms application: Layout, Render, Presentation
Layout:
WPF layout system provides a greater flexibility in arranging the elements on the fly. It is based on the Element Bounding Box (as opposed to precise pixels in WinForms) and Measure and Arrange mechanics (as opposed to UpdateLayout in WinForms) that automatically and dynamically finds the place for each element without any need for a manual update.
Basically, all elements bounding box are measured first and then are arranged using multiple methods such as Measure, MeasureCore, ArrangeCore, MeasureOverride, etc.
Unlike WinForms, where you have a pixel-perfect size for everything, in WPF you have much more options and complexity such as Width, ActualWidth and DesiredSize (and even Transforms as LayoutTransform) for the same element.
This is why
As you type in a WPF TextBox, its width might increase and push other elements away or even push some elements into a new row (like the menu bar you've observed)
As the size of a control changes, it affects the available space for other elements. So their size and location might change accordingly.
When the window is being re-sized or resolution is changed, it immediately updates the layout and changes the size of elements in order to fill or fit the space. Here you'll find out more about Layouts.
using Margin alone (without using layout capabilities) to arrange elements is not the best idea in WPF. As it's the WinForms mindset which isn't much helpful while developing WPF.
Render:
WPF uses double data type for Layout (as opposed to pixel-perfect WinForms) and therefore you might see the edges blurry sometimes, but it can be avoided with SnapToDevicePixels=true.
WPF is much more efficient in utilizing the GPU to render a GUI. Try a grid of 30x30 TextBoxes in a Windows Forms application and a WPF application. No matter how messy you write the WPF, it never blinks and it still runs much faster than Windows Forms. Even adding a handful of animations, visual effects and styles on them does not hurt your performance like in Windows Forms.
Remark: To avoid a speed decrease and blinking in a Windows Forms application, you should set DoubleBuffer of the form to "true".
You can use any Transform as RenderTransform to easily implement smooth zoom/rotate, or develop custom GPU-based shader effects, and much more in WPF. (I think everyone agrees that doing such things in WinForms is feasible but real pain and you most likely will give up and move to GDI+ or DX if not out of frustration then because of the bad performance.)
And the last and the most important:
Focus on presentation:
When develping WPF Applications you have to stop thinking in Windows Forms: No more UI events, accessing controls by their names and writing logic in code-behind and start to think in WPF: Binding, Commands, Resources, Styles, Templates, Converters, DependencyProperties and their callbacks.
The real power of WPF lies in separation of 'View' and 'Logic', Which can be achieved using the MVVM pattern.
It makes the most visually-complicated problems quite simple and easy to develop and easy to write Unit Tests for.
Once you got the hang of it, you will realize there's no limit in how you can present the data or show off an awesome GUI looks.
If you've planned to switch to WPF, you've made the right decision. Always stick to MVVM and AVOID CODE-BEHIND AT ALL COSTS! (i.e. unless you are doing a pure UI operation: do not write code in .xaml.cs files, do not access x:Name in cs files and avoid UI events.)
Windows Forms (WinForms) and Windows Presentation Foundation (WPF) are two different ways of building the user interface for your application. Windows Forms is the older technology and its controls are found in the System.Windows.Forms namespace. WPF is a newer technology and its controls are found in the System.Windows.Controls namespace.
WPF
Pros:
Powerful styling and skinning structure
Easy to create your own look and feel
Does support Windows Forms
The future technology for developing Windows Vista applications
The ability to reuse existing code
Highly advanced data binding possible
Cons:
Declarative vs. procedural code
Requires .NET Framework 3.0
Compared to Windows Forms, still in development phase
Requires Dx9 compatible video card for advanced graphics
Windows Forms
Pros:
Extensive documentation to be found on the Internet
Plenty of examples
Does support WPF
Cons:
How long will this be supported? (I've read somewhere that Microsoft is just developing WPF now, only maintenance for Windows Forms).
Design your own look and feel in an application is a lot of work.

Does WPF use native Windows contols?

Does it perform drawing by itself, or uses the native UI components provided by Windows in any way?
WPF sort of uses native controls because WPF is the new native way to render controls in Windows - what you consider native is legacy win32, and basically slowly on the way to history.
MS did a lot of optimization in DirectX to allow WPF efficiently to render using the GPU. This is a new "native" interface that is also used to render the Vista upward AERO interface. WPF goes directly to a native layer that then does whatever it can in the GPU - including text rendering.
Now, the reall tricky part in your question is "native UI components provided by windows in ANY MEANS" - well, these low level functions are provided by Windows, so the answer is yes. Primitive drawing operations in a new API were added, but they were added specifically FOR WPF, which is now considered to be sort of the new "native windows presentation layer". MS is slowly moving away from the Win32 API towards WPF for generic presentations (Direct X etc. stays around - WPF is way too generic to be usable for example for high performance first person shooters). As such, given WPF is the new "native components layer", the question gets really tricky to answer ;)
In WPF you can skin all of the controls in whatever way you please by overriding the templates. You absolutely can't do this with win32 controls, so therefore it can't use them.
It uses DirectX 9 to perform all its drawing. It doesn't use WinForms controls

Is there a secret trick to force antialiasing inside Viewport3D in Windows XP?

Under Windows XP WPF true 3D content (which is usually displayed using the Viewport3D control) looks extremely ugly because it is by default not antialiased as the rest of the WPF graphics are. Especially at lower resolution the experience is so bad that it can not be used in production code.
I have managed to force antialiasing on some Nvidia graphics cards using the settings of the driver. Unfortunately, this sometimes yields ugly artifacts and only works with specific cards and driver versions. The official word from Microsoft on this regard is that antialiased 3D is generally not supported under Windows XP and the artifact I see result from the fact that WPF already does its own antialiasing (on XP only for 2D).
So I was wondering if there is maybe some other secret trick that lets me force antialiasing on WPF 3D content under Windows XP.
Have you tried this (from your thread on MSDN forums)?
Well, it seems the reference in the MSDN link above incorrectly specify the affected registry root key. In MSDN it is specified as HKEY_CURRENT_USER, while the correct root key should be HKEY_LOCAL_MACHINE. I've tried setting up the HKEY_LOCAL_MACHINE\Software\Microsoft\Avalon.Graphics\MaxMultiplesampleType to '4' and I can get antialiasing for my WPF Application on XP.
The feeling I get from Matthew MacDonald's Pro WPF Windows Presentation Foundation in .NET 3.0 is that it's not possible:
There's one exception to WPF's software support. Due to poor driver support, WPF only performs antialiasing for 3-D drawings if you're running your application on Windows Vista (and you have a native Windows Vista driver for your video card).
I've never seen anything to suggest that you can enable AA in WPF 3D on anything but Vista, but if there is a way it's new to me and I'd love to know as well!
Does your video card support Shader 2.0? You can refer to this wiki page to see if it does...

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