D2D 的一些 note – Artificial Intelligence Swift Note

我猜想 D2D 只是 MS 搞的一套对 D3D的封装，可以把D3D 和 GDI，GDI+ 更好的集成，

主要还是用GPU来做 GUI。

带着这个疑问，我开始查找：

首先看 MSDN 怎么说？

关键词：

Windows Imaging Component (WIC)

IE9 用的是 D2D

Purpose

Direct2D is a hardware-accelerated, immediate-mode, 2-D graphics API that provides high performance and high-quality rendering for 2-D geometry, bitmaps, and text. The Direct2D API is designed to interoperate well with GDI, GDI+, and Direct3D.

硬件加速，高性能，高质量，2D的几何，可以集成GDI，GDI+，D3D，看来不是对D3D的封装。

因为从sample 来看，它不需要安装DX SDK.

MS还是很伟大的，最近几年的开发doc 写的很good。

http://msdn.microsoft.com/en-us/library/windows/desktop/dd370990(v=VS.85).aspx

Developer audience

Direct2D is designed primarily for use by the following classes of developers:

Developers of large, enterprise-scale, native applications.
Developers who create control toolkits and libraries for consumption by downstream developers.
Developers who require server-side rendering of 2-D graphics.
Developers who use Direct3D graphics and need simple, high-performance 2-D and text rendering for menus, user-interface (UI) elements, and Heads-up Displays (HUDs).

就是为了解决在 3D 的应用中 UI的性能问题。

来看看它需要的最小运行时库：

Run-time requirements

Windows 7 or Windows Vista with Service Pack 2 (SP2) and Platform Update for Windows Vista
Windows Server 2008 R2 or Windows Server 2008 with Service Pack 2 (SP2) and Platform Update for Windows Server 2008

最后我找到了开发 D2D 的tech lead 的blog：

http://blogs.technet.com/b/thomasolsen/archive/2008/10/29/introducing-the-microsoft-direct2d-api.aspx

Direct2D (or D2D) is a native immediate-mode 2D graphics rendering API that is built on top of Direct3D, and offers some compelling performance and visual quality improvements over GDI and GDI+:

· Hardware-acceleration

· Software fallback when hardware isn’t available

· Interoperability with GDI, GDI+, and Direct3D

· ClearType text rendering

· Per primitive antialiasing

· Device-independent coordinate system

· Draw and fill commands for geometries (lines, curves) and bitmaps

· Solid color, linear, radial, and bitmap brushes.

· Rendering to intermediate layers

· Rich geometry operations (eg. unions, intersections, widening, outlining, etc)

· Server-side rendering

· Preservation of rendering state

所以证明我的猜想是正确的。不过人家 2008年就做了。

作者还解释了为什么要开发 D2D，以及 D2D 的名称来源：

So, we embarked on building the new API, which went through several geeky name changes, until it emerged from the primordial acronym-soup as Direct2D. This isn’t surprising, given that my team is part of the same group that produces Direct3D. It was a natural fit.

Software Fallback – Should automatically fall back to software when hardware isn’t available (eg. session 0, server rendering scenarios).

关键还可以向后兼容，如果硬件不支持的，可以fallback to software。

还有最好的一点是：

Device-Independent Coordinate System – Should allow applications to be written that automatically handle DPI changes and differences.

· Rich Geometry – Should provide a rich set of functions for both defining geometries and performing common geometric operations (eg. combining, intersecting)

设备无关的坐标系统，这一点真的非常重要，从我多年的开发经验来看。

More Direct2D Blogs

Tom Mulcahy — Tom is a Software Design Engineer on the Direct2D team, and owns a good swathe of infrastructure (bitmaps and texture management, WIC interop, clipping, etc). Prior to Direct2D, Tom worked on WPF and is widely regarded as our resident video guru.
http://blogs.msdn.com/tmulcahy/default.aspx

Mark Lawrence — Mark is a Senior Software Design Engineer on the Direct2D team, and driving force behind the design and philosophy of the Direct2D API. He brings a ton of experience from his previous work on WPF, Windows Print architecture, and private industry.
http://blogs.technet.com/MarkLawrence/

Ben Constable — Ben is a Senior Software Design Engineer on the Direct2D team, and implemented all of the Direct3D and GDI Interop functionality within Direct2D. He is a self-described “graphics nerd” who brings considerable experience in 2D and 3D rendering to the team, and has contributed to numerous Microsoft products (Visual Studio, Windows, Office, SQL, etc).

http://blogs.msdn.com/bencon/

最终说一点：万变不离其宗：

Or should we regard Direct2D as WPF re-surfacing in the unmanaged world?

Direct2D and WPF are targeted at different customers. Direct2D is a lightweight native code API which uses an immediate-mode calling pattern (like Direct3D), and will be used primarily by native C/C++ developers. WPF is a managed code framework which uses a retained-mode calling pattern, and will be used primarily by .NET developers.

习惯C++ 的可以选择 D2D 来作WPF 的效果。呵呵。

几个重要的问题：

“Server-side rendering” Does this mean support for RDP?

This is a two-part answer. Direct2D is built on top of Direct3D 10.1 and, since D3D10.1 provides both bitmap- and primitive-level remoting via RDP, it does mean support for RDP.

And, what will it take for broad adoption? Unfortunately, there seems to be a dearth of WPF apps.

Developers should use whatever tool is appropriate for their needs. If you’re writing native C/C++ code, and you need to do high-quality 2D rendering with hardware acceleration on Win7, you should use Direct2D. If you’re using managed .NET code, you should use WPF. The technologies are not in competition.

你熟悉啥，就用啥，技术无法比。

– Related to the previous question: What version(s) of D3D does this run on? Will it be backwards compatible?

It runs on Direct3D 10.1, which includes so-called 10Level9 functionality — which allows you to run D3D10.1 apps on a D3D9 driver.

需要 10.1 但可以跑在 D3D9

还可以制作 video playback，就是因为是建立在 D3D 上的。

does D3D10 GPU run as D3D10Level9 device for D3D10.1?

No, D3D10Level9 is only used in conjunction with a D3D9 driver.

http://channel9.msdn.com/blogs/pdc2008/pc03 channel19 的video PDC 2008

Can Direct2D ‘help out’ in WPF? I mean, my experience with WPF is its quite slow in terms of rendering compared to GDI/GDI+. Maybe you guys can build an additional layer that can make WPF render using Direct2D

WPF can interop with Direct3D9. Read these articles for more details.

http://msdn.microsoft.com/en-us/library/system.windows.interop.d3dimage.aspx

http://msdn.microsoft.com/en-us/library/cc656910.aspx

http://msdn.microsoft.com/en-us/library/cc656710.aspx

涉及 WPF 与 Win32 interoperability 。

http://msdn.microsoft.com/en-us/library/ms742522.aspx

D2D animation ： http://blogs.msdn.com/b/directx/archive/2009/12/12/animated-2d-graphics-for-ui-games-and-demos.aspx