CWT ― 可支援不同繪圖函式庫的AWT實作

Abstract

抽象視窗工具組(Abstract Window Toolkit，以下簡稱AWT)是一套在Java中專門負責開發圖形使用者介面(GUI)的API。基本上，AWT可以分為兩個部分，使用者介面工具組(UI Toolkit)與繪圖工具組(Graphics Toolkit)。繪圖工具組這個部分，包含基本的影像處理與繪圖功能，也是影響Java繪圖效能最關鍵的部分。與繪圖加速卡有著密切關係的繪圖函式庫目前有兩大主流，分別為業界開放標準的OpenGL，以及微軟的DirectX。Java的繪圖效能不彰，主要來自虛擬機器(Virtual Machine)本身的瓶頸。如何突破這個瓶頸，獲得硬體加速的直接支援，繪圖函式庫的支援將會是關鍵性的因素。

為了能提升Java的繪圖效能，並使許多現有的Java程式可以因此而受惠。本論文提出了一套開放式的架構，稱為CYC Window Toolkit(簡稱CWT)，以AWT為共同的API，並針對繪圖工具組的這個部分作改善，使其可以採用不同繪圖函式庫來實作。並達成以下三項特性：1.提升繪圖效能(Performance Improvement)、2.向下相容性(Backward Compatible)、3.可移植性(Portability)。

Abstract Window Toolkit (AWT) is one of API in Java, which providing programmers to build Graphical User Interface (GUI). Basically, AWT has two parts, UI Toolkit and Graphics Toolkit. Graphics Toolkit includes basic functionalities for drawing and image processing; it’s also the key part to affect Java rendering performance. Graphics library is close coupled with graphics cards. In the present, this graphics library has two main streams, OpenGL and DirectX. OpenGL is open standard in industry. DirectX is proposed by Microsoft. Java’s bad rendering performance is due to the bottleneck of Virtual Machine. How to break through this bottleneck to get hardware-accelerated rendering support, graphics library will be the key role。

In order to improve Java rendering performance and let most existed Java program benefit from this. This thesis proposes an open architecture, called CYC Window Toolkit (CWT), which lets AWT API be the common interface and makes the Graphics Toolkit of AWT supported different implementations over different graphics libraries。And finally have this three features：1. Performance Improvement, 2. Backward Compatible, 3. Portability.