本論文提出一應用於電子書之字形呈像系統。向量字形的呈像主要包含兩個步驟: 曲線線段的繪製和字體封閉區間內的填色，相較於傳統利用許多極短的直線來逼近曲線線段的繪製方式，本系統應用了adaptive forward-difference演算法來繪製曲線，此外對於字形的填色方式，本論文採用了local-minimum table和vertex table來取代傳統的global edge table以減少記憶體空間的需求。最後，為了改善字形的呈像品質，本系統應用了以往僅見於三維圖學系統的FLIPQUAD取樣點策略之反鋸齒技術，採用這項技術相對於傳統的RGSS取樣點策略不僅呈像品質較佳也可以降低記憶體需求和填色計算成本達25%。本字形繪製系統實做於ARM核心的平台上並且使用了FreeType字形解譯器將之轉換為符合標準二維向量圖形介面OpenVG的繪圖指令，此標準應用程式介面(API)被實做於QT視窗系統和嵌入式Linux平台上。本論文所提出的字形繪製系統展示一個完全利用開放原始碼的解決方案並且可以被應用於各式各樣的嵌入式環境中。

In this thesis, an efficient font-rendering system for E-book applications was presented. The rendering of vector-type fonts mainly consists of two procedures: the rasterization of outline curves, and the filling of font interiors. Different from the conventional rendering systems which approximate the curve using many tiny straight lines, our system applies the fast adaptive forward-difference algorithm to render the curve. In addition, for the filling of fonts, this thesis adopts the local-minimum table and the vertex table to substitute the conventional global edge table in order to reduce the memory requirement. Finally, in order to improve the rendering quality of the fonts, our system has applied the super-sampling anti-aliasing technique based on the FLIPQUAD sample patterns used in three-dimensional graphic systems in order to reduce both the required buffer size and the filling operation complexity by 25% for the similar rendering quality. Our rendering system has been implemented in an ARM-based platform. The FreeType fonts parser has been used, and transformed into the application programming interface (API) commands of a two-dimensional vector graphics standard called OpenVG. This standard APIs have been built on the QT window and Embedded Linux operational systems. The rendering system proposed by this thesis represents a total open-source solution, and can be applied to many embedded applications.

Chapter 1 概論 1
1.1 研究動機 1
1.2 論文大綱 2
Chapter 2 字形繪製系統架構之介紹 3
2.1 電子書閱讀系統 3
2.2 OpenVG 4
2.2.1 使用OpenVG繪製字形 5
2.3 向量與點陣字形 7
2.4 字型檔解譯器FreeType 8
2.5 QT 8
2.6 Embedded Linux 9
Chapter 3 基本向量圖形繪製流程 10
3.1 路徑描點(Path tessellation) 10
3.2 多邊形填色(polygon fill) 10
3.3 圖形反鋸齒 12
Chapter 4 路徑描點 14
4.1 描點方式 14
4.1.1 直線逼近之作法 14
4.1.2 基於整數座標點之作法 15
4.2 不同描點方法所造成之填色誤差 15
4.3 填色誤差之比較方式 20
Chapter 5 圖形之填色 22
5.1 傳統填色方式 22
5.2 基於以整數座標表示路徑輪廓位置的填色方法 26
5.3 填色方法之優劣分析 31
Chapter 6 圖形反鋸齒研究 36
6.1 針對二維向量圖形之反鋸齒技術 36
6.2 反鋸齒之取樣點策略 38
6.2.1 One sample per pixel 38
6.2.2 OGSS 39
6.2.3 RGSS 39
6.2.4 8-Queen 39
6.2.5 FLIPQUAD 40
6.2.6 各式取樣點之計算成本分析 42
6.3 應用反鋸齒技術於字形呈像 43
Chapter 7 字形呈像系統之實作 46
7.1 整體系統架構 46
7.2 轉換原始字型繪製格式為OpenVG繪製指令 46
7.3 整合OpenVG API於QT系統 52
7.4 系統成果展示 54
Chapter 8 結論與未來研究方向 56
Appendix A Embedded Linux的安裝與啟動 57
A1 使用u-boot啟動Linux 57
A2 Root-file system和NFS 58
A3 Linux kernel compilation 59
Appendix B QT的編譯與安裝 60
B1 The QT-4.6 compilation 60
B2 一個簡單的QT應用程式和編譯 60
B3 執行QT應用程式於Embedded Linux上 63
Appendix C OpenVG RI的編譯與移植 63
C1 OpenVG 1.1 RI的小錯誤修正 63
C2 OpenVG RI的編譯與移植 63
Appendix D FreeType的編譯與使用 64
D1 Embedded Linux的編譯方式 64
D1.1 基於ARM平台的FreeType-2.3.12錯誤修正 64
D2 Windows的編譯方式 65
D3 新細明體的解譯問題 65
Appendix E Linux Driver Note 65
E1 The communication flow 65
E2 The driver arch 65
E3 The Driver compilation 68
E4 The Driver execution 69
Appendix F 參考文獻 69

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