一Cairo 概念 ................................................................................................................................... 3 环境 (Context) ............................................................................................................................. 3 路径 (Path) ................................................................................................................................... 3 源 (Source) ................................................................................................................................... 3 外观 (Surface) .............................................................................................................................. 3 蒙板 (Mask) ................................................................................................................................. 4 图案 (Pattern) ............................................................................................................................... 4 二Cairo 后端 ................................................................................................................................... 4 1. PNG 图像 ................................................................................................................................. 4 2. PDF 文件 ................................................................................................................................. 5 3. SVG 文件 ................................................................................................................................. 6 4. GTK 窗口 ................................................................................................................................ 7 三 基本绘图 ..................................................................................................................................... 9 直线段 .......................................................................................................................................... 9 描绘 (Stroke) 与填充 (Fill) ..................................................................................................... 12 虚线 (Dash) ................................................................................................................................ 14 线帽 (Line caps) ........................................................................................................................ 17 线的交合 (Line joins) ................................................................................................................ 19 四 高级形状绘制 ........................................................................................................................... 21 基本形状..................................................................................................................................... 21 复杂的图形................................................................................................................................. 24 填充 (Fill) .................................................................................................................................. 27 纯色 (Solid color) .................................................................................................................. 27 图案 (Pattern) ......................................................................................................................... 28 渐变 (Gradient) ...................................................................................................................... 32 五 透明........................................................................................................................................... 35 透明的矩形................................................................................................................................. 35 淡出的效果................................................................................................................................. 37 “等待”的演示 ............................................................................................................................. 40 六 合成........................................................................................................................................... 43 七 裁剪与遮蔽 ............................................................................................................................... 46 裁剪 ............................................................................................................................................ 46 裁剪矩形..................................................................................................................................... 49 遮蔽 ............................................................................................................................................ 53 变换 ............................................................................................................................................ 55 平移......................................................................................................................................... 55 旋转......................................................................................................................................... 56 缩放......................................................................................................................................... 58 错切......................................................................................................................................... 60 椭圆......................................................................................................................................... 63 星星......................................................................................................................................... 65 七 文本........................................................................................................................................... 68 灵魂伙伴..................................................................................................................................... 68 一个字接一个字…… ................................................................................................................. 71 膨胀 ............................................................................................................................................ 73 八 图像........................................................................................................................................... 76 图像的显示................................................................................................................................. 77 垂帘效果（Blind Down） ......................................................................................................... 78 光谱效果..................................................................................................................................... 81