ps如何创建扫描线

在PostScript（PS）中创建扫描线（scan line）通常涉及到使用路径（path）命令来绘制线条，或者使用`shading`功能来创建类似扫描线的图案。以下是一些基本的步骤和示例，说明如何在PostScript中创建扫描线：

使用路径命令绘制扫描线

1. 设置画布和初始状态：

```ps

%!PS-Adobe-3.0

%%DocumentSettings: 1

/llx 0 def

/lly 0 def

/urx 595 def

/ury 842 def

/currentmatrix currentmatrix def

```

2. 创建路径：

```ps

/scanlinepath newpath def

100 100 moveto

100 800 lineto

```

3. 填充路径：

```ps

scanlinepath closepath fill

```

4. 结束文档：

```ps

showpage

```

使用`shading`功能创建扫描线

1. 定义扫描线图案：

```ps

/scanline shadingtype /Function make shadingdef

1 0 0 1 setrgbcolor

```

2. 创建扫描线：

```ps

/scanlinepattern << /Function

/FunctionType 2

/ColorType 0

/NumColors 1

/Data

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