AGG第二十七课 agg::conv_clip_polyline裁剪线区域

应用场景

路径点超出渲染范围N远

头文件

#include”agg/include/agg_conv_clip_polyline.h”

简单例子

 void ClipPathByPolyline()

  {

   agg::rendering_buffer &rbuf = rbuf_window();

   agg::pixfmt_bgr24 pixf(rbuf);

   typedef agg::renderer_base<agg::pixfmt_bgr24> renderer_base_type;

   renderer_base_type renb(pixf);

   typedef agg::renderer_scanline_aa_solid<renderer_base_type>renderder_scanline_type;

   renderder_scanline_type rensl(renb);

   agg::rasterizer_scanline_aa<> ras;

   agg::scanline_u8 sl;

   ras.reset();

   agg::path_storage ps;

   ps.move_to(100,540);

   ps.line_to(168.889,471.429);

   ps.line_to(237.778,402.857);

   ps.line_to(306.667,334.286);

   ps.line_to(651.111,-8.57143);

   ps.line_to(720,-6.85714e+19);

   ps.line_to(200,400);

   ps.line_to(400,400);

   ps.line_to(200,500);

   ps.line_to(700,400);

   agg::conv_clip_polyline<agg::path_storage> polyline(ps);

   polyline.clip_box(0,0,600,800);

   agg::conv_dash<agg::conv_clip_polyline<agg::path_storage> >dash(polyline);

   dash.add_dash(10,10);

   agg::conv_stroke<agg::conv_dash<agg::conv_clip_polyline<agg::path_storage>> > stroke(dash);

   stroke.width(2);

   ras.add_path(stroke);

   agg::render_scanlines_aa_solid(ras,sl,renb,agg::rgba8(255,0,0));

  }

限制：

Here the lines will be clipped beforecalculating the rest. But if you have

very wide lines you will see some defects

To avoid it you may want to extend theclipping area to the maximal line width.