AGG第二十七課 agg::conv_clip_polyline裁剪線區域

應用場景

路徑點超出渲染范圍N遠

頭文件

#include"agg/include/agg_conv_clip_polyline.h"

簡單例子

 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.