Question

我在C ++中使用cairo图形，并输出为pdf。但是，当图形包含在文档（LaTeX）中时，图形周围会有太多空白。一个程序如何开罗在图形周围放置一个紧密的边框？

Answer 1

在调用cairo_pdf_surface_create（）时传递所需的宽度和高度。之后，您几乎可以自行选择要用图形填充多少空间。如果您要求开罗一直画到边缘，就可以。

我唯一想到的另一件事是LaTeX添加了边框。但是，这不在我的专业知识范围内。

Answer 2

/*
https://cairographics.org/manual/cairo-Recording-Surfaces.html
*/

#include <stdio.h>
#include <math.h>

#include <cairo.h>
#include <cairo-svg.h>
#include <cairo-ps.h>
#include <cairo-pdf.h>

void star(cairo_t* cr, double radius)
  {
  double theta = 0.8*M_PI;
  cairo_save(cr);
  cairo_move_to(cr, 0.0, -radius);
  for(int i=0; i<5; i++)
    {
    cairo_rotate(cr, theta);
    cairo_line_to(cr, 0.0, -radius);
    }
  cairo_fill(cr);
  cairo_restore(cr);
  }

int main()
  {
  // set recording surface
  cairo_surface_t* record = cairo_recording_surface_create(CAIRO_CONTENT_COLOR_ALPHA, NULL);
  cairo_t* cr = cairo_create(record);
  // start image
  cairo_set_source_rgb(cr, 0.0, 0.0, 0.0); // set color to black
  star(cr, 100);                           // big star
  cairo_set_source_rgb(cr, 0.0, 0.0, 1.0); // set color to blue
  star(cr, 95);                            // smaller star
  // end image
  double x0, y0, width, height;
  cairo_recording_surface_ink_extents(record, &x0, &y0, &width, &height);
  // printf("Size %lf by %lf at (%lf, %lf)\n", width, height, x0, y0);

  // create pdf image
  const char* outputfile = "bb.pdf";
  cairo_surface_t* target = cairo_pdf_surface_create(outputfile, width, height);
  cairo_t*         crt    = cairo_create(target);
  // copy recorded image to target and paint
  cairo_set_source_surface(crt, record, -x0, -y0);
  cairo_paint(crt);
  // clean up
  cairo_destroy (cr);
  cairo_surface_destroy (record);
  cairo_destroy (crt);
  cairo_surface_destroy (target);
  }

开罗pdf边界框

2 个答案: