如何使用开罗绘制左上角和右下角的矩形？

Question

我尝试使用开罗绘制一个矩形，其左上角和右下角切角，类似于Qt徽标。

这就是我想要的： 这是我得到的：

代码如下：

#include <stdio.h>
#include <stdlib.h>
#include <cairo.h>

int main()
{
    double height = 500, width = 250;

    cairo_surface_t *surface = cairo_image_surface_create (CAIRO_FORMAT_ARGB32, 500, 500);
    cairo_t *cr = cairo_create (surface);

    cairo_move_to(cr,0,0);
    cairo_line_to(cr,width,0);
    cairo_line_to(cr,width,height - height/4);
    cairo_line_to(cr,width - height/4,height);
    cairo_line_to(cr,0,height);

    cairo_set_line_width (cr, 10.0);
    cairo_set_line_cap (cr, CAIRO_LINE_CAP_ROUND);
    cairo_stroke (cr);

    cairo_destroy (cr);
    cairo_surface_write_to_png (surface, "hello.png");
    cairo_surface_destroy (surface);

    return 0;
}

我没有得到想要的结果，有人可以给个小费吗？无论我采用哪种编程语言。

Answer 1

随着形状的更新，您只是错过了第一笔画。 其余的笔划需要相应地向右移动。

double cutoff = height/4.0;
cairo_move_to(cr, 0, cutoff);
cairo_line_to(cr, cutoff, 0);
cairo_line_to(cr, width + cutoff, 0);
cairo_line_to(cr, width + cutoff, height - cutoff);
cairo_line_to(cr, width, height);
cairo_line_to(cr, cutoff, height);