如何使用 cairo 绘制左上角和右下角的矩形？

Question

我尝试用cairo画了一个左上右下切角的矩形，类似Qt的logo。

这是我想要的：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;
}

我没有得到我想要的结果，有人可以给点提示吗？无论我使用哪种编程语言。

Answer 1

使用更新后的形状，您只是错过了第一笔画。剩余的笔画需要相应的右移

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);

如何使用 cairo 绘制左上角和右下角的矩形？

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