rtgui_dc绘制图形看不见

发布于 2021-07-16 15:02:21 浏览：752 订阅该版

show_demo中win值非空，rect为屏幕坐标值，但屏上没有任何显示，我设置背景色蓝色。请大神指教一下！
//启动线程	rt_thread_t tid1;
 
    	tid1 = rt_thread_create("mygui",
        rt_gui_entry, RT_NULL,
        2048, 25, 10);

if (tid1 != RT_NULL)
      {
		rt_thread_startup(tid1);
	}

//event

rt_bool_t dc_event_handler(struct rtgui_object *object, rtgui_event_t *event)
{
    rt_bool_t err;
    struct rtgui_win *win = RTGUI_WIN(object);

err = rtgui_win_event_handler(RTGUI_OBJECT(win), event);
    if (event->type == RTGUI_EVENT_PAINT)
        show_demo(win);

return err;
}
//showdemo
/*!
    \brief      rt_gui thread
    \param[in]  pvParameters not used
    \param[out] none
    \retval     none
*/
static void rt_gui_entry(void *parameter)
{
    struct rtgui_win *main_win;
    struct rtgui_app *app;

/* create gui app */
    app = rtgui_app_create("gui_demo");
    if (app == RT_NULL)
        return;

main_win = rtgui_mainwin_create(RT_NULL, "UiWindow", RTGUI_WIN_STYLE_NO_TITLE);
    if (main_win == RT_NULL)
    {
        rtgui_app_destroy(app);
        return;
    }
    rtgui_object_set_event_handler(RTGUI_OBJECT(main_win), dc_event_handler);
    rtgui_win_show(main_win, RT_FALSE);

rtgui_app_run(app);
    rtgui_win_destroy(main_win);
    rtgui_app_destroy(app);

}

static rt_bool_t show_demo(struct rtgui_win *win)
{
    struct rtgui_dc *dc;
    rtgui_rect_t rect;

dc = rtgui_dc_begin_drawing(RTGUI_WIDGET(win));
    if (dc == RT_NULL)
    {
        rt_kprintf("dc is null \n");
        return RT_FALSE;
    }
    rtgui_dc_get_rect(dc, &rect);

/* draw circular */
    {
        rt_int16_t x, y, r;

x = rect.x2 / 2 / 2;
        y = rect.y2 / 2 / 2;
        r = x > y ? y : x;
        r -= y / 10;
        rtgui_dc_draw_circle(dc, x, y, r);
    }

/* draw image */
    {
        rtgui_rect_t draw_rect;
        struct rtgui_image *img;

img = rtgui_image_create_from_mem("png", _picture_png, sizeof(_picture_png), RT_TRUE);
        if (img != RT_NULL)
        {
            draw_rect.x1 = rect.x2 / 2 + (rect.x2 / 2 - img->w) / 2;
            draw_rect.y1 = (rect.y2 / 2 - img->h) / 2;
            draw_rect.x2 = draw_rect.x1 + img->w;
            draw_rect.y2 = draw_rect.y1 + img->h;
            rtgui_image_blit(img, dc, &draw_rect);
        }
    }

/* draw text */
    {
        rtgui_color_t fc;
        rtgui_rect_t draw_rect;
        char *text_buf = "Hello RT-thread!";

fc = RTGUI_DC_FC(dc);
        RTGUI_DC_FC(dc) = RED;
        draw_rect.x1 = rect.x2 * 2 / 5;
        draw_rect.y1 = rect.y2 * 3 / 4;
        draw_rect.x2 = rect.x2;
        draw_rect.y2 = rect.y2;
        rtgui_dc_draw_text(dc, text_buf, &draw_rect);
        RTGUI_DC_FC(dc) = fc;
    }

rtgui_dc_end_drawing(dc, RT_TRUE);

return RT_TRUE;
}

附图

![1626418805444.jpg](https://oss-club.rt-thread.org/uploads/20210716/e6a59c9b1e6b17fed56879fa30c82e29.jpg.webp)