?SDL（Simple DirectMediaLayer）是一套開放源代碼的跨平臺多媒體開發庫，使用C語言寫成。SDL提供了數種控制圖像、聲音、輸出入的函數，讓開發者只要用相同或是相似的代碼就可以開發出跨多個平臺（Linux、Windows、MacOS X等）的應用軟件。現SDL多用于開發游戲、模擬器、媒體播放器等多媒體應用領域。

1.天氣獲取

?? 天氣獲取采用命令行瀏覽器curl，天氣獲取接口使用心知天氣網；

??心知天氣是中國氣象局官方授權的商業氣象服務公司,基于氣象數值預報和人工智能技術,提供高精度氣象數據、天氣監控機器人、氣象數據可視化產品，本次天氣數據獲取從心知天氣網平臺獲取。

2.天氣獲取與解析示例

/******************解析 天氣數據****************
形參：u8* buff原始數據
			u8 *Weather_stat天氣數據標志
			u8 *data解析獲取到的數據
返回值：0---成功，其他值---失敗
************************************************/
u8 Weather_analysis(u8* buff,u8 *Weather_stat,u8 *data)
{
	char *p=NULL;
	u16 i=0;
	p=strstr((char *)buff,(char *)Weather_stat);//獲取溫度
	if(p)
	{
		p+=strlen((char *)Weather_stat)+2;
		i=0;
		while(*p!='"' && *p!='?')
		{
			data[i++]=*p++;
		}
		data[i]='?';
		return 0;
	}
	else return 1;
}
/*獲取天氣數據*/
int Http_GetWeather(void)
{
	FILE *fp=popen("curl  api.seniverse.com/v3/weather/now.json?key=SwD4-ybQxhedD1z7U'&'location=nanchang'&'language=zh-Hans'&'unit=c","r");
	if(fp==NULL)
	{
		printf("重定向失敗n");
		return -1;
	}
	char wthread_buff[1025];
	int cnt=fread(wthread_buff,1,1024,fp);
	wthread_buff[cnt]='?';
	char buff[100];
	wchar_t wc_buff[200];
	int stat;
	/*
		{"results":[{"location":{"id":"WT47HJP3HEMP","name":"南昌","country":"CN","path":"南昌,南昌,江西,中國",
		"timezone":"Asia/Shanghai","timezone_offset":"+08:00"},"now":{"text":"陰","code":"9","temperature":"16"},"last_update":"2021-11-20T16:57:46+08:00"}]}
	*/
	/*解析天氣數據*/
	Weather_analysis(wthread_buff,(u8 *)""name"",(u8 *)weather_info.city_name);//城市名稱
		
	if(!Weather_analysis(wthread_buff,(u8 *)""temperature"",(u8 *)buff))//獲取溫度
	{
		snprintf((char *)weather_info.city_temp,sizeof(weather_info.city_temp),"%s℃",buff);
	}
	Weather_analysis(wthread_buff,""text"",(u8 *)weather_info.city_weather);
	if(!Weather_analysis(wthread_buff,(u8 *)""code"",(u8 *)buff))//天氣代碼
	{
		weather_info.city_code=atoi(buff);//字符串轉整數
	}
	//printf("name:%sttemp:%st天氣:%st天氣代號:%dn",weather_info.city_name,weather_info.city_temp,weather_info.city_weather,weather_info.city_code);
	pclose(fp);
	return 0;
}

3.顯示時間和天氣示例

        sec=time(NULL);
		if(sec!=sec2)
		{
			sec2=sec;
			count++;
			localtime_r(&sec2,&result);//將秒單位時間轉換為時間結構體
			strftime(buff,sizeof(buff),"%H:%M",&result);//時間格式化打印
			//printf("buff=%sn",buff);
			TTF_SetFontSize(ttffont,100);
			surface1=TTF_RenderUTF8_Blended(ttffont,buff,color2);
			rect.h=surface1->h;
			rect.w=surface1->w;
			rect.x=800/2-surface1->w/2;/*要顯示的x起始位置*/
			rect.y=120;/*要顯示的y起始位置*/
 			srcrect.h=surface1->h;
			srcrect.w=surface1->w;
			sdltext1=SDL_CreateTextureFromSurface(render,surface1);
			SDL_RenderCopy(render,sdltext2,&rect,&rect);
			SDL_RenderCopy(render,sdltext1,&srcrect,&rect);
			SDL_FreeSurface(surface1);/*釋放surface*/
			SDL_DestroyTexture(sdltext1);/*釋放表面*/
		
			TTF_SetFontSize(ttffont,50);
			strftime(week_buff,sizeof(week_buff),"%w",&result);
			week_cnt=atoi(week_buff);
			strftime(buff,sizeof(buff),"%Y/%m/%d 星期",&result);//時間格式化打印
			strncat(buff,week[week_cnt],sizeof(buff));
			strncat(buff," | ",sizeof(buff));
			surface2=TTF_RenderUTF8_Blended(ttffont,buff,color2);
			rect.h=surface2->h;
			rect.w=surface2->w;
			rect.x=800/2-surface2->w/2-40;/*要顯示的x起始位置*/
			rect.y=240;/*要顯示的y起始位置*/
			wather_x=rect.x+surface2->w;
			wather_y=rect.y;
 			srcrect.h=surface2->h;
			srcrect.w=surface2->w;
			sdltext3=SDL_CreateTextureFromSurface(render,surface2);
			SDL_RenderCopy(render,sdltext2,&rect,&rect);
			SDL_RenderCopy(render,sdltext3,&srcrect,&rect);
			SDL_FreeSurface(surface2);/*釋放surface*/
			SDL_DestroyTexture(sdltext3);/*釋放表面*/
			if(count>=60)/*60s獲取一次天氣數據*/
			{
				count=0;
				if(!Http_GetWeather())/*獲取天氣*/
				{
					char image[50];
					snprintf(image,sizeof(image),"./weather_photo/%d.png",weather_info.city_code);
					SDL_Surface *weather_surface=IMG_Load(image);
					if(weather_surface)
					{	
						SDL_Rect rect;
						rect.x=wather_x;
						rect.y=wather_y;
						rect.w=50;
						rect.h=50;
						srcrect.h=weather_surface->h;
						srcrect.w=weather_surface->w;
						SDL_Texture *sdltext=SDL_CreateTextureFromSurface(render,weather_surface);/*創建*/
						SDL_RenderCopy(render,sdltext2,&rect,&rect);
						SDL_RenderCopy(render,sdltext,&srcrect,&rect);
						SDL_FreeSurface(weather_surface);/*釋放surface*/
						SDL_DestroyTexture(sdltext);/*釋放表面*/
						/*顯示溫度*/
						SDL_Surface *temp_surface=TTF_RenderUTF8_Blended(ttffont,weather_info.city_temp,color2);
						SDL_Texture *temp_sdltext=SDL_CreateTextureFromSurface(render,temp_surface);
						rect.x=wather_x+50;
						rect.y=wather_y;
						srcrect.h=temp_surface->h;
						srcrect.w=temp_surface->w;
						SDL_RenderCopy(render,sdltext2,&rect,&rect);
						SDL_RenderCopy(render,temp_sdltext,&srcrect,&rect);
						SDL_FreeSurface(temp_surface);/*釋放surface*/
						SDL_DestroyTexture(temp_sdltext);/*釋放表面*/
					}
				}
			}
			SDL_RenderPresent(render);//更新顯示
		}

審核編輯：湯梓紅