C++获取屏幕分辨率（屏幕窗口大小），屏幕显示比例（DPI）几种方法

1、获取屏幕的分辨率的几种方

#include <>

#include <iostream>
int main(void) {
	HWND hd = GetDesktopWindow();
	// 方法一
	RECT rect;
	// 只获得窗口客户区的大小
	GetClientRect(hd, &rect);
	int client_width = ( - );
	int client_height = ( - );
	std::cout << "client width:" << client_width << std::endl;
	std::cout << "client height:" << client_height << std::endl;
	// 获取到的是窗口在屏幕上的位置
	GetWindowRect(hd, &rect);
	int window_width = ( - );
	int window_height = ( - );
	std::cout << "window width:" << window_width << std::endl;
	std::cout << "window height:" << window_height << std::endl;

	// 方法二
	// 不带菜单栏的大小
	int no_menu_bar_width = GetSystemMetrics(SM_CXFULLSCREEN);
	int no_menu_bar__height = GetSystemMetrics(SM_CYFULLSCREEN);
	std::cout << "no menu bar width:" << no_menu_bar_width << std::endl;
	std::cout << "no menu bar height:" << no_menu_bar__height << std::endl;
	// 带标题栏和菜单栏
	int have_menu_bar_width = GetSystemMetrics(SM_CXSCREEN);
	int have_menu_bar_height = GetSystemMetrics(SM_CYSCREEN);
	std::cout << "have menu bar width:" << window_width << std::endl;
	std::cout << "have menu bar height:" << window_height << std::endl;

	//方法三
	HDC hdc = GetDC(NULL);                           // 得到屏幕DC  
	client_width = GetDeviceCaps(hdc, HORZRES);      // 宽  
	client_height = GetDeviceCaps(hdc, VERTRES);     // 高   
	ReleaseDC(NULL, hdc);                            // 释放DC
	std::cout << "client width:" << client_width << std::endl;
	std::cout << "client height:" << client_height << std::endl;

	//方法四
	SystemParametersInfo(SPI_GETWORKAREA, 0, &rect, SPIF_SENDCHANGE);
	client_width = ( - );
	client_height = ( - );
	std::cout << "client width:" << client_width << std::endl;
	std::cout << "client height:" << client_height << std::endl;

	//方法五
	hdc = GetDC(NULL);
	client_width = GetDeviceCaps(hdc, DESKTOPHORZRES);
	client_height = GetDeviceCaps(hdc, DESKTOPVERTRES);
	ReleaseDC(NULL, hdc);
	std::cout << "client width:" << client_width << std::endl;
	std::cout << "client height:" << client_height << std::endl;

	getchar();
	return 0;
}

2、获取屏幕显示比例（目前只支持Windows 10 1607版本的系统）

#include <iostream>
#include <>

int main(void) {
	HWND hd = GetDesktopWindow();
	int zoom = GetDpiForWindow(hd);
	double dpi = 0;
	switch (zoom) {
	case 96:
		dpi = 1;
		std::cout << "100%" << std::endl;
		break;
	case 120:
		dpi = 1.25;
		std::cout << "125%" << std::endl;
		break;
	case 144:
		dpi = 1.5;
		std::cout << "150%" << std::endl;
		break;
	case 192:
		dpi = 2;
		std::cout << "200%" << std::endl;
		break;
	default:
		std::cout << "error" << std::endl;
		break;
	}
	getchar();
	return 0;
}

3、在获取屏幕显示比例的时候，我们可以发现方法一到方法四都是获取的是缩放后的屏幕分辨率，要想获得最初的屏幕我们需要乘以对应的dpi就可以了。

int client_width = ( - ) * dpi;
int client_height = ( - ) * dpi;