Windows下获取多个显示屏幕的分辨率

一、方法一，使用 EnumDisplayMonitors 获取屏幕分辨率 

#include <Windows.h>
#include <iostream>

BOOL CALLBACK EnumMonitor(HMONITOR handle, HDC hdc, LPRECT rect, LPARAM param) {
	std::vector<MONITORINFO> *list = (std::vector<MONITORINFO>*)param;
	MONITORINFO mi;
	mi.cbSize = sizeof(mi);
	GetMonitorInfo(handle, &mi);
	std::cout << "is MONITORINFOF_PRIMARY:" << mi.dwFlags << std::endl;
	list->push_back(mi);
	return true;
}


int main(void) {
	// 获取当前显示器的数目
	int numbers = GetSystemMetrics(SM_CMONITORS);
	std::cout << "numbers:" << numbers << std::endl;
	
	std::vector<MONITORINFO> monitor_list;
	EnumDisplayMonitors(NULL, NULL, EnumMonitor, (LPARAM)&monitor_list);
	for (size_t i = 0; i < monitor_list.size(); ++i) {
		std::cout << "width:" << (monitor_list[i].rcMonitor.right - monitor_list[i].rcMonitor.left) << std::endl;
		std::cout << "height:" << (monitor_list[i].rcMonitor.bottom - monitor_list[i].rcMonitor.top) << std::endl;
	}
	getchar();
	return 0;
}

但是这里获取到的分辨率大小是经过缩放显示之后的大小

二、方案二：使用 EnumDisplaySettingsExW 获取

上面获取的分辨率有一点问题就是获取到的大小是缩放过后的，大小不是屏幕的真正大小，接下来我们使用 EnumDisplaySettingsExW 获取

#include <Windows.h>

#include <iostream>
#include <vector>

RECT GetScreenRect(int screen) {

	DISPLAY_DEVICEW device;
	device.cb = sizeof(device);
	BOOL result = EnumDisplayDevicesW(NULL, screen, &device, 0);

	DEVMODEW device_mode;
	device_mode.dmSize = sizeof(device_mode);
	device_mode.dmDriverExtra = 0;
	result = EnumDisplaySettingsExW(device.DeviceName, ENUM_CURRENT_SETTINGS, &device_mode, 0);

	int x = device_mode.dmPosition.x;
	int y = device_mode.dmPosition.y;
	int width = device_mode.dmPelsWidth;
	int height = device_mode.dmPelsHeight;

	return { x, y, x + width, y + height };
}
int main(void) {
	// 获取当前显示器的数目
	int numbers = GetSystemMetrics(SM_CMONITORS);
	std::cout << "numbers:" << numbers << std::endl;
	for (int i = 0; i < numbers; ++i) {
		auto size = GetScreenRect(i);
		std::cout << "width:" << (size.right - size.left) << std::endl;
		std::cout << "height:" << (size.bottom - size.top) << std::endl;
	}
	getchar();
	return 0;
}

输出的大小符合我们实际的大小，也不用判断 dpi 的属性