我最近一直在使用 WINAPI 来检索缩放设置和屏幕分辨率,我遇到了这种奇怪的行为。
我有一个小的 C++ 程序(下面有列表),它可以检索 VERTRES、HORZRES、DESKTOPVERTRES 和 DESKTOPHORZRES 的值。我的程序还将 DPI 感知模式设置为 1(系统级感知)。我注意到 VERTRES、HORZRES 报告的值取决于系统启动时使用的系统比例因子。
所以在我的笔记本电脑上,我将系统缩放系数配置为 150%,分辨率为 1920x1080。那是启动时的配置。当我检索 HORZRES 和 DESKTOPHORZRES 时,两个值都报告为 1920。
如果我将缩放设置更改为 100% 并且不重新启动计算机,则下次检索这些值时,它们会报告为 2880(对于 HORZRES)和 1920(对于 DESKTOPHORZRES)。
在我重新启动计算机并将缩放设置设置为 100% 后,这两个值再次报告为 1920。
如果我再次将缩放比例更改为 150%,则值将报告为 1280 (HORZRES) 和 1920 (DESKTOPHORZRES)。
仅当我将 DPI 感知设置为 1 时才观察到所描述的行为,如果它设置为 0(“不感知”)或 2(“每屏幕感知”)值始终报告为 1280(HORZRES)和 1920(DESKTOPHORZRES)无论在启动时如何配置缩放。
我想知道为什么 HORZRES(或 VERTRES)报告的值取决于系统启动时使用的比例因子?这是预期的行为吗?
如果上面已经在某处进行了描述,我将不胜感激任何参考。
#include "stdafx.h"
#include <iostream>
#include <vector>
#include <cerrno>
#include <string>
#include <sstream>
#include <math.h>
#include <Windows.h>
#include <shellscalingapi.h>
#include <winuser.h>
class Rectangular
{
public:
Rectangular(int height, int width) : height(height), width(width) {};
const int height;
const int width;
};
class MonitorInfo
{
public:
MonitorInfo(std::string device_name, Rectangular logical_resolution, Rectangular physical_resolution, Rectangular physical_size_mm) :
device_name(device_name), logical_resolution(logical_resolution), physical_resolution(physical_resolution),
physical_size_mm(physical_size_mm), scaling(static_cast<int>(std::round(100.0*(float)physical_resolution.height / (float)logical_resolution.height))) {};
void print_to_stdout() const;
const std::string device_name;
const Rectangular logical_resolution;
const Rectangular physical_resolution;
const Rectangular physical_size_mm;
const int scaling;
};
class MonitorsInformation
{
public:
MonitorsInformation();
const std::vector<MonitorInfo>& get_monitors_info() const { return monitors; }
std::string get_last_error_string() const { return last_error; }
Rectangular get_monitors_rectangular() const;
private:
RECT rectangular_combined;
std::vector<MonitorInfo> monitors;
std::string last_error;
static BOOL CALLBACK MonitorEnum(HMONITOR hMon, HDC hdc, LPRECT lprcMonitor, LPARAM pData);
};
void MonitorInfo::print_to_stdout() const
{
std::cout << "\nDevice: " << device_name << "\nLogical Screen resolution: " << logical_resolution.width << "x" << logical_resolution.height;
std::cout << "\nPhysical Screen resolution: " << physical_resolution.width << "x" << physical_resolution.height;
std::cout << "\nDPI ratio: " << scaling;
std::cout << "\nPhysical Size(mm): " << physical_size_mm.width << "x" << physical_size_mm.height << "\n";
}
MonitorsInformation::MonitorsInformation() : rectangular_combined(RECT()), last_error(std::string()), monitors(std::vector<MonitorInfo>())
{
EnumDisplayMonitors(0, 0, MonitorEnum, (LPARAM)this);
}
BOOL CALLBACK MonitorsInformation::MonitorEnum(HMONITOR hMon, HDC hdc, LPRECT lprcMonitor, LPARAM pData)
{
MonitorsInformation* pThis = reinterpret_cast<MonitorsInformation*>(pData);
MONITORINFOEXA monitor_info;
monitor_info.cbSize = sizeof(MONITORINFOEXA);
if (!GetMonitorInfoA(hMon, &monitor_info))
{
pThis->last_error = "GetMonitorInfoA failed with error: " + errno;
return FALSE;
}
UnionRect(&pThis->rectangular_combined, &pThis->rectangular_combined, lprcMonitor);
HDC device_context = CreateDCA(NULL, monitor_info.szDevice, NULL, NULL);
int LogicalScreenHeight = GetDeviceCaps(device_context, VERTRES);
int LogicalScreenWidth = GetDeviceCaps(device_context, HORZRES);
int PhysicalScreenHeight = GetDeviceCaps(device_context, DESKTOPVERTRES);
int PhysicalScreenWidth = GetDeviceCaps(device_context, DESKTOPHORZRES);
pThis->monitors.push_back(
MonitorInfo(
std::string(monitor_info.szDevice),
Rectangular(
LogicalScreenHeight,
LogicalScreenWidth),
Rectangular(
PhysicalScreenHeight,
PhysicalScreenWidth),
Rectangular(
GetDeviceCaps(device_context, VERTSIZE),
GetDeviceCaps(device_context, HORZSIZE))));
return TRUE;
}
Rectangular MonitorsInformation::get_monitors_rectangular() const
{
return Rectangular(
std::abs(rectangular_combined.top) + std::abs(rectangular_combined.bottom),
std::abs(rectangular_combined.left) + std::abs(rectangular_combined.right));
}
int main()
{
SetProcessDPIAware();
for (;;)
{
MonitorsInformation MonitorsInfo;
char exit_char = 'N';
std::cout << "You have " << MonitorsInfo.get_monitors_info().size() << " monitors connected.\n";
printf("Screen rectangular. %d x %d\n",
MonitorsInfo.get_monitors_rectangular().width, MonitorsInfo.get_monitors_rectangular().height);
for (auto &monitor : MonitorsInfo.get_monitors_info())
{
monitor.print_to_stdout();
}
std::cout << "Would you like to repeat? [Y]/[N]\n";
std::cin >> exit_char;
if (exit_char == 'N' || exit_char == 'n')
{
break;
}
}
return 0;
}