Defined _WIN32_WINNT in the project properties to be 0x0600 (i.e. Vista). (Note: DLLs may still have code that requires 7+ functionality.) Cleaned up throw_helpers and made it so that Windows-specific helpers are only included if _WIN32_WINNT is defined. Added a timer class to get proper elapsed time values. Fixed up the sample draw code so that it works with the (now correct) elapsed time value passed to it.

Author: mikebmcl

win32/N3888_RefImpl/N3888_RefImpl.vcxproj

@@ -83,7 +83,7 @@
       <PrecompiledHeader>NotUsing</PrecompiledHeader>
       <WarningLevel>Level4</WarningLevel>
       <Optimization>Disabled</Optimization>
-      <PreprocessorDefinitions>WIN32;_DEBUG;_WINDOWS;%(PreprocessorDefinitions)</PreprocessorDefinitions>
+      <PreprocessorDefinitions>WIN32;_WIN32_WINNT=0x0600;_DEBUG;_WINDOWS;%(PreprocessorDefinitions)</PreprocessorDefinitions>
       <SDLCheck>true</SDLCheck>
       <AdditionalIncludeDirectories>$(ProjectDir)include\;%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>
       <PrecompiledHeaderFile>pch.h</PrecompiledHeaderFile>
@@ -105,7 +105,7 @@ cmd /c copy "$(ProjectDir)DLLs\$(PlatformTarget)\$(Configuration)\zlib1.pdb" "$(
       <PrecompiledHeader>NotUsing</PrecompiledHeader>
       <WarningLevel>Level4</WarningLevel>
       <Optimization>Disabled</Optimization>
-      <PreprocessorDefinitions>WIN32;_DEBUG;_WINDOWS;%(PreprocessorDefinitions)</PreprocessorDefinitions>
+      <PreprocessorDefinitions>WIN32;_WIN32_WINNT=0x0600;_DEBUG;_WINDOWS;%(PreprocessorDefinitions)</PreprocessorDefinitions>
       <SDLCheck>true</SDLCheck>
       <AdditionalIncludeDirectories>$(ProjectDir)include\;%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>
       <PrecompiledHeaderFile>pch.h</PrecompiledHeaderFile>
@@ -129,7 +129,7 @@ cmd /c copy "$(ProjectDir)DLLs\$(PlatformTarget)\$(Configuration)\zlib1.pdb" "$(
       <Optimization>MaxSpeed</Optimization>
       <FunctionLevelLinking>true</FunctionLevelLinking>
       <IntrinsicFunctions>true</IntrinsicFunctions>
-      <PreprocessorDefinitions>WIN32;NDEBUG;_WINDOWS;%(PreprocessorDefinitions)</PreprocessorDefinitions>
+      <PreprocessorDefinitions>WIN32;_WIN32_WINNT=0x0600;NDEBUG;_WINDOWS;%(PreprocessorDefinitions)</PreprocessorDefinitions>
       <SDLCheck>true</SDLCheck>
       <AdditionalOptions> /Qvec-report:2</AdditionalOptions>
       <AdditionalIncludeDirectories>$(ProjectDir)include\;%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>
@@ -154,7 +154,7 @@ cmd /c copy "$(ProjectDir)DLLs\$(PlatformTarget)\$(Configuration)\zlib1.dll" "$(
       <Optimization>MaxSpeed</Optimization>
       <FunctionLevelLinking>true</FunctionLevelLinking>
       <IntrinsicFunctions>true</IntrinsicFunctions>
-      <PreprocessorDefinitions>WIN32;NDEBUG;_WINDOWS;%(PreprocessorDefinitions)</PreprocessorDefinitions>
+      <PreprocessorDefinitions>WIN32;_WIN32_WINNT=0x0600;NDEBUG;_WINDOWS;%(PreprocessorDefinitions)</PreprocessorDefinitions>
       <SDLCheck>true</SDLCheck>
       <AdditionalOptions> /Qvec-report:2</AdditionalOptions>
       <AdditionalIncludeDirectories>$(ProjectDir)include\;%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>

win32/N3888_RefImpl/entrypoint-win32.cpp

@@ -59,15 +59,18 @@ int WINAPI wWinMain(
 
 	Win32RenderWindow window(800, 600, L"N3888_RefImpl Main Window");
 
+	not_proposed::timer timer;
+
 	// Main message loop:
 	while (msg.message != WM_QUIT) 
 	{
 		if (!PeekMessageW(&msg, NULL, 0, 0, PM_REMOVE)) {
 			// Draw to the off-screen buffer.
+			timer.update();
 			sample_draw sampleDraw;
 			auto& renderTarget = *window.GetSurface();
 			auto rtCtxt = context(renderTarget);
-			sampleDraw(rtCtxt, static_cast<double>(GetTickCount64()));
+			sampleDraw(rtCtxt, timer.get_elapsed_time());
 
 			// Flush to ensure that it is drawn to the window.
 			window.GetSurface()->flush();

win32/N3888_RefImpl/entrypoint-win32.h

@@ -11,9 +11,86 @@
 #include <KnownFolders.h>
 #include <shellapi.h>
 
+#include <stdexcept>
+#include "throw_helpers.h"
+
 // Forward declarations of functions included in this code module:
 ATOM				MyRegisterClass(HINSTANCE hInstance);
 BOOL				InitInstance(HINSTANCE, int, HWND&);
 LRESULT CALLBACK	WndProc(HWND, UINT, WPARAM, LPARAM);
 INT_PTR CALLBACK	About(HWND, UINT, WPARAM, LPARAM);
 
+namespace not_proposed {
+	class timer {
+		bool m_supportsHPC;
+		LARGE_INTEGER m_frequencyHPC;
+		LARGE_INTEGER m_startCountHPC;
+		LARGE_INTEGER m_lastCountHPC;
+		ULONGLONG m_startTickCount64;
+		ULONGLONG m_lastTickCount64;
+		double m_elapsedTime;
+		double m_totalTime;
+
+	public:
+		timer()
+			: m_supportsHPC()
+			, m_frequencyHPC()
+			, m_startCountHPC()
+			, m_lastCountHPC()
+			, m_startTickCount64()
+			, m_lastTickCount64()
+			, m_elapsedTime()
+			, m_totalTime() {
+			reset();
+		}
+
+		void reset() {
+			// Though it's highly unlikely, it's not impossible that the computer doesn't support a high-resolution
+			// performance counter, which is required for this API.
+			m_supportsHPC = ::QueryPerformanceFrequency(&m_frequencyHPC) != 0;
+
+			if (m_supportsHPC) {
+				// If this returns zero there's a runtime error of some sort per the API.
+				if (::QueryPerformanceCounter(&m_startCountHPC) == 0) {
+					throw_get_last_error<::std::runtime_error>("Failed call to QueryPerformanceCounter.");
+				}
+				m_lastCountHPC = m_startCountHPC;
+			}
+			else {
+				// Fall back to the inaccurate timer.
+				m_lastTickCount64 = m_startTickCount64 = ::GetTickCount64();
+			}
+		}
+
+		// Returns elapsed time since last call to Update or Reset.
+		void update() {
+			if (m_supportsHPC) {
+				LARGE_INTEGER currentCountHPC;
+				if (QueryPerformanceCounter(&currentCountHPC) == 0) {
+					throw_get_last_error<::std::runtime_error>("Failed call to QueryPerformanceCounter.");
+				}
+				const double millisecondsPerSecond = 1000.0;
+				m_elapsedTime = (static_cast<double>(currentCountHPC.QuadPart - m_lastCountHPC.QuadPart) / static_cast<double>(m_frequencyHPC.QuadPart)) * millisecondsPerSecond;
+				m_totalTime += m_elapsedTime;
+				m_lastCountHPC = currentCountHPC;
+			}
+			else {
+				auto currentTickCount = ::GetTickCount64();
+				if (currentTickCount < m_lastTickCount64) {
+					currentTickCount = m_lastTickCount64;
+				}
+				m_elapsedTime = static_cast<double>(currentTickCount - m_lastTickCount64);
+				m_totalTime += m_elapsedTime;
+				m_lastTickCount64 = currentTickCount;
+			}
+		}
+
+		double get_elapsed_time() {
+			return m_elapsedTime;
+		}
+
+		double get_total_time() {
+			return m_totalTime;
+		}
+	};
+}

win32/N3888_RefImpl/sample_draw.cpp

@@ -29,6 +29,9 @@ void sample_draw::operator()(::std::experimental::drawing::context& ctxt, double
 	//context.set_source(pattern);
 	//context.paint();
 
+	static double timer = 0.0;
+	timer += elapsedTimeInMilliseconds;
+
 	ctxt.save();
 	auto scp = solid_color_pattern(0.0, 0.0, 1.0);
 	ctxt.set_source(scp);
@@ -116,7 +119,7 @@ void sample_draw::operator()(::std::experimental::drawing::context& ctxt, double
 	matrix m;
 	m.init_translate(300.0, 400.0);
 	const double two_pi = 3.1415926535897932 * 2.0;
-	m.rotate(two_pi * (fmod(elapsedTimeInMilliseconds, 4000.0) / 4000.0));
+	m.rotate(two_pi * (fmod(timer, 4000.0) / 4000.0));
 	ctxt.set_matrix(m);
 	ctxt.new_path();
 	ctxt.move_to(-100.0, 0.0);

win32/N3888_RefImpl/throw_helpers.h

@@ -1,4 +1,6 @@
 #pragma once
+#ifndef THROW_HELPERS_H
+#define THROW_HELPERS_H
 
 #include <sstream>
 #include <string>
@@ -20,9 +22,10 @@ inline void throw_if_null(void* ptr, const char* msg) {
 	}
 }
 
-template <class exception_type>
-inline void throw_get_last_error(const char* backupMessage) {
-	auto errorCode = GetLastError();
+#if defined(_WIN32_WINNT)
+
+// Returns the system error message as a string or, if there is no message, the result of calling ::std::to_string on errorCode.
+inline ::std::string get_last_error_string(DWORD errorCode = GetLastError(), bool* foundSystemMessage = nullptr) {
 	const auto strCount = 0xFFFF;
 	::std::unique_ptr<char[]> str(new char[strCount]);
 	ZeroMemory(str.get(), strCount * sizeof(char));
@@ -39,12 +42,33 @@ inline void throw_get_last_error(const char* backupMessage) {
 		);
 
 	if (char_count == 0) {
-		std::stringstream error_str;
-		error_str << backupMessage << " Error code: " << errorCode;
-		throw exception_type(error_str.str());
+		if (foundSystemMessage != nullptr) {
+			*foundSystemMessage = false;
+		}
+		return ::std::to_string(errorCode);
 	}
 	else {
-		throw exception_type(std::string(str.get()));
+		if (foundSystemMessage != nullptr) {
+			*foundSystemMessage = true;
+		}
+		return ::std::string(str.get());
 	}
 }
 
+template <class exception_type>
+inline void throw_get_last_error(const char* backupMessage, DWORD errorCode = GetLastError()) {
+	bool foundMessage;
+	auto error_message = get_last_error_string(errorCode, &foundMessage);
+	if (foundMessage) {
+		throw exception_type(error_message);
+	}
+	else {
+		::std::stringstream error_str;
+		error_str << backupMessage << " Error code: " << error_message;
+		throw exception_type(error_str.str());
+	}
+}
+
+#endif
+
+#endif