C++14 upgrade to C++17: 部分字符串类型修改为wstring_view

sdttttt · sdttttt · commit 3cb98527ff47 · 2025-08-28T14:44:39.000+08:00
diff --git a/CMakeLists.txt b/CMakeLists.txt
@@ -1,11 +1,12 @@
 cmake_minimum_required(VERSION 3.10)
 project(Timer VERSION 0.2)
 
-set(CMAKE_CXX_STANDARD 14)
-set(CMAKE_CXX_STANDARD_REQUIRED True)
+set(CMAKE_CXX_STANDARD 17)
+set(CMAKE_CXX_STANDARD_REQUIRED ON)
 
 file(GLOB SOURCES "*.cpp" "timer.rc")
 add_executable(timer WIN32 ${SOURCES})
 target_compile_definitions(timer PRIVATE _UNICODE UNICODE)
+target_compile_features(timer PRIVATE cxx_std_17)
 
 set(CMAKE_RUNTIME_OUTPUT_DIRECTORY ${PROJECT_SOURCE_DIR}/bin)
diff --git a/date.cpp b/date.cpp
@@ -9,7 +9,7 @@ namespace Date {
             const auto now = std::chrono::system_clock::now();
             const auto now_t = std::chrono::system_clock::to_time_t(now);
 
-            struct tm tm;
+            struct tm tm{};
             localtime_s(&tm, &now_t);
             return tm;
         }
@@ -26,18 +26,18 @@ namespace Date {
 
 
     std::chrono::hours CurrTimeHour() {
-        auto tm = currTM();
+        const auto tm = currTM();
 
         return std::chrono::hours(tm.tm_hour);
     }
 
     std::chrono::minutes CurrTimeMin() {
-        auto tm = currTM();
+        const auto tm = currTM();
         return std::chrono::minutes(tm.tm_min);
     }
 
     std::chrono::seconds CurrTimeSec() {
-        auto tm = currTM();
+        const auto tm = currTM();
         return std::chrono::seconds(tm.tm_sec);
     }
 
diff --git a/digital_font.cpp b/digital_font.cpp
@@ -1,6 +1,6 @@
 #include <windows.h>
 #include <gdiplus.h>
-#include <cmath>
+#include <string_view>
 #include <array>
 #include "gdi_obj.h"
 #include "digital_font.h"
@@ -136,27 +136,27 @@ namespace DigitalFont {
     }
 
     // 绘制时钟
-    void DrawClock(HDC hdc, std::wstring &time_str) {
+    void DrawClock(HDC hdc, const std::wstring_view time_str) {
         if (time_str.empty()) return;
 
         int start_x = PAINT_START_X;
-        int start_y = PAINT_START_Y;
+        constexpr int start_y = PAINT_START_Y;
 
-        for (wchar_t c: time_str) {
+        for (const wchar_t c: time_str) {
             // 数字
             if (c >= L'0' && c <= L'9') {
-                int digit = c - L'0';
+                const int digit = c - L'0';
                 DrawBkDigit(hdc, start_x, start_y, digit);
                 // 每个数码管数字的长度是 SEG_LENGTH + 2*SEG_WIDTH
                 start_x += SEG_LENGTH + 2 * SEG_WIDTH + DIGIT_SPACING;
             }
 
             // 冒号
             if (c == L':') {
-                int colon_y = start_y + (SEG_LENGTH * 2 + SEG_WIDTH * 3) / 2;
+                constexpr int colon_y = start_y + (SEG_LENGTH * 2 + SEG_WIDTH * 3) / 2;
 
                 IGDI::AutoGDI<HBRUSH> brush(CreateSolidBrush(RGB(0, 0, 0)));
-                HBRUSH old_brash = (HBRUSH) SelectObject(hdc, brush);
+                const auto old_brash = static_cast<HBRUSH>(SelectObject(hdc, brush));
 
                 Rectangle(hdc,
                           start_x, colon_y - COLON_SIZE - COLON_OFFSET_Y,
diff --git a/digital_font.h b/digital_font.h
@@ -15,8 +15,7 @@ namespace DigitalFont {
     constexpr auto COLON_GAP = 20; // 冒号之间的间距
     constexpr auto COLON_OFFSET_Y = 8; // 冒号的偏移量
 
-
     void DrawDigit(HDC hdc, int x, int y, int digit);
 
-    void DrawClock(HDC hdc, std::wstring &time_str);
+    void DrawClock(HDC hdc, std::wstring_view time_str);
 }
diff --git a/font.cpp b/font.cpp
@@ -7,7 +7,7 @@
 
 namespace Font {
     namespace {
-        HFONT createScaledFont(HDC hdc, _In_ const RECT &rect, _In_ const std::wstring &str) {
+        HFONT createScaledFont(HDC hdc, _In_ const RECT &rect, _In_ const std::wstring_view str) {
             // 计算字体大小
             int font_size_height = rect.bottom - rect.top;
             int font_size_width = rect.right - rect.left;
@@ -33,7 +33,7 @@ namespace Font {
         }
     }
 
-    void DrawScaledText(HDC hdc, _In_ RECT &rect, _In_ const std::wstring &str) {
+    void DrawScaledText(HDC hdc, _In_ RECT &rect, _In_ const std::wstring_view str) {
         if (str.empty()) return;
 
         IGDI::AutoGDI<HFONT> h_font(createScaledFont(hdc, rect, str));
@@ -42,7 +42,7 @@ namespace Font {
 
         DrawText(
             hdc,
-            str.c_str(),
+            str.data(),
             -1,
             &rect,
             DT_SINGLELINE
diff --git a/font.h b/font.h
@@ -6,5 +6,5 @@
 constexpr auto FONT_FAMILY = L"Arial";
 
 namespace Font {
-    void DrawScaledText(HDC hdc, _In_ RECT &rect, _In_ const std::wstring &str);
+    void DrawScaledText(HDC hdc, _In_ RECT &rect, _In_ const std::wstring_view str);
 }
diff --git a/gdi_obj.h b/gdi_obj.h
@@ -5,24 +5,29 @@
 // 自动包装GDI对象，在对象生命周期结束时自动释放
 namespace IGDI {
     template<typename T>
-    struct is_gdi_type : std::false_type {
+    struct is_gdi_type {
+        static constexpr bool value = false;
     };
 
     template<>
-    struct is_gdi_type<HFONT> : std::true_type {
+    struct is_gdi_type<HFONT> {
+        static constexpr bool value = true;
     };
 
     template<>
-    struct is_gdi_type<HBRUSH> : std::true_type {
+    struct is_gdi_type<HBRUSH> {
+        static constexpr bool value = true;
     };
 
     template<>
-    struct is_gdi_type<HPEN> : std::true_type {
+    struct is_gdi_type<HPEN> {
+        static constexpr bool value = true;
     };
 
     template<typename T>
     class AutoGDI {
-        static_assert(is_gdi_type<T>::value, "T must be a GDI object");
+        static_assert(is_gdi_type<T>::value == true, "T must be a GDI object");
+
         T obj;
 
     public:
diff --git a/main.cpp b/main.cpp
@@ -5,7 +5,7 @@
 
 
 int WINAPI WinMain(
-    _In_ HINSTANCE hInstance,
+    _In_ const HINSTANCE hInstance,
     _In_opt_ HINSTANCE hPrevInstance,
     _In_ LPSTR lpCmdLine,
     _In_ int nCmdShow
@@ -14,14 +14,14 @@ int WINAPI WinMain(
         SetProcessDpiAwarenessContext(DPI_AWARENESS_CONTEXT_PER_MONITOR_AWARE_V2);
     }
 
-    auto ret = CreateTimeClassAndWindow(hInstance, nCmdShow);
+    const auto ret = CreateTimeClassAndWindow(hInstance, nCmdShow);
     if (ret > 0) {
         return ret;
     }
 
     MSG msg;
 
-    while (GetMessage(&msg, NULL, 0, 0) > 0) {
+    while (GetMessage(&msg, nullptr, 0, 0) > 0) {
         TranslateMessage(&msg);
         DispatchMessage(&msg);
     }
diff --git a/setting_window.cpp b/setting_window.cpp
@@ -38,7 +38,7 @@ static LRESULT CALLBACK settingWndProc(
 }
 
 
-static void registerSettingClass(_In_ HINSTANCE hInstance) {
+static void registerSettingClass(_In_ const HINSTANCE hInstance) {
     WNDCLASSEX setting_wcex;
 
     setting_wcex.cbSize = sizeof(WNDCLASSEX);
@@ -65,23 +65,24 @@ static void registerSettingClass(_In_ HINSTANCE hInstance) {
 /// <param name="hInstance">应用程序实例的句柄。</param>
 /// <param name="nCmdShow">窗口显示方式的标志。</param>
 /// <returns>如果成功则返回 0，失败则返回 1。</returns>
-int CreateSettingClassAndWindow(_In_ HINSTANCE hInstance, _In_ int nCmdShow) {
+int CreateSettingClassAndWindow(_In_ HINSTANCE hInstance, _In_ const int nCmdShow) {
     WNDCLASSEX setting_wcex = {sizeof(WNDCLASSEX)};
     if (FALSE == GetClassInfoEx(hInstance, TEST_CLASS_NAME, &setting_wcex)) {
         registerSettingClass(hInstance);
     }
 
-    HWND setting_hwnd = CreateWindowEx(
+
+    const HWND setting_hwnd = CreateWindowEx(
         0,
         TEST_CLASS_NAME,
         TEST_WINDOW_TITLE,
         WS_OVERLAPPEDWINDOW,
         CW_USEDEFAULT, CW_USEDEFAULT,
         TEST_WINDOW_WIDTH, TEST_WINDOW_HEIGHT,
-        NULL,
-        NULL,
+        nullptr,
+        nullptr,
         hInstance,
-        NULL
+        nullptr
     );
     Debug::TryLastErrorMessageBox();
 
diff --git a/time_window.cpp b/time_window.cpp
@@ -25,25 +25,25 @@ struct WindowDisplay {
 };
 
 
-static void Exit(HWND hwnd) {
+static void Exit(const HWND hwnd) {
     KillTimer(hwnd, DATE_TIMER_ID);
     KillTimer(hwnd, ANIMATION_TIMER_ID);
     PostQuitMessage(0);
 }
 
-static void timerWindowFadeIn(HWND hwnd, WindowDisplay &wd) {
+static void timerWindowFadeIn(const HWND hwnd, WindowDisplay &wd) {
     wd.is_show = TRUE;
     wd.fading = TRUE;
-    SetTimer(hwnd, ANIMATION_TIMER_ID, 10, NULL); // 启动新定时器
+    SetTimer(hwnd, ANIMATION_TIMER_ID, 10, nullptr); // 启动新定时器
 }
 
-static void timerWindowFadeOut(HWND hwnd, WindowDisplay &wd) {
+static void timerWindowFadeOut(const HWND hwnd, WindowDisplay &wd) {
     wd.is_show = FALSE;
     wd.fading = TRUE;
-    SetTimer(hwnd, ANIMATION_TIMER_ID, 10, NULL); // 启动新定时器
+    SetTimer(hwnd, ANIMATION_TIMER_ID, 10, nullptr); // 启动新定时器
 }
 
-static void updateTimerWindowFadeAnimation(HWND hwnd, WindowDisplay &wd) {
+static void updateTimerWindowFadeAnimation(const HWND hwnd, WindowDisplay &wd) {
     // 提醒窗口开始动画
     if (wd.fading && wd.is_show) {
         wd.alpha += FADE_DURATION;
@@ -119,7 +119,7 @@ static LRESULT CALLBACK timeWndProc(
                     g_step_down.reset(Date::NextHourDistance());
                 }
 
-                InvalidateRect(hWnd, NULL, TRUE);
+                InvalidateRect(hWnd, nullptr, TRUE);
             }
 
             if (wParam == ANIMATION_TIMER_ID) {
diff --git a/time_window.h b/time_window.h
@@ -48,11 +48,12 @@ int CreateTimeClassAndWindow(_In_ HINSTANCE hInstance, _In_ int nCmdShow);
 // 抵达目标点后不会停止，可以继续调用step来继续步进
 class StepCountDown {
 public:
-    StepCountDown(long long down, long long count = 0) : count(count), down(down) {
+    explicit StepCountDown(const long long down, const long long count = 0) : count(count), down(down) {
     }
 
-    StepCountDown(std::chrono::seconds down,
-                  std::chrono::seconds count = std::chrono::seconds(0)) : count(count.count()), down(down.count()) {
+    explicit StepCountDown(const std::chrono::seconds down,
+                           const std::chrono::seconds count = std::chrono::seconds(0)) : count(count.count()),
+        down(down.count()) {
     }
 
     StepCountDown() : StepCountDown(0, 0) {
@@ -66,12 +67,13 @@ class StepCountDown {
         return abs(static_cast<int>(this->down - this->count));
     }
 
-    void reset(long long end, long long start = 0) {
+
+    void reset(const long long end, const long long start = 0) {
         this->count = start;
         this->down = end;
     }
 
-    void reset(std::chrono::seconds end, long long start = 0) {
+    void reset(const std::chrono::seconds end, const long long start = 0) {
         this->count = start;
         this->down = end.count();
     }

Original file line number	Diff line number	Diff line change
`@@ -9,7 +9,7 @@ namespace Date {`
`9`	`9`	`const auto now = std::chrono::system_clock::now();`
`10`	`10`	`const auto now_t = std::chrono::system_clock::to_time_t(now);`
`11`	`11`
`12`		`- struct tm tm;`
	`12`	`+ struct tm tm{};`
`13`	`13`	`localtime_s(&tm, &now_t);`
`14`	`14`	`return tm;`
`15`	`15`	`}`
`@@ -26,18 +26,18 @@ namespace Date {`
`26`	`26`
`27`	`27`
`28`	`28`	`std::chrono::hours CurrTimeHour() {`
`29`		`- auto tm = currTM();`
	`29`	`+ const auto tm = currTM();`
`30`	`30`
`31`	`31`	`return std::chrono::hours(tm.tm_hour);`
`32`	`32`	`}`
`33`	`33`
`34`	`34`	`std::chrono::minutes CurrTimeMin() {`
`35`		`- auto tm = currTM();`
	`35`	`+ const auto tm = currTM();`
`36`	`36`	`return std::chrono::minutes(tm.tm_min);`
`37`	`37`	`}`
`38`	`38`
`39`	`39`	`std::chrono::seconds CurrTimeSec() {`
`40`		`- auto tm = currTM();`
	`40`	`+ const auto tm = currTM();`
`41`	`41`	`return std::chrono::seconds(tm.tm_sec);`
`42`	`42`	`}`
`43`	`43`
Original file line number	Diff line number	Diff line change
`@@ -15,8 +15,7 @@ namespace DigitalFont {`
`15`	`15`	`constexpr auto COLON_GAP = 20; // 冒号之间的间距`
`16`	`16`	`constexpr auto COLON_OFFSET_Y = 8; // 冒号的偏移量`
`17`	`17`
`18`		`-`
`19`	`18`	`void DrawDigit(HDC hdc, int x, int y, int digit);`
`20`	`19`
`21`		`- void DrawClock(HDC hdc, std::wstring &time_str);`
	`20`	`+ void DrawClock(HDC hdc, std::wstring_view time_str);`
`22`	`21`	`}`
Original file line number	Diff line number	Diff line change
`@@ -6,5 +6,5 @@`
`6`	`6`	`constexpr auto FONT_FAMILY = L"Arial";`
`7`	`7`
`8`	`8`	`namespace Font {`
`9`		`- void DrawScaledText(HDC hdc, _In_ RECT &rect, _In_ const std::wstring &str);`
	`9`	`+ void DrawScaledText(HDC hdc, _In_ RECT &rect, _In_ const std::wstring_view str);`
`10`	`10`	`}`