Fix font scaling bug on high DPI display. See rizonesoft/Notepad3#608 …

…and XhmikosR/notepad2-mod#175.

src/Helpers.c

@@ -142,6 +142,14 @@ BOOL IniSectionSetString(LPWSTR lpCachedIniSection, LPCWSTR lpName, LPCWSTR lpSt
 	return FALSE;
 }
 
+UINT GetCurrentPPI(HWND hwnd) {
+	HDC hDC = GetDC(hwnd);
+	UINT ppi = GetDeviceCaps(hDC, LOGPIXELSY);
+	ReleaseDC(hwnd, hDC);
+	ppi = max_u(ppi, USER_DEFAULT_SCREEN_DPI);
+	return ppi;
+}
+
 UINT GetCurrentDPI(HWND hwnd) {
 	UINT dpi = 0;
 	if (IsWin10AndAbove()) {
@@ -167,9 +175,8 @@ UINT GetCurrentDPI(HWND hwnd) {
 	}
 
 	if (dpi == 0) {
-		// FIXME: seems always get 96
 		HDC hDC = GetDC(hwnd);
-		dpi = GetDeviceCaps(hDC, LOGPIXELSX);
+		dpi = GetDeviceCaps(hDC, LOGPIXELSY);
 		ReleaseDC(hwnd, hDC);
 	}
 
@@ -488,6 +495,11 @@ BOOL SetWindowTitle(HWND hwnd, UINT uIDAppName, BOOL bIsElevated, UINT uIDUntitl
 	lstrcat(szTitle, pszSep);
 	lstrcat(szTitle, szAppName);
 
+#if 0
+	wsprintf(szAppName, L"; dpi=%u, %u", g_uCurrentDPI, g_uCurrentPPI);
+	lstrcat(szTitle, szAppName);
+#endif
+
 	return SetWindowText(hwnd, szTitle);
 }
 

src/Helpers.h

@@ -73,6 +73,7 @@ extern HINSTANCE g_hInstance;
 extern HANDLE g_hDefaultHeap;
 extern UINT16 g_uWinVer;
 extern UINT g_uCurrentDPI;
+extern UINT g_uCurrentPPI;
 extern WCHAR szIniFile[MAX_PATH];
 
 // MSDN: Operating System Version
@@ -100,6 +101,7 @@ extern WCHAR szIniFile[MAX_PATH];
 #endif
 
 #define RoundToCurrentDPI(value)	((g_uCurrentDPI*(value) + USER_DEFAULT_SCREEN_DPI/2) / USER_DEFAULT_SCREEN_DPI)
+#define ScaleFontSize(value)		MulDiv(g_uCurrentDPI, (value), g_uCurrentPPI)
 
 #define NP2HeapAlloc(size)			HeapAlloc(g_hDefaultHeap, HEAP_ZERO_MEMORY, (size))
 #define NP2HeapFree(hMem)			HeapFree(g_hDefaultHeap, 0, hMem)
@@ -153,6 +155,7 @@ static inline void EndWaitCursor(void) {
 	SetCursorPos(pt.x, pt.y);
 }
 
+UINT GetCurrentPPI(HWND hwnd);
 UINT GetCurrentDPI(HWND hwnd);
 BOOL PrivateIsAppThemed(void);
 HRESULT PrivateSetCurrentProcessExplicitAppUserModelID(PCWSTR AppID);

src/Notepad2.c

@@ -292,6 +292,7 @@ HANDLE		g_hDefaultHeap;
 HANDLE		g_hScintilla;
 UINT16		g_uWinVer;
 UINT		g_uCurrentDPI = USER_DEFAULT_SCREEN_DPI;
+UINT		g_uCurrentPPI = USER_DEFAULT_SCREEN_DPI;
 WCHAR		g_wchAppUserModelID[38] = L"";
 WCHAR		g_wchWorkingDirectory[MAX_PATH] = L"";
 
@@ -1405,12 +1406,12 @@ LRESULT CALLBACK MainWndProc(HWND hwnd, UINT umsg, WPARAM wParam, LPARAM lParam)
 //
 //
 static inline void UpdateSelectionMarginWidth() {
-	int width = bShowSelectionMargin ? RoundToCurrentDPI(16) : 0;
+	int width = bShowSelectionMargin ? ScaleFontSize(16) : 0;
 	SendMessage(hwndEdit, SCI_SETMARGINWIDTHN, 1, width);
 }
 
 static inline void UpdateFoldMarginWidth() {
-	int width = bShowCodeFolding ? RoundToCurrentDPI(13) : 0;
+	int width = bShowCodeFolding ? ScaleFontSize(13) : 0;
 	SciCall_SetMarginWidth(MARGIN_FOLD_INDEX, width);
 }
 
@@ -1486,6 +1487,7 @@ void SetWrapVisualFlags(void) {
 LRESULT MsgCreate(HWND hwnd, WPARAM wParam, LPARAM lParam) {
 	HINSTANCE hInstance = ((LPCREATESTRUCT)lParam)->hInstance;
 	g_uCurrentDPI = GetCurrentDPI(hwnd);
+	g_uCurrentPPI = GetCurrentPPI(hwnd);
 
 	// Setup edit control
 	hwndEdit = EditCreate(hwnd);
@@ -1827,11 +1829,12 @@ void CreateBars(HWND hwnd, HINSTANCE hInstance) {
 //
 void MsgDPIChanged(HWND hwnd, WPARAM wParam, LPARAM lParam) {
 	g_uCurrentDPI = HIWORD(wParam);
+	g_uCurrentPPI = GetCurrentPPI(hwnd);
 	RECT* const rc = (RECT *)lParam;
 	Sci_Position pos = SciCall_GetCurrentPos();
 #if 0
-	char buf[64];
-	sprintf(buf, "WM_DPICHANGED: dpi=%u\n", g_uCurrentDPI);
+	char buf[128];
+	sprintf(buf, "WM_DPICHANGED: dpi=%u, %u\n", g_uCurrentDPI, g_uCurrentPPI);
 	SendMessage(hwndEdit, SCI_INSERTTEXT, 0, (LPARAM)buf);
 #endif
 

src/Styles.c

@@ -2578,7 +2578,7 @@ void Style_SetStyles(HWND hwnd, int iStyle, LPCWSTR lpszStyle) {
 
 	// Size
 	if (Style_StrGetSizeEx(lpszStyle, &iValue)) {
-		iValue = RoundToCurrentDPI(iValue);
+		iValue = ScaleFontSize(iValue);
 		SendMessage(hwnd, SCI_STYLESETSIZEFRACTIONAL, iStyle, (LPARAM)iValue);
 	}