changed DPI handling: dpi is now pushed into every control and saved there

10 files changed, 232 insertions, 121 deletions

diff --git a/alf/alf.cpp b/alf/alf.cpp
index deffd1a..30a998c 100644
--- a/alf/alf.cpp
+++ b/alf/alf.cpp
@@ -174,16 +174,24 @@ ALF_GetModalResult(HWND win)
 }
 
 int
-ALF_CentipointsToPixels(HWND win, int cptValue)
+ALF_CentipointsToPixels(int cptValue, int dpi)
 {
-    return (int)SendMessage(win, ALF_WM_CENTIPOINTTOPX, (WPARAM)cptValue, 0);
+    return MulDiv(cptValue, dpi, 7200);
+}
+
+int
+ALF_GetDpi(HWND window)
+{
+    return (int)SendMessage(window, ALF_WM_GETDPI, 0, 0);
 }
 
 void
 ALF_ResizeWindow(HWND win, int cptWidth, int cptHeight)
 {
-    int pxwidth = ALF_CentipointsToPixels(win, cptWidth);
-    int pxheight = ALF_CentipointsToPixels(win, cptHeight);
+    int dpi = ALF_GetDpi(win);
+
+    int pxwidth = ALF_CentipointsToPixels(cptWidth, dpi);
+    int pxheight = ALF_CentipointsToPixels(cptHeight, dpi);
 
     ALF_ResizeWindowPx(win, pxwidth, pxheight);
 }
@@ -408,7 +416,7 @@ ALF_ShouldMessageBubble(HWND hwnd, UINT msg, WPARAM wparam, LPARAM lparam)
     if (!GetParent(hwnd))
         return FALSE;
 
-    return msg == ALF_WM_CENTIPOINTTOPX
+    return msg == ALF_WM_GETDPI
         || msg == WM_COMMAND || msg == WM_NOTIFY
         || msg == WM_MEASUREITEM || msg == WM_DRAWITEM
         || msg == WM_CTLCOLORBTN || msg == WM_CTLCOLOREDIT
diff --git a/alf/alf.h b/alf/alf.h
index 48b7834..d300342 100644
--- a/alf/alf.h
+++ b/alf/alf.h
@@ -8,12 +8,6 @@ extern "C" {
 #endif
 
 typedef struct {
-    UINT    dpi;
-    LOGFONT lfMessageFont;
-    HFONT   hMessageFont;
-} ALFWindowFonts;
-
-typedef struct {
     void (*create)(void * /*closure*/, HWND /*window*/);
     void (*destroy)(void * /*closure*/, HWND /*window*/);
     BOOL (*close)(void * /*closure*/, HWND /*window*/);
@@ -48,6 +42,7 @@ typedef struct {
 #define ALF_LAYOUT_INHERITBGCOLOR   0x80
 #define ALF_LAYOUT_TRANSPARENTBG   0x100
 #define ALF_LAYOUT_SENDBGCHANGE    0x200
+#define ALF_LAYOUT_SENDDPICHANGE   0x400
 
 
 // label style flags
@@ -76,7 +71,7 @@ typedef struct {
 #define ALF_WM_REMOVEWIDGET     (ALF_WM__BASE + 6)
 #define ALF_WM_SETMODALRESULT   (ALF_WM__BASE + 7)
 #define ALF_WM_GETMODALRESULT   (ALF_WM__BASE + 8)
-#define ALF_WM_CENTIPOINTTOPX   (ALF_WM__BASE + 9)
+#define ALF_WM_GETDPI           (ALF_WM__BASE + 9)
 #define ALF_WM_SETFOCUS         (ALF_WM__BASE + 10)
 #define ALF_WM_BACKGROUNDCHANGE (ALF_WM__BASE + 11)
 #define ALF_WM_APPLYSIZE        (ALF_WM__BASE + 12)
@@ -106,6 +101,7 @@ typedef struct {
 #define ALF_WM_LYT_SETROWFLAGS  (ALF_WM__BASE + 36)
 #define ALF_WM_GETTEXTCOLOR     (ALF_WM__BASE + 37)
 #define ALF_WM_SETTEXTCOLOR     (ALF_WM__BASE + 38)
+#define ALF_WM_DPICHANGE        (ALF_WM__BASE + 39)
 
 #define ALF_WM_LBL_GETSTYLE     (ALF_WM__BASE + 201)
 #define ALF_WM_LBL_SETSTYLE     (ALF_WM__BASE + 202)
@@ -173,7 +169,10 @@ BOOL
 ALF_PreTranslateMessage(HWND hwnd, MSG *message);
 
 int
-ALF_CentipointsToPixels(HWND win, int cptValue);
+ALF_CentipointsToPixels(int cptValue, int dpi);
+
+int
+ALF_GetDpi(HWND hwnd);
 
 LRESULT
 ALF_DefWindowProc(HWND hwnd, UINT msg, WPARAM wparam, LPARAM lparam);
@@ -208,7 +207,7 @@ ALF_InvalidateLayout(HWND win);
 void
 ALF_InvalidateBackground(HWND win);
 
-// Recalculates the window's DPI and all fonts and applies them to child widgets.
+// Recalculates the window's fonts and applies them to child widgets.
 // ALF does this automatically on a DPI or settings change so you shouldn't have
 // to call ALF_UpdateFonts().
 void
diff --git a/alf/alfbutton.cpp b/alf/alfbutton.cpp
index ddf607d..579fdce 100644
--- a/alf/alfbutton.cpp
+++ b/alf/alfbutton.cpp
@@ -19,6 +19,7 @@ typedef struct {
     UINT itemStateCurrent;
     DWORD uxDefaultAnimationDuration;
     BOOL uxIsDefaultAnimating;
+    int dpi;
 } ALFButtonPriv;
 
 static void CALLBACK
@@ -294,9 +295,9 @@ ALF__ButtonSubclassProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam, UINT
         ALF_Free(textbuf);
 
         int xpadding = ALF_Compat_GetSystemMetricsForDpi(SM_CXEDGE,
-            (UINT)ALF_CentipointsToPixels(GetParent(hwnd), 7200)) * 2 + 6;
+            (UINT)priv->dpi) * 2 + 6;
         int ypadding = ALF_Compat_GetSystemMetricsForDpi(SM_CYEDGE,
-            (UINT)ALF_CentipointsToPixels(GetParent(hwnd), 7200)) * 2 + 4;
+            (UINT)priv->dpi) * 2 + 4;
 
         SIZE *pSize = (SIZE*)(void*)lParam;
         if (pSize->cx < r.right - r.left + xpadding) {
@@ -473,6 +474,10 @@ ALF__ButtonSubclassProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam, UINT
         ALF_InvalidateLayout(GetParent(hwnd));
     } else if (uMsg == WM_SETFONT) {
         ALF_InvalidateLayout(GetParent(hwnd));
+    } else if (uMsg == ALF_WM_DPICHANGE) {
+        priv->dpi = (int)lParam;
+        ALF_InvalidateLayout(GetParent(hwnd));
+        return TRUE;
     }
 
     return ALF_Compat_DefSubclassProc(hwnd, uMsg, wParam, lParam);
@@ -494,12 +499,13 @@ ALF_AddButton(HWND win, WORD id, int x, int y, const TCHAR *text)
     ALFButtonPriv *priv = ALF_New(ALFButtonPriv, 1);
     priv->uxStateCurrent = -1;
     priv->uxStatePrev = -1;
+    priv->dpi = 96;
 
     ALF_Compat_SetWindowSubclass(hwndButton, ALF__ButtonSubclassProc, 0, (DWORD_PTR)priv);
 
     SendMessage(hwndButton, WM_THEMECHANGED, 0, 0);
 
-    ALF_AddWidget(win, x, y, hwndButton, 0, 0, ALF_LAYOUT_SIZE_QUERY | ALF_LAYOUT_INHERITFONT);
+    ALF_AddWidget(win, x, y, hwndButton, 0, 0, ALF_LAYOUT_SIZE_QUERY | ALF_LAYOUT_INHERITFONT | ALF_LAYOUT_SENDDPICHANGE);
 
     return hwndButton;
 }
diff --git a/alf/alfcombobox.cpp b/alf/alfcombobox.cpp
index 6d3af5e..994806e 100644
--- a/alf/alfcombobox.cpp
+++ b/alf/alfcombobox.cpp
@@ -17,6 +17,38 @@ typedef struct {
     DWORD  comboStyle;
 } ALFComboCreateParams;
 
+typedef struct {
+    HWND hwndChild;
+    int  dpi;
+} ALFComboPriv;
+
+static ALFComboPriv *
+ALF_Combo_InitializePriv(HWND hwnd, ALFComboCreateParams *params)
+{
+    ALFComboPriv *priv = ALF_New(ALFComboPriv, 1);
+    priv->dpi = 96;
+
+    DWORD comboStyle = params->comboStyle | CBS_OWNERDRAWFIXED | CBS_HASSTRINGS;
+
+    priv->hwndChild = CreateWindowEx(0,
+                                     TEXT("COMBOBOX"),
+                                     TEXT(""),
+                                     WS_CHILD | WS_VISIBLE | WS_VSCROLL | WS_TABSTOP | comboStyle,
+                                     0, 0, 100, 200 /* FIXME needed for commctl32 v5, what is the best value here? */,
+                                     hwnd,
+                                     (HMENU) GetWindowLongPtrW(hwnd, GWLP_ID),
+                                     ALF_HINSTANCE,
+                                     NULL);
+
+    return priv;
+}
+
+static void
+ALF_Combo_FreePriv(ALFComboPriv *priv)
+{
+    ALF_Free(priv);
+}
+
 static int
 ALF__ComboItemHeight(HWND hwnd)
 {
@@ -48,83 +80,80 @@ ALF__ComboItemHeight(HWND hwnd)
 static LRESULT CALLBACK
 ALF__ComboWindowProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
 {
-    HWND   hwndChild = (HWND)GetWindowLongPtr(hwnd, 0);
+    ALFComboPriv *priv = (ALFComboPriv *)GetWindowLongPtr(hwnd, 0);
 
     if (uMsg == WM_CREATE) {
         ALFComboCreateParams *params = (ALFComboCreateParams*)((CREATESTRUCT*)lParam)->lpCreateParams;
-        DWORD comboStyle = params->comboStyle | CBS_OWNERDRAWFIXED | CBS_HASSTRINGS;
-
-        HWND hwndCombo = CreateWindowEx(0,
-                                        TEXT("COMBOBOX"),
-                                        TEXT(""),
-                                        WS_CHILD | WS_VISIBLE | WS_VSCROLL | WS_TABSTOP | comboStyle,
-                                        0, 0, 100, 200 /* FIXME needed for commctl32 v5, what is the best value here? */,
-                                        hwnd,
-                                        (HMENU) GetWindowLongPtrW(hwnd, GWLP_ID),
-                                        ((CREATESTRUCT*)lParam)->hInstance,
-                                        NULL);
-
-        SetWindowLongPtr(hwnd, 0, (LONG_PTR)hwndCombo);
+
+        priv = ALF_Combo_InitializePriv(hwnd, params);
+        SetWindowLongPtr(hwnd, 0, (LONG_PTR)priv);
+    }
+
+    if (uMsg == WM_DESTROY) {
+        ALF_Combo_FreePriv(priv);
+        priv = NULL;
+        SetWindowLongPtr(hwnd, 0, 0);
     }
-    if (uMsg == WM_ENABLE && hwndChild) {
-        EnableWindow(hwndChild, (BOOL)wParam);
+
+    if (uMsg == WM_ENABLE && priv) {
+        EnableWindow(priv->hwndChild, (BOOL)wParam);
         return 0;
     }
-    if (uMsg == WM_SETTEXT && hwndChild) {
-        SetWindowText(hwndChild, (TCHAR*)lParam);
+    if (uMsg == WM_SETTEXT && priv) {
+        SetWindowText(priv->hwndChild, (TCHAR*)lParam);
         ALF_InvalidateLayout(GetParent(hwnd));
     }
-    if (uMsg == WM_GETTEXTLENGTH && hwndChild) {
-        return (LRESULT)GetWindowTextLength(hwndChild);
+    if (uMsg == WM_GETTEXTLENGTH && priv) {
+        return (LRESULT)GetWindowTextLength(priv->hwndChild);
     }
-    if (uMsg == WM_GETTEXT && hwndChild) {
-        return GetWindowText(hwndChild, (TCHAR*)lParam, (int)wParam);
+    if (uMsg == WM_GETTEXT && priv) {
+        return GetWindowText(priv->hwndChild, (TCHAR*)lParam, (int)wParam);
     }
-    if (uMsg == WM_SETFONT && hwndChild) {
-        SendMessage(hwndChild, WM_SETFONT, wParam, lParam);
-        SendMessage(hwndChild, CB_SETITEMHEIGHT, (WPARAM)0, (LPARAM)ALF__ComboItemHeight(hwnd));
+    if (uMsg == WM_SETFONT && priv) {
+        SendMessage(priv->hwndChild, WM_SETFONT, wParam, lParam);
+        SendMessage(priv->hwndChild, CB_SETITEMHEIGHT, (WPARAM)0, (LPARAM)ALF__ComboItemHeight(hwnd));
 
         ALF_InvalidateLayout(GetParent(hwnd));
 
         return 0;
     }
-    if (uMsg == WM_GETFONT && hwndChild) {
-        return SendMessage(hwndChild, WM_GETFONT, wParam, lParam);
+    if (uMsg == WM_GETFONT && priv) {
+        return SendMessage(priv->hwndChild, WM_GETFONT, wParam, lParam);
     }
-    if (uMsg == ALF_CB_GETSTYLE && hwndChild) {
-        return GetWindowLong(hwndChild, GWL_STYLE);
+    if (uMsg == ALF_CB_GETSTYLE && priv) {
+        return GetWindowLong(priv->hwndChild, GWL_STYLE);
     }
-    if ((uMsg == ALF_CB_FINDSTRINGEXACT || uMsg == CB_FINDSTRINGEXACT) && hwndChild) {
-        return SendMessage(hwndChild, CB_FINDSTRINGEXACT, wParam, lParam);
+    if ((uMsg == ALF_CB_FINDSTRINGEXACT || uMsg == CB_FINDSTRINGEXACT) && priv) {
+        return SendMessage(priv->hwndChild, CB_FINDSTRINGEXACT, wParam, lParam);
     }
-    if ((uMsg == ALF_CB_ADDSTRING || uMsg == CB_ADDSTRING) && hwndChild) {
-        return SendMessage(hwndChild, CB_ADDSTRING, wParam, lParam);
+    if ((uMsg == ALF_CB_ADDSTRING || uMsg == CB_ADDSTRING) && priv) {
+        return SendMessage(priv->hwndChild, CB_ADDSTRING, wParam, lParam);
     }
-    if ((uMsg == ALF_CB_INSERTSTRING || uMsg == CB_INSERTSTRING) && hwndChild) {
-        return SendMessage(hwndChild, CB_INSERTSTRING, wParam, lParam);
+    if ((uMsg == ALF_CB_INSERTSTRING || uMsg == CB_INSERTSTRING) && priv) {
+        return SendMessage(priv->hwndChild, CB_INSERTSTRING, wParam, lParam);
     }
-    if ((uMsg == ALF_CB_DELETESTRING || uMsg == CB_DELETESTRING) && hwndChild) {
-        return SendMessage(hwndChild, CB_DELETESTRING, wParam, lParam);
+    if ((uMsg == ALF_CB_DELETESTRING || uMsg == CB_DELETESTRING) && priv) {
+        return SendMessage(priv->hwndChild, CB_DELETESTRING, wParam, lParam);
     }
-    if ((uMsg == ALF_CB_GETCURSEL || uMsg == CB_GETCURSEL) && hwndChild) {
-        return SendMessage(hwndChild, CB_GETCURSEL, wParam, lParam);
+    if ((uMsg == ALF_CB_GETCURSEL || uMsg == CB_GETCURSEL) && priv) {
+        return SendMessage(priv->hwndChild, CB_GETCURSEL, wParam, lParam);
     }
-    if ((uMsg == ALF_CB_SETCURSEL || uMsg == CB_SETCURSEL) && hwndChild) {
-        LRESULT curSel = SendMessage(hwndChild, CB_GETCURSEL, 0, 0);
+    if ((uMsg == ALF_CB_SETCURSEL || uMsg == CB_SETCURSEL) && priv) {
+        LRESULT curSel = SendMessage(priv->hwndChild, CB_GETCURSEL, 0, 0);
         if ((WPARAM)curSel != wParam) {
-            LRESULT newSel = SendMessage(hwndChild, CB_SETCURSEL, wParam, 0);
-            SendMessage(hwnd, WM_COMMAND, MAKEWPARAM(GetWindowLong(hwndChild, GWL_ID), CBN_SELCHANGE), (LPARAM)hwndChild);
+            LRESULT newSel = SendMessage(priv->hwndChild, CB_SETCURSEL, wParam, 0);
+            SendMessage(hwnd, WM_COMMAND, MAKEWPARAM(GetWindowLong(priv->hwndChild, GWL_ID), CBN_SELCHANGE), (LPARAM)priv->hwndChild);
             return newSel;
         }
     }
-    if ((uMsg == ALF_CB_GETLBTEXTLEN || uMsg == CB_GETLBTEXTLEN) && hwndChild) {
-        return SendMessage(hwndChild, CB_GETLBTEXTLEN, wParam, lParam);
+    if ((uMsg == ALF_CB_GETLBTEXTLEN || uMsg == CB_GETLBTEXTLEN) && priv) {
+        return SendMessage(priv->hwndChild, CB_GETLBTEXTLEN, wParam, lParam);
     }
-    if ((uMsg == ALF_CB_GETLBTEXT || uMsg == CB_GETLBTEXT) && hwndChild) {
-        return SendMessage(hwndChild, CB_GETLBTEXT, wParam, lParam);
+    if ((uMsg == ALF_CB_GETLBTEXT || uMsg == CB_GETLBTEXT) && priv) {
+        return SendMessage(priv->hwndChild, CB_GETLBTEXT, wParam, lParam);
     }
 
-    if (uMsg == WM_COMMAND && (HWND)lParam == hwndChild) {
+    if (uMsg == WM_COMMAND && priv && (HWND)lParam == priv->hwndChild) {
         // XXX: for whatever reason, Win95 (and only win95 - doesn't happen on NT)
         // sends a wrong ID value in WPARAM. We fix it by replacing it with our own id.
         return SendMessage(GetParent(hwnd), WM_COMMAND, MAKEWPARAM(GetWindowLong(hwnd, GWL_ID), HIWORD(wParam)), (LPARAM)hwnd);
@@ -143,12 +172,12 @@ ALF__ComboWindowProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
             if (GetTextMetrics(hDc, &tm)) {
                 SIZE *ps = (SIZE*)lParam;
                 if (!ps->cx) {
-                    ps->cx = ALF_CentipointsToPixels(GetParent(hwnd), 12000);
+                    ps->cx = ALF_CentipointsToPixels(12000, priv->dpi);
                 }
 
                 if (!ps->cy) {
                     ps->cy = tm.tmHeight + 2*ALF_Compat_GetSystemMetricsForDpi(
-                            SM_CYEDGE, (UINT)ALF_CentipointsToPixels(GetParent(hwnd), 7200))
+                            SM_CYEDGE, (UINT)priv->dpi)
                         + 4 /* padding internal to the edit control */;
                 }
             }
@@ -225,30 +254,36 @@ ALF__ComboWindowProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
         return TRUE;
     }
 
-    if (uMsg == WM_WINDOWPOSCHANGED && hwndChild) {
+    if (uMsg == WM_WINDOWPOSCHANGED && priv) {
         WINDOWPOS *pos = (WINDOWPOS *)lParam;
         if (!(pos->flags & SWP_NOSIZE)) {
             // XXX: When resizing the combo box, it will improperly draw a selection.
             // this appears to be a well-known bug that is still not fixed, even in Win10.
             // workaround based on https://stackoverflow.com/questions/49603893/how-to-deal-with-invalidly-painted-combobox-control-in-win32-winapi
-            LRESULT sel = SendMessage(hwndChild, CB_GETEDITSEL, 0, 0);
-            SendMessage(hwndChild, CB_SETEDITSEL, 0, -1);
+            LRESULT sel = SendMessage(priv->hwndChild, CB_GETEDITSEL, 0, 0);
+            SendMessage(priv->hwndChild, CB_SETEDITSEL, 0, -1);
             // SWP_NOCOPYBITS because NT 3.51 doesn't properly repaint the drop-down button
-            SetWindowPos(hwndChild, NULL, 0, 0, pos->cx, 200, SWP_NOZORDER|SWP_NOACTIVATE|SWP_NOCOPYBITS);
-            SendMessage(hwndChild, CB_SETEDITSEL, 0, (LPARAM)sel);
+            SetWindowPos(priv->hwndChild, NULL, 0, 0, pos->cx, 200, SWP_NOZORDER|SWP_NOACTIVATE|SWP_NOCOPYBITS);
+            SendMessage(priv->hwndChild, CB_SETEDITSEL, 0, (LPARAM)sel);
 
             int heightOffset = 0;
             if (ALF_Compat_IsMinWindowsVersion(4, 0)) {
                 heightOffset = - 2*ALF_Compat_GetSystemMetricsForDpi(
-                            SM_CYEDGE, (UINT)ALF_CentipointsToPixels(GetParent(hwnd), 7200))
+                            SM_CYEDGE, (UINT)priv->dpi)
                             - 2;
             }
 
-            SendMessage(hwndChild, CB_SETITEMHEIGHT, (WPARAM)-1, pos->cy + heightOffset);
-            SendMessage(hwndChild, CB_SETITEMHEIGHT, (WPARAM)0, (LPARAM)ALF__ComboItemHeight(hwnd));
+            SendMessage(priv->hwndChild, CB_SETITEMHEIGHT, (WPARAM)-1, pos->cy + heightOffset);
+            SendMessage(priv->hwndChild, CB_SETITEMHEIGHT, (WPARAM)0, (LPARAM)ALF__ComboItemHeight(hwnd));
         }
     }
 
+    if (uMsg == ALF_WM_DPICHANGE && priv) {
+        priv->dpi = (int)lParam;
+        ALF_InvalidateLayout(GetParent(hwnd));
+        return TRUE;
+    }
+
     return DefWindowProc(hwnd, uMsg, wParam, lParam);
 }
 
@@ -295,7 +330,7 @@ ALF_InternalAddComboBox(HWND win, WORD id, int x, int y, DWORD style, const TCHA
     if (defaultText)
         SetWindowText(hwndCombo, defaultText);
 
-    ALF_AddWidget(win, x, y, hwndCombo, 0, 0, ALF_LAYOUT_SIZE_QUERY | ALF_LAYOUT_INHERITFONT);
+    ALF_AddWidget(win, x, y, hwndCombo, 0, 0, ALF_LAYOUT_SIZE_QUERY | ALF_LAYOUT_INHERITFONT | ALF_LAYOUT_SENDDPICHANGE);
 
     return hwndCombo;
 }
diff --git a/alf/alflabel.cpp b/alf/alflabel.cpp
index 37f1e83..13c86ae 100644
--- a/alf/alflabel.cpp
+++ b/alf/alflabel.cpp
@@ -7,27 +7,32 @@ typedef struct {
     HFONT    font;
     ALFColor bgcolor;
     ALFColor textcolor;
+    int      dpi;
 } ALFLabelPriv;
 
 TCHAR *_alf_labelClass;
 
 static int
-ALF__LabelTopPadding(HWND hwnd)
+ALF__LabelTopPadding(HWND hwnd, ALFLabelPriv *priv)
 {
+    (void)hwnd;
+
     // some pixels on top to align with the edit control
     // see also: alfedit.cpp
     return ALF_Compat_GetSystemMetricsForDpi(
-                SM_CYEDGE, (UINT)ALF_CentipointsToPixels(GetParent(hwnd), 7200))
+                SM_CYEDGE, (UINT)priv->dpi)
             + (!ALF_Compat_IsMinWindowsVersion(4, 0) ? 2 : 1) /* internal padding in edit control */;
 }
 
 static int
-ALF__LabelLeftPadding(HWND hwnd, HDC hdc)
+ALF__LabelLeftPadding(HWND hwnd, HDC hdc, ALFLabelPriv *priv)
 {
+    (void)hwnd;
+
     // some pixels on the left to align with the edit control
     // see also: alfedit.cpp
     int p = ALF_Compat_GetSystemMetricsForDpi(
-                SM_CXEDGE, (UINT)ALF_CentipointsToPixels(GetParent(hwnd), 7200));
+                SM_CXEDGE, (UINT)priv->dpi);
 
     p += 1;
 
@@ -98,9 +103,9 @@ ALF_Label_Paint(HWND hwnd, ALFLabelPriv *priv, HDC hdc, RECT *r)
     }
 
     if ((priv->style & ALF_LABEL_HALIGN_MASK) == ALF_LABEL_ALIGN_LEFT_LIKE_EDIT)
-        rc.left += ALF__LabelLeftPadding(hwnd, hdc);
+        rc.left += ALF__LabelLeftPadding(hwnd, hdc, priv);
     if ((priv->style & ALF_LABEL_VALIGN_MASK) == ALF_LABEL_ALIGN_TOP_LIKE_EDIT)
-        rc.top += ALF__LabelTopPadding(hwnd);
+        rc.top += ALF__LabelTopPadding(hwnd, priv);
 
     TCHAR *text = ALF_Text(hwnd);
 
@@ -160,12 +165,12 @@ ALF_Label_CalculateSize(HWND hwnd, ALFLabelPriv *priv, SIZE *pSize)
         if (pSize->cx == 0) {
             pSize->cx = r.right - r.left;
             if ((priv->style & ALF_LABEL_HALIGN_MASK) == ALF_LABEL_ALIGN_LEFT_LIKE_EDIT)
-                pSize->cx += ALF__LabelLeftPadding(hwnd, hdcLabel);
+                pSize->cx += ALF__LabelLeftPadding(hwnd, hdcLabel, priv);
         }
         if (pSize->cy == 0) {
             pSize->cy = r.bottom - r.top;
             if ((priv->style & ALF_LABEL_VALIGN_MASK) == ALF_LABEL_ALIGN_TOP_LIKE_EDIT)
-                pSize->cy += ALF__LabelTopPadding(hwnd);
+                pSize->cy += ALF__LabelTopPadding(hwnd, priv);
         }
 
         SelectFont(hdcLabel, oldFont);
@@ -275,6 +280,10 @@ ALF__LabelWindowProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
         return TRUE;
     } else if (uMsg == ALF_WM_GETTEXTCOLOR) {
         return (LRESULT)priv->textcolor;
+    } else if (uMsg == ALF_WM_DPICHANGE) {
+        priv->dpi = (int)lParam;
+        ALF_InvalidateLayout(GetParent(hwnd));
+        return TRUE;
     } else if (uMsg == WM_DESTROY) {
         ALF_Free(priv);
         SetWindowLongPtr(hwnd, 0, 0);
@@ -299,9 +308,10 @@ ALF_AddLabel(HWND win, WORD id, int x, int y, const TCHAR *text)
     priv->style = ALF_LABEL_ALIGN_LEFT | ALF_LABEL_ALIGN_TOP_LIKE_EDIT;
     priv->bgcolor = ALF_COLOR_SYS(COLOR_BTNFACE);
     priv->textcolor = ALF_COLOR_SYS(COLOR_BTNTEXT);
+    priv->dpi = 96;
     SetWindowLongPtr(hwndLabel, 0, (LONG_PTR)priv);
 
-    ALF_AddWidget(win, x, y, hwndLabel, 0, 0, ALF_LAYOUT_SIZE_QUERY | ALF_LAYOUT_INHERITFONT | ALF_LAYOUT_INHERITBGCOLOR | ALF_LAYOUT_SENDBGCHANGE);
+    ALF_AddWidget(win, x, y, hwndLabel, 0, 0, ALF_LAYOUT_SIZE_QUERY | ALF_LAYOUT_INHERITFONT | ALF_LAYOUT_INHERITBGCOLOR | ALF_LAYOUT_SENDBGCHANGE | ALF_LAYOUT_SENDDPICHANGE);
 
     return hwndLabel;
 }
diff --git a/alf/alflayout.cpp b/alf/alflayout.cpp
index 5c1ad55..15b8f5d 100644
--- a/alf/alflayout.cpp
+++ b/alf/alflayout.cpp
@@ -76,6 +76,7 @@ ALF_Layout_Init(ALFLayout *layout)
     layout->rows = ALF_New(ALFLayoutRowOrColumn, (SIZE_T)layout->nRows);
     layout->nColumns = 1;
     layout->columns = ALF_New(ALFLayoutRowOrColumn, (SIZE_T)layout->nColumns);
+    layout->dpi = 96;
 }
 
 void
@@ -127,6 +128,20 @@ ALF_Layout_ForwardBgColor(ALFLayout *layout, HWND window, WPARAM wparam, LPARAM
 }
 
 static void
+ALF_Layout_ForwardDpiChange(ALFLayout *layout, HWND window, WPARAM wparam, LPARAM lparam)
+{
+    ALF_FOR_LIST(ALFWidgetPriv, list, &layout->widgets, i) {
+        if (i->flags & ALF_LAYOUT_SENDDPICHANGE) {
+            SendMessage(i->hwnd, ALF_WM_DPICHANGE, wparam, lparam);
+        }
+
+        if (i->flags & ALF_LAYOUT_SIZE_EDIT) {
+            ALF_Layout_Invalidate(layout, window);
+        }
+    }
+}
+
+static void
 ALF_Layout_HandleBackgroundChange(ALFLayout *layout, HWND window)
 {
     (void)window;
@@ -162,7 +177,7 @@ ALF_Layout_EnsureColumnExists(ALFLayout *layout, int colno)
 static void
 ALF_Layout_CalcEditSize(HWND hwndWindow, ALFLayout *layout, HWND hwndEdit, SIZE *ps)
 {
-    (void)layout;
+    (void)hwndWindow;
 
     HDC hDc = GetDC(hwndEdit);
     HFONT font = (HFONT)SendMessage(hwndEdit, WM_GETFONT, 0, 0);
@@ -174,12 +189,12 @@ ALF_Layout_CalcEditSize(HWND hwndWindow, ALFLayout *layout, HWND hwndEdit, SIZE
 
     if (GetTextMetrics(hDc, &tm)) {
         if (!ps->cx) {
-            ps->cx = ALF_CentipointsToPixels(hwndWindow, 12000);
+            ps->cx = ALF_CentipointsToPixels(12000, layout->dpi);
         }
 
         if (!ps->cy) {
             ps->cy = tm.tmHeight + 2*ALF_Compat_GetSystemMetricsForDpi(
-                    SM_CYEDGE, (UINT)ALF_CentipointsToPixels(hwndWindow, 7200))
+                    SM_CYEDGE, (UINT)layout->dpi)
                 + 4 /* padding internal to the edit control */;
         }
     }
@@ -196,8 +211,8 @@ ALF_Layout_CalcMinWidgetSize(ALFLayout *layout, ALFWidgetPriv *c, HWND window, S
         s->cx = c->width;
         s->cy = c->height;
     } else {
-        s->cx = ALF_CentipointsToPixels(window, c->width);
-        s->cy = ALF_CentipointsToPixels(window, c->height);
+        s->cx = ALF_CentipointsToPixels(c->width, layout->dpi);
+        s->cy = ALF_CentipointsToPixels(c->height, layout->dpi);
     }
 
     switch (c->flags & ALF_LAYOUT_SIZETYPE_MASK) {
@@ -224,7 +239,7 @@ ALF_Layout_CalcSizes(ALFLayout* layout, HWND window)
         if (layout->columns[i].requestedFlags & ALF_LAYOUT_SIZE_PX) {
             layout->columns[i].calculatedMinWidth = layout->columns[i].requestedMinWidth;
         } else {
-            layout->columns[i].calculatedMinWidth = ALF_CentipointsToPixels(window, layout->columns[i].requestedMinWidth);
+            layout->columns[i].calculatedMinWidth = ALF_CentipointsToPixels(layout->columns[i].requestedMinWidth, layout->dpi);
         }
 
         layout->columns[i].calculatedExpandNumerator = layout->columns[i].requestedExpandNumerator;
@@ -239,7 +254,7 @@ ALF_Layout_CalcSizes(ALFLayout* layout, HWND window)
         if (layout->rows[i].requestedFlags & ALF_LAYOUT_SIZE_PX) {
             layout->rows[i].calculatedMinWidth = layout->rows[i].requestedMinWidth;
         } else {
-            layout->rows[i].calculatedMinWidth = ALF_CentipointsToPixels(window, layout->rows[i].requestedMinWidth);
+            layout->rows[i].calculatedMinWidth = ALF_CentipointsToPixels(layout->rows[i].requestedMinWidth, layout->dpi);
         }
         layout->rows[i].calculatedExpandNumerator = layout->rows[i].requestedExpandNumerator;
         layout->rowExpandDenominator += layout->rows[i].requestedExpandNumerator;
@@ -447,6 +462,9 @@ ALF_Layout_AddWidget(ALFLayout* layout, HWND window, const ALFAddWidgetParams* p
     if (w->flags & ALF_LAYOUT_INHERITBGCOLOR) {
         SendMessage(w->hwnd, ALF_WM_SETBGCOLOR, 0, (LPARAM)ALF_BackgroundColor(window));
     }
+    if (w->flags & ALF_LAYOUT_SENDDPICHANGE) {
+        SendMessage(w->hwnd, ALF_WM_DPICHANGE, 0, (LPARAM)layout->dpi);
+    }
 
     ALF_ListInsert(layout->widgets.prev, &w->list);
 
@@ -602,6 +620,8 @@ ALF_Layout_SetWidgetFlags(ALFLayout *layout, HWND window, HWND needle, DWORD fla
                 ALF_Layout_ForwardFontToWidget(layout, window, w, (HFONT)SendMessage(window, WM_GETFONT, 0, 0), 0);
             if (flags & ALF_LAYOUT_INHERITBGCOLOR)
                 SendMessage(w->hwnd, ALF_WM_SETBGCOLOR, 0, (LPARAM)ALF_BackgroundColor(window));
+            if (flags & ALF_LAYOUT_SENDDPICHANGE)
+                SendMessage(w->hwnd, ALF_WM_DPICHANGE, 0, (LPARAM)layout->dpi);
 
             ALF_Layout_Invalidate(layout, window);
 
@@ -792,6 +812,20 @@ ALF_Layout_HandleMessage(ALFLayout *layout, HWND hwnd, UINT msg, WPARAM wparam,
         return TRUE;
     }
 
+    if (msg == ALF_WM_DPICHANGE) {
+        int dpi = (int)lparam;
+        if (dpi != layout->dpi) {
+            layout->dpi = dpi;
+            ALF_Layout_ForwardDpiChange(layout, hwnd, wparam, lparam);
+            ALF_Layout_Invalidate(layout, hwnd);
+        }
+        return TRUE;
+    }
+
+    if (msg == ALF_WM_GETDPI) {
+        return (LRESULT)layout->dpi;
+    }
+
     if (msg == ALF_WM_INVALIDATELAYOUT) {
         ALF_Layout_Invalidate(layout, hwnd);
         return TRUE;
diff --git a/alf/alflayout.h b/alf/alflayout.h
index ce2350f..4d97eb5 100644
--- a/alf/alflayout.h
+++ b/alf/alflayout.h
@@ -53,6 +53,7 @@ typedef struct {
     int                   biggestColumnNo;
     int                   biggestRowNo;
     DWORD                 layoutValididityFlags;
+    int                   dpi;
 } ALFLayout;
 
 void
diff --git a/alf/alfnotebook.cpp b/alf/alfnotebook.cpp
index 501b072..6ffbe5d 100644
--- a/alf/alfnotebook.cpp
+++ b/alf/alfnotebook.cpp
@@ -17,6 +17,7 @@ typedef struct {
     HTHEME   hTheme;
     ALFColor themeTabBgColor;
     DWORD    flags;
+    int      dpi;
 } ALFNotebookPriv;
 
 typedef struct {
@@ -137,6 +138,16 @@ ALF_Notebook_PropagateFontToPages(HWND hwndNotebook, ALFNotebookPriv *priv, HFON
 }
 
 static void
+ALF_Notebook_PropagateDpiChange(HWND hwndNotebook, ALFNotebookPriv *priv, WPARAM wparam, LPARAM lparam)
+{
+    int n = ALF_Notebook_InternalTabCount(hwndNotebook, priv->hwndTabCtrl);
+    for (int i = 0; i < n; ++i) {
+        HWND hwndPanel = ALF_NotebookTabPanel(hwndNotebook, i);
+        SendMessage(hwndPanel, ALF_WM_DPICHANGE, wparam, lparam);
+    }
+}
+
+static void
 ALF_Notebook_InternalHandleThemeChange(HWND hwndNotebook, ALFNotebookPriv *priv)
 {
     ALF_Compat_CloseThemeData(priv->hTheme);
@@ -172,6 +183,7 @@ ALF_Notebook_InternalAddTab(HWND notebook, ALFNotebookPriv *priv, const TCHAR *t
     SetWindowPos(hwndPanel, NULL, r.left, r.top, r.right - r.left, r.bottom - r.top, SWP_HIDEWINDOW|SWP_NOACTIVATE|SWP_NOZORDER|SWP_NOOWNERZORDER);
 
     SendMessage(hwndPanel, WM_SETFONT, (WPARAM)SendMessage(priv->hwndTabCtrl, WM_GETFONT, 0, 0), 0);
+    SendMessage(hwndPanel, ALF_WM_DPICHANGE, 0, (LPARAM)priv->dpi);
 
     ALF_Notebook_SetSingleTabBackground(notebook, priv, hwndPanel);
 
@@ -458,6 +470,10 @@ ALF__NotebookWindowProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
         return (LRESULT)ALF_Notebook_GetWidgetFlags(hwnd, priv, (HWND)wParam);
     } else if (uMsg == ALF_WM_LYT_SETWDGTFLAGS) {
         return (LRESULT)ALF_Notebook_SetWidgetFlags(hwnd, priv, (HWND)wParam, (DWORD)lParam);
+    } else if (uMsg == ALF_WM_DPICHANGE) {
+        priv->dpi = (int)lParam;
+        ALF_Notebook_PropagateDpiChange(hwnd, priv, wParam, lParam);
+        return TRUE;
     }
 
     return DefWindowProc(hwnd, uMsg, wParam, lParam);
@@ -499,7 +515,7 @@ ALF_AddNotebook(HWND parent, WORD id, int x, int y)
                                     ALF_HINSTANCE,
                                     NULL);
 
-    ALF_AddWidget(parent, x, y, hwndNtbk, 0, 0, ALF_LAYOUT_SIZE_QUERY | ALF_LAYOUT_INHERITFONT);
+    ALF_AddWidget(parent, x, y, hwndNtbk, 0, 0, ALF_LAYOUT_SIZE_QUERY | ALF_LAYOUT_INHERITFONT | ALF_LAYOUT_SENDDPICHANGE);
 
     return hwndNtbk;
 }
diff --git a/alf/alfpanel.cpp b/alf/alfpanel.cpp
index 7e109bb..663dbd0 100644
--- a/alf/alfpanel.cpp
+++ b/alf/alfpanel.cpp
@@ -210,7 +210,7 @@ ALF_AddPanel(HWND parent, WORD id, int x, int y)
 {
     HWND hwndPanel = ALF_CreatePanelWindow(parent, id);
 
-    ALF_AddWidget(parent, x, y, hwndPanel, 0, 0, ALF_LAYOUT_SIZE_QUERY | ALF_LAYOUT_INHERITFONT | ALF_LAYOUT_INHERITBGCOLOR | ALF_LAYOUT_SENDBGCHANGE);
+    ALF_AddWidget(parent, x, y, hwndPanel, 0, 0, ALF_LAYOUT_SIZE_QUERY | ALF_LAYOUT_INHERITFONT | ALF_LAYOUT_INHERITBGCOLOR | ALF_LAYOUT_SENDBGCHANGE | ALF_LAYOUT_SENDDPICHANGE);
 
     return hwndPanel;
 }
diff --git a/alf/alfwindow.cpp b/alf/alfwindow.cpp
index c11fede..d372ebc 100644
--- a/alf/alfwindow.cpp
+++ b/alf/alfwindow.cpp
@@ -3,12 +3,12 @@
 typedef struct {
     ALFWindowVTable    *vtbl;
     void               *closure;
-    ALFWindowFonts      fonts;
     int                 modalResult;
     ALFLayout           layout;
     WORD                defid;
     HWND                hwndFocus;
     HFONT               font;
+    HFONT               hMessageFont;
     ALFColor            bgcolor;
 } ALFWindowPriv;
 
@@ -30,8 +30,8 @@ ALF_DestroyWindowPriv(ALFWindowPriv *priv)
 
     ALF_Layout_Clear(&priv->layout);
 
-    if (priv->fonts.hMessageFont)
-        DeleteObject(priv->fonts.hMessageFont);
+    if (priv->hMessageFont)
+        DeleteObject(priv->hMessageFont);
 
     ALF_Free(priv);
 }
@@ -39,39 +39,34 @@ ALF_DestroyWindowPriv(ALFWindowPriv *priv)
 static void
 ALF_UpdateFontsPriv(HWND win, ALFWindowPriv *priv)
 {
-    priv->fonts.dpi = ALF_Compat_GetDpiForWindow(win);
-
     // XXX: SystemParametersInfoForDpi is Unicode-only and needs Vista+ NONCLIENTMETRICS,
     ALF_NONCLIENTMETRICSW_VISTA ncm;
     ZeroMemory(&ncm, sizeof(ncm));
     ncm.cbSize = sizeof(ncm);
 
-    if (ALF_Compat_SystemParametersInfoForDpi(SPI_GETNONCLIENTMETRICS, ncm.cbSize, &ncm, 0, priv->fonts.dpi)) {
+    LOGFONT lfMessageFont;
+    ZeroMemory(&lfMessageFont, sizeof(lfMessageFont));
+
+    if (ALF_Compat_SystemParametersInfoForDpi(SPI_GETNONCLIENTMETRICS, ncm.cbSize, &ncm, 0, (UINT)priv->layout.dpi)) {
 #ifdef UNICODE
-        priv->fonts.lfMessageFont = ncm.lfMessageFont;
+        lfMessageFont = ncm.lfMessageFont;
 #else
-        ALF_Compat_LogFontWtoA(&ncm.lfMessageFont, &priv->fonts.lfMessageFont);
+        ALF_Compat_LogFontWtoA(&ncm.lfMessageFont, &lfMessageFont);
 #endif
     } else {
         // FIXME! fallback to default font, 8pt MS Shell Dlg
-        ZeroMemory(&priv->fonts.lfMessageFont, sizeof(priv->fonts.lfMessageFont));
+        ZeroMemory(&lfMessageFont, sizeof(lfMessageFont));
 
-        priv->fonts.lfMessageFont.lfHeight = -MulDiv(8, (int)priv->fonts.dpi, 72);
-        lstrcpy(priv->fonts.lfMessageFont.lfFaceName, TEXT("MS Shell Dlg"));
+        lfMessageFont.lfHeight = -MulDiv(8, priv->layout.dpi, 72);
+        lstrcpy(lfMessageFont.lfFaceName, TEXT("MS Shell Dlg"));
     }
 
-    if (priv->fonts.hMessageFont) {
-        DeleteObject(priv->fonts.hMessageFont);
+    if (priv->hMessageFont) {
+        DeleteObject(priv->hMessageFont);
     }
-    priv->fonts.hMessageFont = CreateFontIndirect(&priv->fonts.lfMessageFont);
-
-    SendMessage(win, WM_SETFONT, (WPARAM)priv->fonts.hMessageFont, (LPARAM)1);
-}
+    priv->hMessageFont = CreateFontIndirect(&lfMessageFont);
 
-static int
-ALF_CentipointsToPxPriv(ALFWindowPriv *priv, int cptValue)
-{
-    return MulDiv(cptValue, (int)priv->fonts.dpi, 7200);
+    SendMessage(win, WM_SETFONT, (WPARAM)priv->hMessageFont, (LPARAM)1);
 }
 
 static void
@@ -173,8 +168,8 @@ ALF_DefWindowProc(HWND hwnd, UINT msg, WPARAM wparam, LPARAM lparam)
         return 0;
     }
 
-    if (msg == ALF_WM_CENTIPOINTTOPX) {
-        return (LRESULT)ALF_CentipointsToPxPriv(priv, (int)wparam);
+    if (msg == ALF_WM_GETDPI) {
+        return (LRESULT)priv->layout.dpi;
     }
 
     if (msg == ALF_WM_SETFOCUS) {
@@ -327,7 +322,7 @@ ALF_DefWindowProc(HWND hwnd, UINT msg, WPARAM wparam, LPARAM lparam)
                                (DWORD)GetWindowLong(hwnd, GWL_STYLE),
                                GetMenu(hwnd) != NULL,
                                (DWORD)GetWindowLong(hwnd, GWL_EXSTYLE),
-                               priv->fonts.dpi)) {
+                               (UINT)priv->layout.dpi)) {
             MINMAXINFO *i = (MINMAXINFO *)lparam;
             i->ptMinTrackSize.x = tmp.right - tmp.left;
             i->ptMinTrackSize.y = tmp.bottom - tmp.top;
@@ -336,7 +331,9 @@ ALF_DefWindowProc(HWND hwnd, UINT msg, WPARAM wparam, LPARAM lparam)
     }
 
     if (msg == WM_CREATE) {
-        ALF_UpdateFontsPriv(hwnd, priv);
+        int dpi = (int)ALF_Compat_GetDpiForWindow(hwnd);
+        SendMessage(hwnd, ALF_WM_DPICHANGE, 0, (LPARAM)dpi); // will also update fonts
+
         if (priv->vtbl->create) {
             priv->vtbl->create(priv->closure, hwnd);
         }
@@ -366,8 +363,9 @@ ALF_DefWindowProc(HWND hwnd, UINT msg, WPARAM wparam, LPARAM lparam)
     }
 
     if (msg == WM_DPICHANGED) {
-        ALF_UpdateFontsPriv(hwnd, priv);
-        ALF_Layout_Invalidate(&priv->layout, hwnd);
+        int dpi = LOWORD(wparam);
+        SendMessage(hwnd, ALF_WM_DPICHANGE, 0, (LPARAM)dpi); // will also update fonts and invalidate layout
+
         RECT *r = (RECT*)lparam;
         SetWindowPos(hwnd, NULL, r->left, r->top, r->right-r->left, r->bottom-r->top, SWP_NOACTIVATE|SWP_NOZORDER);
     }
@@ -428,6 +426,10 @@ ALF_DefWindowProc(HWND hwnd, UINT msg, WPARAM wparam, LPARAM lparam)
             }
         }
 
+        if (msg == ALF_WM_DPICHANGE) {
+            ALF_UpdateFontsPriv(hwnd, priv);
+        }
+
         return ret;
     }