From 3478304e389ed8e07c8772093a724853ee8163d1 Mon Sep 17 00:00:00 2001
From: Melwyn Francis Carlo <66683108+melwyncarlo@users.noreply.github.com>
Date: Thu, 25 Sep 2025 08:48:52 +0530
Subject: [PATCH 1/2] Update _backend_tk.py

---
 lib/matplotlib/backends/_backend_tk.py | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/lib/matplotlib/backends/_backend_tk.py b/lib/matplotlib/backends/_backend_tk.py
index f87e3a52b08a..fdc299ded488 100644
--- a/lib/matplotlib/backends/_backend_tk.py
+++ b/lib/matplotlib/backends/_backend_tk.py
@@ -602,6 +602,8 @@ def destroy(*args):
                 self.window.protocol("WM_DELETE_WINDOW", destroy)
                 self.window.deiconify()
                 self.canvas._tkcanvas.focus_set()
+                if self._window_dpi.get() != 96:
+                    self._update_window_dpi()
             else:
                 self.canvas.draw_idle()
             if mpl.rcParams['figure.raise_window']:

From b5e669ac5d79b9c10a29413f78c64441a5a0d0f0 Mon Sep 17 00:00:00 2001
From: Melwyn Francis Carlo <66683108+melwyncarlo@users.noreply.github.com>
Date: Thu, 25 Sep 2025 08:51:27 +0530
Subject: [PATCH 2/2] Update _tkagg.cpp

---
 src/_tkagg.cpp | 41 ++++++++++++++++++++++++++---------------
 1 file changed, 26 insertions(+), 15 deletions(-)

diff --git a/src/_tkagg.cpp b/src/_tkagg.cpp
index 955ce2103f90..3931815eca99 100644
--- a/src/_tkagg.cpp
+++ b/src/_tkagg.cpp
@@ -152,6 +152,22 @@ mpl_tk_blit(py::object interp_obj, const char *photo_name,
 }
 
 #ifdef WIN32_DLL
+void update_tk_window_dpi(HWND hwnd, Tcl_Interp *interp, std::string dpi) {
+    // This variable naming must match the name used in
+    // lib/matplotlib/backends/_backend_tk.py:FigureManagerTk.
+    std::string var_name("window_dpi");
+    var_name += std::to_string((unsigned long long)hwnd);
+    if (TCL_SETVAR) {
+        TCL_SETVAR(interp, var_name.c_str(), dpi.c_str(), 0);
+    } else if (TCL_SETVAR2) {
+        TCL_SETVAR2(interp, var_name.c_str(), NULL, dpi.c_str(), 0);
+    } else {
+        // This should be prevented at import time, and therefore unreachable.
+        // But defensively throw just in case.
+        throw std::runtime_error("Unable to call Tcl_SetVar or Tcl_SetVar2");
+    }
+}
+
 LRESULT CALLBACK
 DpiSubclassProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam,
                 UINT_PTR uIdSubclass, DWORD_PTR dwRefData)
@@ -165,24 +181,10 @@ DpiSubclassProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam,
         // call Python code, we must not also call *any* Tk code from Python.
         // So stay with Tcl calls in C only.
         {
-            // This variable naming must match the name used in
-            // lib/matplotlib/backends/_backend_tk.py:FigureManagerTk.
-            std::string var_name("window_dpi");
-            var_name += std::to_string((unsigned long long)hwnd);
-
             // X is high word, Y is low word, but they are always equal.
             std::string dpi = std::to_string(LOWORD(wParam));
-
             Tcl_Interp* interp = (Tcl_Interp*)dwRefData;
-            if (TCL_SETVAR) {
-                TCL_SETVAR(interp, var_name.c_str(), dpi.c_str(), 0);
-            } else if (TCL_SETVAR2) {
-                TCL_SETVAR2(interp, var_name.c_str(), NULL, dpi.c_str(), 0);
-            } else {
-                // This should be prevented at import time, and therefore unreachable.
-                // But defensively throw just in case.
-                throw std::runtime_error("Unable to call Tcl_SetVar or Tcl_SetVar2");
-            }
+            update_tk_window_dpi(hwnd, interp, dpi);
         }
         return 0;
     case WM_NCDESTROY:
@@ -235,6 +237,15 @@ mpl_tk_enable_dpi_awareness(py::object UNUSED_ON_NON_WINDOWS(frame_handle_obj),
         // Per monitor aware means we need to handle WM_DPICHANGED by wrapping
         // the Window Procedure, and the Python side needs to trace the Tk
         // window_dpi variable stored on interp.
+        typedef UINT (WINAPI *GetDpiForWindow_t)(HWND);
+        GetDpiForWindow_t GetDpiForWindowPtr =
+            (GetDpiForWindow_t)GetProcAddress(user32, "GetDpiForWindow");
+        if (GetDpiForWindowPtr == NULL) {
+            FreeLibrary(user32);
+            return py::cast(false);
+        }
+        UINT dpi = GetDpiForWindowPtr(frame_handle);
+        update_tk_window_dpi(frame_handle, interp, std::to_string(dpi));
         SetWindowSubclass(frame_handle, DpiSubclassProc, 0, (DWORD_PTR)interp);
     }
     FreeLibrary(user32);