Add initial support for HiDPI in TkAgg on Windows.

QuLogic · QuLogic · commit 52c07fea85c6 · 2020-12-24T22:48:17.000-05:00
At the moment, Tk does not support updating the 'scaling' value when the
monitor pixel ratio changes, or the window is moved to a different one.
diff --git a/lib/matplotlib/backends/_backend_tk.py b/lib/matplotlib/backends/_backend_tk.py
@@ -166,7 +166,7 @@ class FigureCanvasTk(FigureCanvasBase):
     def __init__(self, figure, master=None, resize_callback=None):
         super().__init__(figure)
         self._idle_draw_id = None
-        w, h = self.figure.bbox.size.astype(int)
+        w, h = self.get_width_height(physical=True)
         self._tkcanvas = tk.Canvas(
             master=master, background="white",
             width=w, height=h, borderwidth=0, highlightthickness=0)
@@ -175,6 +175,7 @@ def __init__(self, figure, master=None, resize_callback=None):
         self._tkcanvas.create_image(w//2, h//2, image=self._tkphoto)
         self._resize_callback = resize_callback
         self._tkcanvas.bind("<Configure>", self.resize)
+        self._tkcanvas.bind("<Map>", self._update_device_pixel_ratio)
         self._tkcanvas.bind("<Key>", self.key_press)
         self._tkcanvas.bind("<Motion>", self.motion_notify_event)
         self._tkcanvas.bind("<Enter>", self.enter_notify_event)
@@ -209,6 +210,18 @@ def filter_destroy(event):
         self._master = master
         self._tkcanvas.focus_set()
 
+    def _update_device_pixel_ratio(self, event=None):
+        # Tk gives scaling with respect to 72 DPI, but most (all?) screens are
+        # scaled vs 96 dpi, and pixel ratio settings are given in whole
+        # percentages, so round to 2 digits.
+        ratio = round(self._master.call('tk', 'scaling') / (96 / 72), 2)
+        if self._set_device_pixel_ratio(ratio):
+            # The easiest way to resize the canvas is to resize the canvas
+            # widget itself, since we implement all the logic for resizing the
+            # canvas backing store on that event.
+            w, h = self.get_width_height(physical=True)
+            self._tkcanvas.configure(width=w, height=h)
+
     def resize(self, event):
         width, height = event.width, event.height
         if self._resize_callback is not None:
diff --git a/setupext.py b/setupext.py
@@ -411,8 +411,8 @@ def get_extensions(self):
             ],
             include_dirs=["src"],
             # psapi library needed for finding Tcl/Tk at run time.
-            libraries=({"linux": ["dl"], "win32": ["psapi"],
-                        "cygwin": ["psapi"]}.get(sys.platform, [])),
+            libraries=({"linux": ["dl"], "win32": ["psapi", "user32"],
+                        "cygwin": ["psapi", "user32"]}.get(sys.platform, [])),
             extra_link_args={"win32": ["-mwindows"]}.get(sys.platform, []))
         add_numpy_flags(ext)
         add_libagg_flags(ext)
diff --git a/src/_tkagg.cpp b/src/_tkagg.cpp
@@ -205,6 +205,9 @@ static PyModuleDef _tkagg_module = {
 
 PyMODINIT_FUNC PyInit__tkagg(void)
 {
+#ifdef WIN32_DLL
+    SetProcessDPIAware(); // Ignore errors in case we are embedded.
+#endif
     load_tkinter_funcs();
     if (PyErr_Occurred()) {
         return NULL;

Original file line number	Diff line number	Diff line change
`@@ -205,6 +205,9 @@ static PyModuleDef _tkagg_module = {`
`205`	`205`
`206`	`206`	`PyMODINIT_FUNC PyInit__tkagg(void)`
`207`	`207`	`{`
	`208`	`+#ifdef WIN32_DLL`
	`209`	`+ SetProcessDPIAware(); // Ignore errors in case we are embedded.`
	`210`	`+#endif`
`208`	`211`	`load_tkinter_funcs();`
`209`	`212`	`if (PyErr_Occurred()) {`
`210`	`213`	`return NULL;`