revert to unified blit code and prevent some races

richardsheridan · richardsheridan · commit a4a920edf87f · 2020-10-24T07:59:06.000-04:00
current status: Relies on tkinter arcana, untested
diff --git a/lib/matplotlib/backends/_backend_tk.py b/lib/matplotlib/backends/_backend_tk.py
@@ -44,10 +44,25 @@ def _restore_foreground_window_at_end():
             _c_internal_utils.Win32_SetForegroundWindow(foreground)
 
 
-def blit(photoimage, aggimage, offsets, bbox=None):
+_blit_args = {}
+_blit_tcl_name = None
+
+
+def _blit(argsid):
+    """
+    Thin wrapper to pass arguments to blit via tkapp.call
+    """
+    args = _blit_args.pop(argsid)
+    _tkagg.blit(*args)
+
+
+def blit(tk_instance, photoimage, aggimage, offsets, bbox=None):
     """
     Blit *aggimage* to *photoimage*.
 
+    A *tk_instance* such as a canvas is required execute the blit.
+    Tcl events must be dispatched to trigger a blit from a non-Tcl thread.
+
     *offsets* is a tuple describing how to fill the ``offset`` field of the
     ``Tk_PhotoImageBlock`` struct: it should be (0, 1, 2, 3) for RGBA8888 data,
     (2, 1, 0, 3) for little-endian ARBG32 (i.e. GBRA8888) data and (1, 2, 3, 0)
@@ -68,8 +83,22 @@ def blit(photoimage, aggimage, offsets, bbox=None):
     else:
         photoimage.blank()
         bboxptr = (0, width, 0, height)
-    _tkagg.blit(
+
+    args = (
         photoimage.tk.interpaddr(), str(photoimage), dataptr, offsets, bboxptr)
+    argsid = str(id)
+    _blit_args[argsid] = args
+
+    global _blit_tcl_name
+    # tkapp.call coerces all arguments to strings
+    try:
+        tk_instance.tk.call(_blit_tcl_name, argsid)
+    except tk.TclError:
+        # need to register with the tk root or constantly re-register
+        # each time tk_instance is destroyed
+        root = tk_instance._root()
+        _blit_tcl_name = root.register(_blit)
+        tk_instance.tk.call(_blit_tcl_name, argsid)
 
 
 class TimerTk(TimerBase):
@@ -123,9 +152,6 @@ def __init__(self, figure, master=None, resize_callback=None):
             width=w, height=h, borderwidth=0, highlightthickness=0)
         self._tkphoto = tk.PhotoImage(
             master=self._tkcanvas, width=w, height=h)
-        self._findphoto_name = self._tkcanvas.register(self._findphoto)
-        self._photoputblock_name = self._tkcanvas.register(self._photoputblock)
-        self._tkpointers = None
         self._tkcanvas.create_image(w//2, h//2, image=self._tkphoto)
         self._resize_callback = resize_callback
         self._tkcanvas.bind("<Configure>", self.resize)
@@ -181,41 +207,6 @@ def resize(self, event):
             int(width / 2), int(height / 2), image=self._tkphoto)
         self.resize_event()
 
-    def _findphoto(self):
-        return _tkagg.findphoto(self._tkphoto.tk.interpaddr(), str(self._tkphoto))
-
-    def _photoputblock(self):
-        photoptr, dataptr, bboxptr = self._tkpointers
-        _tkagg.photoputblock(photoptr, dataptr, (0, 1, 2, 3), bboxptr)
-
-    def blit(self, bbox=None):
-        """
-        Blit *aggimage* to *photoimage*.
-
-        *offsets* is a tuple describing how to fill the ``offset`` field of the
-        ``Tk_PhotoImageBlock`` struct: it should be (0, 1, 2, 3) for RGBA8888 data,
-        (2, 1, 0, 3) for little-endian ARBG32 (i.e. GBRA8888) data and (1, 2, 3, 0)
-        for big-endian ARGB32 (i.e. ARGB8888) data.
-
-        If *bbox* is passed, it defines the region that gets blitted.
-        """
-        data = np.asarray(self.renderer._renderer)
-        height, width = data.shape[:2]
-        dataptr = (height, width, data.ctypes.data)
-        if bbox is not None:
-            (x1, y1), (x2, y2) = bbox.__array__()
-            x1 = max(math.floor(x1), 0)
-            x2 = min(math.ceil(x2), width)
-            y1 = max(math.floor(y1), 0)
-            y2 = min(math.ceil(y2), height)
-            bboxptr = (x1, x2, y1, y2)
-        else:
-            self._tkphoto.blank()
-            bboxptr = (0, width, 0, height)
-        photoptr = self._master.tk.call(self._findphoto_name)
-        self._tkpointers = photoptr, dataptr, bboxptr
-        self._master.tk.call(self._photoputblock_name)
-
     def draw_idle(self):
         # docstring inherited
         if not self._idle:
diff --git a/lib/matplotlib/backends/backend_tkagg.py b/lib/matplotlib/backends/backend_tkagg.py
@@ -1,13 +1,17 @@
 from .backend_agg import FigureCanvasAgg
 from ._backend_tk import (
-    _BackendTk, FigureCanvasTk, FigureManagerTk, NavigationToolbar2Tk)
+    _BackendTk, FigureCanvasTk, FigureManagerTk, NavigationToolbar2Tk, blit)
 
 
 class FigureCanvasTkAgg(FigureCanvasAgg, FigureCanvasTk):
     def draw(self):
         super().draw()
         self.blit()
 
+    def blit(self, bbox=None):
+        blit(self._tkcanvas, self._tkphoto,
+             self.renderer._renderer, (0, 1, 2, 3), bbox=bbox)
+
 
 @_BackendTk.export
 class _BackendTkAgg(_BackendTk):
diff --git a/lib/matplotlib/backends/backend_tkcairo.py b/lib/matplotlib/backends/backend_tkcairo.py
@@ -21,7 +21,7 @@ def draw(self):
         self.figure.draw(self._renderer)
         buf = np.reshape(surface.get_data(), (height, width, 4))
         _backend_tk.blit(
-            self._tkphoto, buf,
+            self._tkcanvas, self._tkphoto, buf,
             (2, 1, 0, 3) if sys.byteorder == "little" else (1, 2, 3, 0))
 
 
diff --git a/src/_tkagg.cpp b/src/_tkagg.cpp
@@ -89,71 +89,8 @@ static PyObject *mpl_tk_blit(PyObject *self, PyObject *args)
     }
 }
 
-static PyObject *mpl_tk_findphoto(PyObject *self, PyObject *args)
-{
-    Tcl_Interp *interp;
-    char const *photo_name;
-    Tk_PhotoHandle photo;
-    if (!PyArg_ParseTuple(args, "O&s:findphoto",convert_voidptr, &interp, &photo_name)) {
-        goto exit;
-    }
-    if (!(photo = TK_FIND_PHOTO(interp, photo_name))) {
-        PyErr_SetString(PyExc_ValueError, "Failed to extract Tk_PhotoHandle");
-        goto exit;
-    }
-exit:
-    if (PyErr_Occurred()) {
-        return NULL;
-    } else {
-        return PyLong_FromVoidPtr((void *)photo);
-    }
-}
-
-static PyObject *mpl_tk_photoputblock(PyObject *self, PyObject *args)
-{
-    int height, width;
-    unsigned char *data_ptr;
-    int o0, o1, o2, o3;
-    int x1, x2, y1, y2;
-    Tk_PhotoHandle photo;
-    Tk_PhotoImageBlock block;
-    if (!PyArg_ParseTuple(args, "O&(iiO&)(iiii)(iiii):photoputblock",
-                          convert_voidptr, &photo,
-                          &height, &width, convert_voidptr, &data_ptr,
-                          &o0, &o1, &o2, &o3,
-                          &x1, &x2, &y1, &y2)) {
-        goto exit;
-    }
-    if (0 > y1 || y1 > y2 || y2 > height || 0 > x1 || x1 > x2 || x2 > width) {
-        PyErr_SetString(PyExc_ValueError, "Attempting to draw out of bounds");
-        goto exit;
-    }
-
-    Py_BEGIN_ALLOW_THREADS
-    block.pixelPtr = data_ptr + 4 * ((height - y2) * width + x1);
-    block.width = x2 - x1;
-    block.height = y2 - y1;
-    block.pitch = 4 * width;
-    block.pixelSize = 4;
-    block.offset[0] = o0;
-    block.offset[1] = o1;
-    block.offset[2] = o2;
-    block.offset[3] = o3;
-    TK_PHOTO_PUT_BLOCK_NO_COMPOSITE(
-        photo, &block, x1, height - y2, x2 - x1, y2 - y1);
-    Py_END_ALLOW_THREADS
-exit:
-    if (PyErr_Occurred()) {
-        return NULL;
-    } else {
-        Py_RETURN_NONE;
-    }
-}
-
 static PyMethodDef functions[] = {
     { "blit", (PyCFunction)mpl_tk_blit, METH_VARARGS },
-    { "findphoto", (PyCFunction)mpl_tk_findphoto, METH_VARARGS },
-    { "photoputblock", (PyCFunction)mpl_tk_photoputblock, METH_VARARGS },
     { NULL, NULL } /* sentinel */
 };
 
