Rewrite the tk C blitting code

anntzer · anntzer · commit dc93a74823d9 · 2018-03-05T00:24:13.000-08:00
... to use the standard Python C-API rather than the tk API.

We do not need to support colormodes other than 2 (i.e. RGBA)
(previously there was 0 = grayscale, 1 = RGB) so it was simpler to just
deprecate the previous function and move everything to a new private one
(matplotlib.backends._backend_tk.blit).
diff --git a/lib/matplotlib/backends/_backend_tk.py b/lib/matplotlib/backends/_backend_tk.py
@@ -1,16 +1,14 @@
-from __future__ import (absolute_import, division, print_function,
-                        unicode_literals)
-
 import six
 from six.moves import tkinter as Tk
 
+import math
 import logging
 import os.path
 import sys
 
-# Paint image to Tk photo blitter extension
-import matplotlib.backends.tkagg as tkagg
+import numpy as np
 
+from . import _tkagg
 from matplotlib.backends.backend_agg import FigureCanvasAgg
 import matplotlib.backends.windowing as windowing
 
@@ -53,6 +51,25 @@ def error_msg_tkpaint(msg, parent=None):
     tkMessageBox.showerror("matplotlib", msg)
 
 
+def blit(photoimage, aggimage, bbox=None):
+    """
+    Blit *aggimage* to *photoimage*.
+
+    If *bbox* is passed, it defines the region that gets blitted.
+    """
+    data = np.asarray(aggimage)
+    height, width = data.shape[:2]
+    dataptr = (height, width, data.ctypes.data)
+    if bbox is not None:
+        (x1, y1), (x2, y2) = bbox.__array__()
+        bboxptr = (math.floor(x1), math.ceil(x2),
+                   math.floor(y1), math.ceil(y2))
+    else:
+        photoimage.blank()
+        bboxptr = (0, width, 0, height)
+    _tkagg.blit(photoimage, dataptr, bboxptr)
+
+
 class TimerTk(TimerBase):
     '''
     Subclass of :class:`backend_bases.TimerBase` that uses Tk's timer events.
diff --git a/lib/matplotlib/backends/backend_tkagg.py b/lib/matplotlib/backends/backend_tkagg.py
@@ -1,4 +1,4 @@
-from . import tkagg  # Paint image to Tk photo blitter extension.
+from . import _backend_tk
 from .backend_agg import FigureCanvasAgg
 from ._backend_tk import (
     _BackendTk, FigureCanvasTk, FigureManagerTk, NavigationToolbar2Tk)
@@ -7,12 +7,12 @@
 class FigureCanvasTkAgg(FigureCanvasAgg, FigureCanvasTk):
     def draw(self):
         super(FigureCanvasTkAgg, self).draw()
-        tkagg.blit(self._tkphoto, self.renderer._renderer, colormode=2)
+        _backend_tk.blit(self._tkphoto, self.renderer._renderer)
         self._master.update_idletasks()
 
     def blit(self, bbox=None):
-        tkagg.blit(
-            self._tkphoto, self.renderer._renderer, bbox=bbox, colormode=2)
+        _backend_tk.blit(
+            self._tkphoto, self.renderer._renderer, bbox=bbox)
         self._master.update_idletasks()
 
 
diff --git a/lib/matplotlib/backends/backend_tkcairo.py b/lib/matplotlib/backends/backend_tkcairo.py
@@ -2,7 +2,7 @@
 
 import numpy as np
 
-from . import tkagg  # Paint image to Tk photo blitter extension.
+from . import _backend_tk
 from .backend_cairo import cairo, FigureCanvasCairo, RendererCairo
 from ._backend_tk import _BackendTk, FigureCanvasTk
 
@@ -22,11 +22,11 @@ def draw(self):
         buf = np.reshape(surface.get_data(), (height, width, 4))
         # Convert from ARGB32 to RGBA8888.  Using .take() instead of directly
         # indexing ensures C-contiguity of the result, which is needed by
-        # tkagg.
+        # _backend_tk.
         buf = buf.take(
             [2, 1, 0, 3] if sys.byteorder == "little" else [1, 2, 3, 0],
             axis=2)
-        tkagg.blit(self._tkphoto, buf, colormode=2)
+        _backend_tk.blit(self._tkphoto, buf)
         self._master.update_idletasks()
 
 
diff --git a/lib/matplotlib/backends/tkagg.py b/lib/matplotlib/backends/tkagg.py
@@ -1,13 +1,15 @@
-from __future__ import (absolute_import, division, print_function,
-                        unicode_literals)
-
-import six
-from six.moves import tkinter as Tk
+import tkinter as Tk
 
 import numpy as np
 
+from matplotlib import cbook
 from matplotlib.backends import _tkagg
 
+
+cbook.warn_deprecated(
+    "3.0", "The matplotlib.backends.tkagg module is deprecated.")
+
+
 def blit(photoimage, aggimage, bbox=None, colormode=1):
     tk = photoimage.tk
 
diff --git a/src/_tkagg.cpp b/src/_tkagg.cpp
@@ -203,9 +203,62 @@ static PyObject *_tkinit(PyObject *self, PyObject *args)
     return Py_None;
 }
 
+static PyObject *mpl_tk_blit(PyObject *self, PyObject *args) {
+    PyObject *py_photo = NULL,
+             *py_tk = NULL,
+             *py_interpaddr = NULL,
+             *py_photo_name = NULL;
+    int height, width;
+    unsigned char *data_ptr;
+    int x1, x2, y1, y2;
+    Tcl_Interp *interp;
+    char const *photo_name;
+    Tk_PhotoHandle photo;
+    Tk_PhotoImageBlock block;
+    if (!PyArg_ParseTuple(args, "O(iin)(iiii):blit",
+                          &py_photo,
+                          &height, &width, &data_ptr,
+                          &x1, &x2, &y1, &y2)) {
+        goto exit;
+    }
+    if (!(py_tk = PyObject_GetAttrString(py_photo, "tk")) ||
+        !(py_interpaddr = PyObject_CallMethod(py_tk, "interpaddr", NULL)) ||
+        !(interp = (Tcl_Interp *)PyLong_AsVoidPtr(py_interpaddr))) {
+        goto exit;
+    }
+    if (!(py_photo_name = PyObject_Str(py_photo)) ||
+        !(photo_name = PyUnicode_AsUTF8(py_photo_name)) ||
+        !(photo = TK_FIND_PHOTO(interp, photo_name))) {
+        // TK_FIND_PHOTO (obviously) does not set an exception on failure.
+        PyErr_SetString(PyExc_ValueError, "Failed to extract Tk_PhotoHandle");
+        goto exit;
+    }
+    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] = 0;
+    block.offset[1] = 1;
+    block.offset[2] = 2;
+    block.offset[3] = 3;
+    TK_PHOTO_PUT_BLOCK_NO_COMPOSITE(
+        photo, &block, x1, height - y2, x2 - x1, y2 - y1);
+exit:
+    Py_XDECREF(py_tk);
+    Py_XDECREF(py_interpaddr);
+    Py_XDECREF(py_photo_name);
+    if (PyErr_Occurred()) {
+        return NULL;
+    } else {
+        Py_RETURN_NONE;
+    }
+}
+
 static PyMethodDef functions[] = {
     /* Tkinter interface stuff */
     { "tkinit", (PyCFunction)_tkinit, 1 },
+    { "blit", (PyCFunction)mpl_tk_blit, 1 },
     { NULL, NULL } /* sentinel */
 };
 
@@ -444,8 +497,9 @@ int load_tkinter_funcs(void)
 }
 #endif // end not Windows
 
-static PyModuleDef _tkagg_module = { PyModuleDef_HEAD_INIT, "_tkagg", "",   -1,  functions,
-                                     NULL,                  NULL,     NULL, NULL };
+static PyModuleDef _tkagg_module = {
+    PyModuleDef_HEAD_INIT, "_tkagg", "", -1, functions, NULL, NULL, NULL, NULL
+};
 
 PyMODINIT_FUNC PyInit__tkagg(void)
 {
