Grid control: backport __call__ from micropython-touch.

README.md

@@ -1255,6 +1255,8 @@ Constructor args:
  in the `Label` as defined by `lwidth`.
 
 Method:  
+* `__call__(row, col=None)` Returns the `Label` instance at a single location.
+If no `col` is provided 1D addressing is assumed.
  * `__getitem__` Returns an iterator enabling `Label` instances to be accessed.
  * `__setitem__` Assign a value to one or more labels. If multiple labels are
  specified and a single text value is passed, all labels will receive that
@@ -1284,7 +1286,18 @@ grid[1:3, 1:3] = (str(n) for n in range(2))  # Produces
 # 0 1
 # 1 1
 ```
-Read access:
+Read access:  
+It is important to note that array index notation always returns an iterator,
+even if only a single element is required. One way to access a single element is
+```python
+it = grid[0 : 0]
+label = next(it)
+```
+however function call syntax is more intuitive:
+```python
+label = grid(0, 0)
+```
+Accessing labels in a single row, by column:
 ```python
 for label in grid[2, 0:]:
     v = label.value()  # Access text of each label in row 2

gui/widgets/grid.py

@@ -20,9 +20,23 @@ def _do_slice(sli, nbytes):
     stop = min(stop if stop >= 0 else max(nbytes + stop, 0), nbytes)
     return (start, stop) if start < stop else None  # Caller should check
 
+
 # lwidth may be integer Label width in pixels or a tuple/list of widths
 class Grid(Widget):
-    def __init__(self, writer, row, col, lwidth, nrows, ncols, invert=False, fgcolor=None, bgcolor=BLACK, bdcolor=None, justify=0):
+    def __init__(
+        self,
+        writer,
+        row,
+        col,
+        lwidth,
+        nrows,
+        ncols,
+        invert=False,
+        fgcolor=None,
+        bgcolor=BLACK,
+        bdcolor=None,
+        justify=0,
+    ):
         self.nrows = nrows
         self.ncols = ncols
         self.ncells = nrows * ncols
@@ -41,7 +55,9 @@ class Grid(Widget):
         c = col
         for _ in range(self.nrows):
             for cw in self.cwidth:
-                self.cells.append(Label(writer, r, c, cw - 4, invert, fgcolor, bgcolor, False, justify))  # No border
+                self.cells.append(
+                    Label(writer, r, c, cw - 4, invert, fgcolor, bgcolor, False, justify)
+                )  # No border
                 c += cw
             r += self.cheight
             c = col
@@ -55,7 +71,7 @@ class Grid(Widget):
     # grid[[r, c]] = {"text": str(n), "fgcolor" : RED}
     def __setitem__(self, *args):
         x = args[1]  # Value
-        indices = do_args(args[: -1], self.nrows, self.ncols)
+        indices = do_args(args[:-1], self.nrows, self.ncols)
         for i in indices:
             try:
                 z = next(x)  # May be a generator
@@ -66,6 +82,9 @@ class Grid(Widget):
             v = self.cells[i].value  # method of Label
             _ = v(**z) if isinstance(x, dict) else v(z)
 
+    def __call__(self, row, col=None):  # Return a single Label
+        return self.cells[row if col is None else col + row * self.ncols]
+
     def show(self):
         super().show()  # Draw border
         if self.has_border:  # Draw grid