Size axis labels based on text contents

Compute the size in pixels the label based on the label's contents.
Eventually we want to have an update system that can iterate through
axes and labels to do this whenever needed (eg. after widget is moved
to a new screen with a different DPI).

piker/ui/_axes.py

@@ -11,6 +11,8 @@ from PyQt5.QtCore import QPointF
 from ._style import _font, hcolor
 from ..data._source import float_digits
 
+_axis_pen = pg.mkPen(hcolor('bracket'))
+
 
 class PriceAxis(pg.AxisItem):
 
@@ -21,15 +23,18 @@ class PriceAxis(pg.AxisItem):
         self.setTickFont(_font)
         self.setStyle(**{
             'textFillLimits': [(0, 0.666)],
+            'tickFont': _font,
             # 'tickTextWidth': 100,
             # 'tickTextHeight': 20,
-            'tickFont': _font,
             # 'tickTextWidth': 40,
             # 'autoExpandTextSpace': True,
             # 'maxTickLength': -20,
             # 'stopAxisAtTick': (True, True),  # doesn't work well on price
         })
         # self.setLabel(**{'font-size': '10pt'})
+        self.setTickFont(_font)
+        self.setPen(_axis_pen)
+
         self.setWidth(40)
 
     # XXX: drop for now since it just eats up h space
@@ -63,11 +68,12 @@ class DynamicDateAxis(pg.AxisItem):
         super().__init__(*args, **kwargs)
         self.linked_charts = linked_charts
         self.setTickFont(_font)
+        self.setPen(_axis_pen)
 
         # default styling
         self.setStyle(**{
             # tickTextOffset=4,
-            'textFillLimits': [(0, 0.70)],
+            'textFillLimits': [(0, 0.666)],
             'tickFont': _font,
         })
         self.setHeight(11)
@@ -95,6 +101,10 @@ class DynamicDateAxis(pg.AxisItem):
 
 class AxisLabel(pg.GraphicsObject):
 
+    _font = _font
+    _w_margin = 0
+    _h_margin = 3
+
     def __init__(
         self,
         parent: pg.GraphicsObject,
@@ -108,6 +118,7 @@ class AxisLabel(pg.GraphicsObject):
         self.opacity = opacity
         self.label_str = ''
         self.digits = digits
+        self._txt_br: QtCore.QRect = None
 
         self.bg_color = pg.mkColor(hcolor(bg_color))
         self.fg_color = pg.mkColor(hcolor(fg_color))
@@ -115,34 +126,52 @@ class AxisLabel(pg.GraphicsObject):
         self.pic = QtGui.QPicture()
         p = QtGui.QPainter(self.pic)
 
-        self.rect = QtCore.QRectF(0, 0, 40, 11)
+        self.rect = None
 
         p.setPen(self.fg_color)
         p.setOpacity(self.opacity)
+
+        self.setFlag(self.ItemIgnoresTransformations)
+
+    def _size_br_from_str(self, value: str) -> None:
+        """Do our best to render the bounding rect to a set margin
+        around provided string contents.
+
+        """
+        txt_br = self._font._fm.boundingRect(value)
+        h, w = txt_br.height(), txt_br.width()
+        self.rect = QtCore.QRectF(
+            0, 0,
+            w + self._w_margin,
+            h + self._h_margin
+        )
+
+    def paint(self, p, option, widget):
+        p.drawPicture(0, 0, self.pic)
+
+        if self.label_str:
+
+            if not self.rect:
+                self._size_br_from_str(self.label_str)
+
+            p.setFont(_font)
+            p.setPen(self.fg_color)
             p.fillRect(self.rect, self.bg_color)
 
             # this adds a nice black outline around the label for some odd
             # reason; ok by us
             p.drawRect(self.rect)
 
-        self.setFlag(self.ItemIgnoresTransformations)
+            p.drawText(option.rect, self.text_flags, self.label_str)
 
-    def paint(self, p, option, widget):
-        p.drawPicture(0, 0, self.pic)
-
-        if self.label_str:
-            p.setFont(_font)
-            p.setPen(self.fg_color)
-            p.drawText(self.rect, self.text_flags, self.label_str)
+    def boundingRect(self):  # noqa
+        return self.rect or QtCore.QRectF()
 
     # uggggghhhh
 
     def tick_to_string(self, tick_pos):
         raise NotImplementedError()
 
-    def boundingRect(self):  # noqa
-        raise NotImplementedError()
-
     def update_label(self, evt_post, point_view):
         raise NotImplementedError()
 
@@ -160,6 +189,8 @@ class AxisLabel(pg.GraphicsObject):
 
 class XAxisLabel(AxisLabel):
 
+    _w_margin = 8
+
     text_flags = (
         QtCore.Qt.TextDontClip
         | QtCore.Qt.AlignCenter
@@ -168,12 +199,6 @@ class XAxisLabel(AxisLabel):
         # | QtCore.Qt.AlignHCenter
     )
 
-    def boundingRect(self):  # noqa
-        # TODO: we need to get the parent axe's dimensions transformed
-        # to abs coords to be 100% correct here:
-        # self.parent.boundingRect()
-        return QtCore.QRectF(0, 0, 40, 11)
-
     def update_label(
         self,
         abs_pos: QPointF,  # scene coords
@@ -201,9 +226,6 @@ class YAxisLabel(AxisLabel):
         # WTF IS THIS FORMAT?
         return ('{: ,.%df}' % self.digits).format(tick_pos).replace(',', ' ')
 
-    def boundingRect(self):  # noqa
-        return QtCore.QRectF(0, 0, 50, 10)
-
     def update_label(
         self,
         abs_pos: QPointF,  # scene coords
@@ -225,15 +247,10 @@ class YSticky(YAxisLabel):
         *args,
         **kwargs
     ) -> None:
-        super().__init__(*args, **kwargs)
-        self._chart = chart
 
-        # XXX: not sure why this wouldn't work with a proxy?
-        # pg.SignalProxy(
-        #     delay=0,
-        #     rateLimit=60,
-        #     slot=last.update_on_resize,
-        # )
+        super().__init__(*args, **kwargs)
+
+        self._chart = chart
         chart.sigRangeChanged.connect(self.update_on_resize)
 
     def update_on_resize(self, vr, r):