ENH: dynamic font size patching utility

docs/source/upcoming_release_notes/570-dynamic_fonts.rst

@@ -0,0 +1,23 @@
+570 dynamic_fontsize
+####################
+
+API Changes
+-----------
+- N/A
+
+Features
+--------
+- Added dynamic font sizer utility which can work with some Qt-provided widgets
+  as well as PyDM widgets.
+
+Bugfixes
+--------
+- N/A
+
+Maintenance
+-----------
+- N/A
+
+Contributors
+------------
+- klauer

typhos/dynamic_font.py

@@ -0,0 +1,190 @@
+"""
+Dynamic font size helper utilities:
+
+Dynamically set widget font size based on its current size.
+"""
+
+from qtpy import QtCore, QtGui, QtWidgets
+from qtpy.QtCore import QRectF, Qt
+
+
+def get_widget_maximum_font_size(
+    widget: QtWidgets.QWidget,
+    text: str,
+    *,
+    pad_width: float = 0.0,
+    pad_height: float = 0.0,
+    precision: float = 0.5,
+) -> float:
+    """
+    Get the maximum font size for the given widget.
+
+    Parameters
+    ----------
+    widget : QtWidgets.QWidget
+        The widget to check.
+    text : str
+        The text for the widget to contain.
+    pad_width : float, optional
+        Padding to be used to reduce the size of the contents rectangle.
+    pad_height : float, optional
+        Padding to be used to reduce the size of the contents rectangle.
+    precision : float
+        Font size precision.
+
+    Returns
+    -------
+    float
+    """
+    font = widget.font()
+    widget_contents_rect = QRectF(widget.contentsRect())
+    target_width = widget_contents_rect.width() - pad_width
+    target_height = widget_contents_rect.height() - pad_height
+
+    # QRectF new_rect
+    current_size = font.pointSizeF()
+
+    if not text or target_width <= 0 or target_height <= 0:
+        return current_size
+
+    step = current_size / 2.0
+
+    # If too small, increase step
+    if step <= precision:
+        step = precision * 4.0
+
+    last_tested_size = current_size
+    curent_height = 0.0
+    current_width = 0.0
+
+    # Only stop when step is small enough and new size is smaller than QWidget
+    while (
+        step > precision
+        or (curent_height > target_height)
+        or (current_width > target_width)
+    ):
+        # Keep last tested value
+        last_tested_size = current_size
+
+        # Test label with its font
+        font.setPointSizeF(current_size)
+        # Use font metrics to test
+        fm = QtGui.QFontMetricsF(font)
+
+        # Check if widget is QLabel
+        if isinstance(widget, QtWidgets.QLabel):
+            if widget.wordWrap():
+                flags = Qt.TextFlag.TextWordWrap | widget.alignment()
+            else:
+                flags = widget.alignment()
+            new_rect = fm.boundingRect(widget_contents_rect, flags, text)
+        else:
+            new_rect = fm.boundingRect(widget_contents_rect, 0, text)
+
+        curent_height = new_rect.height()
+        current_width = new_rect.width()
+
+        # If new font size is too big, decrease it
+        if (curent_height > target_height) or (current_width > target_width):
+            current_size -= step
+            # if step is small enough, keep it constant, so it converges to
+            # biggest font size
+            if step > precision:
+                step /= 2.0
+            # Do not allow negative size
+            if current_size <= 0:
+                break
+        else:
+            # If new font size is smaller than maximum possible size, increase
+            # it
+            current_size += step
+
+    return last_tested_size
+
+
+def patch_widget(
+    widget: QtWidgets.QWidget,
+    *,
+    pad_percent: float = 0.0,
+) -> None:
+    """
+    Patch the widget to dynamically change its font.
+
+    Parameters
+    ----------
+    widget : QtWidgets.QWidget
+        The widget to patch.
+    pad_percent : float, optional
+        The normalized padding percentage (0.0 - 1.0) to use in determining the
+        maximum font size. Content margin settings determine the content
+        rectangle, and this padding is applied as a percentage on top of that.
+    """
+    def paintEvent(event: QtGui.QPaintEvent) -> None:
+        font = widget.font()
+        font_size = get_widget_maximum_font_size(
+            widget, widget.text(),
+            pad_width=widget.width() * pad_percent,
+            pad_height=widget.height() * pad_percent,
+        )
+        if abs(font.pointSizeF() - font_size) > 0.1:
+            font.setPointSizeF(font_size)
+            widget.setFont(font)
+        return orig_paint_event(event)
+
+    def minimumSizeHint() -> QtCore.QSize:
+        # Do not give any size hint as it it changes during paintEvent
+        return QtWidgets.QWidget.minimumSizeHint(widget)
+
+    def sizeHint() -> QtCore.QSize:
+        # Do not give any size hint as it it changes during paintEvent
+        return QtWidgets.QWidget.sizeHint(widget)
+
+    if hasattr(widget.paintEvent, "_patched_methods_"):
+        return
+
+    orig_paint_event = widget.paintEvent
+
+    paintEvent._patched_methods_ = (
+        widget.paintEvent,
+        widget.sizeHint,
+        widget.minimumSizeHint,
+    )
+    widget.paintEvent = paintEvent
+    widget.sizeHint = sizeHint
+    widget.minimumSizeHint = minimumSizeHint
+
+
+def unpatch_widget(widget: QtWidgets.QWidget) -> None:
+    """
+    Remove dynamic font size patch from the widget, if previously applied.
+
+    Parameters
+    ----------
+    widget : QtWidgets.QWidget
+        The widget to unpatch.
+    """
+    if not hasattr(widget.paintEvent, "_patched_methods_"):
+        return
+
+    (
+        widget.paintEvent,
+        widget.sizeHint,
+        widget.minimumSizeHint,
+    ) = widget.paintEvent._patched_methods_
+
+
+def is_patched(widget: QtWidgets.QWidget) -> bool:
+    """
+    Check if widget has been patched for dynamically-resizing fonts.
+
+    Parameters
+    ----------
+    widget : QtWidgets.QWidget
+        The widget to check.
+
+    Returns
+    -------
+    bool
+        True if the widget has been patched.
+    """
+    return hasattr(widget.paintEvent, "_patched_methods_")

typhos/positioner.py

@@ -5,7 +5,7 @@
 from pydm.widgets.channel import PyDMChannel
 from qtpy import QtCore, QtWidgets, uic
 
-from . import utils, widgets
+from . import dynamic_font, utils, widgets
 from .alarm import KindLevel, _KindLevel
 from .status import TyphosStatusThread
 
@@ -117,6 +117,8 @@ def __init__(self, parent=None):
         self.show_expert_button = False
         self._after_set_moving(False)
 
+        dynamic_font.patch_widget(self.ui.user_readback, pad_percent=0.01)
+
     def _clear_status_thread(self):
         """Clear a previous status thread."""
         if self._status_thread is None:

typhos/tests/test_dynamic_font.py

@@ -0,0 +1,54 @@
+from __future__ import annotations
+
+import pytest
+import pytestqt.qtbot
+from qtpy import QtCore, QtGui, QtWidgets
+
+from typhos.tests import conftest
+
+from ..dynamic_font import is_patched, patch_widget, unpatch_widget
+
+
+@pytest.mark.parametrize(
+    "cls",
+    [
+        QtWidgets.QLabel,
+        QtWidgets.QPushButton,
+    ]
+)
+def test_patching(
+    request: pytest.FixtureRequest,
+    cls: type[QtWidgets.QWidget],
+    qtbot: pytestqt.qtbot.QtBot,
+) -> None:
+    widget = cls()
+    widget.setText("Test\ntext")
+    widget.setFixedSize(500, 500)
+    qtbot.add_widget(widget)
+
+    original_font_size = widget.font().pointSizeF()
+    conftest.save_image(
+        widget,
+        f"{request.node.name}_{cls.__name__}_default_font_size",
+    )
+    print("Starting font size", original_font_size)
+
+    event = QtGui.QPaintEvent(QtCore.QRect(0, 0, widget.width(), widget.height()))
+
+    assert not is_patched(widget)
+    patch_widget(widget)
+    assert is_patched(widget)
+
+    widget.paintEvent(event)
+    new_font_size = widget.font().pointSizeF()
+    print("Patched font size", new_font_size)
+    assert original_font_size != new_font_size
+
+    assert is_patched(widget)
+    unpatch_widget(widget)
+    assert not is_patched(widget)
+
+    conftest.save_image(
+        widget,
+        f"{request.node.name}_{cls.__name__}_dynamic_font_size",
+    )

typhos/widgets.py

@@ -22,7 +22,7 @@
 from qtpy.QtWidgets import (QAction, QDialog, QDockWidget, QPushButton,
                             QToolBar, QVBoxLayout, QWidget)
 
-from . import plugins, utils, variety
+from . import dynamic_font, plugins, utils, variety
 from .textedit import TyphosTextEdit  # noqa: F401
 from .tweakable import TyphosTweakable  # noqa: F401
 from .variety import use_for_variety_read, use_for_variety_write
@@ -393,6 +393,18 @@ def unit_changed(self, new_unit):
         if new_unit.lower() in EXPONENTIAL_UNITS and default:
             self.displayFormat = DisplayFormat.Exponential
 
+    @Property(bool, "dynamicFontSize")
+    def dynamic_font_size(self) -> bool:
+        """Dynamically adjust the font size"""
+        return dynamic_font.is_patched(self)
+
+    @dynamic_font_size.setter
+    def dynamic_font_size(self, value: bool):
+        if value:
+            dynamic_font.patch_widget(self)
+        else:
+            dynamic_font.unpatch_widget(self)
+
 
 class TyphosSidebarItem(ParameterItem):
     """