"""
Array label
===========
:mod:`cv2PySide6.labels` provides subclasses of ``QLabel`` with utilities.
"""
import enum
import numpy as np
from PySide6.QtCore import Qt, Slot
from PySide6.QtGui import QPixmap
from PySide6.QtWidgets import QLabel, QSizePolicy
from qimage2ndarray import array2qimage # type: ignore[import]
__all__ = [
"ScalableQLabel",
"NDArrayLabel",
]
[docs]
class ScalableQLabel(QLabel):
"""
A label which can scale the pixmap before displaying.
Pixmap can be downscaled or upscaled to fit to the label size, depending on
:meth:`pixmapScaleMode`.
:meth:`setPixmap` scales the input pixmap and update to label.
:meth:`originalPixmap` returns current unscaled pixmap.
Notes
=====
Do not modify the size policy and minimum size value. Changing them makes the
label not shrinkable.
"""
[docs]
class PixmapScaleMode(enum.Enum):
"""
This enum defines how the pixmap is scaled before being displayed.
Attributes
==========
PM_NoScale
Pixmap is never scaled. If the label size is smaller than the pixmap
size, only a part of the pixmap is displayed.
PM_DownScaleOnly
Pixmap is scaled, but never larger than its original size.
PM_UpScaleOnly
Pixmap is scaled, but never smaller than its original size.
PM_AllScale
Pixmap is scaled to any size.
"""
PM_NoScale = 0
PM_DownScaleOnly = 1
PM_UpScaleOnly = 2
PM_AllScale = 3
PM_NoScale = PixmapScaleMode.PM_NoScale
PM_DownScaleOnly = PixmapScaleMode.PM_DownScaleOnly
PM_UpScaleOnly = PixmapScaleMode.PM_UpScaleOnly
PM_AllScale = PixmapScaleMode.PM_AllScale
def __init__(self, parent=None):
super().__init__(parent)
self._original_pixmap = QPixmap()
self._pixmapScaleMode = self.PM_DownScaleOnly
# make label shrinkable
self.setSizePolicy(QSizePolicy.Expanding, QSizePolicy.Expanding)
self.setMinimumSize(1, 1) # (0, 0) prevents resizing
[docs]
def originalPixmap(self) -> QPixmap:
"""Original pixmap before scaling."""
return self._original_pixmap
[docs]
def pixmapScaleMode(self) -> PixmapScaleMode:
"""Mode to scale the pixmap. Default is :attr:`PM_DownScaleOnly`."""
return self._pixmapScaleMode
@Slot(PixmapScaleMode)
def setPixmapScaleMode(self, flag: PixmapScaleMode):
"""Set :meth:`pixmapScaleMode` to *flag* and update the label."""
self._pixmapScaleMode = flag
self.update()
@Slot(QPixmap)
def setPixmap(self, pixmap: QPixmap):
"""Scale the pixmap and display."""
self._original_pixmap = pixmap
mode = self.pixmapScaleMode()
if mode == self.PM_NoScale:
flag = False
else:
w, h = pixmap.width(), pixmap.height()
new_w = self.width()
new_h = self.height()
if mode == self.PM_DownScaleOnly:
flag = new_w < w or new_h < h
elif mode == self.PM_UpScaleOnly:
flag = new_w > w or new_h > h
elif mode == self.PM_AllScale:
flag = True
else:
msg = "Unrecognized pixmap scale mode: %s" % mode
raise TypeError(msg)
if flag:
pixmap = pixmap.scaled(new_w, new_h, Qt.KeepAspectRatio)
super().setPixmap(pixmap)
def paintEvent(self, event):
super().paintEvent(event)
self.setPixmap(self.originalPixmap())
[docs]
class NDArrayLabel(ScalableQLabel):
"""
Scalable label which can receive and display :class:`numpy.ndarray` image.
Image array can be set by :meth:`setArray`.
Examples
========
>>> import cv2
>>> from PySide6.QtWidgets import QApplication
>>> import sys
>>> from cv2PySide6 import NDArrayLabel, get_data_path
>>> img = cv2.imread(get_data_path('hello.jpg'))
>>> def runGUI():
... app = QApplication(sys.argv)
... label = NDArrayLabel()
... label.setArray(cv2.cvtColor(img, cv2.COLOR_BGR2RGB))
... label.show()
... app.exec()
... app.quit()
>>> runGUI() # doctest: +SKIP
"""
@Slot(np.ndarray)
def setArray(self, array: np.ndarray):
"""
Convert the array to pixmap using :func:`qimage2ndarray.array2qimage`,
and display.
"""
if array.size > 0:
pixmap = QPixmap.fromImage(array2qimage(array))
else:
pixmap = QPixmap()
self.setPixmap(pixmap)