support padded QImage

pyqtgraph/functions.py

@@ -1685,21 +1685,25 @@ def makeQImage(imgData, alpha=None, copy=True, transpose=True):
 def qimage_to_ndarray(qimg):
     img_ptr = qimg.bits()
 
-    if hasattr(img_ptr, 'setsize'): # PyQt sip.voidptr
+    if img_ptr is None:
+        raise ValueError("Null QImage not supported")
+
+    h, w = qimg.height(), qimg.width()
+    bpl = qimg.bytesPerLine()
+    depth = qimg.depth()
+    logical_bpl = w * depth // 8
+
+    if QT_LIB.startswith('PyQt'):
         # sizeInBytes() was introduced in Qt 5.10
         # however PyQt5 5.12 will fail with:
         #   "TypeError: QImage.sizeInBytes() is a private method"
         # note that sizeInBytes() works fine with:
         #   PyQt5 5.15, PySide2 5.12, PySide2 5.15
-        try:
+        img_ptr.setsize(h * bpl)
-            # 64-bits size
+
-            nbytes = qimg.sizeInBytes()
+    memory = np.frombuffer(img_ptr, dtype=np.ubyte).reshape((h, bpl))
-        except (TypeError, AttributeError):
+    memory = memory[:, :logical_bpl]
-            # 32-bits size
-            nbytes = qimg.byteCount()
-        img_ptr.setsize(nbytes)
 
-    depth = qimg.depth()
     if depth in (8, 24, 32):
         dtype = np.uint8
         nchan = depth // 8
@@ -1708,10 +1712,12 @@ def qimage_to_ndarray(qimg):
         nchan = depth // 16
     else:
         raise ValueError("Unsupported Image Type")
-    shape = qimg.height(), qimg.width()
+
+    shape = h, w
     if nchan != 1:
         shape = shape + (nchan,)
-    return np.frombuffer(img_ptr, dtype=dtype).reshape(shape)
+    arr = memory.view(dtype).reshape(shape)
+    return arr
 
 
 def imageToArray(img, copy=False, transpose=True):

tests/test_functions.py

@@ -9,6 +9,7 @@ import pytest
 from numpy.testing import assert_array_almost_equal
 
 import pyqtgraph as pg
+from pyqtgraph.Qt import QtGui
 
 np.random.seed(12345)
 
@@ -340,3 +341,24 @@ def test_ndarray_from_qpolygonf():
     poly = pg.functions.create_qpolygonf(0)
     arr = pg.functions.ndarray_from_qpolygonf(poly)
     assert isinstance(arr, np.ndarray)
+
+
+def test_qimage_to_ndarray():
+    # for QImages created w/o specifying bytesPerLine, Qt will pad
+    # each line to a multiple of 4-bytes.
+    # test that we can handle such QImages.
+    h = 10
+
+    fmt = QtGui.QImage.Format.Format_RGB888
+    for w in [5, 6, 7, 8]:
+        qimg = QtGui.QImage(w, h, fmt)
+        qimg.fill(0)
+        arr = pg.functions.qimage_to_ndarray(qimg)
+        assert arr.shape == (h, w, 3)
+
+    fmt = QtGui.QImage.Format.Format_Grayscale8
+    for w in [5, 6, 7, 8]:
+        qimg = QtGui.QImage(w, h, fmt)
+        qimg.fill(0)
+        arr = pg.functions.qimage_to_ndarray(qimg)
+        assert arr.shape == (h, w)