Add ImageItem tests, fix image downsampling bug

pyqtgraph/graphicsItems/ImageItem.py

@@ -300,8 +300,11 @@ class ImageItem(GraphicsObject):
             y = self.mapToDevice(QtCore.QPointF(0,1))
             w = Point(x-o).length()
             h = Point(y-o).length()
-            xds = int(1/max(1, w))
-            yds = int(1/max(1, h))
+            if w == 0 or h == 0:
+                self.qimage = None
+                return
+            xds = int(1.0/w)
+            yds = int(1.0/h)
             image = fn.downsample(self.image, xds, axis=0)
             image = fn.downsample(image, yds, axis=1)
         else:

pyqtgraph/graphicsItems/tests/test_ImageItem.py

@@ -1,17 +1,109 @@
-import gc
-import weakref
+import time
 import pytest
-# try:
-#     import faulthandler
-#     faulthandler.enable()
-# except ImportError:
-#     pass
-
 from pyqtgraph.Qt import QtCore, QtGui, QtTest
 import numpy as np
 import pyqtgraph as pg
+from pyqtgraph.tests import assertImageApproved
+
 app = pg.mkQApp()
 
+
+def test_ImageItem():
+    
+    view = pg.plot()
+    view.resize(200, 200)
+    img = pg.ImageItem(border=0.5)
+    view.addItem(img)
+    
+    
+    # test mono float
+    np.random.seed(0)
+    data = np.random.normal(size=(20, 20))
+    dmax = data.max()
+    data[:10, 1] = dmax + 10
+    data[1, :10] = dmax + 12
+    data[3, :10] = dmax + 13
+    img.setImage(data)
+    
+    QtTest.QTest.qWaitForWindowShown(view)
+    time.sleep(0.1)
+    app.processEvents()
+    assertImageApproved(view, 'imageitem/init', 'Init image item. View is auto-scaled, image axis 0 marked by 1 line, axis 1 is marked by 2 lines. Origin in bottom-left.')
+    
+    # ..with colormap
+    cmap = pg.ColorMap([0, 0.25, 0.75, 1], [[0, 0, 0, 255], [255, 0, 0, 255], [255, 255, 0, 255], [255, 255, 255, 255]])
+    img.setLookupTable(cmap.getLookupTable())
+    assertImageApproved(view, 'imageitem/lut', 'Set image LUT.')
+    
+    # ..and different levels
+    img.setLevels([dmax+9, dmax+13])
+    assertImageApproved(view, 'imageitem/levels1', 'Levels show only axis lines.')
+
+    img.setLookupTable(None)
+
+    # test mono int
+    data = np.fromfunction(lambda x,y: x+y*10, (129, 128)).astype(np.int16)
+    img.setImage(data)
+    assertImageApproved(view, 'imageitem/gradient_mono_int', 'Mono int gradient.')
+    
+    img.setLevels([640, 641])
+    assertImageApproved(view, 'imageitem/gradient_mono_int_levels', 'Mono int gradient w/ levels to isolate diagonal.')
+
+    # test mono byte
+    data = np.fromfunction(lambda x,y: x+y, (129, 128)).astype(np.ubyte)
+    img.setImage(data)
+    assertImageApproved(view, 'imageitem/gradient_mono_byte', 'Mono byte gradient.')
+    
+    img.setLevels([127, 128])
+    assertImageApproved(view, 'imageitem/gradient_mono_byte_levels', 'Mono byte gradient w/ levels to isolate diagonal.')
+
+    # test RGBA byte
+    data = np.zeros((100, 100, 4), dtype='ubyte')
+    data[..., 0] = np.linspace(0, 255, 100).reshape(100, 1)
+    data[..., 1] = np.linspace(0, 255, 100).reshape(1, 100)
+    data[..., 3] = 255
+    img.setImage(data)
+    assertImageApproved(view, 'imageitem/gradient_rgba_byte', 'RGBA byte gradient.')
+    
+    img.setLevels([[128, 129], [128, 255], [0, 1], [0, 255]])
+    assertImageApproved(view, 'imageitem/gradient_rgba_byte_levels', 'RGBA byte gradient. Levels set to show x=128 and y>128.')
+    
+    # test RGBA float
+    data = data.astype(float)
+    img.setImage(data / 1e9)
+    assertImageApproved(view, 'imageitem/gradient_rgba_float', 'RGBA float gradient.')
+
+    # checkerboard to test alpha
+    img2 = pg.ImageItem()
+    img2.setImage(np.fromfunction(lambda x,y: (x+y)%2, (10, 10)), levels=[-1,2])
+    view.addItem(img2)
+    img2.scale(10, 10)
+    img2.setZValue(-10)
+    
+    data[..., 0] *= 1e-9
+    data[..., 1] *= 1e9
+    data[..., 3] = np.fromfunction(lambda x,y: np.sin(0.1 * (x+y)), (100, 100))
+    img.setImage(data, levels=[[0, 128e-9],[0, 128e9],[0, 1],[-1, 1]])
+    assertImageApproved(view, 'imageitem/gradient_rgba_float_alpha', 'RGBA float gradient with alpha.')    
+
+    # test composition mode
+    img.setCompositionMode(QtGui.QPainter.CompositionMode_Plus)
+    assertImageApproved(view, 'imageitem/gradient_rgba_float_additive', 'RGBA float gradient with alpha and additive composition mode.')    
+    
+    img2.hide()
+    img.setCompositionMode(QtGui.QPainter.CompositionMode_SourceOver)
+    
+    # test downsampling
+    data = np.fromfunction(lambda x,y: np.cos(0.002 * x**2), (800, 100))
+    img.setImage(data, levels=[-1, 1])
+    assertImageApproved(view, 'imageitem/resolution_without_downsampling', 'Resolution test without downsampling.')
+    
+    img.setAutoDownsample(True)
+    assertImageApproved(view, 'imageitem/resolution_with_downsampling_x', 'Resolution test with downsampling axross x axis.')
+    
+    img.setImage(data.T, levels=[-1, 1])
+    assertImageApproved(view, 'imageitem/resolution_with_downsampling_y', 'Resolution test with downsampling across y axis.')
+
 @pytest.mark.skipif(pg.Qt.USE_PYSIDE, reason="pyside does not have qWait")
 def test_dividebyzero():
     import pyqtgraph as pg