Mouse Coordinates Do Not Update Correctly for Non-Square Images in PyQtGraph's ImageView

[JosephDemarest]

Short description

When using PyQtGraph's ImageView, mouse coordinates cease to update correctly when moving the cursor over an image with non-square dimensions (e.g., 4056x3040). Changing the image to a square dimension (e.g., 4056x4056) resolves the issue, suggesting a problem with handling non-square images.

Code to reproduce

import sys
import numpy as np
import pyqtgraph as pg
from PyQt5 import QtWidgets

class SimpleImageView(pg.ImageView):
    def __init__(self, image_data, *args, **kwargs):
        super(SimpleImageView, self).__init__(*args, **kwargs)
        self.setImage(image_data)
        self.scene.sigMouseMoved.connect(self.on_mouse_moved)

    def on_mouse_moved(self, pos):
        if self.imageItem.sceneBoundingRect().contains(pos):
            mouse_point = self.view.mapSceneToView(pos)
            x, y = int(mouse_point.x()), int(mouse_point.y())

            if 0 <= x < self.image.shape[1] and 0 <= y < self.image.shape[0]:
                print(f"Mouse coordinates: X: {x}, Y: {y}")
            else:
                print("Mouse is outside the image bounds.")

def main():
    app = QtWidgets.QApplication(sys.argv)
    image_data = np.random.rand(3040, 4056) * 255  # Square image
    image_data = image_data.astype(np.uint8)
    image_view = SimpleImageView(image_data)
    image_view.show()
    sys.exit(app.exec_())

if __name__ == '__main__':
    main()

Expected behavior

The application should continuously update and print the mouse coordinates as the cursor moves over different parts of the image, regardless of the image's aspect ratio.

Real behavior

The mouse coordinates stop updating and printing when the cursor moves beyond a certain point on non-square images. For example, with an image of size 4056x3040, the coordinates cease to update beyond 3040 in either dimension. However, when the image is resized to be square (e.g., 4056x4056), the full range of coordinates is correctly updated and printed.

Tested environment(s)

• PyQtGraph version: 0.13.3
• Qt Python binding: pyqtgraph.Qt PyQt5 5.15.9 Qt 5.15.8
• Python version: 3.11.2
• NumPy version: 1.24.2
• Operating system: Linux-6.1.63-v8_16k+-aarch64-with-glibc2.36

AND

• PyQtGraph version: 0.13.3
• Qt Python binding: pyqtgraph.Qt PyQt5 5.15.10 Qt 5.15.11
• Python version: 3.11.7
• NumPy version: 1.26.4
• Operating system: Linux-6.7.4-arch1-1-x86_64-with-glibc2.39

Additional context

The issue is not observed with square images, suggesting that the problem lies in how ImageView handles images with non-square dimensions. This could potentially be a limitation or bug within PyQtGraph's handling of such images.

[PhatCamel]

I am seeing similar issues but I don't know that it's exactly because the images are not square. I do find that when I do an image of 3000 x 3000 I get the proper cursor coordinate behavior, however when I do 3100 X 3000 I don't see the proper behavior. I also noticed though that with square images that are small, I tried 300 x 300 I see a similar issue as with the 3100 x 3000 image although this image is square. I also tried 1000 x 1000 and had the same issue (not sure where the cutoff point is).

EDIT:

I actually found the issue I was having was related to resizing the window of the widget, the coordinates do not update to where the image is after resizing for smaller images. I have verified though that having non-square images (even before any window resizing) seems to have the problem you described.