How to catch libpng error bad adaptive filter in PyQt5

Question

I have a list of pictures which are displayed simultanously. They are all picked up in a for loop and added to a list.

Unfortunately some PNGs are corrupted. There is no way for me to tell in advance which are corrupted, also there is no chance to convert such PNG.

There must be a way to ignore the faulty PNGs and skip them.

Currently my code looks like this:

for file in os.listdir(path):
        # checking if file is png format
        if file.endswith('.png'):
            pic             = os.path.join(self.path_selected, file)
            img_label       = qtw.QWidget()
            pixmap          = qtg.QPixmap(pic).scaledToWidth(img_width)

            img_label.setPixmap(pixmap)
            self.img_mosaique.layout().addWidget(img_label, img_row_count, img_col_count)

            # Adding paths of images to a list
            self.img_mosaique.set_image_path(pic)

As you can see currently I am adding also faulty pictures.

As far as I found out, libpng does not throw any exceptions. I had found a solution to use this

try:
    Image.open(path).tobytes()
except IOError:
    print('detect error img %s' % path)
    continue

Source: libpng warning: Ignoring bad adaptive filter type

I could not make it work with this solution.

Answer 1

Qt for efficiency reasons does not use exceptions to indicate the failures but other means, in the case of QPixmap loading a corrupt image this will return a null QPixmap so you only have to verify that.

for file in os.listdir(path):
    if file.endswith(".png"):
        pic = os.path.join(self.path_selected, file)
        img_label = qtw.QWidget()
        pixmap = qtg.QPixmap(pic)
        if pixmap.isNull():
            continue
        img_label.setPixmap(pixmap.scaledToWidth(img_width))
        self.img_mosaique.layout().addWidget(img_label, img_row_count, img_col_count)
        self.img_mosaique.set_image_path(pic)