Drop the Zoom +/− toolbar actions; show the window through the page's uncovered corners

The wheel (and Fit, Ctrl+0) remain. The stitched page has white in
areas that were never scanned; when the view rotates it to level the
text, those triangles stuck out white against the dark window. The
page is now shown with its exact-white pixels transparent, so the
window colour shows through there instead.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

myscan/app.py

@@ -30,12 +30,20 @@ from .ocr import Ocr, layout, paragraph_joins, reflow, text_direction
 IMAGE_FILTER = "Images (*.png *.jpg *.jpeg *.tif *.tiff *.bmp *.webp)"
 
 
-def to_qimage(img):
+def to_qimage(img, page=False):
-    """BGR or grayscale uint8 array -> QImage (a copy)."""
+    """BGR or grayscale uint8 array -> QImage (a copy). With `page`, exact-white pixels
+    (the uncovered corners of a stitched page) become transparent, so when the view
+    rotates the page to level it those corners show the window background through."""
     img = np.ascontiguousarray(img)
     h, w = img.shape[:2]
-    fmt = QImage.Format_Grayscale8 if img.ndim == 2 else QImage.Format_BGR888
+    if not page:
-    return QImage(img.data, w, h, img.strides[0], fmt).copy()
+        fmt = QImage.Format_Grayscale8 if img.ndim == 2 else QImage.Format_BGR888
+        return QImage(img.data, w, h, img.strides[0], fmt).copy()
+    bgra = cv2.cvtColor(img, cv2.COLOR_GRAY2BGRA if img.ndim == 2 else cv2.COLOR_BGR2BGRA)
+    uncovered = (img == 255).all(axis=-1) if img.ndim == 3 else (img == 255)
+    bgra[uncovered, 3] = 0
+    bgra = np.ascontiguousarray(bgra)
+    return QImage(bgra.data, w, h, bgra.strides[0], QImage.Format_ARGB32).copy()
 
 
 def imread(path):
@@ -90,7 +98,7 @@ class Bridge(QObject):
         self.start_event, self.stop_event = threading.Event(), threading.Event()
 
     def publish(self, name, bgr):
-        (self.frame if name == "frame" else self.page).emit(to_qimage(bgr))
+        (self.frame if name == "frame" else self.page).emit(to_qimage(bgr, page=(name == "page")))
 
     def set_status(self, **kw):
         self.state = {**self.state, **kw}
@@ -616,8 +624,6 @@ class MainWindow(QMainWindow):
         self.act_boxes = act("Boxes", lambda on: self.view.show_boxes(on), "Ctrl+B", "Show recognised lines on the page", True)
         self.act_boxes.setChecked(True)
         act("Fit", lambda: self.view.fit(), "Ctrl+0", "Fit the page to the window")
-        act("Zoom +", lambda: self.view.zoom(1.25), QKeySequence.ZoomIn)
-        act("Zoom −", lambda: self.view.zoom(0.8), QKeySequence.ZoomOut)
         for a in (self.act_save, self.act_copy):
             a.setEnabled(False)
 
@@ -735,7 +741,7 @@ class MainWindow(QMainWindow):
         self.page_id += 1
         self.view.set_lines([])
         self.view.angle = 0.0
-        self.view.set_image(to_qimage(img))
+        self.view.set_image(to_qimage(img, page=True))
         name = os.path.basename(path) if path else "page"
         self.page_title = f"Page — {name}  ({img.shape[1]}×{img.shape[0]})"
         self.page_head.setText(self.page_title)
@@ -802,7 +808,7 @@ class MainWindow(QMainWindow):
             return
         if flipped:          # the boxes are on the page turned the right way up
             self.image = np.ascontiguousarray(self.image[::-1, ::-1])
-            self.view.set_image(to_qimage(self.image))
+            self.view.set_image(to_qimage(self.image, page=True))
         self.lines = lines
         self.text, spans = layout(lines)
         self.view.set_lines(lines, self.text, spans)