fix: transpose selected region correctly #397

On wayland, window and screen dimensions reported by Qt differ if "normal" scaling is used, or the experimental fractional scaling (scale-monitor-framebuffer). To transpose the selected region from window position to screenshot position robustly, it's better to use Qt's window dimensions as reference instead of the Qt's screen dimensions.
dynobo · Dec 4, 2023 · 98691bc · 98691bc
1 parent dc8fced
commit 98691bc
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Showing 3 changed files with 19 additions and 10 deletions.
diff --git a/CHANGELOG b/CHANGELOG
@@ -2,7 +2,7 @@
 
 # Changelog
 
-## v0.5.0beta2 (not yet released)
+## v0.5.0 (not yet released)
 
 - All: Fix issue where introduction window was still visible on the screen capture UI.
   ([#536 comment](https://github.com/dynobo/normcap/issues/536#issuecomment-1752110232))
@@ -16,6 +16,10 @@
   replaced by `"`. (You can still use "raw"-mode to leave them intact.)
 - Windows, macOS: Fix notifications not clickable in "raw"-Mode.
   ([#438 comment](https://github.com/dynobo/normcap/issues/438#issuecomment-1752175090))
+- Linux: Fig segfault in AppImage.
+  ([#543](https://github.com/dynobo/normcap/issues/534))
+- Linux: Fix incorrect selection when display scaling is active.
+  ([#397](https://github.com/dynobo/normcap/issues/397))
 - Linux: Add support for using `xclip` to copy result to clipboard. This seems more
   stable on Wayland systems than `wl-clipboard`, at least until compatibility with
   latest Gnome updates is restored.

diff --git a/normcap/gui/window.py b/normcap/gui/window.py
@@ -14,8 +14,9 @@
 import logging
 import sys
 import tempfile
+from dataclasses import dataclass
 from pathlib import Path
-from typing import Any, Callable, NamedTuple, cast
+from typing import Any, Callable, cast
 
 from PySide6 import QtCore, QtGui, QtWidgets
 
@@ -33,7 +34,8 @@
 logger = logging.getLogger(__name__)
 
 
-class DebugInfo(NamedTuple):
+@dataclass
+class DebugInfo:
     screen: Screen | None = None
     window: QtWidgets.QMainWindow | None = None
     scale_factor: float = 1
@@ -166,7 +168,7 @@ def _get_scale_factor(self) -> float:
         """Calculate scale factor from image and screen dimensions."""
         if not self.screen_.screenshot:
             raise ValueError("Screenshot image is missing!")
-        return self.screen_.screenshot.width() / self.screen_.width
+        return self.screen_.screenshot.width() / self.width()
 
     def _add_image_container(self) -> None:
         """Add widget showing screenshot."""
@@ -338,6 +340,8 @@ def resizeEvent(self, event: QtGui.QResizeEvent) -> None:  # noqa: N802
         """Adjust child widget on resize."""
         super().resizeEvent(event)
         self.ui_container.resize(self.size())
+        if self.ui_container.debug_info:
+            self.ui_container.debug_info.scale_factor = self._get_scale_factor()
 
     def showEvent(self, event: QtGui.QShowEvent) -> None:  # noqa: N802
         """Update background image on show/reshow."""
@@ -386,17 +390,17 @@ def _draw_debug_infos(self, painter: QtGui.QPainter, rect: QtCore.QRect) -> None
             "[ Screen ]",
             f"Size: {self.debug_info.screen.size}",
             f"Position: {self.debug_info.screen.coords}",
-            f"Selected region: {selection.geometry}",
             f"Device pixel ratio: {self.debug_info.screen.device_pixel_ratio}",
             "",
             "[ Window ]",
             f"Size: {self.debug_info.window.size().toTuple()}",
             f"Position: {cast(tuple, self.debug_info.window.geometry().getCoords())}",
             f"Device pixel ratio: {self.debug_info.window.devicePixelRatio()}",
+            f"Selected region: {selection.coords}",
             "",
             "[ Screenshot ]",
             f"Size: {self.debug_info.screen.screenshot.size().toTuple()}",
-            f"Selected region (scaled): {selection_scaled.geometry}",
+            f"Selected region (scaled): {selection_scaled.coords}",
             "",
             "[ Scaling detected ]",
             f"Factor: {self.debug_info.scale_factor:.2f}",

diff --git a/tests/tests_gui/test_window.py b/tests/tests_gui/test_window.py
@@ -25,15 +25,15 @@ def test_move_active_window_to_position_raises_on_non_linux():
 
 @pytest.mark.gui()
 @pytest.mark.parametrize(
-    ("img_size", "screen_size", "expected_factor"),
+    ("img_size", "window_size", "expected_factor"),
     [
         ((600, 400), (600, 400), 1.0),
         ((300, 200), (600, 400), 0.5),
         ((1200, 800), (600, 400), 2.0),
     ],
 )
 def test_window_get_scale_factor(
-    qtbot, temp_settings, img_size, screen_size, expected_factor
+    qtbot, temp_settings, img_size, window_size, expected_factor
 ):
     # GIVEN a screenshot of a certain size
     #   and a certain (Qt) screen size
@@ -42,14 +42,15 @@ def test_window_get_scale_factor(
         device_pixel_ratio=1.0,
         left=0,
         top=0,
-        right=screen_size[0] - 1,
-        bottom=screen_size[1] - 1,
+        right=window_size[0] - 1,
+        bottom=window_size[1] - 1,
         index=0,
         screenshot=image,
     )
 
     # WHEN the window is shown
     win = window.Window(screen=screen, settings=temp_settings, parent=None)
+    win.resize(QtCore.QSize(*window_size))
     qtbot.addWidget(win)
 
     # THEN the expected scaling factor should be calculated