Add a custom log handler

napari/__init__.py

@@ -2,6 +2,8 @@
 
 from lazy_loader import attach as _attach
 
+from napari.utils._logging import _get_custom_log_stream
+
 try:
     from napari._version import version as __version__
 except ImportError:
@@ -42,6 +44,8 @@
     'viewer': ['Viewer', 'current_viewer'],
 }
 
+_LOG_STREAM = _get_custom_log_stream()
+
 # All imports in __init__ are hidden inside of `__getattr__` to prevent
 # importing the full chain of packages required when calling `import napari`.
 #

napari/_qt/_qapp_model/qactions/_help.py

@@ -45,6 +45,12 @@ def _show_about(window: Window):
         ],
         status_tip=trans._('About napari'),
     ),
+    Action(
+        id='napari.window.help.log',
+        title=trans._('Show log'),
+        callback=Window._open_log_dialog,
+        menus=[{'id': MenuId.MENUBAR_HELP, 'group': MenuGroup.RENDER}],
+    ),
 ]
 
 if ask_opt_in is not None:

napari/_qt/dialogs/log_dialog.py

@@ -0,0 +1,58 @@
+from qtpy.QtCore import Qt
+from qtpy.QtWidgets import (
+    QDialog,
+    QHBoxLayout,
+    QLabel,
+    QTextEdit,
+    QVBoxLayout,
+)
+
+from napari import _LOG_STREAM
+from napari._qt.dialogs.qt_about import QtCopyToClipboardButton
+from napari.utils.translations import trans
+
+
+class LogDialog(QDialog):
+    def __init__(
+        self,
+        parent=None,
+    ) -> None:
+        super().__init__(parent._qt_window)
+
+        self.layout = QVBoxLayout()
+
+        # Description
+        title_label = QLabel(trans._('napari log'))
+        title_label.setTextInteractionFlags(
+            Qt.TextInteractionFlag.TextSelectableByMouse
+        )
+        self.layout.addWidget(title_label)
+
+        # Add information
+        self.infoTextBox = QTextEdit()
+        self.infoTextBox.setTextInteractionFlags(
+            Qt.TextInteractionFlag.TextSelectableByMouse
+        )
+        self.infoTextBox.setLineWrapMode(QTextEdit.NoWrap)
+        # Add text copy button
+        self.infoCopyButton = QtCopyToClipboardButton(self.infoTextBox)
+        self.info_layout = QHBoxLayout()
+        self.info_layout.addWidget(self.infoTextBox, 1)
+        self.info_layout.addWidget(
+            self.infoCopyButton, 0, Qt.AlignmentFlag.AlignTop
+        )
+        self.info_layout.setAlignment(Qt.AlignmentFlag.AlignTop)
+        self.layout.addLayout(self.info_layout)
+
+        self.infoTextBox.setText(str(_LOG_STREAM))
+        self.infoTextBox.setMinimumSize(
+            int(self.infoTextBox.document().size().width() + 19),
+            int(min(self.infoTextBox.document().size().height() + 10, 500)),
+        )
+
+        self.setLayout(self.layout)
+
+        self.setObjectName('LogDialog')
+        self.setWindowTitle(trans._('napari log'))
+        self.setWindowModality(Qt.WindowModality.ApplicationModal)
+        self.exec_()

napari/_qt/qt_main_window.py

@@ -1669,6 +1669,11 @@ def _screenshot_dialog(self):
         if dial.exec_():
             update_save_history(dial.selectedFiles()[0])
 
+    def _open_log_dialog(self):
+        from napari._qt.dialogs.log_dialog import LogDialog
+
+        LogDialog(parent=self)
+
 
 def _instantiate_dock_widget(wdg_cls, viewer: 'Viewer'):
     # if the signature is looking a for a napari viewer, pass it.

napari/utils/_logging.py

@@ -0,0 +1,49 @@
+import logging
+
+# keep track of all the logging info in a stream
+_LOG_SEPARATOR = '<NAPARI_LOG_SEPARATOR>'
+
+
+class _LogHandler:
+    def __init__(self):
+        self.logs = []
+
+    def write(self, log_msg):
+        level_name, time, thread, msg = log_msg.split(_LOG_SEPARATOR)
+        levels = logging.getLevelNamesMapping()
+        level_value = levels[level_name]
+        self.logs.append((level_value, level_name, time, thread, msg))
+
+    def flush(self):
+        pass
+
+    def __str__(self):
+        return ''.join(
+            [
+                f'[{time}] ({thread}) {level_name}: {msg}'
+                for _, level_name, time, thread, msg in self.logs
+            ]
+        )
+
+    def logs_at_level(self, level=logging.DEBUG):
+        if isinstance(level, str):
+            level = logging.getLevelName(level)
+        return [
+            (level_value, *others)
+            for level_value, *others in self.logs
+            if level_value >= level
+        ]
+
+
+def _get_custom_log_stream():
+    log_stream = _LogHandler()
+    handler = logging.StreamHandler(log_stream)
+    handler.setFormatter(
+        logging.Formatter(
+            f'%(levelname)s{_LOG_SEPARATOR}%(asctime)s{_LOG_SEPARATOR}%(threadName)s{_LOG_SEPARATOR}%(message)s'
+        )
+    )
+    logger = logging.getLogger('napari')
+    logger.setLevel(logging.DEBUG)
+    logger.addHandler(handler)
+    return log_stream