ida: add adjustable font menu in IDA plugin

CHANGELOG.md

@@ -3,6 +3,7 @@
 ## master (unreleased)
 
 ### New Features
+- ida plugin: add a "Font…" action so users can adjust the explorer font on demand, with desktop DPI awareness baked in #2570
 
 ### Breaking Changes
 
@@ -163,7 +164,7 @@ Additionally a Binary Ninja bug has been fixed. Released binaries now include AR
 
 ### Bug Fixes
 
-- binja: fix a crash during feature extraction when the MLIL is unavailable @xusheng6 #2714 
+- binja: fix a crash during feature extraction when the MLIL is unavailable @xusheng6 #2714
 
 ### capa Explorer Web
 

capa/ida/plugin/form.py

@@ -60,6 +60,7 @@
 CAPA_SETTINGS_RULEGEN_AUTHOR = "rulegen_author"
 CAPA_SETTINGS_RULEGEN_SCOPE = "rulegen_scope"
 CAPA_SETTINGS_ANALYZE = "analyze"
+CAPA_SETTINGS_FONT = "font"
 
 
 CAPA_OFFICIAL_RULESET_URL = f"https://github.com/mandiant/capa-rules/releases/tag/v{capa.version.__version__}"
@@ -117,10 +118,12 @@ def mouseReleaseEvent(self, e):
 
 
 class CapaSettingsInputDialog(QtWidgets.QDialog):
-    def __init__(self, title, parent=None):
+    def __init__(self, title, parent=None, on_font_changed=None):
         """ """
         super().__init__(parent)
 
+        self.on_font_changed = on_font_changed
+
         self.setWindowTitle(title)
         self.setMinimumWidth(500)
         self.setWindowFlags(self.windowFlags() & ~QtCore.Qt.WindowContextHelpButtonHint)
@@ -130,9 +133,14 @@ def __init__(self, title, parent=None):
         self.edit_rule_scope = QtWidgets.QComboBox()
         self.edit_rules_link = QtWidgets.QLabel()
         self.edit_analyze = QtWidgets.QComboBox()
+        self.btn_font = QtWidgets.QPushButton("Font")
         self.btn_delete_results = QtWidgets.QPushButton(
             self.style().standardIcon(QtWidgets.QStyle.SP_BrowserStop), "Delete cached capa results"
         )
+        self.font = QtGui.QFontDatabase.systemFont(QtGui.QFontDatabase.FixedFont)
+        font_str = settings.user.get(CAPA_SETTINGS_FONT, "")
+        if font_str:
+            self.font.fromString(font_str)
 
         self.edit_rules_link.setText(
             f'<a href="{CAPA_OFFICIAL_RULESET_URL}">Download and extract official capa rules</a>'
@@ -154,6 +162,7 @@ def __init__(self, title, parent=None):
         layout.addRow("", self.edit_rules_link)
 
         layout.addRow("Plugin start option", self.edit_analyze)
+        layout.addRow("Explorer font", self.btn_font)
         if capa.ida.helpers.idb_contains_cached_results():
             self.btn_delete_results.clicked.connect(capa.ida.helpers.delete_cached_results)
             self.btn_delete_results.clicked.connect(lambda state: self.btn_delete_results.setEnabled(False))
@@ -167,16 +176,33 @@ def __init__(self, title, parent=None):
 
         layout.addWidget(buttons)
 
+        self.btn_font.clicked.connect(self.select_font)
         buttons.accepted.connect(self.accept)
         buttons.rejected.connect(self.reject)
 
+    def select_font(self):
+        """launch the font dialog"""
+        original_font = QtGui.QFont(self.font)
+        dialog = QtWidgets.QFontDialog(self.font, self)
+        dialog.setWindowTitle("Select Plugin Font")
+        if self.on_font_changed:
+            dialog.currentFontChanged.connect(self.on_font_changed)
+
+        if dialog.exec_():
+            self.font = dialog.currentFont()
+            if self.on_font_changed:
+                self.on_font_changed(self.font)
+        elif self.on_font_changed:
+            self.on_font_changed(original_font)
+
     def get_values(self):
         """ """
         return (
             self.edit_rule_path.text(),
             self.edit_rule_author.text(),
             self.edit_rule_scope.currentText(),
             self.edit_analyze.currentIndex(),
+            self.font.toString(),
         )
 
 
@@ -304,6 +330,33 @@ def load_interface(self):
 
         # load parent view
         self.load_view_parent()
+        self.load_font()
+
+    def load_font(self):
+        """load the user-configured font or fall back to the system fixed font"""
+        font_str = settings.user.get(CAPA_SETTINGS_FONT, "")
+        font = QtGui.QFontDatabase.systemFont(QtGui.QFontDatabase.FixedFont)
+        if font_str:
+            font.fromString(font_str)
+        self.update_fonts(font)
+
+    def update_fonts(self, font: QtGui.QFont):
+        """propagate the selected font throughout the plugin UI"""
+        expanded_items = []
+        if hasattr(self, "view_tree") and self.view_tree:
+            expanded_items = self.view_tree.get_expanded_source_items()
+
+        if hasattr(self, "model_data") and self.model_data:
+            self.model_data.update_font(font)
+        if hasattr(self, "view_tree") and self.view_tree:
+            self.view_tree.update_font(font)
+            self.view_tree.restore_expanded_source_items(expanded_items)
+        if hasattr(self, "view_rulegen_preview") and self.view_rulegen_preview:
+            self.view_rulegen_preview.update_font(font)
+        if hasattr(self, "view_rulegen_editor") and self.view_rulegen_editor:
+            self.view_rulegen_editor.update_font(font)
+        if hasattr(self, "view_rulegen_features") and self.view_rulegen_features:
+            self.view_rulegen_features.update_font(font)
 
     def load_view_tabs(self):
         """load tabs"""
@@ -416,9 +469,8 @@ def load_view_rulegen_tab(self):
         left = QtWidgets.QWidget()
         left.setLayout(layout2)
 
-        font = QtGui.QFont()
+        font = QtGui.QFontDatabase.systemFont(QtGui.QFontDatabase.FixedFont)
         font.setBold(True)
-        font.setPointSize(11)
 
         label1 = QtWidgets.QLabel()
         label1.setAlignment(QtCore.Qt.AlignLeft)
@@ -1301,14 +1353,25 @@ def slot_save(self):
 
     def slot_settings(self):
         """ """
-        dialog = CapaSettingsInputDialog("capa explorer settings", parent=self.parent)
+        original_font = QtGui.QFontDatabase.systemFont(QtGui.QFontDatabase.FixedFont)
+        font_str = settings.user.get(CAPA_SETTINGS_FONT, "")
+        if font_str:
+            original_font.fromString(font_str)
+
+        dialog = CapaSettingsInputDialog(
+            "capa explorer settings", parent=self.parent, on_font_changed=self.update_fonts
+        )
         if dialog.exec_():
             (
                 settings.user[CAPA_SETTINGS_RULE_PATH],
                 settings.user[CAPA_SETTINGS_RULEGEN_AUTHOR],
                 settings.user[CAPA_SETTINGS_RULEGEN_SCOPE],
                 settings.user[CAPA_SETTINGS_ANALYZE],
+                settings.user[CAPA_SETTINGS_FONT],
             ) = dialog.get_values()
+            self.load_font()
+        else:
+            self.update_fonts(original_font)
 
     def save_program_analysis(self):
         """ """

capa/ida/plugin/model.py

@@ -61,6 +61,13 @@ def __init__(self, parent=None):
         super().__init__(parent)
         # root node does not have parent, contains header columns
         self.root_node = CapaExplorerDataItem(None, ["Rule Information", "Address", "Details"])
+        self.current_font = QtGui.QFontDatabase.systemFont(QtGui.QFontDatabase.FixedFont)
+
+    def update_font(self, font: QtGui.QFont):
+        """update the font used to render items"""
+        self.beginResetModel()
+        self.current_font = font
+        self.endResetModel()
 
     def reset(self):
         """reset UI elements (e.g. checkboxes, IDA color highlights)
@@ -134,7 +141,8 @@ def data(self, model_index, role):
             CapaExplorerDataModel.COLUMN_INDEX_DETAILS,
         ):
             # set font for virtual address and details columns
-            font = QtGui.QFont("Courier", weight=QtGui.QFont.Medium)
+            font = QtGui.QFont(self.current_font)
+            font.setWeight(QtGui.QFont.Medium)
             if column == CapaExplorerDataModel.COLUMN_INDEX_VIRTUAL_ADDRESS:
                 font.setBold(True)
             return font
@@ -156,10 +164,13 @@ def data(self, model_index, role):
             and column == CapaExplorerDataModel.COLUMN_INDEX_RULE_INFORMATION
         ):
             # set bold font for important items
-            font = QtGui.QFont()
+            font = QtGui.QFont(self.current_font)
             font.setBold(True)
             return font
 
+        if role == QtCore.Qt.FontRole:
+            return QtGui.QFont(self.current_font)
+
         if role == QtCore.Qt.ForegroundRole and column == CapaExplorerDataModel.COLUMN_INDEX_VIRTUAL_ADDRESS:
             # set color for virtual address column
             return QtGui.QColor(37, 147, 215)
@@ -244,6 +255,15 @@ def parent(self, model_index):
 
         return self.createIndex(parent.row(), 0, parent)
 
+    def index_from_item(self, item, column=0):
+        """return the model index for the given item"""
+        if item is None or item == self.root_node:
+            return QtCore.QModelIndex()
+
+        parent = item.parent()
+        parent_index = self.index_from_item(parent, 0)
+        return self.index(item.row(), column, parent_index)
+
     def iterateChildrenIndexFromRootIndex(self, model_index, ignore_root=True):
         """depth-first traversal of child nodes