ida: add adjustable font menu in IDA plugin

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__}"
@@ -304,6 +305,39 @@ 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 slot_font(self):
+        """launch the font dialog and apply the chosen font"""
+        font_str = settings.user.get(CAPA_SETTINGS_FONT, "")
+        current_font = QtGui.QFontDatabase.systemFont(QtGui.QFontDatabase.FixedFont)
+        if font_str:
+            current_font.fromString(font_str)
+        font, ok = QtWidgets.QFontDialog.getFont(current_font, self.parent, "Select Plugin Font")
+        if ok:
+            settings.user[CAPA_SETTINGS_FONT] = font.toString()
+            self.update_fonts(font)
+
+    def update_fonts(self, font: QtGui.QFont):
+        """propagate the selected font throughout the plugin UI"""
+        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)
+        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"""
@@ -345,22 +379,26 @@ def load_view_buttons(self):
         reset_button = QtWidgets.QPushButton("Reset Selections")
         save_button = QtWidgets.QPushButton("Save")
         settings_button = QtWidgets.QPushButton("Settings")
+        font_button = QtWidgets.QPushButton("Font...")
 
         analyze_button.clicked.connect(self.slot_analyze)
         reset_button.clicked.connect(self.slot_reset)
         save_button.clicked.connect(self.slot_save)
         settings_button.clicked.connect(self.slot_settings)
+        font_button.clicked.connect(self.slot_font)
 
         layout = QtWidgets.QHBoxLayout()
         layout.addWidget(analyze_button)
         layout.addWidget(reset_button)
         layout.addWidget(settings_button)
+        layout.addWidget(font_button)
         layout.addStretch(3)
         layout.addWidget(save_button, alignment=QtCore.Qt.AlignRight)
 
         self.view_analyze_button = analyze_button
         self.view_reset_button = reset_button
         self.view_settings_button = settings_button
+        self.view_font_button = font_button
         self.view_save_button = save_button
         self.view_buttons = layout
 
@@ -416,9 +454,8 @@ 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)

capa/ida/plugin/model.py

@@ -61,6 +61,12 @@ 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.current_font = font
+        self.layoutChanged.emit()
 
     def reset(self):
         """reset UI elements (e.g. checkboxes, IDA color highlights)
@@ -134,7 +140,8 @@ 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 +163,13 @@ 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)

capa/ida/plugin/view.py

@@ -182,11 +182,20 @@ def __init__(self, parent=None):
         """ """
         super().__init__(parent)
 
-        self.setFont(QtGui.QFont("Courier", weight=QtGui.QFont.Bold))
+        self.current_font = QtGui.QFontDatabase.systemFont(QtGui.QFontDatabase.FixedFont)
+        font = QtGui.QFont(self.current_font)
+        font.setBold(True)
+        self.setFont(font)
         self.setLineWrapMode(QtWidgets.QTextEdit.NoWrap)
         self.setHorizontalScrollBarPolicy(QtCore.Qt.ScrollBarAsNeeded)
         self.setAcceptRichText(False)
 
+    def update_font(self, font: QtGui.QFont):
+        self.current_font = font
+        preview_font = QtGui.QFont(self.current_font)
+        preview_font.setBold(True)
+        self.setFont(preview_font)
+
     def reset_view(self):
         """ """
         self.clear()
@@ -347,6 +356,7 @@ def __init__(self, preview, parent=None):
         self.reset_view()
 
         self.is_editing = False
+        self.current_font = QtGui.QFontDatabase.systemFont(QtGui.QFontDatabase.FixedFont)
 
     @staticmethod
     def get_column_feature_index():
@@ -498,6 +508,20 @@ def slot_item_double_clicked(self, o, column):
             o.setFlags(o.flags() & ~QtCore.Qt.ItemIsEditable)
             self.is_editing = True
 
+    def update_font(self, font: QtGui.QFont):
+        """apply a new font to the editor and restyle existing nodes"""
+        self.current_font = font
+        self.setFont(font)
+        self.header().setFont(font)
+        for node in iterate_tree(self):
+            if getattr(node, "capa_type", None) == CapaExplorerRulegenEditor.get_node_type_expression():
+                self.style_expression_node(node)
+            elif getattr(node, "capa_type", None) == CapaExplorerRulegenEditor.get_node_type_feature():
+                self.style_feature_node(node)
+            elif getattr(node, "capa_type", None) == CapaExplorerRulegenEditor.get_node_type_comment():
+                self.style_comment_node(node)
+        self.slot_resize_columns_to_content()
+
     def update_preview(self):
         """ """
         rule_text = self.preview.toPlainText()
@@ -577,17 +601,16 @@ def load_custom_context_menu_expression(self, pos):
 
     def style_expression_node(self, o):
         """ """
-        font = QtGui.QFont()
+        font = QtGui.QFont(self.current_font)
         font.setBold(True)
 
         o.setFont(CapaExplorerRulegenEditor.get_column_feature_index(), font)
 
     def style_feature_node(self, o):
         """ """
-        font = QtGui.QFont()
+        font = QtGui.QFont(self.current_font)
         brush = QtGui.QBrush()
 
-        font.setFamily("Courier")
         font.setWeight(QtGui.QFont.Medium)
         brush.setColor(QtGui.QColor(*COLOR_GREEN_RGB))
 
@@ -596,9 +619,8 @@ def style_feature_node(self, o):
 
     def style_comment_node(self, o):
         """ """
-        font = QtGui.QFont()
+        font = QtGui.QFont(self.current_font)
         font.setBold(True)
-        font.setFamily("Courier")
 
         o.setFont(CapaExplorerRulegenEditor.get_column_feature_index(), font)
 
@@ -814,6 +836,7 @@ def __init__(self, editor, parent=None):
 
         self.parent_items = {}
         self.editor = editor
+        self.current_font = QtGui.QFontDatabase.systemFont(QtGui.QFontDatabase.FixedFont)
 
         self.setHeaderLabels(["Feature", "Address"])
         self.setStyleSheet("QTreeView::item {padding-right: 15 px;padding-bottom: 2 px;}")
@@ -972,14 +995,15 @@ def show_item_and_parents(_o):
 
     def style_parent_node(self, o):
         """ """
-        font = QtGui.QFont()
+        font = QtGui.QFont(self.current_font)
         font.setBold(True)
 
         o.setFont(CapaExplorerRulegenFeatures.get_column_feature_index(), font)
 
     def style_leaf_node(self, o):
         """ """
-        font = QtGui.QFont("Courier", weight=QtGui.QFont.Bold)
+        font = QtGui.QFont(self.current_font)
+        font.setBold(True)
         brush = QtGui.QBrush()
 
         o.setFont(CapaExplorerRulegenFeatures.get_column_feature_index(), font)
@@ -990,6 +1014,17 @@ def style_leaf_node(self, o):
 
         brush.setColor(QtGui.QColor(*COLOR_BLUE_RGB))
         o.setForeground(CapaExplorerRulegenFeatures.get_column_address_index(), brush)
+    def update_font(self, font: QtGui.QFont):
+        """apply a new font to the feature tree and restyle nodes"""
+        self.current_font = font
+        self.setFont(font)
+        self.header().setFont(font)
+        for node in iterate_tree(self):
+            if getattr(node, "capa_type", None) == CapaExplorerRulegenFeatures.get_node_type_parent():
+                self.style_parent_node(node)
+            elif getattr(node, "capa_type", None) == CapaExplorerRulegenFeatures.get_node_type_leaf():
+                self.style_leaf_node(node)
+        self.slot_resize_columns_to_content()
 
     def set_parent_node(self, o):
         """ """
@@ -1133,6 +1168,10 @@ def __init__(self, model, parent=None):
 
         self.setStyleSheet("QTreeView::item {padding-right: 15 px;padding-bottom: 2 px;}")
 
+    def update_font(self, font: QtGui.QFont):
+        self.setFont(font)
+        self.header().setFont(font)
+
     def reset_ui(self, should_sort=True):
         """reset user interface changes