Add ScrollUp and ScrollDown commands for viewport scrolling, refine mouse wheel handling in GUI and terminal, and bump version to 1.2.2.

CMakeLists.txt

@@ -4,7 +4,7 @@ project(kte)
 include(GNUInstallDirs)
 
 set(CMAKE_CXX_STANDARD 17)
-set(KTE_VERSION "1.2.1")
+set(KTE_VERSION "1.2.2")
 
 # Default to terminal-only build to avoid SDL/OpenGL dependency by default.
 # Enable with -DBUILD_GUI=ON when SDL2/OpenGL/Freetype are available.
@@ -16,36 +16,36 @@ option(KTE_UNDO_DEBUG "Enable undo instrumentation logs" OFF)
 option(KTE_ENABLE_TREESITTER "Enable optional Tree-sitter highlighter adapter" OFF)
 
 if (CMAKE_HOST_UNIX)
-	message(STATUS "Build system is POSIX.")
+    message(STATUS "Build system is POSIX.")
 else ()
-	message(STATUS "Build system is NOT POSIX.")
+    message(STATUS "Build system is NOT POSIX.")
 endif ()
 
 if (MSVC)
-	add_compile_options("/W4" "$<$<CONFIG:RELEASE>:/O2>")
+    add_compile_options("/W4" "$<$<CONFIG:RELEASE>:/O2>")
 else ()
-	add_compile_options(
-		"-Wall"
-		"-Wextra"
-		"-Werror"
-		"$<$<CONFIG:DEBUG>:-g>"
-		"$<$<CONFIG:RELEASE>:-O2>")
-	if ("${CMAKE_CXX_COMPILER_ID}" STREQUAL "Clang")
-		add_compile_options("-stdlib=libc++")
-	else ()
-		# nothing special for gcc at the moment
-	endif ()
+    add_compile_options(
+            "-Wall"
+            "-Wextra"
+            "-Werror"
+            "$<$<CONFIG:DEBUG>:-g>"
+            "$<$<CONFIG:RELEASE>:-O2>")
+    if ("${CMAKE_CXX_COMPILER_ID}" STREQUAL "Clang")
+        add_compile_options("-stdlib=libc++")
+    else ()
+        # nothing special for gcc at the moment
+    endif ()
 endif ()
 add_compile_definitions(KGE_PLATFORM=${CMAKE_HOST_SYSTEM_NAME})
 add_compile_definitions(KTE_VERSION_STR="v${KTE_VERSION}")
 if (KTE_ENABLE_TREESITTER)
-	add_compile_definitions(KTE_ENABLE_TREESITTER)
+    add_compile_definitions(KTE_ENABLE_TREESITTER)
 endif ()
 
 message(STATUS "Build system: ${CMAKE_HOST_SYSTEM_NAME}")
 
 if (${BUILD_GUI})
-	include(cmake/imgui.cmake)
+    include(cmake/imgui.cmake)
 endif ()
 
 # NCurses for terminal mode
@@ -55,250 +55,250 @@ find_package(Curses REQUIRED)
 include_directories(${CURSES_INCLUDE_DIR})
 
 set(SYNTAX_SOURCES
-	syntax/GoHighlighter.cc
-	syntax/CppHighlighter.cc
-	syntax/JsonHighlighter.cc
-	syntax/ErlangHighlighter.cc
-	syntax/MarkdownHighlighter.cc
-	syntax/TreeSitterHighlighter.cc
-	syntax/LispHighlighter.cc
-	syntax/HighlighterEngine.cc
-	syntax/RustHighlighter.cc
-	syntax/HighlighterRegistry.cc
-	syntax/SqlHighlighter.cc
-	syntax/NullHighlighter.cc
-	syntax/ForthHighlighter.cc
-	syntax/PythonHighlighter.cc
-	syntax/ShellHighlighter.cc
+        syntax/GoHighlighter.cc
+        syntax/CppHighlighter.cc
+        syntax/JsonHighlighter.cc
+        syntax/ErlangHighlighter.cc
+        syntax/MarkdownHighlighter.cc
+        syntax/TreeSitterHighlighter.cc
+        syntax/LispHighlighter.cc
+        syntax/HighlighterEngine.cc
+        syntax/RustHighlighter.cc
+        syntax/HighlighterRegistry.cc
+        syntax/SqlHighlighter.cc
+        syntax/NullHighlighter.cc
+        syntax/ForthHighlighter.cc
+        syntax/PythonHighlighter.cc
+        syntax/ShellHighlighter.cc
 )
 
 if (KTE_ENABLE_TREESITTER)
-	list(APPEND SYNTAX_SOURCES
-		TreeSitterHighlighter.cc)
+    list(APPEND SYNTAX_SOURCES
+            TreeSitterHighlighter.cc)
 endif ()
 
 set(COMMON_SOURCES
-	GapBuffer.cc
-	PieceTable.cc
-	Buffer.cc
-	Editor.cc
-	Command.cc
-	HelpText.cc
-	KKeymap.cc
-	TerminalInputHandler.cc
-	TerminalRenderer.cc
-	TerminalFrontend.cc
-	TestInputHandler.cc
-	TestRenderer.cc
-	TestFrontend.cc
-	UndoNode.cc
-	UndoTree.cc
-	UndoSystem.cc
+        GapBuffer.cc
+        PieceTable.cc
+        Buffer.cc
+        Editor.cc
+        Command.cc
+        HelpText.cc
+        KKeymap.cc
+        TerminalInputHandler.cc
+        TerminalRenderer.cc
+        TerminalFrontend.cc
+        TestInputHandler.cc
+        TestRenderer.cc
+        TestFrontend.cc
+        UndoNode.cc
+        UndoTree.cc
+        UndoSystem.cc
 
-	${SYNTAX_SOURCES}
+        ${SYNTAX_SOURCES}
 )
 
 
 set(SYNTAX_HEADERS
-	syntax/GoHighlighter.h
-	syntax/HighlighterEngine.h
-	syntax/ShellHighlighter.h
-	syntax/MarkdownHighlighter.h
-	syntax/LispHighlighter.h
-	syntax/SqlHighlighter.h
-	syntax/ForthHighlighter.h
-	syntax/JsonHighlighter.h
-	syntax/TreeSitterHighlighter.h
-	syntax/NullHighlighter.h
-	syntax/CppHighlighter.h
-	syntax/ErlangHighlighter.h
-	syntax/LanguageHighlighter.h
-	syntax/RustHighlighter.h
-	syntax/PythonHighlighter.h
+        syntax/GoHighlighter.h
+        syntax/HighlighterEngine.h
+        syntax/ShellHighlighter.h
+        syntax/MarkdownHighlighter.h
+        syntax/LispHighlighter.h
+        syntax/SqlHighlighter.h
+        syntax/ForthHighlighter.h
+        syntax/JsonHighlighter.h
+        syntax/TreeSitterHighlighter.h
+        syntax/NullHighlighter.h
+        syntax/CppHighlighter.h
+        syntax/ErlangHighlighter.h
+        syntax/LanguageHighlighter.h
+        syntax/RustHighlighter.h
+        syntax/PythonHighlighter.h
 )
 
 if (KTE_ENABLE_TREESITTER)
-	list(APPEND THEME_HEADERS
-		TreeSitterHighlighter.h)
+    list(APPEND THEME_HEADERS
+            TreeSitterHighlighter.h)
 endif ()
 
 set(THEME_HEADERS
-	themes/ThemeHelpers.h
-	themes/EInk.h
-	themes/Gruvbox.h
-	themes/Solarized.h
-	themes/Plan9.h
-	themes/Nord.h
+        themes/ThemeHelpers.h
+        themes/EInk.h
+        themes/Gruvbox.h
+        themes/Solarized.h
+        themes/Plan9.h
+        themes/Nord.h
 )
 
 set(COMMON_HEADERS
-	GapBuffer.h
-	PieceTable.h
-	Buffer.h
-	Editor.h
-	AppendBuffer.h
-	Command.h
-	HelpText.h
-	KKeymap.h
-	InputHandler.h
-	TerminalInputHandler.h
-	Renderer.h
-	TerminalRenderer.h
-	Frontend.h
-	TerminalFrontend.h
-	TestInputHandler.h
-	TestRenderer.h
-	TestFrontend.h
-	UndoNode.h
-	UndoTree.h
-	UndoSystem.h
-	Highlight.h
+        GapBuffer.h
+        PieceTable.h
+        Buffer.h
+        Editor.h
+        AppendBuffer.h
+        Command.h
+        HelpText.h
+        KKeymap.h
+        InputHandler.h
+        TerminalInputHandler.h
+        Renderer.h
+        TerminalRenderer.h
+        Frontend.h
+        TerminalFrontend.h
+        TestInputHandler.h
+        TestRenderer.h
+        TestFrontend.h
+        UndoNode.h
+        UndoTree.h
+        UndoSystem.h
+        Highlight.h
 
-	${SYNTAX_HEADERS}
-	${THEME_HEADERS}
+        ${SYNTAX_HEADERS}
+        ${THEME_HEADERS}
 )
 
 # kte (terminal-first) executable
 add_executable(kte
-	main.cc
-	${COMMON_SOURCES}
-	${COMMON_HEADERS}
+        main.cc
+        ${COMMON_SOURCES}
+        ${COMMON_HEADERS}
 )
 
 if (KTE_USE_PIECE_TABLE)
-	target_compile_definitions(kte PRIVATE KTE_USE_PIECE_TABLE=1)
+    target_compile_definitions(kte PRIVATE KTE_USE_PIECE_TABLE=1)
 endif ()
 if (KTE_UNDO_DEBUG)
-	target_compile_definitions(kte PRIVATE KTE_UNDO_DEBUG=1)
+    target_compile_definitions(kte PRIVATE KTE_UNDO_DEBUG=1)
 endif ()
 
 target_link_libraries(kte ${CURSES_LIBRARIES})
 
 if (KTE_ENABLE_TREESITTER)
-	# Users can provide their own tree-sitter include/lib via cache variables
-	set(TREESITTER_INCLUDE_DIR "" CACHE PATH "Path to tree-sitter include directory")
-	set(TREESITTER_LIBRARY "" CACHE FILEPATH "Path to tree-sitter library (.a/.dylib)")
-	if (TREESITTER_INCLUDE_DIR)
-		target_include_directories(kte PRIVATE ${TREESITTER_INCLUDE_DIR})
-	endif ()
-	if (TREESITTER_LIBRARY)
-		target_link_libraries(kte ${TREESITTER_LIBRARY})
-	endif ()
+    # Users can provide their own tree-sitter include/lib via cache variables
+    set(TREESITTER_INCLUDE_DIR "" CACHE PATH "Path to tree-sitter include directory")
+    set(TREESITTER_LIBRARY "" CACHE FILEPATH "Path to tree-sitter library (.a/.dylib)")
+    if (TREESITTER_INCLUDE_DIR)
+        target_include_directories(kte PRIVATE ${TREESITTER_INCLUDE_DIR})
+    endif ()
+    if (TREESITTER_LIBRARY)
+        target_link_libraries(kte ${TREESITTER_LIBRARY})
+    endif ()
 endif ()
 
 install(TARGETS kte
-	RUNTIME DESTINATION ${CMAKE_INSTALL_BINDIR}
+        RUNTIME DESTINATION ${CMAKE_INSTALL_BINDIR}
 )
 
 # Man pages
 install(FILES docs/kte.1 DESTINATION ${CMAKE_INSTALL_MANDIR}/man1)
 
 if (BUILD_TESTS)
-	# test_undo executable for testing undo/redo system
-	add_executable(test_undo
-		test_undo.cc
-		${COMMON_SOURCES}
-		${COMMON_HEADERS}
-	)
+    # test_undo executable for testing undo/redo system
+    add_executable(test_undo
+            test_undo.cc
+            ${COMMON_SOURCES}
+            ${COMMON_HEADERS}
+    )
 
-	if (KTE_USE_PIECE_TABLE)
-		target_compile_definitions(test_undo PRIVATE KTE_USE_PIECE_TABLE=1)
-	endif ()
+    if (KTE_USE_PIECE_TABLE)
+        target_compile_definitions(test_undo PRIVATE KTE_USE_PIECE_TABLE=1)
+    endif ()
 
-	if (KTE_UNDO_DEBUG)
-		target_compile_definitions(test_undo PRIVATE KTE_UNDO_DEBUG=1)
-	endif ()
+    if (KTE_UNDO_DEBUG)
+        target_compile_definitions(test_undo PRIVATE KTE_UNDO_DEBUG=1)
+    endif ()
 
 
-	target_link_libraries(test_undo ${CURSES_LIBRARIES})
-	if (KTE_ENABLE_TREESITTER)
-		if (TREESITTER_INCLUDE_DIR)
-			target_include_directories(test_undo PRIVATE ${TREESITTER_INCLUDE_DIR})
-		endif ()
-		if (TREESITTER_LIBRARY)
-			target_link_libraries(test_undo ${TREESITTER_LIBRARY})
-		endif ()
-	endif ()
+    target_link_libraries(test_undo ${CURSES_LIBRARIES})
+    if (KTE_ENABLE_TREESITTER)
+        if (TREESITTER_INCLUDE_DIR)
+            target_include_directories(test_undo PRIVATE ${TREESITTER_INCLUDE_DIR})
+        endif ()
+        if (TREESITTER_LIBRARY)
+            target_link_libraries(test_undo ${TREESITTER_LIBRARY})
+        endif ()
+    endif ()
 endif ()
 
 if (${BUILD_GUI})
-	target_sources(kte PRIVATE
-		Font.h
-		GUIConfig.cc
-		GUIConfig.h
-		GUIRenderer.cc
-		GUIRenderer.h
-		GUIInputHandler.cc
-		GUIInputHandler.h
-		GUIFrontend.cc
-		GUIFrontend.h)
-	target_compile_definitions(kte PRIVATE KTE_BUILD_GUI=1)
-	target_link_libraries(kte imgui)
+    target_sources(kte PRIVATE
+            Font.h
+            GUIConfig.cc
+            GUIConfig.h
+            GUIRenderer.cc
+            GUIRenderer.h
+            GUIInputHandler.cc
+            GUIInputHandler.h
+            GUIFrontend.cc
+            GUIFrontend.h)
+    target_compile_definitions(kte PRIVATE KTE_BUILD_GUI=1)
+    target_link_libraries(kte imgui)
 
-	# kge (GUI-first) executable
-	add_executable(kge
-		main.cc
-		${COMMON_SOURCES}
-		${COMMON_HEADERS}
-		GUIConfig.cc
-		GUIConfig.h
-		GUIRenderer.cc
-		GUIRenderer.h
-		GUIInputHandler.cc
-		GUIInputHandler.h
-		GUIFrontend.cc
-		GUIFrontend.h)
-	target_compile_definitions(kge PRIVATE KTE_BUILD_GUI=1 KTE_DEFAULT_GUI=1 KTE_FONT_SIZE=${KTE_FONT_SIZE})
-	if (KTE_UNDO_DEBUG)
-		target_compile_definitions(kge PRIVATE KTE_UNDO_DEBUG=1)
-	endif ()
-	target_link_libraries(kge ${CURSES_LIBRARIES} imgui)
+    # kge (GUI-first) executable
+    add_executable(kge
+            main.cc
+            ${COMMON_SOURCES}
+            ${COMMON_HEADERS}
+            GUIConfig.cc
+            GUIConfig.h
+            GUIRenderer.cc
+            GUIRenderer.h
+            GUIInputHandler.cc
+            GUIInputHandler.h
+            GUIFrontend.cc
+            GUIFrontend.h)
+    target_compile_definitions(kge PRIVATE KTE_BUILD_GUI=1 KTE_DEFAULT_GUI=1 KTE_FONT_SIZE=${KTE_FONT_SIZE})
+    if (KTE_UNDO_DEBUG)
+        target_compile_definitions(kge PRIVATE KTE_UNDO_DEBUG=1)
+    endif ()
+    target_link_libraries(kge ${CURSES_LIBRARIES} imgui)
 
-	# On macOS, build kge as a proper .app bundle
-	if (APPLE)
-		# Define the icon file
-		set(MACOSX_BUNDLE_ICON_FILE kge.icns)
-		set(kge_ICON "${CMAKE_CURRENT_SOURCE_DIR}/${MACOSX_BUNDLE_ICON_FILE}")
+    # On macOS, build kge as a proper .app bundle
+    if (APPLE)
+        # Define the icon file
+        set(MACOSX_BUNDLE_ICON_FILE kge.icns)
+        set(kge_ICON "${CMAKE_CURRENT_SOURCE_DIR}/${MACOSX_BUNDLE_ICON_FILE}")
 
-		# Add icon to the target sources and mark it as a resource
-		target_sources(kge PRIVATE ${kge_ICON})
-		set_source_files_properties(${kge_ICON} PROPERTIES
-			MACOSX_PACKAGE_LOCATION Resources)
+        # Add icon to the target sources and mark it as a resource
+        target_sources(kge PRIVATE ${kge_ICON})
+        set_source_files_properties(${kge_ICON} PROPERTIES
+                MACOSX_PACKAGE_LOCATION Resources)
 
-		# Configure Info.plist with version and identifiers
-		set(KGE_BUNDLE_ID "dev.wntrmute.kge")
-		configure_file(
-			${CMAKE_CURRENT_LIST_DIR}/cmake/Info.plist.in
-			${CMAKE_CURRENT_BINARY_DIR}/kge-Info.plist
-			@ONLY)
+        # Configure Info.plist with version and identifiers
+        set(KGE_BUNDLE_ID "dev.wntrmute.kge")
+        configure_file(
+                ${CMAKE_CURRENT_LIST_DIR}/cmake/Info.plist.in
+                ${CMAKE_CURRENT_BINARY_DIR}/kge-Info.plist
+                @ONLY)
 
-		set_target_properties(kge PROPERTIES
-			MACOSX_BUNDLE TRUE
-			MACOSX_BUNDLE_GUI_IDENTIFIER ${KGE_BUNDLE_ID}
-			MACOSX_BUNDLE_BUNDLE_NAME "kge"
-			MACOSX_BUNDLE_ICON_FILE ${MACOSX_BUNDLE_ICON_FILE}
-			MACOSX_BUNDLE_INFO_PLIST "${CMAKE_CURRENT_BINARY_DIR}/kge-Info.plist")
+        set_target_properties(kge PROPERTIES
+                MACOSX_BUNDLE TRUE
+                MACOSX_BUNDLE_GUI_IDENTIFIER ${KGE_BUNDLE_ID}
+                MACOSX_BUNDLE_BUNDLE_NAME "kge"
+                MACOSX_BUNDLE_ICON_FILE ${MACOSX_BUNDLE_ICON_FILE}
+                MACOSX_BUNDLE_INFO_PLIST "${CMAKE_CURRENT_BINARY_DIR}/kge-Info.plist")
 
-		add_dependencies(kge kte)
-		add_custom_command(TARGET kge POST_BUILD
-			COMMAND ${CMAKE_COMMAND} -E copy
-			$<TARGET_FILE:kte>
-			$<TARGET_FILE_DIR:kge>/kte
-			COMMENT "Copying kte binary into kge.app bundle")
+        add_dependencies(kge kte)
+        add_custom_command(TARGET kge POST_BUILD
+                COMMAND ${CMAKE_COMMAND} -E copy
+                $<TARGET_FILE:kte>
+                $<TARGET_FILE_DIR:kge>/kte
+                COMMENT "Copying kte binary into kge.app bundle")
 
-		install(TARGETS kge
-			BUNDLE DESTINATION .
-		)
+        install(TARGETS kge
+                BUNDLE DESTINATION .
+        )
 
-		install(TARGETS kte
-			RUNTIME DESTINATION kge.app/Contents/MacOS
-		)
-	else ()
-		install(TARGETS kge
-			RUNTIME DESTINATION ${CMAKE_INSTALL_BINDIR}
-		)
-	endif ()
-	# Install kge man page only when GUI is built
-	install(FILES docs/kge.1 DESTINATION ${CMAKE_INSTALL_MANDIR}/man1)
-	install(FILES kge.png DESTINATION ${CMAKE_INSTALL_PREFIX}/share/icons)
+        install(TARGETS kte
+                RUNTIME DESTINATION kge.app/Contents/MacOS
+        )
+    else ()
+        install(TARGETS kge
+                RUNTIME DESTINATION ${CMAKE_INSTALL_BINDIR}
+        )
+    endif ()
+    # Install kge man page only when GUI is built
+    install(FILES docs/kge.1 DESTINATION ${CMAKE_INSTALL_MANDIR}/man1)
+    install(FILES kge.png DESTINATION ${CMAKE_INSTALL_PREFIX}/share/icons)
 endif ()

Command.cc

@@ -42,12 +42,11 @@ compute_render_x(const std::string &line, const std::size_t curx, const std::siz
 static void
 ensure_cursor_visible(const Editor &ed, Buffer &buf)
 {
-	const std::size_t rows = ed.Rows();
 	const std::size_t cols = ed.Cols();
-	if (rows == 0 || cols == 0)
+	if (cols == 0)
 		return;
 
-	const std::size_t content_rows = rows > 0 ? rows - 1 : 0; // last row = status
+	const std::size_t content_rows = ed.ContentRows();
 	const std::size_t cury         = buf.Cury();
 	const std::size_t curx         = buf.Curx();
 	std::size_t rowoffs            = buf.Rowoffs();
@@ -3004,9 +3003,7 @@ cmd_page_up(CommandContext &ctx)
 	ensure_at_least_one_line(*buf);
 	auto &rows               = buf->Rows();
 	int repeat               = ctx.count > 0 ? ctx.count : 1;
-	std::size_t content_rows = ctx.editor.Rows() > 0 ? ctx.editor.Rows() - 1 : 0;
-	if (content_rows == 0)
-		content_rows = 1;
+	std::size_t content_rows = std::max<std::size_t>(1, ctx.editor.ContentRows());
 
 	// Base on current top-of-screen (row offset)
 	std::size_t rowoffs = buf->Rowoffs();
@@ -3030,7 +3027,6 @@ cmd_page_up(CommandContext &ctx)
 		y = rows.empty() ? 0 : rows.size() - 1;
 	buf->SetOffsets(rowoffs, 0);
 	buf->SetCursor(0, y);
-	ensure_cursor_visible(ctx.editor, *buf);
 	return true;
 }
 
@@ -3046,9 +3042,7 @@ cmd_page_down(CommandContext &ctx)
 	ensure_at_least_one_line(*buf);
 	auto &rows               = buf->Rows();
 	int repeat               = ctx.count > 0 ? ctx.count : 1;
-	std::size_t content_rows = ctx.editor.Rows() > 0 ? ctx.editor.Rows() - 1 : 0;
-	if (content_rows == 0)
-		content_rows = 1;
+	std::size_t content_rows = std::max<std::size_t>(1, ctx.editor.ContentRows());
 
 	std::size_t rowoffs = buf->Rowoffs();
 	// Compute maximum top offset
@@ -3069,7 +3063,74 @@ cmd_page_down(CommandContext &ctx)
 	std::size_t y = std::min<std::size_t>(rowoffs, rows.empty() ? 0 : rows.size() - 1);
 	buf->SetOffsets(rowoffs, 0);
 	buf->SetCursor(0, y);
-	ensure_cursor_visible(ctx.editor, *buf);
+	return true;
+}
+
+
+static bool
+cmd_scroll_up(CommandContext &ctx)
+{
+	Buffer *buf = ctx.editor.CurrentBuffer();
+	if (!buf)
+		return false;
+	ensure_at_least_one_line(*buf);
+	const auto &rows         = buf->Rows();
+	std::size_t content_rows = std::max<std::size_t>(1, ctx.editor.ContentRows());
+	std::size_t rowoffs      = buf->Rowoffs();
+
+	// Scroll up by 3 lines (or count if specified), without moving cursor
+	int scroll_amount = ctx.count > 0 ? ctx.count : 3;
+	if (rowoffs >= static_cast<std::size_t>(scroll_amount))
+		rowoffs -= static_cast<std::size_t>(scroll_amount);
+	else
+		rowoffs = 0;
+
+	buf->SetOffsets(rowoffs, buf->Coloffs());
+
+	// If cursor is now below the visible area, move it to the last visible line
+	std::size_t cury = buf->Cury();
+	if (cury >= rowoffs + content_rows) {
+		std::size_t new_y = rowoffs + content_rows - 1;
+		if (new_y >= rows.size() && !rows.empty())
+			new_y = rows.size() - 1;
+		buf->SetCursor(buf->Curx(), new_y);
+	}
+
+	return true;
+}
+
+
+static bool
+cmd_scroll_down(CommandContext &ctx)
+{
+	Buffer *buf = ctx.editor.CurrentBuffer();
+	if (!buf)
+		return false;
+	ensure_at_least_one_line(*buf);
+	const auto &rows         = buf->Rows();
+	std::size_t content_rows = std::max<std::size_t>(1, ctx.editor.ContentRows());
+	std::size_t rowoffs      = buf->Rowoffs();
+
+	// Scroll down by 3 lines (or count if specified), without moving cursor
+	int scroll_amount = ctx.count > 0 ? ctx.count : 3;
+
+	// Compute maximum top offset
+	std::size_t max_top = 0;
+	if (!rows.empty() && rows.size() > content_rows)
+		max_top = rows.size() - content_rows;
+
+	rowoffs += static_cast<std::size_t>(scroll_amount);
+	if (rowoffs > max_top)
+		rowoffs = max_top;
+
+	buf->SetOffsets(rowoffs, buf->Coloffs());
+
+	// If cursor is now above the visible area, move it to the first visible line
+	std::size_t cury = buf->Cury();
+	if (cury < rowoffs) {
+		buf->SetCursor(buf->Curx(), rowoffs);
+	}
+
 	return true;
 }
 
@@ -3682,6 +3743,8 @@ InstallDefaultCommands()
 	CommandRegistry::Register({CommandId::MoveEnd, "end", "Move to end of line", cmd_move_end});
 	CommandRegistry::Register({CommandId::PageUp, "page-up", "Page up", cmd_page_up});
 	CommandRegistry::Register({CommandId::PageDown, "page-down", "Page down", cmd_page_down});
+	CommandRegistry::Register({CommandId::ScrollUp, "scroll-up", "Scroll viewport up", cmd_scroll_up});
+	CommandRegistry::Register({CommandId::ScrollDown, "scroll-down", "Scroll viewport down", cmd_scroll_down});
 	CommandRegistry::Register({CommandId::WordPrev, "word-prev", "Move to previous word", cmd_word_prev});
 	CommandRegistry::Register({CommandId::WordNext, "word-next", "Move to next word", cmd_word_next});
 	CommandRegistry::Register({
@@ -3800,4 +3863,4 @@ Execute(Editor &ed, const std::string &name, const std::string &arg, int count)
 		return false;
 	CommandContext ctx{ed, arg, count};
 	return cmd->handler ? cmd->handler(ctx) : false;
-}
+}

Command.h

@@ -58,6 +58,8 @@ enum class CommandId {
 	MoveEnd,
 	PageUp,
 	PageDown,
+	ScrollUp, // scroll viewport up (towards beginning) without moving cursor
+	ScrollDown, // scroll viewport down (towards end) without moving cursor
 	WordPrev,
 	WordNext,
 	DeleteWordPrev, // delete previous word (ESC BACKSPACE)

Editor.h

@@ -32,6 +32,16 @@ public:
 	}
 
 
+	[[nodiscard]] std::size_t ContentRows() const
+	{
+		// Always compute from current rows_ to avoid stale values.
+		// Reserve 1 row for status line.
+		if (rows_ == 0)
+			return 1;
+		return std::max<std::size_t>(1, rows_ - 1);
+	}
+
+
 	// Mode and flags (mirroring legacy fields)
 	void SetMode(int m)
 	{
@@ -553,4 +563,4 @@ private:
 	std::string replace_with_tmp_;
 };
 
-#endif // KTE_EDITOR_H
+#endif // KTE_EDITOR_H

GUIFrontend.cc

@@ -203,28 +203,7 @@ GUIFrontend::Step(Editor &ed, bool &running)
 		input_.ProcessSDLEvent(e);
 	}
 
-	// Execute pending mapped inputs (drain queue)
-	for (;;) {
-		MappedInput mi;
-		if (!input_.Poll(mi))
-			break;
-		if (mi.hasCommand) {
-			// Track kill ring before and after to sync GUI clipboard when it changes
-			const std::string before = ed.KillRingHead();
-			Execute(ed, mi.id, mi.arg, mi.count);
-			const std::string after = ed.KillRingHead();
-			if (after != before && !after.empty()) {
-				// Update the system clipboard to mirror the kill ring head in GUI
-				SDL_SetClipboardText(after.c_str());
-			}
-		}
-	}
-
-	if (ed.QuitRequested()) {
-		running = false;
-	}
-
-	// Start a new ImGui frame
+	// Start a new ImGui frame BEFORE processing commands so dimensions are correct
 	ImGui_ImplOpenGL3_NewFrame();
 	ImGui_ImplSDL2_NewFrame(window_);
 	ImGui::NewFrame();
@@ -264,6 +243,27 @@ GUIFrontend::Step(Editor &ed, bool &running)
 		}
 	}
 
+	// Execute pending mapped inputs (drain queue) AFTER dimensions are updated
+	for (;;) {
+		MappedInput mi;
+		if (!input_.Poll(mi))
+			break;
+		if (mi.hasCommand) {
+			// Track kill ring before and after to sync GUI clipboard when it changes
+			const std::string before = ed.KillRingHead();
+			Execute(ed, mi.id, mi.arg, mi.count);
+			const std::string after = ed.KillRingHead();
+			if (after != before && !after.empty()) {
+				// Update the system clipboard to mirror the kill ring head in GUI
+				SDL_SetClipboardText(after.c_str());
+			}
+		}
+	}
+
+	if (ed.QuitRequested()) {
+		running = false;
+	}
+
 	// No runtime font UI; always use embedded font.
 
 	// Draw editor UI
@@ -318,4 +318,4 @@ GUIFrontend::LoadGuiFont_(const char * /*path*/, float size_px)
 }
 
 
-// No runtime font reload or system font resolution in this simplified build.
+// No runtime font reload or system font resolution in this simplified build.

GUIInputHandler.cc

@@ -285,15 +285,11 @@ GUIInputHandler::ProcessSDLEvent(const SDL_Event &e)
 	bool produced = false;
 	switch (e.type) {
 	case SDL_MOUSEWHEEL: {
-		// If ImGui wants to capture the mouse (e.g., hovering the File Picker list),
-		// don't translate wheel events into editor scrolling.
-		// This prevents background buffer scroll while using GUI widgets.
-		ImGuiIO &io = ImGui::GetIO();
-		if (io.WantCaptureMouse) {
-			return true; // consumed by GUI
-		}
-
-		// Map vertical wheel to line-wise cursor movement (MoveUp/MoveDown)
+		// Map vertical wheel to viewport scrolling (ScrollUp/ScrollDown)
+		// Note: We don't check WantCaptureMouse here because ImGui sets it to true
+		// whenever the mouse is over any ImGui window (including our editor content area).
+		// The NoScrollWithMouse flag on the child window prevents ImGui from handling
+		// scroll internally, so we can safely process wheel events ourselves.
 		int dy = e.wheel.y;
 #ifdef SDL_MOUSEWHEEL_FLIPPED
 		if (e.wheel.direction == SDL_MOUSEWHEEL_FLIPPED)
@@ -301,7 +297,7 @@ GUIInputHandler::ProcessSDLEvent(const SDL_Event &e)
 #endif
 		if (dy != 0) {
 			int repeat   = dy > 0 ? dy : -dy;
-			CommandId id = dy > 0 ? CommandId::MoveUp : CommandId::MoveDown;
+			CommandId id = dy > 0 ? CommandId::ScrollUp : CommandId::ScrollDown;
 			std::lock_guard<std::mutex> lk(mu_);
 			for (int i = 0; i < repeat; ++i) {
 				q_.push(MappedInput{true, id, std::string(), 0});
@@ -372,7 +368,7 @@ GUIInputHandler::ProcessSDLEvent(const SDL_Event &e)
 			// Digits without shift, or a plain '-'
 			const bool is_digit_key = (key >= SDLK_0 && key <= SDLK_9) && !(mods & KMOD_SHIFT);
 			const bool is_minus_key = (key == SDLK_MINUS);
-			if (uarg_active_ && uarg_collecting_ && (is_digit_key || is_minus_key)) {
+			if (uarg_active_ && uarg_collecting_ &&(is_digit_key || is_minus_key)) {
 				suppress_text_input_once_ = true;
 			}
 		}
@@ -564,7 +560,12 @@ GUIInputHandler::ProcessSDLEvent(const SDL_Event &e)
 
 	if (produced && mi.hasCommand) {
 		// Attach universal-argument count if present, then clear the state
-		if (uarg_active_ && mi.id != CommandId::UArgStatus) {
+		if (uarg_active_ &&mi
+		
+		.
+		id != CommandId::UArgStatus
+		)
+		{
 			int count = 0;
 			if (!uarg_had_digits_ && !uarg_negative_) {
 				count = (uarg_value_ > 0) ? uarg_value_ : 4;
@@ -597,4 +598,4 @@ GUIInputHandler::Poll(MappedInput &out)
 	out = q_.front();
 	q_.pop();
 	return true;
-}
+}

GUIRenderer.cc

@@ -66,55 +66,66 @@ GUIRenderer::Draw(Editor &ed)
 	if (!buf) {
 		ImGui::TextUnformatted("[no buffer]");
 	} else {
-		const auto &lines = buf->Rows();
-		// Reserve space for status bar at bottom
-		ImGui::BeginChild("scroll", ImVec2(0, -ImGui::GetFrameHeightWithSpacing()), false,
-		                  ImGuiWindowFlags_HorizontalScrollbar | ImGuiWindowFlags_NoScrollWithMouse);
-		// Detect click-to-move inside this scroll region
-		ImVec2 list_origin  = ImGui::GetCursorScreenPos();
-		float scroll_y      = ImGui::GetScrollY();
-		float scroll_x      = ImGui::GetScrollX();
-		std::size_t rowoffs = 0; // we render from the first line; scrolling is handled by ImGui
+		const auto &lines   = buf->Rows();
 		std::size_t cy      = buf->Cury();
 		std::size_t cx      = buf->Curx();
 		const float line_h  = ImGui::GetTextLineHeight();
 		const float row_h   = ImGui::GetTextLineHeightWithSpacing();
 		const float space_w = ImGui::CalcTextSize(" ").x;
+
 		// Two-way sync between Buffer::Rowoffs and ImGui scroll position:
 		// - If command layer changed Buffer::Rowoffs since last frame, drive ImGui scroll from it.
 		// - Otherwise, propagate ImGui scroll to Buffer::Rowoffs so command layer has an up-to-date view.
-		// This prevents clicks/wheel from being immediately overridden by stale offsets.
+		static long prev_buf_rowoffs = -1; // previous frame's Buffer::Rowoffs
+		static long prev_buf_coloffs = -1; // previous frame's Buffer::Coloffs
+
+		const long buf_rowoffs = static_cast<long>(buf->Rowoffs());
+		const long buf_coloffs = static_cast<long>(buf->Coloffs());
+
+		// Detect programmatic change (e.g., page_down command changed rowoffs)
+		// Use SetNextWindowScroll BEFORE BeginChild to set initial scroll position
+		if (prev_buf_rowoffs >= 0 && buf_rowoffs != prev_buf_rowoffs) {
+			float target_y = static_cast<float>(buf_rowoffs) * row_h;
+			ImGui::SetNextWindowScroll(ImVec2(-1.0f, target_y));
+		}
+		if (prev_buf_coloffs >= 0 && buf_coloffs != prev_buf_coloffs) {
+			float target_x = static_cast<float>(buf_coloffs) * space_w;
+			float target_y = static_cast<float>(buf_rowoffs) * row_h;
+			ImGui::SetNextWindowScroll(ImVec2(target_x, target_y));
+		}
+
+		// Reserve space for status bar at bottom
+		ImGui::BeginChild("scroll", ImVec2(0, -ImGui::GetFrameHeightWithSpacing()), false,
+		                  ImGuiWindowFlags_HorizontalScrollbar | ImGuiWindowFlags_NoScrollWithMouse);
+
+		// Get child window position and scroll for click handling
+		ImVec2 child_window_pos = ImGui::GetWindowPos();
+		float scroll_y          = ImGui::GetScrollY();
+		float scroll_x          = ImGui::GetScrollX();
+		std::size_t rowoffs     = 0; // we render from the first line; scrolling is handled by ImGui
+
+		// Synchronize buffer offsets from ImGui scroll if user scrolled manually
 		bool forced_scroll = false;
 		{
-			static long prev_buf_rowoffs = -1; // previous frame's Buffer::Rowoffs
-			static long prev_buf_coloffs = -1; // previous frame's Buffer::Coloffs
-			static float prev_scroll_y   = -1.0f; // previous frame's ImGui scroll Y in pixels
-			static float prev_scroll_x   = -1.0f; // previous frame's ImGui scroll X in pixels
+			static float prev_scroll_y = -1.0f; // previous frame's ImGui scroll Y in pixels
+			static float prev_scroll_x = -1.0f; // previous frame's ImGui scroll X in pixels
 
-			const long buf_rowoffs = static_cast<long>(buf->Rowoffs());
-			const long buf_coloffs = static_cast<long>(buf->Coloffs());
 			const long scroll_top  = static_cast<long>(scroll_y / row_h);
 			const long scroll_left = static_cast<long>(scroll_x / space_w);
 
-			// Detect programmatic change (e.g., keyboard navigation ensured visibility)
+			// Check if rowoffs was programmatically changed this frame
 			if (prev_buf_rowoffs >= 0 && buf_rowoffs != prev_buf_rowoffs) {
-				ImGui::SetScrollY(static_cast<float>(buf_rowoffs) * row_h);
-				scroll_y      = ImGui::GetScrollY();
 				forced_scroll = true;
 			}
-			if (prev_buf_coloffs >= 0 && buf_coloffs != prev_buf_coloffs) {
-				ImGui::SetScrollX(static_cast<float>(buf_coloffs) * space_w);
-				scroll_x      = ImGui::GetScrollX();
-				forced_scroll = true;
-			}
-			// If user scrolled, update buffer offsets accordingly
-			if (prev_scroll_y >= 0.0f && scroll_y != prev_scroll_y) {
+
+			// If user scrolled (not programmatic), update buffer offsets accordingly
+			if (prev_scroll_y >= 0.0f && scroll_y != prev_scroll_y && !forced_scroll) {
 				if (Buffer *mbuf = const_cast<Buffer *>(buf)) {
 					mbuf->SetOffsets(static_cast<std::size_t>(std::max(0L, scroll_top)),
 					                 mbuf->Coloffs());
 				}
 			}
-			if (prev_scroll_x >= 0.0f && scroll_x != prev_scroll_x) {
+			if (prev_scroll_x >= 0.0f && scroll_x != prev_scroll_x && !forced_scroll) {
 				if (Buffer *mbuf = const_cast<Buffer *>(buf)) {
 					mbuf->SetOffsets(mbuf->Rowoffs(),
 					                 static_cast<std::size_t>(std::max(0L, scroll_left)));
@@ -122,11 +133,12 @@ GUIRenderer::Draw(Editor &ed)
 			}
 
 			// Update trackers for next frame
-			prev_buf_rowoffs = static_cast<long>(buf->Rowoffs());
-			prev_buf_coloffs = static_cast<long>(buf->Coloffs());
-			prev_scroll_y    = ImGui::GetScrollY();
-			prev_scroll_x    = ImGui::GetScrollX();
+			prev_scroll_y = scroll_y;
+			prev_scroll_x = scroll_x;
 		}
+		prev_buf_rowoffs = buf_rowoffs;
+		prev_buf_coloffs = buf_coloffs;
+
 		// Synchronize cursor and scrolling.
 		// Ensure the cursor is visible even on the first frame or when it didn't move,
 		// unless we already forced scrolling from Buffer::Rowoffs this frame.
@@ -165,24 +177,16 @@ GUIRenderer::Draw(Editor &ed)
 		// Handle mouse click before rendering to avoid dependent on drawn items
 		if (ImGui::IsWindowHovered() && ImGui::IsMouseClicked(ImGuiMouseButton_Left)) {
 			ImVec2 mp = ImGui::GetIO().MousePos;
-			// Compute viewport-relative row so (0) is top row of the visible area
-			float vy_f = (mp.y - list_origin.y - scroll_y) / row_h;
-			long vy    = static_cast<long>(vy_f);
-			if (vy < 0)
-				vy = 0;
+			// Compute content-relative position accounting for scroll
+			// mp.y - child_window_pos.y gives us pixels from top of child window
+			// Adding scroll_y gives us pixels from top of content (buffer row 0)
+			float content_y = (mp.y - child_window_pos.y) + scroll_y;
+			long by_l       = static_cast<long>(content_y / row_h);
+			if (by_l < 0)
+				by_l = 0;
 
-			// Clamp vy within visible content height to avoid huge jumps
-			ImVec2 cr_min = ImGui::GetWindowContentRegionMin();
-			ImVec2 cr_max = ImGui::GetWindowContentRegionMax();
-			float child_h = (cr_max.y - cr_min.y);
-			long vis_rows = static_cast<long>(child_h / row_h);
-			if (vis_rows < 1)
-				vis_rows = 1;
-			if (vy >= vis_rows)
-				vy = vis_rows - 1;
-
-			// Translate viewport row to buffer row using Buffer::Rowoffs
-			std::size_t by = buf->Rowoffs() + static_cast<std::size_t>(vy);
+			// Convert to buffer row
+			std::size_t by = static_cast<std::size_t>(by_l);
 			if (by >= lines.size()) {
 				if (!lines.empty())
 					by = lines.size() - 1;
@@ -190,58 +194,43 @@ GUIRenderer::Draw(Editor &ed)
 					by = 0;
 			}
 
-			// Compute desired pixel X inside the viewport content (subtract horizontal scroll)
-			float px = (mp.x - list_origin.x - scroll_x);
-			if (px < 0.0f)
-				px = 0.0f;
+			// Compute content-relative X position accounting for scroll
+			// mp.x - child_window_pos.x gives us pixels from left edge of child window
+			// Adding scroll_x gives us pixels from left edge of content (column 0)
+			float content_x = (mp.x - child_window_pos.x) + scroll_x;
+			if (content_x < 0.0f)
+				content_x = 0.0f;
 
 			// Empty buffer guard: if there are no lines yet, just move to 0:0
 			if (lines.empty()) {
 				Execute(ed, CommandId::MoveCursorTo, std::string("0:0"));
 			} else {
-				// Convert pixel X to a render-column target including horizontal col offset
-				// Use our own tab expansion of width 8 to match command layer logic.
+				// Convert pixel X to source column accounting for tabs
 				std::string line_clicked = static_cast<std::string>(lines[by]);
 				const std::size_t tabw   = 8;
-				// We iterate source columns computing absolute rendered column (rx_abs) from 0,
-				// then translate to viewport-space by subtracting Coloffs.
-				std::size_t coloffs = buf->Coloffs();
-				std::size_t rx_abs  = 0; // absolute rendered column
-				std::size_t i       = 0; // source column iterator
 
-				// Fast-forward i until rx_abs >= coloffs to align with leftmost visible column
-				if (!line_clicked.empty() && coloffs > 0) {
-					while (i < line_clicked.size() && rx_abs < coloffs) {
-						if (line_clicked[i] == '\t') {
-							rx_abs += (tabw - (rx_abs % tabw));
-						} else {
-							rx_abs += 1;
-						}
-						++i;
-					}
-				}
-
-				// Now search for closest source column to clicked px within/after viewport
-				std::size_t best_col = i; // default to first visible column
+				// Iterate through source columns, computing rendered position, to find closest match
+				std::size_t rx       = 0; // rendered column position
+				std::size_t best_col = 0;
 				float best_dist      = std::numeric_limits<float>::infinity();
-				while (true) {
-					// For i in [current..size], evaluate candidate including the implicit end position
-					std::size_t rx_view = (rx_abs >= coloffs) ? (rx_abs - coloffs) : 0;
-					float rx_px         = static_cast<float>(rx_view) * space_w;
-					float dist          = std::fabs(px - rx_px);
-					if (dist <= best_dist) {
+
+				for (std::size_t i = 0; i <= line_clicked.size(); ++i) {
+					// Check current position
+					float rx_px = static_cast<float>(rx) * space_w;
+					float dist  = std::fabs(content_x - rx_px);
+					if (dist < best_dist) {
 						best_dist = dist;
 						best_col  = i;
 					}
-					if (i == line_clicked.size())
-						break;
-					// advance to next source column
-					if (line_clicked[i] == '\t') {
-						rx_abs += (tabw - (rx_abs % tabw));
-					} else {
-						rx_abs += 1;
+
+					// Advance to next position if not at end
+					if (i < line_clicked.size()) {
+						if (line_clicked[i] == '\t') {
+							rx += (tabw - (rx % tabw));
+						} else {
+							rx += 1;
+						}
 					}
-					++i;
 				}
 
 				// Dispatch absolute buffer coordinates (row:col)
@@ -374,7 +363,8 @@ GUIRenderer::Draw(Editor &ed)
 						p, col, expanded.c_str() + vx0, expanded.c_str() + vx1);
 				}
 				// We drew text via draw list (no layout advance). Manually advance the cursor to the next line.
-				ImGui::SetCursorScreenPos(ImVec2(line_pos.x, line_pos.y + line_h));
+				// Use row_h (with spacing) to match click calculation and ensure consistent line positions.
+				ImGui::SetCursorScreenPos(ImVec2(line_pos.x, line_pos.y + row_h));
 			} else {
 				// No syntax: draw as one run
 				ImGui::TextUnformatted(expanded.c_str());

TerminalInputHandler.cc

@@ -35,16 +35,16 @@ map_key_to_command(const int ch,
 	case KEY_MOUSE: {
 		MEVENT ev{};
 		if (getmouse(&ev) == OK) {
-			// Mouse wheel → map to MoveUp/MoveDown one line per wheel notch
+			// Mouse wheel → scroll viewport without moving cursor
 #ifdef BUTTON4_PRESSED
 			if (ev.bstate & (BUTTON4_PRESSED | BUTTON4_RELEASED | BUTTON4_CLICKED)) {
-				out = {true, CommandId::MoveUp, "", 0};
+				out = {true, CommandId::ScrollUp, "", 0};
 				return true;
 			}
 #endif
 #ifdef BUTTON5_PRESSED
 			if (ev.bstate & (BUTTON5_PRESSED | BUTTON5_RELEASED | BUTTON5_CLICKED)) {
-				out = {true, CommandId::MoveDown, "", 0};
+				out = {true, CommandId::ScrollDown, "", 0};
 				return true;
 			}
 #endif
@@ -320,4 +320,4 @@ TerminalInputHandler::Poll(MappedInput &out)
 {
 	out = {};
 	return decode_(out) && out.hasCommand;
-}
+}

TerminalRenderer.cc

@@ -34,6 +34,8 @@ TerminalRenderer::Draw(Editor &ed)
 
 	const Buffer *buf = ed.CurrentBuffer();
 	int content_rows  = rows - 1; // last line is status
+	if (content_rows < 1)
+		content_rows = 1;
 
 	int saved_cur_y = -1, saved_cur_x = -1; // logical cursor position within content area
 	if (buf) {