Add 'CenterOnCursor' command and improve cursor scrolling logic

- Introduced `CommandId::CenterOnCursor` to center viewport on the cursor line.
- Improved scrolling behavior in `ImGuiRenderer` to avoid aggressive centering and keep visible lines stable.
- Updated `make-app-release` to rename the output app to `kge-qt.app`.
- Adjusted padding in `ImGuiFrontend` to align with `ImGuiRenderer` settings for consistent scrolling.
- Bumped version to 1.4.1.

CMakeLists.txt

@@ -4,7 +4,7 @@ project(kte)
 include(GNUInstallDirs)
 
 set(CMAKE_CXX_STANDARD 20)
-set(KTE_VERSION "1.4.0")
+set(KTE_VERSION "1.4.1")
 
 # Default to terminal-only build to avoid SDL/OpenGL dependency by default.
 # Enable with -DBUILD_GUI=ON when SDL2/OpenGL/Freetype are available.

Command.cc

@@ -109,6 +109,33 @@ ensure_cursor_visible(const Editor &ed, Buffer &buf)
 }
 
 
+static bool
+cmd_center_on_cursor(CommandContext &ctx)
+{
+	Buffer *buf = ctx.editor.CurrentBuffer();
+	if (!buf)
+		return false;
+	const auto &rows    = buf->Rows();
+	std::size_t total   = rows.size();
+	std::size_t content = ctx.editor.ContentRows();
+	if (content == 0)
+		content = 1;
+	std::size_t cy          = buf->Cury();
+	std::size_t half        = content / 2;
+	std::size_t new_rowoffs = (cy > half) ? (cy - half) : 0;
+	// Clamp to valid range
+	if (total > content) {
+		std::size_t max_rowoffs = total - content;
+		if (new_rowoffs > max_rowoffs)
+			new_rowoffs = max_rowoffs;
+	} else {
+		new_rowoffs = 0;
+	}
+	buf->SetOffsets(new_rowoffs, buf->Coloffs());
+	return true;
+}
+
+
 static void
 ensure_at_least_one_line(Buffer &buf)
 {
@@ -4445,6 +4472,11 @@ InstallDefaultCommands()
 	// Syntax highlighting (public commands)
 	CommandRegistry::Register({CommandId::Syntax, "syntax", "Syntax: on|off|reload", cmd_syntax, true});
 	CommandRegistry::Register({CommandId::SetOption, "set", "Set option: key=value", cmd_set_option, true});
+	// Viewport control
+	CommandRegistry::Register({
+		CommandId::CenterOnCursor, "center-on-cursor", "Center viewport on current line", cmd_center_on_cursor,
+		false, false
+	});
 }
 
 

Command.h

@@ -106,6 +106,8 @@ enum class CommandId {
 	// Syntax highlighting
 	Syntax, // ":syntax on|off|reload"
 	SetOption, // generic ":set key=value" (v1: filetype=<lang>)
+	// Viewport control
+	CenterOnCursor, // center the viewport on the current cursor line (C-k k)
 };
 
 

ImGuiFrontend.cc

@@ -272,10 +272,11 @@ GUIFrontend::Step(Editor &ed, bool &running)
 		float disp_w = io.DisplaySize.x > 0 ? io.DisplaySize.x : static_cast<float>(width_);
 		float disp_h = io.DisplaySize.y > 0 ? io.DisplaySize.y : static_cast<float>(height_);
 
-		// Account for the GUI window padding and the status bar height used in GUIRenderer
-		const ImGuiStyle &style = ImGui::GetStyle();
-		float pad_x             = style.WindowPadding.x;
-		float pad_y             = style.WindowPadding.y;
+		// Account for the GUI window padding and the status bar height used in ImGuiRenderer.
+		// ImGuiRenderer pushes WindowPadding = (6,6) every frame, so use the same constants here
+		// to avoid mismatches that would cause premature scrolling.
+		const float pad_x = 6.0f;
+		const float pad_y = 6.0f;
 		// Status bar reserves one frame height (with spacing) inside the window
 		float status_h = ImGui::GetFrameHeightWithSpacing();
 

ImGuiRenderer.cc

@@ -140,7 +140,8 @@ ImGuiRenderer::Draw(Editor &ed)
 		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.
+		// Ensure the cursor is visible, but avoid aggressive centering so that
+		// the same lines remain visible until the cursor actually goes off-screen.
 		{
 			// Compute visible row range using the child window height
 			float child_h  = ImGui::GetWindowHeight();
@@ -151,15 +152,30 @@ ImGuiRenderer::Draw(Editor &ed)
 			long last_row = first_row + vis_rows - 1;
 
 			long cyr = static_cast<long>(cy);
-			if (cyr < first_row || cyr > last_row) {
-				float target = (static_cast<float>(cyr) - std::max(0L, vis_rows / 2)) * row_h;
+			if (cyr < first_row) {
+				// Scroll just enough to bring the cursor line to the top
+				float target = static_cast<float>(cyr) * row_h;
+				if (target < 0.f)
+					target = 0.f;
+				float max_y = ImGui::GetScrollMaxY();
+				if (max_y >= 0.f && target > max_y)
+					target = max_y;
+				ImGui::SetScrollY(target);
+				scroll_y  = ImGui::GetScrollY();
+				first_row = static_cast<long>(scroll_y / row_h);
+				last_row  = first_row + vis_rows - 1;
+			} else if (cyr > last_row) {
+				// Scroll just enough to bring the cursor line to the bottom
+				long new_first = cyr - vis_rows + 1;
+				if (new_first < 0)
+					new_first = 0;
+				float target = static_cast<float>(new_first) * row_h;
 				float max_y  = ImGui::GetScrollMaxY();
 				if (target < 0.f)
 					target = 0.f;
 				if (max_y >= 0.f && target > max_y)
 					target = max_y;
 				ImGui::SetScrollY(target);
-				// refresh local variables
 				scroll_y  = ImGui::GetScrollY();
 				first_row = static_cast<long>(scroll_y / row_h);
 				last_row  = first_row + vis_rows - 1;

KKeymap.cc

@@ -42,6 +42,9 @@ KLookupKCommand(const int ascii_key, const bool ctrl, CommandId &out) -> bool
 	case 'a':
 		out = CommandId::MarkAllAndJumpEnd;
 		return true;
+	case 'k':
+		out = CommandId::CenterOnCursor; // C-k k center current line
+		return true;
 	case 'b':
 		out = CommandId::BufferSwitchStart;
 		return true;
@@ -215,4 +218,4 @@ KLookupEscCommand(const int ascii_key, CommandId &out) -> bool
 		break;
 	}
 	return false;
-}
+}

make-app-release

@@ -20,9 +20,10 @@ cmake -S . -B cmake-build-release -DBUILD_GUI=ON -DCMAKE_BUILD_TYPE=Release -DEN
 
 cd cmake-build-release-qt
 make clean
-rm -fr kge.app*
+rm -fr kge.app* kge-qt.app*
 make
-zip -r kge.app.zip kge.app 
-sha256sum kge.app.zip
+mv kge.app kge-qt.app
+zip -r kge-qt.app.zip kge-qt.app 
+sha256sum kge-qt.app.zip
 open .
 cd ..