Terminal: Fix Canvas with 0x0 size

Author: MorganCaron

modules/Terminal/Canvas.mpp

@@ -39,7 +39,7 @@ export namespace CppUtils::Terminal
 			using namespace std::literals;
 			const auto terminalSize = getTerminalSize();
 			const auto viewportSize = m_viewport.getSize();
-			const auto startLine = terminalSize.height() - viewportSize.height() - 1;
+			const auto startLine = terminalSize.height() > viewportSize.height() ? terminalSize.height() - viewportSize.height() - 1 : 0;
 			auto stringBuffer = ""s;
 			auto needFlush = false;
 			auto lastAttributes = CharAttributes{};
@@ -91,7 +91,10 @@ export namespace CppUtils::Terminal
 			}
 			if (needFlush)
 				std::fflush(stdout);
-			setCursorPosition({0, terminalSize.height() > 0 ? terminalSize.height() - 1 : 0});
+			{
+				const auto height = getTerminalSize().height();
+				setCursorPosition({0, height > 0 ? height - 1 : 0});
+			}
 		}
 
 		inline auto print() noexcept -> void

modules/Terminal/Size.mpp

@@ -26,11 +26,12 @@ export namespace CppUtils::Terminal
 #elif defined(OS_LINUX) or defined(OS_MACOS)
 	[[nodiscard]] inline auto getTerminalSize() -> Container::Size2
 	{
-		auto windowsSize = winsize{};
-		ioctl(STDOUT_FILENO, TIOCGWINSZ, std::addressof(windowsSize));
+		auto terminalSize = winsize{};
+		if (ioctl(STDOUT_FILENO, TIOCGWINSZ, std::addressof(terminalSize)) == -1)
+			return Container::Size2{0, 0};
 		return Container::Size2{
-			static_cast<std::size_t>(windowsSize.ws_col),
-			static_cast<std::size_t>(windowsSize.ws_row)};
+			static_cast<std::size_t>(terminalSize.ws_col),
+			static_cast<std::size_t>(terminalSize.ws_row)};
 	}
 #endif
 }

tests/Terminal/Canvas.mpp

@@ -9,6 +9,24 @@ namespace CppUtils::UnitTest::Terminal::Canvas
 		using namespace std::literals;
 		using namespace std::chrono_literals;
 
+		suite.addTest("Canvas with 0x0 size", [&] {
+			auto canvas = CppUtils::Terminal::Canvas{CppUtils::Container::Size2{0, 0}};
+			canvas.fill('.');
+			canvas.print();
+		});
+
+		suite.addTest("Canvas with 0 height", [&] {
+			auto canvas = CppUtils::Terminal::Canvas{CppUtils::Container::Size2{10, 0}};
+			canvas.fill('.');
+			canvas.print();
+		});
+
+		suite.addTest("Canvas with 0 width", [&] {
+			auto canvas = CppUtils::Terminal::Canvas{CppUtils::Container::Size2{0, 10}};
+			canvas.fill('.');
+			canvas.print();
+		});
+
 		suite.addTest("Size", [&] {
 			{
 				auto canvas = CppUtils::Terminal::Canvas{CppUtils::Container::Size2{10, 5}};