Calculator: Add a Rounding menu

This menu has three actions. Each one of them enable a different level
of rounding: to 0, 2 or 4 digits.

5 files changed, 35 insertions, 5 deletions

diff --git a/Userland/Applications/Calculator/CalculatorWidget.cpp b/Userland/Applications/Calculator/CalculatorWidget.cpp
index cfe111fe38..a2f1c53666 100644
--- a/Userland/Applications/Calculator/CalculatorWidget.cpp
+++ b/Userland/Applications/Calculator/CalculatorWidget.cpp
@@ -218,3 +218,9 @@ void CalculatorWidget::keydown_event(GUI::KeyEvent& event)
 
     update_display();
 }
+
+void CalculatorWidget::set_rounding_length(unsigned rounding_threshold)
+{
+    m_keypad.set_rounding_length(rounding_threshold);
+    update_display();
+}
diff --git a/Userland/Applications/Calculator/CalculatorWidget.h b/Userland/Applications/Calculator/CalculatorWidget.h
index 07845cd3df..6415af4277 100644
--- a/Userland/Applications/Calculator/CalculatorWidget.h
+++ b/Userland/Applications/Calculator/CalculatorWidget.h
@@ -21,6 +21,8 @@ public:
     String get_entry();
     void set_entry(Crypto::BigFraction);
 
+    void set_rounding_length(unsigned);
+
 private:
     CalculatorWidget();
     void add_operation_button(GUI::Button&, Calculator::Operation);
diff --git a/Userland/Applications/Calculator/Keypad.cpp b/Userland/Applications/Calculator/Keypad.cpp
index b94fd79e2d..e1624d7a0d 100644
--- a/Userland/Applications/Calculator/Keypad.cpp
+++ b/Userland/Applications/Calculator/Keypad.cpp
@@ -113,10 +113,8 @@ void Keypad::set_to_0()
 
 String Keypad::to_string() const
 {
-    // TODO: Implement custom rounding length in the calculator.
-    constexpr auto maximum_precision = 6;
     if (m_state == State::External)
-        return m_internal_value.to_string(maximum_precision);
+        return m_internal_value.to_string(m_displayed_fraction_length);
 
     StringBuilder builder;
 
@@ -136,3 +134,8 @@ String Keypad::to_string() const
 
     return builder.to_string();
 }
+
+void Keypad::set_rounding_length(unsigned rounding_threshold)
+{
+    m_displayed_fraction_length = rounding_threshold;
+}
diff --git a/Userland/Applications/Calculator/Keypad.h b/Userland/Applications/Calculator/Keypad.h
index 0410e31b51..b71b9214da 100644
--- a/Userland/Applications/Calculator/Keypad.h
+++ b/Userland/Applications/Calculator/Keypad.h
@@ -29,6 +29,8 @@ public:
     void set_value(Crypto::BigFraction);
     void set_to_0();
 
+    void set_rounding_length(unsigned);
+
     String to_string() const;
 
 private:
@@ -46,6 +48,8 @@ private:
 
     mutable Crypto::BigFraction m_internal_value {};
 
+    unsigned m_displayed_fraction_length { 0 };
+
     enum class State {
         External,
         TypingInteger,
diff --git a/Userland/Applications/Calculator/main.cpp b/Userland/Applications/Calculator/main.cpp
index 0e6bf8c2f8..c2076ccaad 100644
--- a/Userland/Applications/Calculator/main.cpp
+++ b/Userland/Applications/Calculator/main.cpp
@@ -8,6 +8,7 @@
 #include <LibCore/System.h>
 #include <LibCrypto/NumberTheory/ModularFunctions.h>
 #include <LibGUI/Action.h>
+#include <LibGUI/ActionGroup.h>
 #include <LibGUI/Application.h>
 #include <LibGUI/Clipboard.h>
 #include <LibGUI/Icon.h>
@@ -16,8 +17,6 @@
 #include <LibGUI/Window.h>
 #include <LibGfx/Bitmap.h>
 #include <LibMain/Main.h>
-#include <stdio.h>
-#include <unistd.h>
 
 ErrorOr<int> serenity_main(Main::Arguments arguments)
 {
@@ -70,6 +69,22 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
         widget->set_entry(Crypto::BigFraction { Crypto::SignedBigInteger(16180339887), power });
     }));
 
+    auto& round_menu = window->add_menu("&Round");
+    GUI::ActionGroup preview_actions;
+
+    static constexpr auto rounding_modes = Array { 0, 2, 4 };
+
+    for (auto const rounding_mode : rounding_modes) {
+        auto round_action = GUI::Action::create_checkable(String::formatted("To &{} digits", rounding_mode), [&widget, rounding_mode](auto&) {
+            widget->set_rounding_length(rounding_mode);
+        });
+
+        preview_actions.add_action(*round_action);
+        round_menu.add_action(*round_action);
+    }
+
+    preview_actions.set_exclusive(true);
+
     auto& help_menu = window->add_menu("&Help");
     help_menu.add_action(GUI::CommonActions::make_about_action("Calculator", app_icon, window));