From 91d438353d8bb6aff23e26ba1ca1bf6b3bdd7f9c Mon Sep 17 00:00:00 2001
From: Adrian Scripca <benishor@gmail.com>
Date: Wed, 10 May 2023 16:14:57 +0300
Subject: [PATCH] Solved inter-thread communication issues by feeding commands
 over a queue.

---
 docs/todo.txt    |   5 +-
 grbl_machine.cpp | 164 +++++++++++++++++++++++++------
 grbl_machine.h   | 115 +++++++++++++++++++---
 main.cpp         | 246 +++++++++++++++++++++++------------------------
 4 files changed, 356 insertions(+), 174 deletions(-)

diff --git a/docs/todo.txt b/docs/todo.txt
index 9f64cea..3f3b606 100644
--- a/docs/todo.txt
+++ b/docs/todo.txt
@@ -33,8 +33,11 @@ DONE            - store Z offset and place it in the heightmap
             - if line contains a Z coordinate, update the Z according to the X and Y
             - if line does not contain a Z coordinate, add a Z coordinate according to the X and Y
 
-Solve bug in which the probing data does not get rendered properly as it gets probed.
+DONE -Let's get rid of the pesky inter-thread communication issue which is causing a lot of confusion.
+DONE - Solve bug in which the probing data does not get rendered properly as it gets probed.
+
 Bug: query coordinate systems after first z probe.
+Refactor: see if we can unify machine state line handling and remove duplication
 
 Edge finding
     - prerequisites
diff --git a/grbl_machine.cpp b/grbl_machine.cpp
index fe6d974..87db1a4 100644
--- a/grbl_machine.cpp
+++ b/grbl_machine.cpp
@@ -560,10 +560,6 @@ void grbl::machine::cancel_jog() const {
     pipe->send_single_char_command(0x85);
 }
 
-void grbl::machine::set_listener(grbl::machine_listener *l) {
-    listener = l;
-}
-
 void grbl::machine::request_unlock() {
     pipe->send("$X");
 }
@@ -615,7 +611,8 @@ void grbl::machine::zero_offset(int which) {
     pipe->send("$#");
     awaiting_responses++;
     while (awaiting_responses > 0);
-    listener->on_parameters_reloaded();
+
+    push_event(std::make_shared<machine_event_parameters_reloaded>());
 }
 
 void grbl::machine::zero_offset_axis(int offset_index, int axis) {
@@ -627,7 +624,8 @@ void grbl::machine::zero_offset_axis(int offset_index, int axis) {
     pipe->send("$#");
     awaiting_responses++;
     while (awaiting_responses > 0);
-    listener->on_parameters_reloaded();
+
+    push_event(std::make_shared<machine_event_parameters_reloaded>());
 }
 
 void grbl::machine::go_to_zero(bool x, bool y, bool z) {
@@ -695,6 +693,23 @@ void grbl::machine::probe_heightmap(grbl::heightmap& grid) {
     switch_to_state(grbl_machine_state::heightmap_probing);
 }
 
+void grbl::machine::push_event(std::shared_ptr<machine_event> event) {
+    std::scoped_lock<std::mutex> lock(event_mutex);
+    events.push_back(event);
+}
+
+std::shared_ptr<grbl::machine_event> grbl::machine::pop_event() {
+    // TODO: make this more efficient
+    std::scoped_lock<std::mutex> lock(event_mutex);
+    if (events.empty())
+        return nullptr;
+    else {
+        auto result = events.front();
+        events.pop_front();
+        return result;
+    }
+}
+
 bool grbl::jog_state::no_jogging() const {
     return !(up_pressed || down_pressed || left_pressed || right_pressed || z_up_pressed || z_down_pressed);
 }
@@ -719,7 +734,7 @@ void grbl::machine_state_connect::on_exit(grbl::machine *m) {
 void grbl::machine_state_connect::on_line_received(std::string line) {
 //    std::cerr << "Should not get content while connecting!" << std::endl;
     if (starts_with(line, "Grbl")) {
-        cnc->listener->on_banner(line);
+        cnc->push_event(std::make_shared<machine_event_banner>(line));
         cnc->switch_to_state(grbl_machine_state::init);
     }
 }
@@ -732,7 +747,7 @@ void grbl::machine_state_init::on_enter(grbl::machine *m) {
 }
 
 void grbl::machine_state_init::on_exit(grbl::machine *m) {
-    cnc->listener->on_init_completed();
+    cnc->push_event(std::make_shared<machine_event_init_completed>());
 }
 
 void grbl::machine_state_init::on_line_received(std::string line) {
@@ -808,15 +823,17 @@ void grbl::machine_state_idle::on_line_received(std::string line) {
             cnc->awaiting_responses--;
         }
     } else if (starts_with(line, "Grbl")) {
-        cnc->listener->on_banner(line);
+        cnc->push_event(std::make_shared<machine_event_banner>(line));
         cnc->reset_machine_state();
     } else if (starts_with(line, "<")) {
         cnc->last_report = parse_status_report(line, cnc->last_report);
-        cnc->listener->on_realtime_status_report(cnc->last_report);
+        cnc->push_event(std::make_shared<machine_event_report_received>(cnc->last_report));
     } else if (starts_with(line, "[MSG:")) {
-        cnc->listener->on_message(line.substr(5, line.size() - 6));
+        auto message = line.substr(5, line.size() - 6);
+        cnc->push_event(std::make_shared<machine_event_message>(message));
     } else if (starts_with(line, "ALARM:")) {
-        cnc->listener->on_alarm(std::stoi(line.substr(6)));
+        auto alarm = std::stoi(line.substr(6));
+        cnc->push_event(std::make_shared<machine_event_alarm>(alarm));
     } else if (starts_with(line, "$")) {
         auto pieces = split_string(line, "=");
         cnc->settings[pieces[0]] = pieces[1];
@@ -835,7 +852,7 @@ void grbl::machine_state_idle::on_line_received(std::string line) {
                 probe_coords[i] = std::stof(coords_as_string[i]);
             }
             bool probe_touched = pieces[2] == "1";
-            cnc->listener->on_probe_result(probe_touched, probe_coords);
+            cnc->push_event(std::make_shared<machine_event_probe_result>(probe_touched, probe_coords));
         }
     }
 }
@@ -884,9 +901,15 @@ void grbl::machine_state_check_program::move_to_next_check_stage() {
             break;
         case check_stage::disable_check_mode:
             if (check_failed) {
-                cnc->listener->on_check_completed(false, cnc->executed_instructions - 1, check_error);
+                bool success = false;
+                size_t failed_idx = cnc->executed_instructions - 1;
+                size_t error = check_error;
+                cnc->push_event(std::make_shared<machine_event_check_completed>(success, failed_idx, error));
             } else {
-                cnc->listener->on_check_completed(true, 0, 0);
+                bool success = true;
+                size_t failed_idx = 0;
+                size_t error = 0;
+                cnc->push_event(std::make_shared<machine_event_check_completed>(success, failed_idx, error));
             }
             cnc->switch_to_state(grbl_machine_state::idle);
             break;
@@ -908,15 +931,17 @@ void grbl::machine_state_check_program::on_line_received(std::string line) {
         move_to_next_check_stage();
 
     } else if (starts_with(line, "Grbl")) {
-        cnc->listener->on_banner(line);
+        cnc->push_event(std::make_shared<machine_event_banner>(line));
         cnc->reset_machine_state();
     } else if (starts_with(line, "<")) {
         cnc->last_report = parse_status_report(line, cnc->last_report);
-        cnc->listener->on_realtime_status_report(cnc->last_report);
+        cnc->push_event(std::make_shared<machine_event_report_received>(cnc->last_report));
     } else if (starts_with(line, "[MSG:")) {
-        cnc->listener->on_message(line.substr(5, line.size() - 6));
+        auto message = line.substr(5, line.size() - 6);
+        cnc->push_event(std::make_shared<machine_event_message>(message));
     } else if (starts_with(line, "ALARM:")) {
-        cnc->listener->on_alarm(std::stoi(line.substr(6)));
+        auto alarm = std::stoi(line.substr(6));
+        cnc->push_event(std::make_shared<machine_event_alarm>(alarm));
     }
 }
 
@@ -970,9 +995,15 @@ void grbl::machine_state_run_program::move_to_next_run_stage() {
         case run_stage::run_program:
             if (run_failed || !continue_program()) {
                 if (run_failed) {
-                    cnc->listener->on_run_completed(false, cnc->executed_instructions - 1, run_error);
+                    bool success = false;
+                    size_t failed_index = cnc->executed_instructions - 1;
+                    size_t error = run_error;
+                    cnc->push_event(std::make_shared<machine_event_run_completed>(success, failed_index, error));
                 } else {
-                    cnc->listener->on_run_completed(true, 0, 0);
+                    bool success = true;
+                    size_t failed_index = 0;
+                    size_t error = 0;
+                    cnc->push_event(std::make_shared<machine_event_run_completed>(success, failed_index, error));
                 }
                 cnc->switch_to_state(grbl_machine_state::idle);
             }
@@ -1013,20 +1044,21 @@ void grbl::machine_state_run_program::on_line_received(std::string line) {
         move_to_next_run_stage();
 
     } else if (starts_with(line, "Grbl")) {
-        cnc->listener->on_banner(line);
+        cnc->push_event(std::make_shared<machine_event_banner>(line));
         cnc->reset_machine_state();
     } else if (starts_with(line, "<")) {
         cnc->last_report = parse_status_report(line, cnc->last_report);
-        cnc->listener->on_realtime_status_report(cnc->last_report);
+        cnc->push_event(std::make_shared<machine_event_report_received>(cnc->last_report));
     } else if (starts_with(line, "[MSG:")) {
-        cnc->listener->on_message(line.substr(5, line.size() - 6));
+        auto message = line.substr(5, line.size() - 6);
+        cnc->push_event(std::make_shared<machine_event_message>(message));
     } else if (starts_with(line, "ALARM:")) {
-        cnc->listener->on_alarm(std::stoi(line.substr(6)));
+        auto alarm = std::stoi(line.substr(6));
+        cnc->push_event(std::make_shared<machine_event_alarm>(alarm));
     }
 }
 
 // heightmap probing
-
 void grbl::machine_state_heightmap_probing::on_connected(grbl::machine *m) {
 
 }
@@ -1062,15 +1094,17 @@ void grbl::machine_state_heightmap_probing::on_line_received(std::string line) {
         error = std::stoi(line.substr(6));
         move_to_next_stage();
     } else if (starts_with(line, "Grbl")) {
-        cnc->listener->on_banner(line);
+        cnc->push_event(std::make_shared<machine_event_banner>(line));
         cnc->reset_machine_state();
     } else if (starts_with(line, "<")) {
         cnc->last_report = parse_status_report(line, cnc->last_report);
-        cnc->listener->on_realtime_status_report(cnc->last_report);
+        cnc->push_event(std::make_shared<machine_event_report_received>(cnc->last_report));
     } else if (starts_with(line, "[MSG:")) {
-        cnc->listener->on_message(line.substr(5, line.size() - 6));
+        auto message = line.substr(5, line.size() - 6);
+        cnc->push_event(std::make_shared<machine_event_message>(message));
     } else if (starts_with(line, "ALARM:")) {
-        cnc->listener->on_alarm(std::stoi(line.substr(6)));
+        auto alarm = std::stoi(line.substr(6));
+        cnc->push_event(std::make_shared<machine_event_alarm>(alarm));
     } else if (starts_with(line, "[PRB")) {
         std::cout << "received PRB" << std::endl;
         line = line.substr(1, line.size() - 2);
@@ -1132,7 +1166,8 @@ void grbl::machine_state_heightmap_probing::move_to_next_stage() {
                 auto delta_z = current_z - z_zero_in_mpos;
                 std::cout << "Z[" << probed_locations << "]  = " << delta_z << std::endl;
                 grid->vertices[probed_locations].z = delta_z;
-                cnc->listener->on_heightmap_probe_acquired(grid);
+
+                cnc->push_event(std::make_shared<machine_event_heightmap_probe_acquired>(grid, probed_locations));
             }
         }
 
@@ -1167,3 +1202,70 @@ void grbl::machine_state_heightmap_probing::move_to_next_stage() {
             break;
     }
 }
+
+
+grbl::machine_event_connect::machine_event_connect() {
+    machine_event::type = machine_event_type::connected;
+}
+
+grbl::machine_event_disconnect::machine_event_disconnect() {
+    machine_event::type = machine_event_type::disconnected;
+}
+
+grbl::machine_event_report_received::machine_event_report_received(const grbl::realtime_status_report& r)
+        : report(r) {
+    machine_event::type = machine_event_type::report_received;
+}
+
+grbl::machine_event_banner::machine_event_banner(const std::string& b)
+        : banner{b} {
+    machine_event::type = machine_event_type::banner;
+}
+
+grbl::machine_event_message::machine_event_message(const std::string& m)
+        : message{m} {
+    machine_event::type = machine_event_type::message;
+}
+
+grbl::machine_event_alarm::machine_event_alarm(int code)
+        : alarm(code) {
+    machine_event::type = machine_event_type::alarm;
+}
+
+grbl::machine_event_init_completed::machine_event_init_completed() {
+    machine_event::type = machine_event_type::init_completed;
+}
+
+grbl::machine_event_run_completed::machine_event_run_completed(bool success, size_t failed_index, size_t error)
+        : success(success),
+          failed_index(failed_index),
+          error(error) {
+    machine_event::type = machine_event_type::run_completed;
+}
+
+grbl::machine_event_check_completed::machine_event_check_completed(bool success, size_t failed_idx, size_t error)
+        : success(success),
+          failed_index(failed_idx),
+          error(error) {
+    machine_event::type = machine_event_type::check_completed;
+}
+
+grbl::machine_event_settings_reloaded::machine_event_settings_reloaded() {
+    machine_event::type = machine_event_type::settings_reloaded;
+}
+
+grbl::machine_event_parameters_reloaded::machine_event_parameters_reloaded() {
+    machine_event::type = machine_event_type::parameters_reloaded;
+}
+
+grbl::machine_event_probe_result::machine_event_probe_result(bool touched, const float *coords)
+        : probe_touched(touched),
+          probe_coords{coords[0], coords[1], coords[2]} {
+    machine_event::type = machine_event_type::probe_result;
+}
+
+grbl::machine_event_heightmap_probe_acquired::machine_event_heightmap_probe_acquired(grbl::heightmap *g, size_t location)
+        : grid(g),
+          probed_location(location) {
+    machine_event::type = machine_event_type::heightmap_probe_acquired;
+}
diff --git a/grbl_machine.h b/grbl_machine.h
index d04bad0..795addc 100644
--- a/grbl_machine.h
+++ b/grbl_machine.h
@@ -2,6 +2,8 @@
 
 #include <map>
 #include <unordered_map>
+#include <memory>
+#include <mutex>
 #include "grbl_communication.h"
 #include "grbl.h"
 #include "heightmap.h"
@@ -116,20 +118,92 @@ static bool operator!=(const jog_state& a, const jog_state& b) {
     return !(a == b);
 }
 
-struct machine_listener {
-    virtual void on_connected() = 0;
-    virtual void on_disconnected() = 0;
-    virtual void on_realtime_status_report(realtime_status_report) = 0;
-    virtual void on_banner(std::string line) = 0;
-    virtual void on_message(std::string message) = 0;
-    virtual void on_alarm(int alarm) = 0;
-    virtual void on_init_completed() = 0;
-    virtual void on_run_completed(bool success, size_t failed_index, size_t error) = 0;
-    virtual void on_check_completed(bool success, size_t failed_index, size_t error) = 0;
-    virtual void on_settings_reloaded() = 0;
-    virtual void on_parameters_reloaded() = 0;
-    virtual void on_probe_result(bool probe_touched, float probe_coords[3]) = 0;
-    virtual void on_heightmap_probe_acquired(heightmap* grid) = 0;
+enum class machine_event_type {
+    connected,
+    disconnected,
+    report_received,
+    banner,
+    message,
+    alarm,
+    init_completed,
+    run_completed,
+    check_completed,
+    settings_reloaded,
+    parameters_reloaded,
+    probe_result,
+    heightmap_probe_acquired,
+};
+
+struct machine_event {
+    machine_event_type type;
+    // TODO: ewwww
+    virtual void omg() {}
+};
+
+struct machine_event_connect : public machine_event {
+    machine_event_connect();
+};
+
+struct machine_event_disconnect : public machine_event {
+    machine_event_disconnect();
+};
+
+struct machine_event_report_received : public machine_event {
+    explicit machine_event_report_received(const realtime_status_report& report);
+    realtime_status_report report;
+};
+
+struct machine_event_banner : public machine_event {
+    explicit machine_event_banner(const std::string& banner);
+    std::string banner;
+};
+
+struct machine_event_message : public machine_event {
+    explicit machine_event_message(const std::string& message);
+    std::string message;
+};
+
+struct machine_event_alarm : public machine_event {
+    explicit machine_event_alarm(int code);
+    int alarm;
+};
+
+struct machine_event_init_completed : public machine_event {
+    machine_event_init_completed();
+};
+
+struct machine_event_run_completed : public machine_event {
+    machine_event_run_completed(bool success, size_t failed_index, size_t error);
+    bool success;
+    size_t failed_index;
+    size_t error;
+};
+
+struct machine_event_check_completed : public machine_event {
+    machine_event_check_completed(bool success, size_t failed_idx, size_t error);
+    bool success;
+    size_t failed_index;
+    size_t error;
+};
+
+struct machine_event_settings_reloaded : public machine_event {
+    machine_event_settings_reloaded();
+};
+
+struct machine_event_parameters_reloaded : public machine_event {
+    machine_event_parameters_reloaded();
+};
+
+struct machine_event_probe_result : public machine_event {
+    machine_event_probe_result(bool touched, const float *coords);
+    bool probe_touched;
+    float probe_coords[3];
+};
+
+struct machine_event_heightmap_probe_acquired : public machine_event {
+    machine_event_heightmap_probe_acquired(heightmap *g, size_t location);
+    grbl::heightmap *grid;
+    size_t probed_location;
 };
 
 
@@ -278,7 +352,6 @@ struct machine : public transport_callbacks {
     machine();
     ~machine();
 
-    void set_listener(grbl::machine_listener *listener);
     void connect();
 
     void set_work_offset(std::string work_offset);
@@ -311,7 +384,18 @@ struct machine : public transport_callbacks {
     void start_z_probe(float min_z, float feed_rate);
 
     void probe_heightmap(grbl::heightmap& grid);
+
+    void push_event(std::shared_ptr<machine_event> event);
+
+    // pops nullptr if queue is empty
+    std::shared_ptr<machine_event> pop_event();
+
+
 protected:
+
+    std::mutex event_mutex;
+    std::deque<std::shared_ptr<machine_event>> events;
+
     void on_connected(transport *transport) override;
     void on_disconnected(transport *transport) override;
     void on_line_received(std::string line, transport *transport) override;
@@ -337,7 +421,6 @@ protected:
 
     volatile size_t awaiting_responses = 0;
     realtime_status_report last_report{};
-    machine_listener *listener = nullptr;
     transport *pipe = nullptr;
     grbl_machine_state state = grbl_machine_state::disconnected;
     program running_program;
diff --git a/main.cpp b/main.cpp
index 62132a3..7cc423c 100644
--- a/main.cpp
+++ b/main.cpp
@@ -49,15 +49,15 @@ using namespace nanogui;
 
 grbl::machine cnc{};
 
-class SenderApp : public Screen, public grbl::machine_listener {
+class SenderApp : public Screen {
 public:
 
     Window *window;
     grbl::jog_state jog;
     TextBox *txt_status;
-    TextBox *txtMessage;
+    TextBox *txt_message;
     nanogui::Color color_red = nanogui::Color(255, 0, 0, 255);
-    nanogui::Color colGreen = nanogui::Color(0, 255, 0, 255);
+    nanogui::Color color_green = nanogui::Color(0, 255, 0, 255);
     int last_alarm = 0;
     grbl::program pgm;
     Button *btn_load_program, *btn_check_program, *btn_run_program;
@@ -242,8 +242,8 @@ public:
         //
         status_text_holder->add<Label>("");
 
-        txtMessage = status_text_holder->add<TextBox>("");
-        txtMessage->set_fixed_width(300);
+        txt_message = status_text_holder->add<TextBox>("");
+        txt_message->set_fixed_width(300);
 
         status_text_holder->add<Label>("");
 
@@ -806,58 +806,8 @@ public:
         return Screen::resize_event(size);
     }
 
-    void on_connected() override {
-    }
-
-    void on_disconnected() override {
-    }
-
-    void on_settings_reloaded() override {
-    }
-
-    void on_parameters_reloaded() override {
-        refresh_offset();
-        update_dro();
-    }
-
-
     grbl::realtime_status_report last_report;
 
-    volatile bool machine_initialized = false;
-
-    void on_init_completed() override {
-        machine_initialized = true;
-        // need to do UI related things in UI thread
-    }
-
-    void on_realtime_status_report(grbl::realtime_status_report report) override {
-//        if (report == last_report) return;
-
-//        if (last_report.status != report.status) {
-        txt_status->set_value(grbl::status_to_string(cnc.get_status().status));
-
-        if (cnc.get_status().status == grbl::machine_status::alarm) {
-            txt_status->set_tooltip(grbl::alarm_to_string(last_alarm));
-        } else {
-            txt_status->set_tooltip(cnc.get_status().sub_status);
-        }
-//        }
-
-
-        // FIXME: ugly way of retrieving the bg color
-        btn_pin_door->set_background_color(report.signals.bit.door ? color_red : btn_load_program->background_color());
-        btn_pin_hold->set_background_color(report.signals.bit.hold ? color_red : btn_load_program->background_color());
-        btn_pin_reset->set_background_color(report.signals.bit.soft_reset ? color_red : btn_load_program->background_color());
-        btn_pin_cycle_start->set_background_color(report.signals.bit.cycle_start ? color_red : btn_load_program->background_color());
-        btn_pin_limit_x->set_background_color(report.signals.bit.x_limit ? color_red : btn_load_program->background_color());
-        btn_pin_limit_y->set_background_color(report.signals.bit.y_limit ? color_red : btn_load_program->background_color());
-        btn_pin_limit_z->set_background_color(report.signals.bit.z_limit ? color_red : btn_load_program->background_color());
-        btn_pin_probe->set_background_color(report.signals.bit.probe ? color_red : btn_load_program->background_color());
-
-        update_dro();
-        last_report = report;
-    }
-
     void update_dro() {
         auto work_pos = cnc.get_work_pos();
 
@@ -874,63 +824,6 @@ public:
         mpos_z_text->set_value(dro_ss.str());
     }
 
-    void on_banner(std::string line) override {
-    }
-
-    void on_message(std::string message) override {
-        txtMessage->set_value(message);
-        set_caption(message);
-    }
-
-    void on_alarm(int alarm) override {
-        last_alarm = alarm;
-    }
-
-    void on_probe_result(bool probe_touched, float *probe_coords) override {
-        std::stringstream ss;
-        ss << "Probing ended. Result: " << std::boolalpha << probe_touched << " at coords: ";
-        for (auto i = 0; i < 3; i++) {
-            ss << probe_coords[i] << ", ";
-        }
-        new MessageDialog(this, MessageDialog::Type::Warning, "Probe result", ss.str());
-    }
-
-    volatile bool should_render_grid = false;
-    void on_heightmap_probe_acquired(grbl::heightmap *grid) override {
-        std::cout << "Updating grid" << std::endl;
-        // let's try to update this from the UI thread since the call is invoked from the
-        // grbl communicator thread.
-        should_render_grid = true;
-    }
-
-    void on_check_completed(bool success, size_t failed_index, size_t error) override {
-        btn_check_program->set_background_color(success ? colGreen : color_red);
-        if (success) {
-            btn_run_program->set_enabled(true);
-            new MessageDialog(this, MessageDialog::Type::Information, "Check result", "Program checked successfully");
-        } else {
-            btn_run_program->set_enabled(false);
-            std::stringstream ss;
-            auto i = pgm.instruction_at(failed_index);
-            ss << "Program check failed at line " << i.line << " (" << i.command << "). Error: " << error << ", "
-               << grbl::error_to_string(error);
-            new MessageDialog(this, MessageDialog::Type::Warning, "Check result", ss.str());
-        }
-    }
-
-    void on_run_completed(bool success, size_t failed_index, size_t error) override {
-        btn_run_program->set_background_color(success ? colGreen : color_red);
-        if (success) {
-            new MessageDialog(this, MessageDialog::Type::Information, "Run result", "Program executed successfully");
-        } else {
-            std::stringstream ss;
-            auto i = pgm.instruction_at(failed_index);
-            ss << "Program execution failed at line " << i.line << " (" << i.command << "). Error: " << error << ", "
-               << grbl::error_to_string(error);
-            new MessageDialog(this, MessageDialog::Type::Warning, "Run result", ss.str());
-        }
-    }
-
 
     bool keyboard_event(int key, int scancode, int action, int modifiers) override {
         if (Screen::keyboard_event(key, scancode, action, modifiers))
@@ -1056,23 +949,125 @@ public:
     }
 
     void draw(NVGcontext *ctx) override {
-        // not pretty but need to do this in UI thread
-        if (machine_initialized) {
-            fill_in_settings();
-            fill_in_parameters();
+        std::shared_ptr<grbl::machine_event> event;
+        while ((event = cnc.pop_event()) != nullptr) {
+            switch (event->type) {
+                case grbl::machine_event_type::connected:
+                    break;
+                case grbl::machine_event_type::disconnected:
+                    break;
+                case grbl::machine_event_type::report_received: {
 
-            perform_layout();
+                    auto ev = dynamic_cast<grbl::machine_event_report_received *>(event.get());
 
-            refresh_offset();
-            update_dro();
-            machine_initialized = false;
+                    txt_status->set_value(grbl::status_to_string(cnc.get_status().status));
+
+                    if (cnc.get_status().status == grbl::machine_status::alarm) {
+                        txt_status->set_tooltip(grbl::alarm_to_string(last_alarm));
+                    } else {
+                        txt_status->set_tooltip(cnc.get_status().sub_status);
+                    }
+
+                    // FIXME: ugly way of retrieving the bg color
+                    btn_pin_door->set_background_color(ev->report.signals.bit.door ? color_red : btn_load_program->background_color());
+                    btn_pin_hold->set_background_color(ev->report.signals.bit.hold ? color_red : btn_load_program->background_color());
+                    btn_pin_reset->set_background_color(
+                            ev->report.signals.bit.soft_reset ? color_red : btn_load_program->background_color());
+                    btn_pin_cycle_start->set_background_color(
+                            ev->report.signals.bit.cycle_start ? color_red : btn_load_program->background_color());
+                    btn_pin_limit_x->set_background_color(
+                            ev->report.signals.bit.x_limit ? color_red : btn_load_program->background_color());
+                    btn_pin_limit_y->set_background_color(
+                            ev->report.signals.bit.y_limit ? color_red : btn_load_program->background_color());
+                    btn_pin_limit_z->set_background_color(
+                            ev->report.signals.bit.z_limit ? color_red : btn_load_program->background_color());
+                    btn_pin_probe->set_background_color(ev->report.signals.bit.probe ? color_red : btn_load_program->background_color());
+
+                    update_dro();
+                    last_report = ev->report;
+                    break;
+                }
+                case grbl::machine_event_type::banner:
+                    break;
+                case grbl::machine_event_type::message: {
+                    auto ev = dynamic_cast<grbl::machine_event_message *>(event.get());
+                    txt_message->set_value(ev->message);
+                    set_caption(ev->message);
+                    break;
+                }
+                case grbl::machine_event_type::alarm: {
+                    auto ev = dynamic_cast<grbl::machine_event_alarm *>(event.get());
+                    last_alarm = ev->alarm;
+                    break;
+                }
+                case grbl::machine_event_type::init_completed:
+                    fill_in_settings();
+                    fill_in_parameters();
+
+                    perform_layout();
+
+                    refresh_offset();
+                    update_dro();
+                    break;
+                case grbl::machine_event_type::run_completed: {
+                    auto ev = dynamic_cast<grbl::machine_event_run_completed *>(event.get());
+                    btn_run_program->set_background_color(ev->success ? color_green : color_red);
+                    if (ev->success) {
+                        new MessageDialog(this, MessageDialog::Type::Information, "Run result", "Program executed successfully");
+                    } else {
+                        std::stringstream ss;
+                        auto i = pgm.instruction_at(ev->failed_index);
+                        ss << "Program execution failed at line " << i.line << " (" << i.command << "). Error: "
+                           << ev->error << ", "
+                           << grbl::error_to_string(ev->error);
+                        new MessageDialog(this, MessageDialog::Type::Warning, "Run result", ss.str());
+                    }
+                    break;
+                }
+                case grbl::machine_event_type::check_completed: {
+                    auto ev = dynamic_cast<grbl::machine_event_check_completed *>(event.get());
+
+                    btn_check_program->set_background_color(ev->success ? color_green : color_red);
+                    if (ev->success) {
+                        btn_run_program->set_enabled(true);
+                        new MessageDialog(this, MessageDialog::Type::Information, "Check result", "Program checked successfully");
+                    } else {
+                        btn_run_program->set_enabled(false);
+                        std::stringstream ss;
+                        auto i = pgm.instruction_at(ev->failed_index);
+                        ss << "Program check failed at line " << i.line << " (" << i.command << "). Error: "
+                           << ev->error << ", "
+                           << grbl::error_to_string(ev->error);
+                        new MessageDialog(this, MessageDialog::Type::Warning, "Check result", ss.str());
+                    }
+                    break;
+                }
+                case grbl::machine_event_type::settings_reloaded:
+                    break;
+                case grbl::machine_event_type::parameters_reloaded:
+                    refresh_offset();
+                    update_dro();
+                    break;
+                case grbl::machine_event_type::probe_result: {
+                    auto ev = dynamic_cast<grbl::machine_event_probe_result *>(event.get());
+
+                    std::stringstream ss;
+                    ss << "Probing ended. Result: " << std::boolalpha << ev->probe_touched << " at coords: ";
+                    for (float probe_coord: ev->probe_coords) {
+                        ss << probe_coord << ", ";
+                    }
+                    new MessageDialog(this, MessageDialog::Type::Warning, "Probe result", ss.str());
+                    break;
+                }
+                case grbl::machine_event_type::heightmap_probe_acquired: {
+                    std::cout << "Updating grid" << std::endl;
+                    auto ev = dynamic_cast<grbl::machine_event_heightmap_probe_acquired *>(event.get());
+                    renderer.update_grid(*ev->grid);
+                    break;
+                }
+            }
         }
 
-        // TODO: change this to something prettier. make a pipe/queue for in-between threads comm
-        if (should_render_grid) {
-            renderer.update_grid(heightmap_grid);
-            should_render_grid = false;
-        }
 
         Widget::draw(ctx);
     }
@@ -1131,7 +1126,6 @@ int main(int argc, char **argv) {
             app->draw_all();
             app->set_visible(true);
 
-            cnc.set_listener(app);
             cnc.connect();
 
             nanogui::mainloop(1 / 60.f * 1000);