Touch on waterfall to set cursor pos (#2624)

* init

* fix typo that found by Copilot

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

---------

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

firmware/application/ui/ui_spectrum.cpp

@@ -1,5 +1,6 @@
 /*
  * Copyright (C) 2015 Jared Boone, ShareBrained Technology, Inc.
+ * Copyleft Mr. Robot 2025
  *
  * This file is part of PortaPack.
  *
@@ -100,6 +101,15 @@ void FrequencyScale::set_channel_filter(
     }
 }
 
+void FrequencyScale::set_cursor_position(const int32_t position) {
+    cursor_position = position;
+
+    cursor_position = std::min<int32_t>(cursor_position, 119);
+    cursor_position = std::max<int32_t>(cursor_position, -120);
+
+    set_dirty();
+}
+
 void FrequencyScale::paint(Painter& painter) {
     const auto r = screen_rect();
 
@@ -240,6 +250,15 @@ bool FrequencyScale::on_key(const KeyEvent key) {
     return false;
 }
 
+bool FrequencyScale::on_touch(const TouchEvent touch) {
+    if (touch.type == TouchEvent::Type::Start) {
+        if (on_select) {
+            on_select((touch.point.x() * spectrum_sampling_rate) / 240);
+        }
+    }
+    return true;
+}
+
 void FrequencyScale::on_tick_second() {
     set_dirty();
     _blink = !_blink;
@@ -285,6 +304,15 @@ void WaterfallWidget::on_channel_spectrum(
         pixel_row);
 }
 
+bool WaterfallWidget::on_touch(const TouchEvent event) {
+    if (event.type == TouchEvent::Type::Start) {
+        if (on_touch_select) {
+            on_touch_select(event.point.x(), event.point.y());
+        }
+    }
+    return true;
+}
+
 void WaterfallWidget::clear() {
     display.fill_rectangle(
         screen_rect(),
@@ -304,6 +332,18 @@ WaterfallView::WaterfallView(const bool cursor) {
         if (on_select) on_select(offset);
     };
 
+    waterfall_widget.on_touch_select = [this](int32_t x, int32_t y) {
+        if (y > screen_height - screen_height * 0.1) return;  // prevent ghost touch
+
+        frequency_scale.focus();  // focus on frequency scale to show cursor
+
+        if (sampling_rate) {
+            // screen x to frequency scale x, NB we need two widgets align
+            int32_t cursor_position = x - (screen_width / 2);
+            frequency_scale.set_cursor_position(cursor_position);
+        }
+    };
+
     if (!waterfall_widget.gradient.load_file(default_gradient_file)) {
         waterfall_widget.gradient.set_default();
     }

firmware/application/ui/ui_spectrum.hpp

@@ -1,5 +1,6 @@
 /*
  * Copyright (C) 2015 Jared Boone, ShareBrained Technology, Inc.
+ * Copyleft Mr. Robot 2025
  *
  * This file is part of PortaPack.
  *
@@ -79,9 +80,11 @@ class FrequencyScale : public Widget {
 
     bool on_encoder(const EncoderEvent delta) override;
     bool on_key(const KeyEvent key) override;
+    bool on_touch(const TouchEvent touch) override;
 
     void set_spectrum_sampling_rate(const int new_sampling_rate);
     void set_channel_filter(const int low_frequency, const int high_frequency, const int transition);
+    void set_cursor_position(const int32_t position);
 
     void paint(Painter& painter) override;
 
@@ -112,11 +115,14 @@ class FrequencyScale : public Widget {
 
 class WaterfallWidget : public Widget {
    public:
+    std::function<void(int32_t offset, int32_t y)> on_touch_select{};
+
     Gradient gradient{};
 
     void on_show() override;
     void on_hide() override;
     void paint(Painter&) override {}
+    bool on_touch(const TouchEvent event) override;
 
     void on_channel_spectrum(const ChannelSpectrum& spectrum);