Add the ability to limit-rate the dashboard updating (#3527)

Co-authored-by: Emma Broman <emma.broman@liu.se>

src/rendering/dashboard.cpp

@@ -49,6 +49,14 @@ namespace {
         "in x and y-direction on screen.",
         openspace::properties::Property::Visibility::User
     };
+
+    constexpr openspace::properties::Property::PropertyInfo RefreshRateInfo = {
+        "RefreshRate",
+        "Refresh Rate (in ms)",
+        "The number of milliseconds between refreshes of the dashboard items. If the "
+        "value is 0 the dashboard is refreshed at the same rate as the main rendering.",
+        openspace::properties::Property::Visibility::AdvancedUser
+    };
 } // namespace
 
 namespace openspace {
@@ -57,9 +65,12 @@ Dashboard::Dashboard()
     : properties::PropertyOwner({ "Dashboard" })
     , _isEnabled(EnabledInfo, true)
     , _startPositionOffset(StartPositionOffsetInfo, glm::ivec2(10, -10))
+    , _refreshRate(RefreshRateInfo, 0, 0, 1000)
+    , _lastRefresh(std::chrono::high_resolution_clock::now())
 {
     addProperty(_isEnabled);
     addProperty(_startPositionOffset);
+    addProperty(_refreshRate);
 }
 
 void Dashboard::addDashboardItem(std::unique_ptr<DashboardItem> item) {
@@ -137,8 +148,17 @@ void Dashboard::render(glm::vec2& penPosition) {
         return;
     }
 
+    auto now = std::chrono::steady_clock::now();
+    bool needsUpdate = (now - _lastRefresh) > std::chrono::milliseconds(_refreshRate);
+    if (needsUpdate) {
+        _lastRefresh = now;
+    }
+
     for (const std::unique_ptr<DashboardItem>& item : _items) {
         if (item->isEnabled()) {
+            if (needsUpdate) {
+                item->update();
+            }
             item->render(penPosition);
         }
     }

src/rendering/dashboardtextitem.cpp

@@ -27,7 +27,9 @@
 #include <openspace/documentation/documentation.h>
 #include <openspace/documentation/verifier.h>
 #include <openspace/engine/globals.h>
+#include <ghoul/font/font.h>
 #include <ghoul/font/fontmanager.h>
+#include <ghoul/font/fontrenderer.h>
 #include <optional>
 
 namespace {
@@ -85,4 +87,14 @@ DashboardTextItem::DashboardTextItem(const ghoul::Dictionary& dictionary, float
     _font = global::fontManager->font(_fontName, _fontSize);
 }
 
+void DashboardTextItem::render(glm::vec2& penPosition) {
+    if (_buffer.empty()) {
+        return;
+    }
+
+    const size_t lines = std::count(_buffer.begin(), _buffer.end(), '\n') + 1;
+    penPosition.y -= _font->height() * lines;
+    RenderFont(*_font, penPosition, _buffer);
+}
+
 } // namespace openspace