perf: predetermine history trail draw function

On every render, we were checking the fields to determine the type of dot
we are rendering. However, we don't need to do this, as the dot type can only change
as part of an ASR load or configuration menu change.

This change saves the draw function as a lambda when something changes, allowing us to
reduce the render time by approximately 25% - went from 12ms to 8ms in testing.

src/plugin/historytrail/HistoryTrailRenderer.cpp

@@ -57,6 +57,9 @@ namespace UKControllerPlugin {
                 userSetting.GetIntegerEntry(this->maxAltitudeFilterUserSettingKey, this->defaultMaxAltitude);
             this->filledDots = userSetting.GetBooleanEntry(this->dotFillUserSettingKey, false);
             this->rotatedDots = userSetting.GetBooleanEntry(this->dotRotateUserSettingKey, false);
+
+            // Load the dot drawing function
+            this->drawDot = this->GetDrawDotFunction();
         }
 
         /*
@@ -136,51 +139,6 @@ namespace UKControllerPlugin {
             return this->antialiasedTrails;
         }
 
-        /*
-            Draws a single dot to the screen.
-        */
-        void
-        HistoryTrailRenderer::DrawDot(GdiGraphicsInterface& graphics, Gdiplus::Pen& pen, const Gdiplus::RectF& area)
-        {
-            if (this->historyTrailType == this->trailTypeDiamond) {
-                graphics.DrawDiamond(area, pen);
-            } else if (this->historyTrailType == this->trailTypeCircle) {
-                graphics.DrawCircle(area, pen);
-            } else if (this->historyTrailType == this->trailTypeLine) {
-                graphics.DrawLine(
-                    pen,
-                    Gdiplus::PointF{area.GetLeft(), area.GetBottom()},
-                    Gdiplus::PointF{area.GetRight(), area.GetTop()});
-            } else {
-                graphics.DrawRect(area, pen);
-            }
-        }
-
-        /*
-            Fills a single dot to the screen.
-        */
-        void
-        HistoryTrailRenderer::FillDot(GdiGraphicsInterface& graphics, Gdiplus::Brush& brush, const Gdiplus::RectF& area)
-        {
-            if (this->historyTrailType == this->trailTypeDiamond) {
-                graphics.FillDiamond(area, brush);
-            } else if (this->historyTrailType == this->trailTypeCircle) {
-                graphics.FillCircle(area, brush);
-            } else {
-                graphics.FillRect(area, brush);
-            }
-        }
-
-        void HistoryTrailRenderer::DoDot(GdiGraphicsInterface& graphics, const Gdiplus::RectF& area)
-        {
-            // Draw the dot
-            if (this->filledDots && this->historyTrailType != this->trailTypeLine) {
-                this->FillDot(graphics, *this->brush, area);
-            } else {
-                this->DrawDot(graphics, *this->pen, area);
-            }
-        }
-
         /*
             Returns the configuration menu item.
         */
@@ -372,9 +330,9 @@ namespace UKControllerPlugin {
                             if (this->rotatedDots) {
                                 graphics.Rotated(
                                     static_cast<Gdiplus::REAL>(position->heading),
-                                    [&graphics, &dot, this]() { this->DoDot(graphics, dot); });
+                                    [&graphics, &dot, this]() { this->drawDot(graphics, dot); });
                             } else {
-                                this->DoDot(graphics, dot);
+                                this->drawDot(graphics, dot);
                             }
                         });
 
@@ -405,5 +363,68 @@ namespace UKControllerPlugin {
         void HistoryTrailRenderer::ResetPosition(void)
         {
         }
+
+        auto HistoryTrailRenderer::GetDoDotFunction() const
+            -> std::function<void(GdiGraphicsInterface&, const Gdiplus::RectF&)>
+        {
+            return this->filledDots && this->historyTrailType != this->trailTypeLine ? this->GetFillDotFunction()
+                                                                                     : this->GetDrawDotFunction();
+        }
+
+        auto HistoryTrailRenderer::GetDrawDotFunction() const
+            -> std::function<void(Windows::GdiGraphicsInterface&, const Gdiplus::RectF&)>
+        {
+            // Diamonds
+            if (this->historyTrailType == this->trailTypeDiamond) {
+                return [this](Windows::GdiGraphicsInterface& graphics, const Gdiplus::RectF& area) {
+                    graphics.DrawDiamond(area, *this->pen);
+                };
+            }
+
+            // Circles
+            if (this->historyTrailType == this->trailTypeCircle) {
+                return [this](Windows::GdiGraphicsInterface& graphics, const Gdiplus::RectF& area) {
+                    graphics.DrawCircle(area, *this->pen);
+                };
+            }
+
+            // Lines
+            if (this->historyTrailType == this->trailTypeLine) {
+                return [this](Windows::GdiGraphicsInterface& graphics, const Gdiplus::RectF& area) {
+                    graphics.DrawLine(
+                        *this->pen,
+                        Gdiplus::PointF{area.GetLeft(), area.GetBottom()},
+                        Gdiplus::PointF{area.GetRight(), area.GetTop()});
+                };
+            }
+
+            // Rectangles
+            return [this](Windows::GdiGraphicsInterface& graphics, const Gdiplus::RectF& area) {
+                graphics.DrawRect(area, *this->pen);
+            };
+        }
+
+        auto HistoryTrailRenderer::GetFillDotFunction() const
+            -> std::function<void(Windows::GdiGraphicsInterface&, const Gdiplus::RectF&)>
+        {
+            // Diamonds
+            if (this->historyTrailType == this->trailTypeDiamond) {
+                return [this](Windows::GdiGraphicsInterface& graphics, const Gdiplus::RectF& area) {
+                    graphics.FillDiamond(area, *this->brush);
+                };
+            }
+
+            // Circles
+            if (this->historyTrailType == this->trailTypeCircle) {
+                return [this](Windows::GdiGraphicsInterface& graphics, const Gdiplus::RectF& area) {
+                    graphics.FillCircle(area, *this->brush);
+                };
+            }
+
+            // Rects
+            return [this](Windows::GdiGraphicsInterface& graphics, const Gdiplus::RectF& area) {
+                graphics.FillRect(area, *this->brush);
+            };
+        }
     } // namespace HistoryTrail
 } // namespace UKControllerPlugin

src/plugin/historytrail/HistoryTrailRenderer.h

@@ -158,10 +158,12 @@ namespace UKControllerPlugin {
             const int defaultMaxAltitude = 99999;
 
             private:
-            void DrawDot(Windows::GdiGraphicsInterface& graphics, Gdiplus::Pen& pen, const Gdiplus::RectF& area);
-
-            void FillDot(Windows::GdiGraphicsInterface& graphics, Gdiplus::Brush& brush, const Gdiplus::RectF& area);
-            void DoDot(Windows::GdiGraphicsInterface& graphics, const Gdiplus::RectF& area);
+            [[nodiscard]] auto GetDoDotFunction() const
+                -> std::function<void(Windows::GdiGraphicsInterface&, const Gdiplus::RectF&)>;
+            [[nodiscard]] auto GetFillDotFunction() const
+                -> std::function<void(Windows::GdiGraphicsInterface&, const Gdiplus::RectF&)>;
+            [[nodiscard]] auto GetDrawDotFunction() const
+                -> std::function<void(Windows::GdiGraphicsInterface&, const Gdiplus::RectF&)>;
 
             // Handles dialogs
             const Dialog::DialogManager& dialogManager;
@@ -222,6 +224,9 @@ namespace UKControllerPlugin {
 
             // The dot command for opening the configuration modal.
             const std::string dotCommand = ".ukcp h";
+
+            // Function for drawing the dot - saved as a lambda so we dont have to keep checking the trail type
+            std::function<void(Windows::GdiGraphicsInterface&, const Gdiplus::RectF&)> drawDot;
         };
     } // namespace HistoryTrail
 } // namespace UKControllerPlugin