From 8980bf2a124f647dbdece9f90b86b2f37c4f3fa5 Mon Sep 17 00:00:00 2001
From: Star Rauchenberger <fefferburbia@gmail.com>
Date: Sun, 19 May 2024 11:21:24 -0400
Subject: Faster subway map rendering

Image quality suffered a bit though.
---
 src/subway_map.cpp | 103 +++++++++++++++++++++++++++++++++++------------------
 1 file changed, 69 insertions(+), 34 deletions(-)

diff --git a/src/subway_map.cpp b/src/subway_map.cpp
index b02c616..51f17c5 100644
--- a/src/subway_map.cpp
+++ b/src/subway_map.cpp
@@ -117,13 +117,77 @@ void SubwayMap::UpdateSunwarp(SubwaySunwarp from_sunwarp,
 
 void SubwayMap::OnPaint(wxPaintEvent &event) {
   if (GetSize() != rendered_.GetSize()) {
-    Redraw();
+    wxSize panel_size = GetSize();
+    wxSize image_size = map_image_.GetSize();
+
+    render_x_ = 0;
+    render_y_ = 0;
+    render_width_ = panel_size.GetWidth();
+    render_height_ = panel_size.GetHeight();
+
+    if (image_size.GetWidth() * panel_size.GetHeight() >
+        panel_size.GetWidth() * image_size.GetHeight()) {
+      render_height_ = (panel_size.GetWidth() * image_size.GetHeight()) /
+                       image_size.GetWidth();
+      render_y_ = (panel_size.GetHeight() - render_height_) / 2;
+    } else {
+      render_width_ = (image_size.GetWidth() * panel_size.GetHeight()) /
+                      image_size.GetHeight();
+      render_x_ = (panel_size.GetWidth() - render_width_) / 2;
+    }
+
+    SetZoomPos({zoom_x_, zoom_y_});
   }
 
   wxBufferedPaintDC dc(this);
   dc.SetBackground(*wxWHITE_BRUSH);
   dc.Clear();
-  dc.DrawBitmap(rendered_, zoom_x_, zoom_y_);
+
+  {
+    wxMemoryDC rendered_dc;
+    rendered_dc.SelectObject(rendered_);
+
+    int dst_x;
+    int dst_y;
+    int dst_w;
+    int dst_h;
+    int src_x;
+    int src_y;
+    int src_w;
+    int src_h;
+
+    int zoomed_width = render_width_ * zoom_;
+    int zoomed_height = render_height_ * zoom_;
+
+    if (zoomed_width <= GetSize().GetWidth()) {
+      dst_x = (GetSize().GetWidth() - zoomed_width) / 2;
+      dst_w = zoomed_width;
+      src_x = 0;
+      src_w = map_image_.GetWidth();
+    } else {
+      dst_x = 0;
+      dst_w = GetSize().GetWidth();
+      src_x = -zoom_x_ * map_image_.GetWidth() / render_width_ / zoom_;
+      src_w =
+          GetSize().GetWidth() * map_image_.GetWidth() / render_width_ / zoom_;
+    }
+
+    if (zoomed_height <= GetSize().GetHeight()) {
+      dst_y = (GetSize().GetHeight() - zoomed_height) / 2;
+      dst_h = zoomed_height;
+      src_y = 0;
+      src_h = map_image_.GetHeight();
+    } else {
+      dst_y = 0;
+      dst_h = GetSize().GetHeight();
+      src_y = -zoom_y_ * map_image_.GetWidth() / render_width_ / zoom_;
+      src_h =
+          GetSize().GetHeight() * map_image_.GetWidth() / render_width_ / zoom_;
+    }
+
+    dc.StretchBlit(dst_x, dst_y, dst_w, dst_h, &rendered_dc, src_x, src_y,
+                   src_w, src_h);
+  }
 
   if (hovered_item_) {
     const SubwayItem &subway_item = GD_GetSubwayItem(*hovered_item_);
@@ -320,7 +384,6 @@ void SubwayMap::OnMouseScroll(wxMouseEvent &event) {
     wxPoint virtual_pos = MapPosToVirtualPos(map_pos);
     SetZoomPos(-(virtual_pos - event.GetPosition()));
 
-    Redraw();
     Refresh();
   }
 
@@ -335,29 +398,7 @@ void SubwayMap::OnTimer(wxTimerEvent &event) {
 }
 
 void SubwayMap::Redraw() {
-  wxSize panel_size = GetSize();
-  wxSize image_size = map_image_.GetSize();
-
-  render_x_ = 0;
-  render_y_ = 0;
-  render_width_ = panel_size.GetWidth();
-  render_height_ = panel_size.GetHeight();
-
-  if (image_size.GetWidth() * panel_size.GetHeight() >
-      panel_size.GetWidth() * image_size.GetHeight()) {
-    render_height_ = (panel_size.GetWidth() * image_size.GetHeight()) /
-                     image_size.GetWidth();
-    render_y_ = (panel_size.GetHeight() - render_height_) / 2;
-  } else {
-    render_width_ = (image_size.GetWidth() * panel_size.GetHeight()) /
-                    image_size.GetHeight();
-    render_x_ = (panel_size.GetWidth() - render_width_) / 2;
-  }
-
-  rendered_ = wxBitmap(map_image_.Scale(
-      render_width_ * zoom_, render_height_ * zoom_, wxIMAGE_QUALITY_BILINEAR));
-
-  SetZoomPos({zoom_x_, zoom_y_});
+  rendered_ = wxBitmap(map_image_);
 
   wxMemoryDC dc;
   dc.SelectObject(rendered_);
@@ -413,15 +454,9 @@ void SubwayMap::Redraw() {
       }
     }
 
-    wxPoint real_area_pos = MapPosToVirtualPos({subway_item.x, subway_item.y});
+    wxPoint real_area_pos = {subway_item.x, subway_item.y};
 
-    int real_area_size =
-        render_width_ * zoom_ *
-        (draw_type == ItemDrawType::kOwl ? OWL_ACTUAL_SIZE : AREA_ACTUAL_SIZE) /
-        image_size.GetWidth();
-    if (real_area_size == 0) {
-      real_area_size = 1;
-    }
+    int real_area_size = (draw_type == ItemDrawType::kOwl ? OWL_ACTUAL_SIZE : AREA_ACTUAL_SIZE);
 
     if (draw_type == ItemDrawType::kBox) {
       dc.SetPen(*wxThePenList->FindOrCreatePen(*wxBLACK, 1));
-- 
cgit 1.4.1