Nav: fixed speed scale for resizing/moving with keyboard/gamepad. (#323)

Fix 04157da29.

docs/CHANGELOG.txt

@@ -172,6 +172,10 @@ Other Changes:
   - Fixed remote/shortcut InputText() not teleporting mouse cursor when
     nav cursor is visible and `io.ConfigNavMoveSetMousePos` is enabled.
   - Fixed a looping/wrapping issue when done in menu layer. (#9178)
+  - Fixed speed scale for resizing/moving with keyboard/gamepad. We incorrectly
+    used io.DisplayFramebufferScale (very old code), effectively making those
+    actions faster on macOS/iOS retina screens.
+    (changed this to use a style scale factor that's not fully formalized yet)
 - Scrollbar: fixed a codepath leading to a divide-by-zero (which would not be
   noticeable by user but detected by sanitizers). (#9089) [@judicaelclair]
 - InvisibleButton: allow calling with size (0,0) to fit to available content 

imgui.cpp

@@ -7006,7 +7006,7 @@ static int ImGui::UpdateWindowManualResize(ImGuiWindow* window, int* border_hove
         if (nav_resize_dir.x != 0.0f || nav_resize_dir.y != 0.0f)
         {
             const float NAV_RESIZE_SPEED = 600.0f;
-            const float resize_step = NAV_RESIZE_SPEED * g.IO.DeltaTime * ImMin(g.IO.DisplayFramebufferScale.x, g.IO.DisplayFramebufferScale.y);
+            const float resize_step = NAV_RESIZE_SPEED * g.IO.DeltaTime * GetScale();
             g.NavWindowingAccumDeltaSize += nav_resize_dir * resize_step;
             g.NavWindowingAccumDeltaSize = ImMax(g.NavWindowingAccumDeltaSize, clamp_rect.Min - window->Pos - window->Size); // We need Pos+Size >= clmap_rect.Min, so Size >= clmap_rect.Min - Pos, so size_delta >= clmap_rect.Min - window->Pos - window->Size
             g.NavWindowingToggleLayer = false;
@@ -14521,7 +14521,7 @@ static void ImGui::NavUpdateWindowing()
         if (nav_move_dir.x != 0.0f || nav_move_dir.y != 0.0f)
         {
             const float NAV_MOVE_SPEED = 800.0f;
-            const float move_step = NAV_MOVE_SPEED * io.DeltaTime * ImMin(io.DisplayFramebufferScale.x, io.DisplayFramebufferScale.y);
+            const float move_step = NAV_MOVE_SPEED * io.DeltaTime * GetScale();
             g.NavWindowingAccumDeltaPos += nav_move_dir * move_step;
             g.NavHighlightItemUnderNav = true;
             ImVec2 accum_floored = ImTrunc(g.NavWindowingAccumDeltaPos);

imgui_internal.h

@@ -3150,6 +3150,7 @@ namespace ImGui
     // - You are calling ImGui functions after ImGui::EndFrame()/ImGui::Render() and before the next ImGui::NewFrame(), which is also illegal.
     IMGUI_API ImGuiIO&         GetIO(ImGuiContext* ctx);
     IMGUI_API ImGuiPlatformIO& GetPlatformIO(ImGuiContext* ctx);
+    inline    float         GetScale()                  { ImGuiContext& g = *GImGui; return g.Style._MainScale; } // FIXME-DPI: I don't want to formalize this just yet. Because reasons. Please don't use.
     inline    ImGuiWindow*  GetCurrentWindowRead()      { ImGuiContext& g = *GImGui; return g.CurrentWindow; }
     inline    ImGuiWindow*  GetCurrentWindow()          { ImGuiContext& g = *GImGui; g.CurrentWindow->WriteAccessed = true; return g.CurrentWindow; }
     IMGUI_API ImGuiWindow*  FindWindowByID(ImGuiID id);