Backends: Added support for SDL 2.0.18+ preciseX/preciseY mouse wheel data for smooth scrolling + scaling for Emscripten. (#4019, #6096)

+ Missing changelog entries.

backends/imgui_impl_glfw.cpp

@@ -16,6 +16,7 @@
 
 // CHANGELOG
 // (minor and older changes stripped away, please see git history for details)
+//  2023-02-02: Inputs: Scaling X value on Emscripten (bug?). (#4019, #6096)
 //  2023-01-04: Inputs: Fixed mods state on Linux when using Alt-GR text input (e.g. German keyboard layout), could lead to broken text input. Revert a 2022/01/17 change were we resumed using mods provided by GLFW, turns out they were faulty.
 //  2022-11-22: Perform a dummy glfwGetError() read to cancel missing names with glfwGetKeyName(). (#5908)
 //  2022-10-18: Perform a dummy glfwGetError() read to cancel missing mouse cursors errors. Using GLFW_VERSION_COMBINED directly. (#5785)
@@ -283,6 +284,10 @@ void ImGui_ImplGlfw_ScrollCallback(GLFWwindow* window, double xoffset, double yo
     if (bd->PrevUserCallbackScroll != nullptr && window == bd->Window)
         bd->PrevUserCallbackScroll(window, xoffset, yoffset);
 
+#ifdef __EMSCRIPTEN__
+    xoffset /= 100.0;
+#endif
+
     ImGuiIO& io = ImGui::GetIO();
     io.AddMouseWheelEvent((float)xoffset, (float)yoffset);
 }

backends/imgui_impl_sdl.cpp

@@ -18,6 +18,7 @@
 
 // CHANGELOG
 // (minor and older changes stripped away, please see git history for details)
+//  2023-02-02: Added support for SDL 2.0.18+ preciseX/preciseY mouse wheel data for smooth scrolling + Scaling X value on Emscripten (bug?). (#4019, #6096)
 //  2023-02-02: Removed SDL_MOUSEWHEEL value clamping, as values seem correct in latest Emscripten. (#4019)
 //  2023-02-01: Flipping SDL_MOUSEWHEEL 'wheel.x' value to match other backends and offer consistent horizontal scrolling direction. (#4019, #6096, #1463)
 //  2022-10-11: Using 'nullptr' instead of 'NULL' as per our switch to C++11.
@@ -262,8 +263,17 @@ bool ImGui_ImplSDL2_ProcessEvent(const SDL_Event* event)
         }
         case SDL_MOUSEWHEEL:
         {
+            //IMGUI_DEBUG_LOG("wheel %.2f %.2f, precise %.2f %.2f\n", (float)event->wheel.x, (float)event->wheel.y, event->wheel.preciseX, event->wheel.preciseY);
+#if SDL_VERSION_ATLEAST(2,0,18) // If this fails to compile on Emscripten: update to latest Emscripten!
+            float wheel_x = -event->wheel.preciseX;
+            float wheel_y = event->wheel.preciseY;
+#else
             float wheel_x = -(float)event->wheel.x;
             float wheel_y = (float)event->wheel.y;
+#endif
+#ifdef __EMSCRIPTEN__
+            wheel_x /= 100.0f;
+#endif
             io.AddMouseWheelEvent(wheel_x, wheel_y);
             return true;
         }

docs/CHANGELOG.txt

@@ -90,13 +90,16 @@ All changes:
 - Backends: OSX: Fixed scroll/wheel scaling for devices emitting events with
   hasPreciseScrollingDeltas==false (e.g. non-Apple mices).
 - Backends: SDL: Removed SDL_MOUSEWHEEL value clamping. (#4019, #6096, #6081)
-  Latest Emscripten seems to emit correct values.
+- Backends: SDL: Added support for SDL 2.0.18+ preciseX/preciseY mouse wheel data
+  for smooth scrolling as reported by SDL. (#4019, #6096)
 - Backend: WebGPU: Fix building for latest WebGPU specs (remove implicit layout generation).
   (#6117, #4116, #3632) [@tonygrue, @bfierz]
 - Examples: refactord all examples to use a "MainLoopStep()" function. This is in order
   to be able to trivially make some compile with Emscripten. (#2492, #3699)
   While not all examples are expected to compile on Emscripten, we try to keep all of them
   as close as possible to each others.
+- Examples: Emscripten: The main SDL+GL and GLFW+GL examples now supports Emscripten.
+  (the dedicated example_emscripten_opengl3/ has been removed) (#2492, #2494, #3699, #3705)
 - Examples: Win32: Fixed examples using RegisterClassW() since 1.89 to also call
   DefWindowProcW() instead of DefWindowProc() so that title text are correctly converted
   when application is compiled without /DUNICODE. (#5725, #5961, #5975) [@markreidvfx]