Slider: fixed support for ImGuiItemFlags_ReadOnly/ImGuiSliderFlags_ReadOnly although it is technically unused/undocumented. (#6758)

Amend fdc526e8f

imgui_internal.h

@@ -885,7 +885,7 @@ enum ImGuiComboFlagsPrivate_
 enum ImGuiSliderFlagsPrivate_
 {
     ImGuiSliderFlags_Vertical               = 1 << 20,  // Should this slider be orientated vertically?
-    ImGuiSliderFlags_ReadOnly               = 1 << 21,
+    ImGuiSliderFlags_ReadOnly               = 1 << 21,  // Consider using g.NextItemData.ItemFlags |= ImGuiItemFlags_ReadOnly instead.
 };
 
 // Extend ImGuiSelectableFlags_

imgui_widgets.cpp

@@ -2898,6 +2898,10 @@ bool ImGui::SliderBehaviorT(const ImRect& bb, ImGuiID id, ImGuiDataType data_typ
             }
         }
 
+        if (set_new_value)
+            if ((g.LastItemData.InFlags & ImGuiItemFlags_ReadOnly) || (flags & ImGuiSliderFlags_ReadOnly))
+                set_new_value = false;
+
         if (set_new_value)
         {
             TYPE v_new = ScaleValueFromRatioT<TYPE, SIGNEDTYPE, FLOATTYPE>(data_type, clicked_t, v_min, v_max, is_logarithmic, logarithmic_zero_epsilon, zero_deadzone_halfsize);
@@ -2943,11 +2947,6 @@ bool ImGui::SliderBehavior(const ImRect& bb, ImGuiID id, ImGuiDataType data_type
     // Read imgui.cpp "API BREAKING CHANGES" section for 1.78 if you hit this assert.
     IM_ASSERT((flags == 1 || (flags & ImGuiSliderFlags_InvalidMask_) == 0) && "Invalid ImGuiSliderFlags flag!  Has the 'float power' argument been mistakenly cast to flags? Call function with ImGuiSliderFlags_Logarithmic flags instead.");
 
-    // Those are the things we can do easily outside the SliderBehaviorT<> template, saves code generation.
-    ImGuiContext& g = *GImGui;
-    if ((g.LastItemData.InFlags & ImGuiItemFlags_ReadOnly) || (flags & ImGuiSliderFlags_ReadOnly))
-        return false;
-
     switch (data_type)
     {
     case ImGuiDataType_S8:  { ImS32 v32 = (ImS32)*(ImS8*)p_v;  bool r = SliderBehaviorT<ImS32, ImS32, float>(bb, id, ImGuiDataType_S32, &v32, *(const ImS8*)p_min,  *(const ImS8*)p_max,  format, flags, out_grab_bb); if (r) *(ImS8*)p_v  = (ImS8)v32;  return r; }