ColorEdit4: improve components width computation to better distribute the error (#7120) (#7123)

imgui_widgets.cpp

@@ -5189,10 +5189,9 @@ bool ImGui::ColorEdit4(const char* label, float col[4], ImGuiColorEditFlags flag
     if ((flags & (ImGuiColorEditFlags_DisplayRGB | ImGuiColorEditFlags_DisplayHSV)) != 0 && (flags & ImGuiColorEditFlags_NoInputs) == 0)
     {
         // RGB/HSV 0..255 Sliders
-        const float w_item_one  = ImMax(1.0f, IM_TRUNC((w_inputs - (style.ItemInnerSpacing.x) * (components - 1)) / (float)components));
-        const float w_item_last = ImMax(1.0f, IM_TRUNC(w_inputs - (w_item_one + style.ItemInnerSpacing.x) * (components - 1)));
+        const float w_items = w_inputs - style.ItemInnerSpacing.x * (components - 1);
 
-        const bool hide_prefix = (w_item_one <= CalcTextSize((flags & ImGuiColorEditFlags_Float) ? "M:0.000" : "M:000").x);
+        const bool hide_prefix = (IM_TRUNC(w_items / components) <= CalcTextSize((flags & ImGuiColorEditFlags_Float) ? "M:0.000" : "M:000").x);
         static const char* ids[4] = { "##X", "##Y", "##Z", "##W" };
         static const char* fmt_table_int[3][4] =
         {
@@ -5208,11 +5207,14 @@ bool ImGui::ColorEdit4(const char* label, float col[4], ImGuiColorEditFlags flag
         };
         const int fmt_idx = hide_prefix ? 0 : (flags & ImGuiColorEditFlags_DisplayHSV) ? 2 : 1;
 
+        float prev_split = 0.0f;
         for (int n = 0; n < components; n++)
         {
             if (n > 0)
                 SameLine(0, style.ItemInnerSpacing.x);
-            SetNextItemWidth((n + 1 < components) ? w_item_one : w_item_last);
+            float next_split = IM_TRUNC(w_items * (n + 1) / components);
+            SetNextItemWidth(next_split - prev_split);
+            prev_split = next_split;
 
             // FIXME: When ImGuiColorEditFlags_HDR flag is passed HS values snap in weird ways when SV values go below 0.
             if (flags & ImGuiColorEditFlags_Float)