ColorEdit: Preserve last saturation value when V=0. Disable Hue editing lock.

This workaround is no longer necessary because preserving hue value prevents it from resetting when it is edited in said condition.

imgui_internal.h

@@ -1121,6 +1121,7 @@ struct ImGuiContext
     ImGuiID                 TempInputTextId;                    // Temporary text input when CTRL+clicking on a slider, etc.
     ImGuiColorEditFlags     ColorEditOptions;                   // Store user options for color edit widgets
     float                   ColorEditLastHue;                   // Backup of last Hue associated to LastColor[3], so we can restore Hue in lossy RGB<>HSV round trips
+    float                   ColorEditLastSaturation;            // Backup of last Saturation associated to LastColor[3], so we can restore Saturation in lossy RGB<>HSV round trips
     float                   ColorEditLastColor[3];
     ImVec4                  ColorPickerRef;                     // Initial/reference color at the time of opening the color picker.
     bool                    DragCurrentAccumDirty;

imgui_widgets.cpp

@@ -4222,8 +4222,13 @@ bool ImGui::ColorEdit4(const char* label, float col[4], ImGuiColorEditFlags flag
     {
         // Hue is lost when converting from greyscale rgb (saturation=0). Restore it.
         ColorConvertRGBtoHSV(f[0], f[1], f[2], f[0], f[1], f[2]);
-        if (f[1] == 0 && memcmp(g.ColorEditLastColor, col, sizeof(float) * 3) == 0)
+        if (memcmp(g.ColorEditLastColor, col, sizeof(float) * 3) == 0)
+        {
+            if (f[1] == 0)
                 f[0] = g.ColorEditLastHue;
+            if (f[2] == 0)
+                f[1] = g.ColorEditLastSaturation;
+        }
     }
     int i[4] = { IM_F32_TO_INT8_UNBOUND(f[0]), IM_F32_TO_INT8_UNBOUND(f[1]), IM_F32_TO_INT8_UNBOUND(f[2]), IM_F32_TO_INT8_UNBOUND(f[3]) };
 
@@ -4262,16 +4267,15 @@ bool ImGui::ColorEdit4(const char* label, float col[4], ImGuiColorEditFlags flag
                 SameLine(0, style.ItemInnerSpacing.x);
             SetNextItemWidth((n + 1 < components) ? w_item_one : w_item_last);
 
-            // Disable Hue edit when Saturation is zero
+            // FIXME: When ImGuiColorEditFlags_HDR flag is passed HS values snap in weird ways when SV values go below 0.
-            const bool disable_hue_edit = (n == 0 && (flags & ImGuiColorEditFlags_DisplayHSV) && i[1] == 0);
             if (flags & ImGuiColorEditFlags_Float)
             {
-                value_changed |= DragFloat(ids[n], &f[n], 1.0f/255.0f, disable_hue_edit ? +FLT_MAX : 0.0f, disable_hue_edit ? -FLT_MAX : hdr ? 0.0f : 1.0f, fmt_table_float[fmt_idx][n]);
+                value_changed |= DragFloat(ids[n], &f[n], 1.0f/255.0f, 0.0f, hdr ? 0.0f : 1.0f, fmt_table_float[fmt_idx][n]);
                 value_changed_as_float |= value_changed;
             }
             else
             {
-                value_changed |= DragInt(ids[n], &i[n], 1.0f, disable_hue_edit ? INT_MAX : 0, disable_hue_edit ? INT_MIN : hdr ? 0 : 255, fmt_table_int[fmt_idx][n]);
+                value_changed |= DragInt(ids[n], &i[n], 1.0f, 0, hdr ? 0 : 255, fmt_table_int[fmt_idx][n]);
             }
             if (!(flags & ImGuiColorEditFlags_NoOptions))
                 OpenPopupOnItemClick("context");
@@ -4354,6 +4358,7 @@ bool ImGui::ColorEdit4(const char* label, float col[4], ImGuiColorEditFlags flag
         if ((flags & ImGuiColorEditFlags_DisplayHSV) && (flags & ImGuiColorEditFlags_InputRGB))
         {
             g.ColorEditLastHue = f[0];
+            g.ColorEditLastSaturation = f[1];
             ColorConvertHSVtoRGB(f[0], f[1], f[2], f[0], f[1], f[2]);
             memcpy(g.ColorEditLastColor, f, sizeof(float) * 3);
         }
@@ -4536,8 +4541,13 @@ bool ImGui::ColorPicker4(const char* label, float col[4], ImGuiColorEditFlags fl
     {
         // Hue is lost when converting from greyscale rgb (saturation=0). Restore it.
         ColorConvertRGBtoHSV(R, G, B, H, S, V);
-        if (S == 0 && memcmp(g.ColorEditLastColor, col, sizeof(float) * 3) == 0)
+        if (memcmp(g.ColorEditLastColor, col, sizeof(float) * 3) == 0)
+        {
+            if (S == 0)
                 H = g.ColorEditLastHue;
+            if (V == 0)
+                S = g.ColorEditLastSaturation;
+        }
     }
     else if (flags & ImGuiColorEditFlags_InputHSV)
     {
@@ -4665,6 +4675,7 @@ bool ImGui::ColorPicker4(const char* label, float col[4], ImGuiColorEditFlags fl
         {
             ColorConvertHSVtoRGB(H >= 1.0f ? H - 10 * 1e-6f : H, S > 0.0f ? S : 10*1e-6f, V > 0.0f ? V : 1e-6f, col[0], col[1], col[2]);
             g.ColorEditLastHue = H;
+            g.ColorEditLastSaturation = S;
             memcpy(g.ColorEditLastColor, col, sizeof(float) * 3);
         }
         else if (flags & ImGuiColorEditFlags_InputHSV)
@@ -4719,8 +4730,13 @@ bool ImGui::ColorPicker4(const char* label, float col[4], ImGuiColorEditFlags fl
             G = col[1];
             B = col[2];
             ColorConvertRGBtoHSV(R, G, B, H, S, V);
-            if (S == 0 && memcmp(g.ColorEditLastColor, col, sizeof(float) * 3) == 0) // Fix local Hue as display below will use it immediately.
+            if (memcmp(g.ColorEditLastColor, col, sizeof(float) * 3) == 0) // Fix local Hue as display below will use it immediately.
+            {
+                if (S == 0)
                     H = g.ColorEditLastHue;
+                if (V == 0)
+                    S = g.ColorEditLastSaturation;
+            }
         }
         else if (flags & ImGuiColorEditFlags_InputHSV)
         {