ColorEdit, ColorPicker: Fixed hue/saturation preservation logic from interfering with the displayed value (but not stored value) of others widgets instances. (#6155)

Amend 30546bc0, accb0261b, 38d22bc4

docs/CHANGELOG.txt

@@ -82,6 +82,8 @@ All changes:
   (Not adding Super+Delete to delete to up to end-of-line on OSX, as OSX doesn't have it)
 - InputText: On OSX, inhibit usage of Alt key to toggle menu when active (used for work skip).
 - Menus: Fixed layout of MenuItem()/BeginMenu() when label contains a '\n'. (#6116) [@imkcy9]
+- ColorEdit, ColorPicker: Fixed hue/saturation preservation logic from interfering with
+  the displayed value (but not stored value) of others widgets instances. (#6155)
 - PlotHistogram, PlotLines: Passing negative sizes honor alignment like other widgets.
 - Combo: Allow SetNextWindowSize() to alter combo popup size. (#6130)
 - Fonts: Assert that in each GlyphRanges[] pairs first is <= second.

imgui_internal.h

@@ -1945,9 +1945,11 @@ struct ImGuiContext
     ImFont                  InputTextPasswordFont;
     ImGuiID                 TempInputId;                        // 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, so we can restore Hue in lossy RGB<>HSV round trips
-    float                   ColorEditLastSat;                   // Backup of last Saturation associated to LastColor, so we can restore Saturation in lossy RGB<>HSV round trips
-    ImU32                   ColorEditLastColor;                 // RGB value with alpha set to 0.
+    ImGuiID                 ColorEditCurrentID;                 // Set temporarily while inside of the parent-most ColorEdit4/ColorPicker4 (because they call each others).
+    ImGuiID                 ColorEditSavedID;                   // ID we are saving/restoring HS for
+    float                   ColorEditSavedHue;                  // Backup of last Hue associated to LastColor, so we can restore Hue in lossy RGB<>HSV round trips
+    float                   ColorEditSavedSat;                  // Backup of last Saturation associated to LastColor, so we can restore Saturation in lossy RGB<>HSV round trips
+    ImU32                   ColorEditSavedColor;                // RGB value with alpha set to 0.
     ImVec4                  ColorPickerRef;                     // Initial/reference color at the time of opening the color picker.
     ImGuiComboPreviewData   ComboPreviewData;
     float                   SliderGrabClickOffset;
@@ -2133,8 +2135,9 @@ struct ImGuiContext
 
         TempInputId = 0;
         ColorEditOptions = ImGuiColorEditFlags_DefaultOptions_;
-        ColorEditLastHue = ColorEditLastSat = 0.0f;
-        ColorEditLastColor = 0;
+        ColorEditCurrentID = ColorEditSavedID = 0;
+        ColorEditSavedHue = ColorEditSavedSat = 0.0f;
+        ColorEditSavedColor = 0;
         SliderGrabClickOffset = 0.0f;
         SliderCurrentAccum = 0.0f;
         SliderCurrentAccumDirty = false;

imgui_widgets.cpp

@@ -4978,28 +4978,32 @@ bool ImGui::ColorEdit3(const char* label, float col[3], ImGuiColorEditFlags flag
     return ColorEdit4(label, col, flags | ImGuiColorEditFlags_NoAlpha);
 }
 
+static void ColorEditRestoreH(const float* col, float* H)
+{
+    ImGuiContext& g = *GImGui;
+    IM_ASSERT(g.ColorEditCurrentID != 0);
+    if (g.ColorEditSavedID != g.ColorEditCurrentID || g.ColorEditSavedColor != ImGui::ColorConvertFloat4ToU32(ImVec4(col[0], col[1], col[2], 0)))
+        return;
+    *H = g.ColorEditSavedHue;
+}
+
 // ColorEdit supports RGB and HSV inputs. In case of RGB input resulting color may have undefined hue and/or saturation.
 // Since widget displays both RGB and HSV values we must preserve hue and saturation to prevent these values resetting.
 static void ColorEditRestoreHS(const float* col, float* H, float* S, float* V)
 {
-    // This check is optional. Suppose we have two color widgets side by side, both widgets display different colors, but both colors have hue and/or saturation undefined.
-    // With color check: hue/saturation is preserved in one widget. Editing color in one widget would reset hue/saturation in another one.
-    // Without color check: common hue/saturation would be displayed in all widgets that have hue/saturation undefined.
-    // g.ColorEditLastColor is stored as ImU32 RGB value: this essentially gives us color equality check with reduced precision.
-    // Tiny external color changes would not be detected and this check would still pass. This is OK, since we only restore hue/saturation _only_ if they are undefined,
-    // therefore this change flipping hue/saturation from undefined to a very tiny value would still be represented in color picker.
     ImGuiContext& g = *GImGui;
-    if (g.ColorEditLastColor != ImGui::ColorConvertFloat4ToU32(ImVec4(col[0], col[1], col[2], 0)))
+    IM_ASSERT(g.ColorEditCurrentID != 0);
+    if (g.ColorEditSavedID != g.ColorEditCurrentID || g.ColorEditSavedColor != ImGui::ColorConvertFloat4ToU32(ImVec4(col[0], col[1], col[2], 0)))
         return;
 
     // When S == 0, H is undefined.
     // When H == 1 it wraps around to 0.
-    if (*S == 0.0f || (*H == 0.0f && g.ColorEditLastHue == 1))
-        *H = g.ColorEditLastHue;
+    if (*S == 0.0f || (*H == 0.0f && g.ColorEditSavedHue == 1))
+        *H = g.ColorEditSavedHue;
 
     // When V == 0, S is undefined.
     if (*V == 0.0f)
-        *S = g.ColorEditLastSat;
+        *S = g.ColorEditSavedSat;
 }
 
 // Edit colors components (each component in 0.0f..1.0f range).
@@ -5022,6 +5026,9 @@ bool ImGui::ColorEdit4(const char* label, float col[4], ImGuiColorEditFlags flag
 
     BeginGroup();
     PushID(label);
+    const bool set_current_color_edit_id = (g.ColorEditCurrentID == 0);
+    if (set_current_color_edit_id)
+        g.ColorEditCurrentID = window->IDStack.back();
 
     // If we're not showing any slider there's no point in doing any HSV conversions
     const ImGuiColorEditFlags flags_untouched = flags;
@@ -5055,7 +5062,7 @@ bool ImGui::ColorEdit4(const char* label, float col[4], ImGuiColorEditFlags flag
         ColorConvertHSVtoRGB(f[0], f[1], f[2], f[0], f[1], f[2]);
     else if ((flags & ImGuiColorEditFlags_InputRGB) && (flags & ImGuiColorEditFlags_DisplayHSV))
     {
-        // Hue is lost when converting from greyscale rgb (saturation=0). Restore it.
+        // Hue is lost when converting from grayscale rgb (saturation=0). Restore it.
         ColorConvertRGBtoHSV(f[0], f[1], f[2], f[0], f[1], f[2]);
         ColorEditRestoreHS(col, &f[0], &f[1], &f[2]);
     }
@@ -5194,10 +5201,11 @@ bool ImGui::ColorEdit4(const char* label, float col[4], ImGuiColorEditFlags flag
                 f[n] = i[n] / 255.0f;
         if ((flags & ImGuiColorEditFlags_DisplayHSV) && (flags & ImGuiColorEditFlags_InputRGB))
         {
-            g.ColorEditLastHue = f[0];
-            g.ColorEditLastSat = f[1];
+            g.ColorEditSavedHue = f[0];
+            g.ColorEditSavedSat = f[1];
             ColorConvertHSVtoRGB(f[0], f[1], f[2], f[0], f[1], f[2]);
-            g.ColorEditLastColor = ColorConvertFloat4ToU32(ImVec4(f[0], f[1], f[2], 0));
+            g.ColorEditSavedID = g.ColorEditCurrentID;
+            g.ColorEditSavedColor = ColorConvertFloat4ToU32(ImVec4(f[0], f[1], f[2], 0));
         }
         if ((flags & ImGuiColorEditFlags_DisplayRGB) && (flags & ImGuiColorEditFlags_InputHSV))
             ColorConvertRGBtoHSV(f[0], f[1], f[2], f[0], f[1], f[2]);
@@ -5209,6 +5217,8 @@ bool ImGui::ColorEdit4(const char* label, float col[4], ImGuiColorEditFlags flag
             col[3] = f[3];
     }
 
+    if (set_current_color_edit_id)
+        g.ColorEditCurrentID = 0;
     PopID();
     EndGroup();
 
@@ -5282,6 +5292,9 @@ bool ImGui::ColorPicker4(const char* label, float col[4], ImGuiColorEditFlags fl
     g.NextItemData.ClearFlags();
 
     PushID(label);
+    const bool set_current_color_edit_id = (g.ColorEditCurrentID == 0);
+    if (set_current_color_edit_id)
+        g.ColorEditCurrentID = window->IDStack.back();
     BeginGroup();
 
     if (!(flags & ImGuiColorEditFlags_NoSidePreview))
@@ -5330,7 +5343,7 @@ bool ImGui::ColorPicker4(const char* label, float col[4], ImGuiColorEditFlags fl
     float R = col[0], G = col[1], B = col[2];
     if (flags & ImGuiColorEditFlags_InputRGB)
     {
-        // Hue is lost when converting from greyscale rgb (saturation=0). Restore it.
+        // Hue is lost when converting from grayscale rgb (saturation=0). Restore it.
         ColorConvertRGBtoHSV(R, G, B, H, S, V);
         ColorEditRestoreHS(col, &H, &S, &V);
     }
@@ -5385,10 +5398,7 @@ bool ImGui::ColorPicker4(const char* label, float col[4], ImGuiColorEditFlags fl
         {
             S = ImSaturate((io.MousePos.x - picker_pos.x) / (sv_picker_size - 1));
             V = 1.0f - ImSaturate((io.MousePos.y - picker_pos.y) / (sv_picker_size - 1));
-
-            // Greatly reduces hue jitter and reset to 0 when hue == 255 and color is rapidly modified using SV square.
-            if (g.ColorEditLastColor == ColorConvertFloat4ToU32(ImVec4(col[0], col[1], col[2], 0)))
-                H = g.ColorEditLastHue;
+            ColorEditRestoreH(col, &H); // Greatly reduces hue jitter and reset to 0 when hue == 255 and color is rapidly modified using SV square.
             value_changed = value_changed_sv = true;
         }
         if (!(flags & ImGuiColorEditFlags_NoOptions))
@@ -5463,9 +5473,10 @@ bool ImGui::ColorPicker4(const char* label, float col[4], ImGuiColorEditFlags fl
         if (flags & ImGuiColorEditFlags_InputRGB)
         {
             ColorConvertHSVtoRGB(H, S, V, col[0], col[1], col[2]);
-            g.ColorEditLastHue = H;
-            g.ColorEditLastSat = S;
-            g.ColorEditLastColor = ColorConvertFloat4ToU32(ImVec4(col[0], col[1], col[2], 0));
+            g.ColorEditSavedHue = H;
+            g.ColorEditSavedSat = S;
+            g.ColorEditSavedID = g.ColorEditCurrentID;
+            g.ColorEditSavedColor = ColorConvertFloat4ToU32(ImVec4(col[0], col[1], col[2], 0));
         }
         else if (flags & ImGuiColorEditFlags_InputHSV)
         {
@@ -5629,6 +5640,8 @@ bool ImGui::ColorPicker4(const char* label, float col[4], ImGuiColorEditFlags fl
     if (value_changed && g.LastItemData.ID != 0) // In case of ID collision, the second EndGroup() won't catch g.ActiveId
         MarkItemEdited(g.LastItemData.ID);
 
+    if (set_current_color_edit_id)
+        g.ColorEditCurrentID = 0;
     PopID();
 
     return value_changed;