Demo: Combos: demonstrate a very simple way to add a filter to a combo. (ocornut#718)

Author: ocornut

docs/CHANGELOG.txt

@@ -57,6 +57,8 @@ Other changes:
   which amusingly made it disappear when using very big font/frame size.
 - Tables: fixed calling SetNextWindowScroll() on clipped scrolling table
   to not leak the value into a subsequent window. (#8196)
+- Demo: Combos: demonstrate a very simple way to add a filter to a combo,
+  by showing the filter inside the combo contents. (#718)
 - Backends: Metal: Fixed a crash on application resources. (#8367, #7419) [@anszom]
 - Backends: WebGPU: Fix for DAWN API rename WGPUProgrammableStageDescriptor -> WGPUComputeState.
   [@PhantomCloak] (#8369)

imgui_demo.cpp

@@ -1435,7 +1435,6 @@ static void ShowDemoWindowWidgets(ImGuiDemoWindowData* demo_data)
 
         // Pass in the preview value visible before opening the combo (it could technically be different contents or not pulled from items[])
         const char* combo_preview_value = items[item_selected_idx];
-
         if (ImGui::BeginCombo("combo 1", combo_preview_value, flags))
         {
             for (int n = 0; n < IM_ARRAYSIZE(items); n++)
@@ -1451,23 +1450,46 @@ static void ShowDemoWindowWidgets(ImGuiDemoWindowData* demo_data)
             ImGui::EndCombo();
         }
 
+        // Show case embedding a filter using a simple trick: displaying the filter inside combo contents.
+        // See https://github.com/ocornut/imgui/issues/718 for advanced/esoteric alternatives.
+        if (ImGui::BeginCombo("combo 2 (w/ filter)", combo_preview_value, flags))
+        {
+            static ImGuiTextFilter filter;
+            if (ImGui::IsWindowAppearing())
+            {
+                ImGui::SetKeyboardFocusHere();
+                filter.Clear();
+            }
+            ImGui::SetNextItemShortcut(ImGuiMod_Ctrl | ImGuiKey_F);
+            filter.Draw("##Filter", -FLT_MIN);
+
+            for (int n = 0; n < IM_ARRAYSIZE(items); n++)
+            {
+                const bool is_selected = (item_selected_idx == n);
+                if (filter.PassFilter(items[n]))
+                    if (ImGui::Selectable(items[n], is_selected))
+                        item_selected_idx = n;
+            }
+            ImGui::EndCombo();
+        }
+
         ImGui::Spacing();
         ImGui::SeparatorText("One-liner variants");
-        HelpMarker("Flags above don't apply to this section.");
+        HelpMarker("The Combo() function is not greatly useful apart from cases were you want to embed all options in a single strings.\nFlags above don't apply to this section.");
 
         // Simplified one-liner Combo() API, using values packed in a single constant string
         // This is a convenience for when the selection set is small and known at compile-time.
         static int item_current_2 = 0;
-        ImGui::Combo("combo 2 (one-liner)", &item_current_2, "aaaa\0bbbb\0cccc\0dddd\0eeee\0\0");
+        ImGui::Combo("combo 3 (one-liner)", &item_current_2, "aaaa\0bbbb\0cccc\0dddd\0eeee\0\0");
 
         // Simplified one-liner Combo() using an array of const char*
         // This is not very useful (may obsolete): prefer using BeginCombo()/EndCombo() for full control.
         static int item_current_3 = -1; // If the selection isn't within 0..count, Combo won't display a preview
-        ImGui::Combo("combo 3 (array)", &item_current_3, items, IM_ARRAYSIZE(items));
+        ImGui::Combo("combo 4 (array)", &item_current_3, items, IM_ARRAYSIZE(items));
 
         // Simplified one-liner Combo() using an accessor function
         static int item_current_4 = 0;
-        ImGui::Combo("combo 4 (function)", &item_current_4, [](void* data, int n) { return ((const char**)data)[n]; }, items, IM_ARRAYSIZE(items));
+        ImGui::Combo("combo 5 (function)", &item_current_4, [](void* data, int n) { return ((const char**)data)[n]; }, items, IM_ARRAYSIZE(items));
 
         ImGui::TreePop();
     }