Demo: add a small easter egg when the 4x4 board of Selectable is filled + tweaked the demo.

imgui_demo.cpp

@@ -1088,27 +1088,34 @@ static void ShowDemoWindowWidgets()
         }
         if (ImGui::TreeNode("Grid"))
         {
-            static int selected[4 * 4] = { 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1 };
-            for (int i = 0; i < 4 * 4; i++)
-            {
-                ImGui::PushID(i);
-                if (ImGui::Selectable("Sailor", selected[i] != 0, 0, ImVec2(50, 50)))
+            static char selected[4][4] = { { 1, 0, 0, 0 }, { 0, 1, 0, 0 }, { 0, 0, 1, 0 }, { 0, 0, 0, 1 } };
+
+            // Add in a bit of silly fun...
+            const float time = (float)ImGui::GetTime();
+            const bool winning_state = memchr(selected, 0, sizeof(selected)) == NULL; // If all cells are selected...
+            if (winning_state)
+                ImGui::PushStyleVar(ImGuiStyleVar_SelectableTextAlign, ImVec2(0.5f + 0.5f * cosf(time * 2.0f), 0.5f + 0.5f * sinf(time * 3.0f)));
+
+            for (int y = 0; y < 4; y++)
+                for (int x = 0; x < 4; x++)
                 {
-                    // Toggle
-                    selected[i] = !selected[i];
-
-                    // Note: We _unnecessarily_ test for both x/y and i here only to silence some static analyzer.
-                    // The second part of each test is unnecessary.
-                    int x = i % 4;
-                    int y = i / 4;
-                    if (x > 0)           { selected[i - 1] ^= 1; }
-                    if (x < 3 && i < 15) { selected[i + 1] ^= 1; }
-                    if (y > 0 && i > 3)  { selected[i - 4] ^= 1; }
-                    if (y < 3 && i < 12) { selected[i + 4] ^= 1; }
+                    if (x > 0)
+                        ImGui::SameLine();
+                    ImGui::PushID(y * 4 + x);
+                    if (ImGui::Selectable("Sailor", selected[y][x] != 0, 0, ImVec2(50, 50)))
+                    {
+                        // Toggle clicked cell + toggle neighbors
+                        selected[y][x] ^= 1;
+                        if (x > 0) { selected[y][x - 1] ^= 1; }
+                        if (x < 3) { selected[y][x + 1] ^= 1; }
+                        if (y > 0) { selected[y - 1][x] ^= 1; }
+                        if (y < 3) { selected[y + 1][x] ^= 1; }
+                    }
+                    ImGui::PopID();
                 }
-                if ((i % 4) < 3) ImGui::SameLine();
-                ImGui::PopID();
-            }
+
+            if (winning_state)
+                ImGui::PopStyleVar();
             ImGui::TreePop();
         }
         if (ImGui::TreeNode("Alignment"))