add null gpu notice (#3768)

src/core/devtools/layer.cpp

@@ -1,4 +1,4 @@
-// SPDX-FileCopyrightText: Copyright 2024 shadPS4 Emulator Project
+// SPDX-FileCopyrightText: Copyright 2025 shadPS4 Emulator Project
 // SPDX-License-Identifier: GPL-2.0-or-later
 
 #include "layer.h"
@@ -460,12 +460,12 @@ void L::Draw() {
 }
 
 void L::TextCentered(const std::string& text) {
-    float window_width = ImGui::GetWindowSize().x;
-    float text_width = ImGui::CalcTextSize(text.c_str()).x;
+    float window_width = GetWindowSize().x;
+    float text_width = CalcTextSize(text.c_str()).x;
     float text_indentation = (window_width - text_width) * 0.5f;
 
-    ImGui::SameLine(text_indentation);
-    ImGui::Text("%s", text.c_str());
+    SameLine(text_indentation);
+    Text("%s", text.c_str());
 }
 
 namespace Overlay {

src/core/devtools/layer.h

@@ -1,4 +1,4 @@
-// SPDX-FileCopyrightText: Copyright 2024 shadPS4 Emulator Project
+// SPDX-FileCopyrightText: Copyright 2025 shadPS4 Emulator Project
 // SPDX-License-Identifier: GPL-2.0-or-later
 
 #pragma once
@@ -9,18 +9,20 @@
 namespace Core::Devtools {
 
 class Layer final : public ImGui::Layer {
-
-    static void DrawMenuBar();
-
-    static void DrawAdvanced();
-
-    static void DrawSimple();
-
 public:
     static void SetupSettings();
 
     void Draw() override;
-    void TextCentered(const std::string& text);
+
+    // Must be inside a window
+    static void DrawNullGpuNotice();
+
+private:
+    static void DrawMenuBar();
+    static void DrawAdvanced();
+    static void DrawSimple();
+
+    static void TextCentered(const std::string& text);
 };
 
 } // namespace Core::Devtools

src/core/devtools/layer_extra.cpp

@@ -0,0 +1,95 @@
+//  SPDX-FileCopyrightText: Copyright 2025 shadPS4 Emulator Project
+//  SPDX-License-Identifier: GPL-2.0-or-later
+
+#include "layer.h"
+
+#include "imgui/imgui_std.h"
+
+#include <imgui.h>
+#include <imgui_internal.h>
+
+#include <cmath>
+#include <numbers>
+
+namespace Core::Devtools {
+
+void Layer::DrawNullGpuNotice() {
+
+    auto* window = ImGui::GetCurrentWindow();
+    if (window->SkipItems) {
+        return;
+    }
+
+    constexpr std::string_view mainNotice = "Null GPU is enabled";
+    constexpr std::string_view detailsNotice =
+        "Disable the nullGpu config to show the game display";
+
+    auto displaySize = window->Size;
+
+    ImVec2 targetSize = displaySize * 0.7f;
+
+    float minFontSize = 1.0f;
+    float maxFontSize = 200.0f;
+    float optimalFontSize = minFontSize;
+
+    static auto lastSize = ImVec2(-1, -1);
+    static float lastFontSize = -1.0f;
+
+    auto* font = ImGui::GetIO().Fonts->Fonts[IMGUI_FONT_TEXT_BIG];
+
+    if (lastSize != targetSize) {
+        while (maxFontSize - minFontSize > 0.1f) {
+            float testFontSize = (minFontSize + maxFontSize) / 2.0f;
+
+            ImVec2 textSize = font->CalcTextSizeA(testFontSize, FLT_MAX, 0.0f, &mainNotice.front(),
+                                                  &mainNotice.back() + 1);
+
+            if (textSize.x <= targetSize.x && textSize.y <= targetSize.y) {
+                optimalFontSize = testFontSize;
+                minFontSize = testFontSize;
+            } else {
+                maxFontSize = testFontSize;
+            }
+        }
+        lastSize = targetSize;
+        lastFontSize = optimalFontSize;
+    } else {
+        optimalFontSize = lastFontSize;
+    }
+    ImVec2 textSize = font->CalcTextSizeA(optimalFontSize, FLT_MAX, 0.0f, &mainNotice.front(),
+                                          &mainNotice.back() + 1);
+
+    ImVec2 textPos = (displaySize - textSize) * 0.5f + window->Pos;
+
+    const float scale = optimalFontSize / font->FontSize;
+    double timeAnim = -std::numbers::pi * ImGui::GetTime();
+    int i = 0;
+    for (auto ch : mainNotice) {
+        double colorTime = sin(timeAnim + i * std::numbers::pi / 6.0) / 2.0 + 0.5;
+        int color = (int)(200 * colorTime) + 55;
+
+        double posTime = sin(timeAnim + i * std::numbers::pi / 15.0) / 2.0 + 0.5;
+
+        auto pos = textPos;
+        pos.y += 10.0 * (posTime < 0.5 ? std::pow(2.0, 20.0 * posTime - 10.0) / 2.0
+                                       : (2.0 - std::pow(2.0, -20.0 * posTime + 10.0)) / 2.0);
+
+        window->DrawList->AddText(font, optimalFontSize, pos, IM_COL32(color, color, color, 255),
+                                  &ch, &ch + 1);
+        textPos.x += font->FindGlyph(ch)->AdvanceX * scale;
+        i++;
+    }
+
+    font = ImGui::GetIO().Fonts->Fonts[IMGUI_FONT_TEXT];
+
+    textPos.y += textSize.y + 1.0;
+
+    optimalFontSize *= 0.2;
+    textSize = font->CalcTextSizeA(optimalFontSize, FLT_MAX, 0.0f, &detailsNotice.front(),
+                                   &detailsNotice.back() + 1);
+    textPos.x = window->Pos.x + (window->Size.x - textSize.x) * 0.5f;
+    window->DrawList->AddText(font, optimalFontSize, textPos, IM_COL32(200, 200, 200, 255),
+                              &detailsNotice.front(), &detailsNotice.back() + 1);
+}
+
+} // namespace Core::Devtools