Contain XCUI ImGui adapters behind explicit host seams

tests/NewEditor/test_xcui_demo_panel.cpp

@@ -0,0 +1,213 @@
+#include <gtest/gtest.h>
+
+#include "panels/XCUIDemoPanel.h"
+
+#include "XCUIBackend/XCUIHostedPreviewPresenter.h"
+#include "XCUIBackend/XCUIPanelCanvasHost.h"
+
+#include <imgui.h>
+
+#include <memory>
+#include <string>
+#include <string_view>
+
+namespace {
+
+using XCEngine::Editor::XCUIBackend::IXCUIHostedPreviewPresenter;
+using XCEngine::Editor::XCUIBackend::IXCUIPanelCanvasHost;
+using XCEngine::Editor::XCUIBackend::XCUIHostedPreviewFrame;
+using XCEngine::Editor::XCUIBackend::XCUIHostedPreviewStats;
+using XCEngine::Editor::XCUIBackend::XCUIPanelCanvasRequest;
+using XCEngine::Editor::XCUIBackend::XCUIPanelCanvasSession;
+using XCEngine::NewEditor::XCUIDemoPanel;
+
+class ImGuiContextScope {
+public:
+    ImGuiContextScope() {
+        IMGUI_CHECKVERSION();
+        ImGui::CreateContext();
+        ImGui::StyleColorsDark();
+    }
+
+    ~ImGuiContextScope() {
+        ImGui::DestroyContext();
+    }
+};
+
+void PrepareImGui(float width = 1280.0f, float height = 900.0f) {
+    ImGuiIO& io = ImGui::GetIO();
+    io.DisplaySize = ImVec2(width, height);
+    io.DeltaTime = 1.0f / 60.0f;
+    unsigned char* fontPixels = nullptr;
+    int fontWidth = 0;
+    int fontHeight = 0;
+    io.Fonts->GetTexDataAsRGBA32(&fontPixels, &fontWidth, &fontHeight);
+    io.Fonts->SetTexID(static_cast<ImTextureID>(1));
+}
+
+class RecordingHostedPreviewPresenter final : public IXCUIHostedPreviewPresenter {
+public:
+    bool Present(const XCUIHostedPreviewFrame& frame) override {
+        ++presentCallCount;
+        lastCanvasRect = frame.canvasRect;
+        lastLogicalSize = frame.logicalSize;
+        lastDebugName = frame.debugName != nullptr ? frame.debugName : "";
+
+        m_lastStats = {};
+        if (frame.drawData == nullptr) {
+            return false;
+        }
+
+        lastDrawListCount = frame.drawData->GetDrawListCount();
+        lastCommandCount = frame.drawData->GetTotalCommandCount();
+        m_lastStats.presented = true;
+        m_lastStats.submittedDrawListCount = lastDrawListCount;
+        m_lastStats.submittedCommandCount = lastCommandCount;
+        return true;
+    }
+
+    const XCUIHostedPreviewStats& GetLastStats() const override {
+        return m_lastStats;
+    }
+
+    std::size_t presentCallCount = 0u;
+    XCEngine::UI::UIRect lastCanvasRect = {};
+    XCEngine::UI::UISize lastLogicalSize = {};
+    std::size_t lastDrawListCount = 0u;
+    std::size_t lastCommandCount = 0u;
+    std::string lastDebugName = {};
+
+private:
+    XCUIHostedPreviewStats m_lastStats = {};
+};
+
+class StubCanvasHost final : public IXCUIPanelCanvasHost {
+public:
+    const char* GetDebugName() const override {
+        return "StubCanvasHost";
+    }
+
+    XCEngine::Editor::XCUIBackend::XCUIPanelCanvasHostBackend GetBackend() const override {
+        return XCEngine::Editor::XCUIBackend::XCUIPanelCanvasHostBackend::Null;
+    }
+
+    XCEngine::Editor::XCUIBackend::XCUIPanelCanvasHostCapabilities GetCapabilities() const override {
+        return {};
+    }
+
+    XCUIPanelCanvasSession BeginCanvas(const XCUIPanelCanvasRequest& request) override {
+        lastRequest = request;
+        ++beginCanvasCallCount;
+        return session;
+    }
+
+    void DrawFilledRect(
+        const XCEngine::UI::UIRect&,
+        const XCEngine::UI::UIColor&,
+        float) override {
+    }
+
+    void DrawOutlineRect(
+        const XCEngine::UI::UIRect&,
+        const XCEngine::UI::UIColor&,
+        float,
+        float) override {
+    }
+
+    void DrawText(
+        const XCEngine::UI::UIPoint&,
+        std::string_view,
+        const XCEngine::UI::UIColor&,
+        float) override {
+    }
+
+    void EndCanvas() override {
+        ++endCanvasCallCount;
+    }
+
+    std::size_t beginCanvasCallCount = 0u;
+    std::size_t endCanvasCallCount = 0u;
+    XCUIPanelCanvasRequest lastRequest = {};
+    XCUIPanelCanvasSession session = {
+        XCEngine::UI::UIRect(0.0f, 0.0f, 960.0f, 640.0f),
+        XCEngine::UI::UIRect(12.0f, 18.0f, 936.0f, 512.0f),
+        XCEngine::UI::UIPoint(120.0f, 140.0f),
+        true,
+        true,
+        true
+    };
+};
+
+void RenderPanelFrame(XCUIDemoPanel& panel, ImGuiContextScope&) {
+    PrepareImGui();
+    ImGui::NewFrame();
+    panel.Render();
+    ImGui::Render();
+}
+
+TEST(NewEditorXCUIDemoPanelTest, DefaultConstructionDoesNotAutoCreateHostedPreviewPresenter) {
+    ImGuiContextScope contextScope;
+
+    auto canvasHost = std::make_unique<StubCanvasHost>();
+    XCUIDemoPanel panel;
+    panel.SetCanvasHost(std::move(canvasHost));
+
+    RenderPanelFrame(panel, contextScope);
+
+    const XCUIHostedPreviewStats& stats = panel.GetLastPreviewStats();
+    EXPECT_FALSE(stats.presented);
+    EXPECT_FALSE(stats.queuedToNativePass);
+    EXPECT_EQ(stats.submittedDrawListCount, 0u);
+    EXPECT_EQ(stats.submittedCommandCount, 0u);
+    EXPECT_EQ(stats.flushedDrawListCount, 0u);
+    EXPECT_EQ(stats.flushedCommandCount, 0u);
+}
+
+TEST(NewEditorXCUIDemoPanelTest, ConstructorUsesGenericNullCanvasHostUntilOuterLayerInjectsOne) {
+    ImGuiContextScope contextScope;
+
+    auto previewPresenter = std::make_unique<RecordingHostedPreviewPresenter>();
+    RecordingHostedPreviewPresenter* previewPresenterPtr = previewPresenter.get();
+
+    XCUIDemoPanel panel(nullptr, std::move(previewPresenter));
+    RenderPanelFrame(panel, contextScope);
+
+    ASSERT_EQ(previewPresenterPtr->presentCallCount, 1u);
+    EXPECT_EQ(previewPresenterPtr->lastDebugName, "XCUI Demo");
+    EXPECT_FLOAT_EQ(previewPresenterPtr->lastCanvasRect.x, 0.0f);
+    EXPECT_GT(previewPresenterPtr->lastCanvasRect.y, 0.0f);
+    EXPECT_FLOAT_EQ(previewPresenterPtr->lastCanvasRect.width, 0.0f);
+    EXPECT_GT(previewPresenterPtr->lastCanvasRect.height, 0.0f);
+    EXPECT_FLOAT_EQ(previewPresenterPtr->lastLogicalSize.width, 0.0f);
+    EXPECT_FLOAT_EQ(
+        previewPresenterPtr->lastLogicalSize.height,
+        previewPresenterPtr->lastCanvasRect.height);
+}
+
+TEST(NewEditorXCUIDemoPanelTest, ClearingHostedPreviewPresenterDoesNotRestoreImGuiFallback) {
+    ImGuiContextScope contextScope;
+
+    auto previewPresenter = std::make_unique<RecordingHostedPreviewPresenter>();
+    RecordingHostedPreviewPresenter* previewPresenterPtr = previewPresenter.get();
+    auto canvasHost = std::make_unique<StubCanvasHost>();
+
+    XCUIDemoPanel panel(nullptr, std::move(previewPresenter));
+    panel.SetCanvasHost(std::move(canvasHost));
+
+    RenderPanelFrame(panel, contextScope);
+    ASSERT_EQ(previewPresenterPtr->presentCallCount, 1u);
+    EXPECT_TRUE(panel.GetLastPreviewStats().presented);
+
+    panel.SetHostedPreviewPresenter(nullptr);
+    RenderPanelFrame(panel, contextScope);
+
+    const XCUIHostedPreviewStats& stats = panel.GetLastPreviewStats();
+    EXPECT_FALSE(stats.presented);
+    EXPECT_FALSE(stats.queuedToNativePass);
+    EXPECT_EQ(stats.submittedDrawListCount, 0u);
+    EXPECT_EQ(stats.submittedCommandCount, 0u);
+    EXPECT_EQ(stats.flushedDrawListCount, 0u);
+    EXPECT_EQ(stats.flushedCommandCount, 0u);
+}
+
+} // namespace