How to prevent imgui ui update from freezing during window move, double click and resize events?

adityachd commented 2 months ago

Version/Branch of Dear ImGui:

Version 1.91, Branch: docking

Back-ends:

imgui_impl_win32.cpp + imgui_impl_dx12.cpp

Compiler, OS:

Windows 11 + MSVC

Full config/build information:

No response

Details:

My Issue/Question:

Hi ! I am making a simple serial terminal application using dear imgui and libserialport library in cpp. In my initial test (and also found by running demo/examples) , I found out that if the application window is dragged or resized, the UI is not resumed until the mouse click is released. As I also saw the demo code, the Hello World Window which shows frame rate, stops updating when title bar is double clicked and not released or the title bar is dragged or the window is resized. I hope there would be a way to prevent the ui from pausing during these events somehow, as the serial monitor needs to update data at all times. Please help.

Thanks and Regards Aditya

Screenshots/Video:

No response

Minimal, Complete and Verifiable Example code:

No response

adityachd commented 2 months ago

I believe the WndProc function is called automatically every time on such window events like dragging etc and wither the calls are multiple i.e until the mouse in released, calls are being made. These events are I think not letting the main loop code to get executed. Is there a way so that on such events, the WndProc function is not called, instead, we poll events in the main while loop and send events to Windows OS using DefWindowProcW once every loop iteration. Please help, my first day with Dear Imgui and I am loving it so far.

GamingMinds-DanielC commented 2 months ago

The problem stems from this basic loop:

while (!done)
{
    while (PeekMessage(...))
    {
        TranslateMessage(...);
        DispatchMessage(...);
    }

    // ImGui frame stuff
}

When a window is f.e. resized, Windows takes control and enters a modal message loop to enforce a few things. So while your window still receives messages through that other loop, your own loop is on hold and all of the ImGui frame stuff is not called.

The way my editor application handles it is basically this:

move ImGui frame stuff into the handler for the WM_PAINT message
secure the paint handler with a flag to make it not reentrant (hidden recursion could mess up your day otherwise)
within your paint handler, invalidate your window again to ensure a constant flow of frames
if your window is disabled, defer to DefWindowProc after handling the above (modal dialogs won't work correctly otherwise)

adityachd commented 2 months ago

Thanks @GamingMinds-DanielC a lot. I'll try this and come back with the result. Thanks again for such a prompt answer.

adityachd commented 2 months ago

Hi ! @GamingMinds-DanielC I tried following the instructions you gave. I am stuck at second step and could not understand the third one also. Please help

move ImGui frame stuff into the handler for the WM_PAINT message Moved the stuff into a separate function and made some stuff global like

WNDCLASSEXW wc;
HWND hwnd;
bool show_demo_window = true;
bool show_another_window = false;
ImVec4 clear_color = ImVec4(0.45f, 0.55f, 0.60f, 1.00f);
bool done = false;
bool wmPaintEnteredFlag = false;
void imGuiStuffFn() {
// Start the Dear ImGui frame
ImGui_ImplDX12_NewFrame();
ImGui_ImplWin32_NewFrame();
ImGui::NewFrame();
// 1. Show the big demo window (Most of the sample code is in ImGui::ShowDemoWindow()! You can browse its code to learn more about Dear ImGui!).
if (show_demo_window)
    ImGui::ShowDemoWindow(&show_demo_window);
// 2. Show a simple window that we create ourselves. We use a Begin/End pair to create a named window.
{
    static float f = 0.0f;
    static int counter = 0;
    ImGui::Begin("Hello, world!");                          // Create a window called "Hello, world!" and append into it.
    ImGui::Text("This is some useful text.");               // Display some text (you can use a format strings too)
    ImGui::Checkbox("Demo Window", &show_demo_window);      // Edit bools storing our window open/close state
    ImGui::Checkbox("Another Window", &show_another_window);
    ImGui::SliderFloat("float", &f, 0.0f, 1.0f);            // Edit 1 float using a slider from 0.0f to 1.0f
    ImGui::ColorEdit3("clear color", (float*)&clear_color); // Edit 3 floats representing a color
    if (ImGui::Button("Button"))                            // Buttons return true when clicked (most widgets return true when edited/activated)
        counter++;
    ImGui::SameLine();
    ImGui::Text("counter = %d", counter);
    ImGui::Text("Application average %.3f ms/frame (%.1f FPS)", 1000.0f / io.Framerate, io.Framerate);
    ImGui::End();
}
// 3. Show another simple window.
if (show_another_window)
{
    ImGui::Begin("Another Window", &show_another_window);   // Pass a pointer to our bool variable (the window will have a closing button that will clear the bool when clicked)
    ImGui::Text("Hello from another window!");
    if (ImGui::Button("Close Me"))
        show_another_window = false;
    ImGui::End();
}
// Rendering
ImGui::Render();
FrameContext* frameCtx = WaitForNextFrameResources();
UINT backBufferIdx = g_pSwapChain->GetCurrentBackBufferIndex();
frameCtx->CommandAllocator->Reset();
D3D12_RESOURCE_BARRIER barrier = {};
barrier.Type = D3D12_RESOURCE_BARRIER_TYPE_TRANSITION;
barrier.Flags = D3D12_RESOURCE_BARRIER_FLAG_NONE;
barrier.Transition.pResource = g_mainRenderTargetResource[backBufferIdx];
barrier.Transition.Subresource = D3D12_RESOURCE_BARRIER_ALL_SUBRESOURCES;
barrier.Transition.StateBefore = D3D12_RESOURCE_STATE_PRESENT;
barrier.Transition.StateAfter = D3D12_RESOURCE_STATE_RENDER_TARGET;
g_pd3dCommandList->Reset(frameCtx->CommandAllocator, nullptr);
g_pd3dCommandList->ResourceBarrier(1, &barrier);
// Render Dear ImGui graphics
const float clear_color_with_alpha[4] = { clear_color.x * clear_color.w, clear_color.y * clear_color.w, clear_color.z * clear_color.w, clear_color.w };
g_pd3dCommandList->ClearRenderTargetView(g_mainRenderTargetDescriptor[backBufferIdx], clear_color_with_alpha, 0, nullptr);
g_pd3dCommandList->OMSetRenderTargets(1, &g_mainRenderTargetDescriptor[backBufferIdx], FALSE, nullptr);
g_pd3dCommandList->SetDescriptorHeaps(1, &g_pd3dSrvDescHeap);
ImGui_ImplDX12_RenderDrawData(ImGui::GetDrawData(), g_pd3dCommandList);
barrier.Transition.StateBefore = D3D12_RESOURCE_STATE_RENDER_TARGET;
barrier.Transition.StateAfter = D3D12_RESOURCE_STATE_PRESENT;
g_pd3dCommandList->ResourceBarrier(1, &barrier);
g_pd3dCommandList->Close();
g_pd3dCommandQueue->ExecuteCommandLists(1, (ID3D12CommandList* const*)&g_pd3dCommandList);
ImGuiIO& io = ImGui::GetIO(); (void)io;
// Update and Render additional Platform Windows
if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
{
    ImGui::UpdatePlatformWindows();
    ImGui::RenderPlatformWindowsDefault(nullptr, (void*)g_pd3dCommandList);
}
// Present
HRESULT hr = g_pSwapChain->Present(1, 0);   // Present with vsync
//HRESULT hr = g_pSwapChain->Present(0, 0); // Present without vsync
g_SwapChainOccluded = (hr == DXGI_STATUS_OCCLUDED);
UINT64 fenceValue = g_fenceLastSignaledValue + 1;
g_pd3dCommandQueue->Signal(g_fence, fenceValue);
g_fenceLastSignaledValue = fenceValue;
frameCtx->FenceValue = fenceValue;
}

Calling this function from inside while loop works fine.

secure the paint handler with a flag to make it not reentrant (hidden recursion could mess up your day otherwise) Added switch case inside WndProc
```
case WM_PAINT:
    if (!wmPaintEnteredFlag) {
        wmPaintEnteredFlag = true;
        imGuiStuffFn();
        wmPaintEnteredFlag = false;
    }
    break;
```
Now the window does not show anything but white screen and closes after a few seconds.
within your paint handler, invalidate your window again to ensure a constant flow of frames Sorry I could not understand which function to call to invalidate window. Please help
if your window is disabled, defer to DefWindowProc after handling the above (modal dialogs won't work correctly otherwise) I am not sure but as this is demo code only so I believe the window is not disabled. Correct me if I am wrong.

Thanks and Regards Aditya

adityachd commented 2 months ago

Adding the wmPaintEnteredFlag check inside the imGuiStuffFn function also made it display the window correctly as before but still dragging and resizing the window halts the code. Here is the whole main file in case you want to see.

// Dear ImGui: standalone example application for DirectX 12

// Learn about Dear ImGui:
// - FAQ                  https://dearimgui.com/faq
// - Getting Started      https://dearimgui.com/getting-started
// - Documentation        https://dearimgui.com/docs (same as your local docs/ folder).
// - Introduction, links and more at the top of imgui.cpp

// Important: to compile on 32-bit systems, the DirectX12 backend requires code to be compiled with '#define ImTextureID ImU64'.
// This is because we need ImTextureID to carry a 64-bit value and by default ImTextureID is defined as void*.
// This define is set in the example .vcxproj file and need to be replicated in your app or by adding it to your imconfig.h file.

#include "imgui.h"
#include "imgui_impl_win32.h"
#include "imgui_impl_dx12.h"
#include <d3d12.h>
#include <dxgi1_4.h>
#include <tchar.h>

#include "my_app.h"

#ifdef _DEBUG
#define DX12_ENABLE_DEBUG_LAYER
#endif

#ifdef DX12_ENABLE_DEBUG_LAYER
#include <dxgidebug.h>
#pragma comment(lib, "dxguid.lib")
#endif

#include "imgui_internal.h"

struct FrameContext
{
    ID3D12CommandAllocator* CommandAllocator;
    UINT64                  FenceValue;
};

// Data
static int const                    NUM_FRAMES_IN_FLIGHT = 3;
static FrameContext                 g_frameContext[NUM_FRAMES_IN_FLIGHT] = {};
static UINT                         g_frameIndex = 0;

static int const                    NUM_BACK_BUFFERS = 3;
static ID3D12Device*                g_pd3dDevice = nullptr;
static ID3D12DescriptorHeap*        g_pd3dRtvDescHeap = nullptr;
static ID3D12DescriptorHeap*        g_pd3dSrvDescHeap = nullptr;
static ID3D12CommandQueue*          g_pd3dCommandQueue = nullptr;
static ID3D12GraphicsCommandList*   g_pd3dCommandList = nullptr;
static ID3D12Fence*                 g_fence = nullptr;
static HANDLE                       g_fenceEvent = nullptr;
static UINT64                       g_fenceLastSignaledValue = 0;
static IDXGISwapChain3*             g_pSwapChain = nullptr;
static bool                         g_SwapChainOccluded = false;
static HANDLE                       g_hSwapChainWaitableObject = nullptr;
static ID3D12Resource*              g_mainRenderTargetResource[NUM_BACK_BUFFERS] = {};
static D3D12_CPU_DESCRIPTOR_HANDLE  g_mainRenderTargetDescriptor[NUM_BACK_BUFFERS] = {};

// Forward declarations of helper functions
bool CreateDeviceD3D(HWND hWnd);
void CleanupDeviceD3D();
void CreateRenderTarget();
void CleanupRenderTarget();
void WaitForLastSubmittedFrame();
FrameContext* WaitForNextFrameResources();
LRESULT WINAPI WndProc(HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam);

WNDCLASSEXW wc;
HWND hwnd;
// Our state
bool show_demo_window = true;
bool show_another_window = false;
ImVec4 clear_color = ImVec4(0.45f, 0.55f, 0.60f, 1.00f);

// Main loop
bool done = false;
bool wmPaintEnteredFlag = false;

void imGuiStuffFn() {
    if (!wmPaintEnteredFlag) {
        wmPaintEnteredFlag = true;

        ImGuiIO& io = ImGui::GetIO(); (void)io;

        // Start the Dear ImGui frame
        ImGui_ImplDX12_NewFrame();
        ImGui_ImplWin32_NewFrame();
        ImGui::NewFrame();

        // 1. Show the big demo window (Most of the sample code is in ImGui::ShowDemoWindow()! You can browse its code to learn more about Dear ImGui!).
        if (show_demo_window)
            ImGui::ShowDemoWindow(&show_demo_window);

        // 2. Show a simple window that we create ourselves. We use a Begin/End pair to create a named window.
        {
            static float f = 0.0f;
            static int counter = 0;

            ImGui::Begin("Hello, world!");                          // Create a window called "Hello, world!" and append into it.

            ImGui::Text("This is some useful text.");               // Display some text (you can use a format strings too)
            ImGui::Checkbox("Demo Window", &show_demo_window);      // Edit bools storing our window open/close state
            ImGui::Checkbox("Another Window", &show_another_window);

            ImGui::SliderFloat("float", &f, 0.0f, 1.0f);            // Edit 1 float using a slider from 0.0f to 1.0f
            ImGui::ColorEdit3("clear color", (float*)&clear_color); // Edit 3 floats representing a color

            if (ImGui::Button("Button"))                            // Buttons return true when clicked (most widgets return true when edited/activated)
                counter++;
            ImGui::SameLine();
            ImGui::Text("counter = %d", counter);

            ImGui::Text("Application average %.3f ms/frame (%.1f FPS)", 1000.0f / io.Framerate, io.Framerate);
            ImGui::End();
        }

        // 3. Show another simple window.
        if (show_another_window)
        {
            ImGui::Begin("Another Window", &show_another_window);   // Pass a pointer to our bool variable (the window will have a closing button that will clear the bool when clicked)
            ImGui::Text("Hello from another window!");
            if (ImGui::Button("Close Me"))
                show_another_window = false;
            ImGui::End();
        }

        // Rendering
        ImGui::Render();

        FrameContext* frameCtx = WaitForNextFrameResources();
        UINT backBufferIdx = g_pSwapChain->GetCurrentBackBufferIndex();
        frameCtx->CommandAllocator->Reset();

        D3D12_RESOURCE_BARRIER barrier = {};
        barrier.Type = D3D12_RESOURCE_BARRIER_TYPE_TRANSITION;
        barrier.Flags = D3D12_RESOURCE_BARRIER_FLAG_NONE;
        barrier.Transition.pResource = g_mainRenderTargetResource[backBufferIdx];
        barrier.Transition.Subresource = D3D12_RESOURCE_BARRIER_ALL_SUBRESOURCES;
        barrier.Transition.StateBefore = D3D12_RESOURCE_STATE_PRESENT;
        barrier.Transition.StateAfter = D3D12_RESOURCE_STATE_RENDER_TARGET;
        g_pd3dCommandList->Reset(frameCtx->CommandAllocator, nullptr);
        g_pd3dCommandList->ResourceBarrier(1, &barrier);

        // Render Dear ImGui graphics
        const float clear_color_with_alpha[4] = { clear_color.x * clear_color.w, clear_color.y * clear_color.w, clear_color.z * clear_color.w, clear_color.w };
        g_pd3dCommandList->ClearRenderTargetView(g_mainRenderTargetDescriptor[backBufferIdx], clear_color_with_alpha, 0, nullptr);
        g_pd3dCommandList->OMSetRenderTargets(1, &g_mainRenderTargetDescriptor[backBufferIdx], FALSE, nullptr);
        g_pd3dCommandList->SetDescriptorHeaps(1, &g_pd3dSrvDescHeap);
        ImGui_ImplDX12_RenderDrawData(ImGui::GetDrawData(), g_pd3dCommandList);
        barrier.Transition.StateBefore = D3D12_RESOURCE_STATE_RENDER_TARGET;
        barrier.Transition.StateAfter = D3D12_RESOURCE_STATE_PRESENT;
        g_pd3dCommandList->ResourceBarrier(1, &barrier);
        g_pd3dCommandList->Close();

        g_pd3dCommandQueue->ExecuteCommandLists(1, (ID3D12CommandList* const*)&g_pd3dCommandList);

        // Update and Render additional Platform Windows
        if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
        {
            ImGui::UpdatePlatformWindows();
            ImGui::RenderPlatformWindowsDefault(nullptr, (void*)g_pd3dCommandList);
        }

        // Present
        HRESULT hr = g_pSwapChain->Present(1, 0);   // Present with vsync
        //HRESULT hr = g_pSwapChain->Present(0, 0); // Present without vsync
        g_SwapChainOccluded = (hr == DXGI_STATUS_OCCLUDED);

        UINT64 fenceValue = g_fenceLastSignaledValue + 1;
        g_pd3dCommandQueue->Signal(g_fence, fenceValue);
        g_fenceLastSignaledValue = fenceValue;
        frameCtx->FenceValue = fenceValue;
        wmPaintEnteredFlag = false;
    }
}
// Main code
int main(int, char**)
{
    // Create application window
    //ImGui_ImplWin32_EnableDpiAwareness();
    wc = { sizeof(wc), CS_CLASSDC, WndProc, 0L, 0L, GetModuleHandle(nullptr), nullptr, nullptr, nullptr, nullptr, L"ImGui Example", nullptr };
    ::RegisterClassExW(&wc);
    hwnd = ::CreateWindowW(wc.lpszClassName, L"Test", WS_OVERLAPPEDWINDOW, 100, 100, 1280, 800, nullptr, nullptr, wc.hInstance, nullptr);

    // Initialize Direct3D
    if (!CreateDeviceD3D(hwnd))
    {
        CleanupDeviceD3D();
        ::UnregisterClassW(wc.lpszClassName, wc.hInstance);
        return 1;
    }

    // Show the window
    ::ShowWindow(hwnd, SW_SHOWDEFAULT);
    ::UpdateWindow(hwnd);

    // Setup Dear ImGui context
    IMGUI_CHECKVERSION();
    ImGui::CreateContext();
    ImGuiIO& io = ImGui::GetIO(); (void)io;
    io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;     // Enable Keyboard Controls
    io.ConfigFlags |= ImGuiConfigFlags_NavEnableGamepad;      // Enable Gamepad Controls
    io.ConfigFlags |= ImGuiConfigFlags_DockingEnable;         // Enable Docking
    io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable;       // Enable Multi-Viewport / Platform Windows
    //io.ConfigViewportsNoAutoMerge = true;
    //io.ConfigViewportsNoTaskBarIcon = true;

    // Setup Dear ImGui style
    ImGui::StyleColorsDark();
    //ImGui::StyleColorsLight();

    // When viewports are enabled we tweak WindowRounding/WindowBg so platform windows can look identical to regular ones.
    ImGuiStyle& style = ImGui::GetStyle();
    if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
    {
        style.WindowRounding = 0.0f;
        style.Colors[ImGuiCol_WindowBg].w = 1.0f;
    }

    // Setup Platform/Renderer backends
    ImGui_ImplWin32_Init(hwnd);
    ImGui_ImplDX12_Init(g_pd3dDevice, NUM_FRAMES_IN_FLIGHT,
        DXGI_FORMAT_R8G8B8A8_UNORM, g_pd3dSrvDescHeap,
        g_pd3dSrvDescHeap->GetCPUDescriptorHandleForHeapStart(),
        g_pd3dSrvDescHeap->GetGPUDescriptorHandleForHeapStart());

    // Load Fonts
    // - If no fonts are loaded, dear imgui will use the default font. You can also load multiple fonts and use ImGui::PushFont()/PopFont() to select them.
    // - AddFontFromFileTTF() will return the ImFont* so you can store it if you need to select the font among multiple.
    // - If the file cannot be loaded, the function will return a nullptr. Please handle those errors in your application (e.g. use an assertion, or display an error and quit).
    // - The fonts will be rasterized at a given size (w/ oversampling) and stored into a texture when calling ImFontAtlas::Build()/GetTexDataAsXXXX(), which ImGui_ImplXXXX_NewFrame below will call.
    // - Use '#define IMGUI_ENABLE_FREETYPE' in your imconfig file to use Freetype for higher quality font rendering.
    // - Read 'docs/FONTS.md' for more instructions and details.
    // - Remember that in C/C++ if you want to include a backslash \ in a string literal you need to write a double backslash \\ !
    //io.Fonts->AddFontDefault();
    //io.Fonts->AddFontFromFileTTF("c:\\Windows\\Fonts\\segoeui.ttf", 18.0f);
    //io.Fonts->AddFontFromFileTTF("../../misc/fonts/DroidSans.ttf", 16.0f);
    //io.Fonts->AddFontFromFileTTF("../../misc/fonts/Roboto-Medium.ttf", 16.0f);
    //io.Fonts->AddFontFromFileTTF("../../misc/fonts/Cousine-Regular.ttf", 15.0f);
    //ImFont* font = io.Fonts->AddFontFromFileTTF("c:\\Windows\\Fonts\\ArialUni.ttf", 18.0f, nullptr, io.Fonts->GetGlyphRangesJapanese());
    //IM_ASSERT(font != nullptr);

    wc.lpfnWndProc = nullptr;
    ::RegisterClassExW(&wc);
    while (!done)
    {
        // Poll and handle messages (inputs, window resize, etc.)
        // See the WndProc() function below for our to dispatch events to the Win32 backend.
        MSG msg;
        while (::PeekMessage(&msg, nullptr, 0U, 0U, PM_REMOVE))
        {
            ::TranslateMessage(&msg);
            ::DispatchMessage(&msg);
            if (msg.message == WM_QUIT)
                done = true;
        }

        if (done)
            break;

        // Handle window screen locked
        if (g_SwapChainOccluded && g_pSwapChain->Present(0, DXGI_PRESENT_TEST) == DXGI_STATUS_OCCLUDED)
        {
            ::Sleep(10);
            continue;
        }
        g_SwapChainOccluded = false;

        imGuiStuffFn();
    }

    WaitForLastSubmittedFrame();

    // Cleanup
    ImGui_ImplDX12_Shutdown();
    ImGui_ImplWin32_Shutdown();
    ImGui::DestroyContext();

    CleanupDeviceD3D();
    ::DestroyWindow(hwnd);
    ::UnregisterClassW(wc.lpszClassName, wc.hInstance);

    return 0;
}

// Helper functions
bool CreateDeviceD3D(HWND hWnd)
{
    // Setup swap chain
    DXGI_SWAP_CHAIN_DESC1 sd;
    {
        ZeroMemory(&sd, sizeof(sd));
        sd.BufferCount = NUM_BACK_BUFFERS;
        sd.Width = 0;
        sd.Height = 0;
        sd.Format = DXGI_FORMAT_R8G8B8A8_UNORM;
        sd.Flags = DXGI_SWAP_CHAIN_FLAG_FRAME_LATENCY_WAITABLE_OBJECT;
        sd.BufferUsage = DXGI_USAGE_RENDER_TARGET_OUTPUT;
        sd.SampleDesc.Count = 1;
        sd.SampleDesc.Quality = 0;
        sd.SwapEffect = DXGI_SWAP_EFFECT_FLIP_DISCARD;
        sd.AlphaMode = DXGI_ALPHA_MODE_UNSPECIFIED;
        sd.Scaling = DXGI_SCALING_STRETCH;
        sd.Stereo = FALSE;
    }

    // [DEBUG] Enable debug interface
#ifdef DX12_ENABLE_DEBUG_LAYER
    ID3D12Debug* pdx12Debug = nullptr;
    if (SUCCEEDED(D3D12GetDebugInterface(IID_PPV_ARGS(&pdx12Debug))))
        pdx12Debug->EnableDebugLayer();
#endif

    // Create device
    D3D_FEATURE_LEVEL featureLevel = D3D_FEATURE_LEVEL_11_0;
    if (D3D12CreateDevice(nullptr, featureLevel, IID_PPV_ARGS(&g_pd3dDevice)) != S_OK)
        return false;

    // [DEBUG] Setup debug interface to break on any warnings/errors
#ifdef DX12_ENABLE_DEBUG_LAYER
    if (pdx12Debug != nullptr)
    {
        ID3D12InfoQueue* pInfoQueue = nullptr;
        g_pd3dDevice->QueryInterface(IID_PPV_ARGS(&pInfoQueue));
        pInfoQueue->SetBreakOnSeverity(D3D12_MESSAGE_SEVERITY_ERROR, true);
        pInfoQueue->SetBreakOnSeverity(D3D12_MESSAGE_SEVERITY_CORRUPTION, true);
        pInfoQueue->SetBreakOnSeverity(D3D12_MESSAGE_SEVERITY_WARNING, true);
        pInfoQueue->Release();
        pdx12Debug->Release();
    }
#endif

    {
        D3D12_DESCRIPTOR_HEAP_DESC desc = {};
        desc.Type = D3D12_DESCRIPTOR_HEAP_TYPE_RTV;
        desc.NumDescriptors = NUM_BACK_BUFFERS;
        desc.Flags = D3D12_DESCRIPTOR_HEAP_FLAG_NONE;
        desc.NodeMask = 1;
        if (g_pd3dDevice->CreateDescriptorHeap(&desc, IID_PPV_ARGS(&g_pd3dRtvDescHeap)) != S_OK)
            return false;

        SIZE_T rtvDescriptorSize = g_pd3dDevice->GetDescriptorHandleIncrementSize(D3D12_DESCRIPTOR_HEAP_TYPE_RTV);
        D3D12_CPU_DESCRIPTOR_HANDLE rtvHandle = g_pd3dRtvDescHeap->GetCPUDescriptorHandleForHeapStart();
        for (UINT i = 0; i < NUM_BACK_BUFFERS; i++)
        {
            g_mainRenderTargetDescriptor[i] = rtvHandle;
            rtvHandle.ptr += rtvDescriptorSize;
        }
    }

    {
        D3D12_DESCRIPTOR_HEAP_DESC desc = {};
        desc.Type = D3D12_DESCRIPTOR_HEAP_TYPE_CBV_SRV_UAV;
        desc.NumDescriptors = 1;
        desc.Flags = D3D12_DESCRIPTOR_HEAP_FLAG_SHADER_VISIBLE;
        if (g_pd3dDevice->CreateDescriptorHeap(&desc, IID_PPV_ARGS(&g_pd3dSrvDescHeap)) != S_OK)
            return false;
    }

    {
        D3D12_COMMAND_QUEUE_DESC desc = {};
        desc.Type = D3D12_COMMAND_LIST_TYPE_DIRECT;
        desc.Flags = D3D12_COMMAND_QUEUE_FLAG_NONE;
        desc.NodeMask = 1;
        if (g_pd3dDevice->CreateCommandQueue(&desc, IID_PPV_ARGS(&g_pd3dCommandQueue)) != S_OK)
            return false;
    }

    for (UINT i = 0; i < NUM_FRAMES_IN_FLIGHT; i++)
        if (g_pd3dDevice->CreateCommandAllocator(D3D12_COMMAND_LIST_TYPE_DIRECT, IID_PPV_ARGS(&g_frameContext[i].CommandAllocator)) != S_OK)
            return false;

    if (g_pd3dDevice->CreateCommandList(0, D3D12_COMMAND_LIST_TYPE_DIRECT, g_frameContext[0].CommandAllocator, nullptr, IID_PPV_ARGS(&g_pd3dCommandList)) != S_OK ||
        g_pd3dCommandList->Close() != S_OK)
        return false;

    if (g_pd3dDevice->CreateFence(0, D3D12_FENCE_FLAG_NONE, IID_PPV_ARGS(&g_fence)) != S_OK)
        return false;

    g_fenceEvent = CreateEvent(nullptr, FALSE, FALSE, nullptr);
    if (g_fenceEvent == nullptr)
        return false;

    {
        IDXGIFactory4* dxgiFactory = nullptr;
        IDXGISwapChain1* swapChain1 = nullptr;
        if (CreateDXGIFactory1(IID_PPV_ARGS(&dxgiFactory)) != S_OK)
            return false;
        if (dxgiFactory->CreateSwapChainForHwnd(g_pd3dCommandQueue, hWnd, &sd, nullptr, nullptr, &swapChain1) != S_OK)
            return false;
        if (swapChain1->QueryInterface(IID_PPV_ARGS(&g_pSwapChain)) != S_OK)
            return false;
        swapChain1->Release();
        dxgiFactory->Release();
        g_pSwapChain->SetMaximumFrameLatency(NUM_BACK_BUFFERS);
        g_hSwapChainWaitableObject = g_pSwapChain->GetFrameLatencyWaitableObject();
    }

    CreateRenderTarget();
    return true;
}

void CleanupDeviceD3D()
{
    CleanupRenderTarget();
    if (g_pSwapChain) { g_pSwapChain->SetFullscreenState(false, nullptr); g_pSwapChain->Release(); g_pSwapChain = nullptr; }
    if (g_hSwapChainWaitableObject != nullptr) { CloseHandle(g_hSwapChainWaitableObject); }
    for (UINT i = 0; i < NUM_FRAMES_IN_FLIGHT; i++)
        if (g_frameContext[i].CommandAllocator) { g_frameContext[i].CommandAllocator->Release(); g_frameContext[i].CommandAllocator = nullptr; }
    if (g_pd3dCommandQueue) { g_pd3dCommandQueue->Release(); g_pd3dCommandQueue = nullptr; }
    if (g_pd3dCommandList) { g_pd3dCommandList->Release(); g_pd3dCommandList = nullptr; }
    if (g_pd3dRtvDescHeap) { g_pd3dRtvDescHeap->Release(); g_pd3dRtvDescHeap = nullptr; }
    if (g_pd3dSrvDescHeap) { g_pd3dSrvDescHeap->Release(); g_pd3dSrvDescHeap = nullptr; }
    if (g_fence) { g_fence->Release(); g_fence = nullptr; }
    if (g_fenceEvent) { CloseHandle(g_fenceEvent); g_fenceEvent = nullptr; }
    if (g_pd3dDevice) { g_pd3dDevice->Release(); g_pd3dDevice = nullptr; }

#ifdef DX12_ENABLE_DEBUG_LAYER
    IDXGIDebug1* pDebug = nullptr;
    if (SUCCEEDED(DXGIGetDebugInterface1(0, IID_PPV_ARGS(&pDebug))))
    {
        pDebug->ReportLiveObjects(DXGI_DEBUG_ALL, DXGI_DEBUG_RLO_SUMMARY);
        pDebug->Release();
    }
#endif
}

void CreateRenderTarget()
{
    for (UINT i = 0; i < NUM_BACK_BUFFERS; i++)
    {
        ID3D12Resource* pBackBuffer = nullptr;
        g_pSwapChain->GetBuffer(i, IID_PPV_ARGS(&pBackBuffer));
        g_pd3dDevice->CreateRenderTargetView(pBackBuffer, nullptr, g_mainRenderTargetDescriptor[i]);
        g_mainRenderTargetResource[i] = pBackBuffer;
    }
}

void CleanupRenderTarget()
{
    WaitForLastSubmittedFrame();

    for (UINT i = 0; i < NUM_BACK_BUFFERS; i++)
        if (g_mainRenderTargetResource[i]) { g_mainRenderTargetResource[i]->Release(); g_mainRenderTargetResource[i] = nullptr; }
}

void WaitForLastSubmittedFrame()
{
    FrameContext* frameCtx = &g_frameContext[g_frameIndex % NUM_FRAMES_IN_FLIGHT];

    UINT64 fenceValue = frameCtx->FenceValue;
    if (fenceValue == 0)
        return; // No fence was signaled

    frameCtx->FenceValue = 0;
    if (g_fence->GetCompletedValue() >= fenceValue)
        return;

    g_fence->SetEventOnCompletion(fenceValue, g_fenceEvent);
    WaitForSingleObject(g_fenceEvent, INFINITE);
}

FrameContext* WaitForNextFrameResources()
{
    UINT nextFrameIndex = g_frameIndex + 1;
    g_frameIndex = nextFrameIndex;

    HANDLE waitableObjects[] = { g_hSwapChainWaitableObject, nullptr };
    DWORD numWaitableObjects = 1;

    FrameContext* frameCtx = &g_frameContext[nextFrameIndex % NUM_FRAMES_IN_FLIGHT];
    UINT64 fenceValue = frameCtx->FenceValue;
    if (fenceValue != 0) // means no fence was signaled
    {
        frameCtx->FenceValue = 0;
        g_fence->SetEventOnCompletion(fenceValue, g_fenceEvent);
        waitableObjects[1] = g_fenceEvent;
        numWaitableObjects = 2;
    }

    WaitForMultipleObjects(numWaitableObjects, waitableObjects, TRUE, INFINITE);

    return frameCtx;
}

// Forward declare message handler from imgui_impl_win32.cpp
extern IMGUI_IMPL_API LRESULT ImGui_ImplWin32_WndProcHandler(HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam);

// Win32 message handler
// You can read the io.WantCaptureMouse, io.WantCaptureKeyboard flags to tell if dear imgui wants to use your inputs.
// - When io.WantCaptureMouse is true, do not dispatch mouse input data to your main application, or clear/overwrite your copy of the mouse data.
// - When io.WantCaptureKeyboard is true, do not dispatch keyboard input data to your main application, or clear/overwrite your copy of the keyboard data.
// Generally you may always pass all inputs to dear imgui, and hide them from your application based on those two flags.
LRESULT WINAPI WndProc(HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam)
{
    if (ImGui_ImplWin32_WndProcHandler(hWnd, msg, wParam, lParam))
        return true;

    switch (msg)
    {
    case WM_SIZE:
        if (g_pd3dDevice != nullptr && wParam != SIZE_MINIMIZED)
        {
            WaitForLastSubmittedFrame();
            CleanupRenderTarget();
            HRESULT result = g_pSwapChain->ResizeBuffers(0, (UINT)LOWORD(lParam), (UINT)HIWORD(lParam), DXGI_FORMAT_UNKNOWN, DXGI_SWAP_CHAIN_FLAG_FRAME_LATENCY_WAITABLE_OBJECT);
            assert(SUCCEEDED(result) && "Failed to resize swapchain.");
            CreateRenderTarget();
        }
        return 0;
    case WM_SYSCOMMAND:
        if ((wParam & 0xfff0) == SC_KEYMENU) // Disable ALT application menu
            return 0;
        break;
    case WM_DESTROY:
        ::PostQuitMessage(0);
        return 0;
        break;
    case WM_PAINT:
        if (!wmPaintEnteredFlag) {
            wmPaintEnteredFlag = true;
            imGuiStuffFn();
            wmPaintEnteredFlag = false;
        }
        break;
    }
    return ::DefWindowProcW(hWnd, msg, wParam, lParam);
}

Thanks and Regards Aditya

GamingMinds-DanielC commented 2 months ago

Do not call imGuiStuffFn() from your main loop, only from WM_PAINT. Also the additional swapchain presentation in your main loop looks unnecessary, the one at the end of imGuiStuffFn() should be sufficient. Your registered window class should include the CS_HREDRAW and CS_VREDRAW flags.

For WM_PAINT try this:

case WM_PAINT:
        if (!wmPaintEnteredFlag) {
            wmPaintEnteredFlag = true;
            imGuiStuffFn();
            wmPaintEnteredFlag = false;

            // invalidate in case of validation by any modal loop
            ::InvalidateRect(hWnd, NULL, FALSE)`
        }

        // let DefWindowProc handle WM_PAINT if f.e. file dialogs are open, otherwise modal prompts are somehow suppressed,
        // also required for message boxes and other modals to work correctly
        if (::IsWindowEnabled(hWnd))
            return 0;

        break;

You basically want to avoid DefWindowProc handling your painting as well, so you need to return 0. Unless you have modals open (they will temporarily disable your window). That case might not be relevant for you right now, but if you ever need modals it gets tricky otherwise.

That's about it for the things I noticed for now, no guarantees that there are no other problem cases left.

adityachd commented 2 months ago

The window is comes white and nothing is rendered inside it. ALso where do I enable CS_HREDRAW and CS_VREDRAW

GamingMinds-DanielC commented 2 months ago

You can set these flags in the WNDCLASSEXW structure you give to RegisterClassExW(). You can read details about that in the Win32 API documentation. If you don't know how to find it, just putting function or structure names into Google will point you in the right direction.

After that you should step through your code with a debugger to check if everything gets called as expected and that variables hold the values they should have. If that doesn't help, maybe a capture with RenderDoc can show you what is wrong.

adityachd commented 2 months ago

Thanks a lot for the help @GamingMinds-DanielC . I has to add a flag(in WM_PAINT) to check if all code before while loop was initialized before running imGuiStuffFn() from WM_PAINT. Seems like WM_PAINT is called even before code is initialized so the window showed nothing and closed itself. Now it updates well as intended. Though it stops execution for maybe less than a second if you click and hold the title bar without dragging. This can stop data reception during that time period as my serial device throws data at 2 Megabaud/s rate. Can this somehow be prevented? Thanks a lot again.

GamingMinds-DanielC commented 2 months ago

No idea. You could add some logging to see what kind of messages are sent to your window. Maybe the message queue is saturated with other messages. WM_PAINT is a low priority message, it usually gets sent when everything else is done. Maybe your window gets validated somehow so that there are no more paint messages for a while, then invalidating in reaction to a short cyclic timer could help.

adityachd commented 2 months ago

Thanks again @GamingMinds-DanielC . I saw the exact same behavior in QT too with windows so again must be a win32 related issue. I'll try and write back if I find any solution to that.

adityachd commented 2 months ago

Hi @GamingMinds-DanielC I added the below code to start timer on mouseclick and stop on release and also added wm_timer handler. But the WM_TIMER is not called at all. added print to check if there is error in setTimer call but there was not error. What seems wrong here?

    case WM_TIMER:
            printf("___%d    %d\n", msg, printCounter++);
            if (!wmPaintEnteredFlag && contextCreated) {
                imGuiStuffFn();
                InvalidateRect(hWnd, NULL, FALSE);
                if (::IsWindowEnabled(hWnd))
                    return 0;
            }
            break;
    case WM_NCLBUTTONDOWN:
        if (!SetTimer(hwnd, 1, 16, (TIMERPROC)NULL))
        {
            printf("er  %8x\n",GetLastError());
        }
        else {
            printf("ner\n");
        }
        break;
    case WM_NCLBUTTONUP:
        KillTimer(hwnd, 1);
        break;

Thanks and regards Aditya

GamingMinds-DanielC commented 2 months ago

The idea was an invalidation of the window with the timer, so just the invalidate call. The frame stuff is better left out of there, that should be nowhere other than in the paint handler.

As to why no timer is called: no idea. If you verified that it is indeed created, it should be set up correctly. But then again the documentation contains this in the remarks section: "The WM_TIMER message is a low-priority message. The GetMessage and PeekMessage functions post this message only when no other higher-priority messages are in the thread's message queue."

So basically, if the paint messages don't come because of a saturated message queue, timers won't come for the same reason. You could log all the messages you get to see if that is the case.

adityachd commented 2 months ago

Thanks again for the help @GamingMinds-DanielC.

ocornut / imgui