Layout issue with QWidget converted form win32 window

gaojinhsu

I have to create a win32 window to render video stream, so I try to convert this win32 window to a QWidget control, Also I want to show some buttons on this win32 window. but the win32 window is always on the top no matter how I configure the layout.

HINSTANCE hInstance = GetModuleHandle(NULL);
WNDCLASSEXW wcex = { sizeof(WNDCLASSEX) };
wcex.cbSize = sizeof(WNDCLASSEX);
wcex.style = CS_HREDRAW | CS_VREDRAW;
wcex.lpfnWndProc = WndProc;
wcex.cbClsExtra = 0;
wcex.cbWndExtra = 0;
wcex.hInstance = hInstance;
wcex.hCursor = LoadCursor(nullptr, IDC_ARROW);
wcex.hbrBackground = (HBRUSH)(COLOR_WINDOW + 1);
wcex.lpszClassName = L"RenderWindow";

static ATOM wnd_class_ = RegisterClassExW(&wcex);
HWND hwnd = ::CreateWindowExW(WS_CHILDWINDOW, L"RenderWindow", L"Engineer", WS_CHILDWINDOW,
        CW_USEDEFAULT, 0, CW_USEDEFAULT, 0, nullptr, nullptr, hInstance, nullptr);

QWindow *native_wnd = QWindow::fromWinId((WId)hwnd);
QWidget *a = QWidget::createWindowContainer(native_wnd);
a->setParent(this);
a->setGeometry(QRect(0, 0, 800, 400));

QPushButton* btn = new QPushButton(this);
btn->setGeometry(QRect(780, 380, 100, 50));
btn->raise();

JonB

@gaojinhsu said in Layout issue with QWidget converted form win32 window:

QWidget::createWindowContainer

https://doc.qt.io/qt-6/qwidget.html#createWindowContainer

The window container has a number of known limitations:

Stacking order; The embedded window will stack on top of the widget hierarchy as an opaque box. The stacking order of multiple overlapping window container instances is undefined.

BTW https://forum.qt.io/topic/89472/qwidget-createwindowcontainer-how-to-put-this-widget-createdby-this-api-to-stackunder-another-qwidget asked the same question, but was never answered.

You might try adding Qt::WindowStaysOnTopHint to the QPushButton, but I don't know whether it will make any difference.

Christian Ehrlicher

@gaojinhsu Don't use hard-coded geometry stuff but use a layout and add your widgers in there.

gaojinhsu

@Christian-Ehrlicher it's just a demo to show how this happens, using layout can't fix it.

Christian Ehrlicher

@gaojinhsu said in Layout issue with QWidget converted form win32 window:

it's just a demo to show how this happens, using layout can't fix it.

So how should we help when you don't post your original code? Your code you show is missing a layout so it won't work.

JonB

@gaojinhsu said in Layout issue with QWidget converted form win32 window:

QWidget::createWindowContainer

https://doc.qt.io/qt-6/qwidget.html#createWindowContainer

The window container has a number of known limitations:

Stacking order; The embedded window will stack on top of the widget hierarchy as an opaque box. The stacking order of multiple overlapping window container instances is undefined.

BTW https://forum.qt.io/topic/89472/qwidget-createwindowcontainer-how-to-put-this-widget-createdby-this-api-to-stackunder-another-qwidget asked the same question, but was never answered.

You might try adding Qt::WindowStaysOnTopHint to the QPushButton, but I don't know whether it will make any difference.

gaojinhsu

@Christian-Ehrlicher Thanks for trying to help, original code is not necessary ,this demo can reproduce this issue, you can create a blank new Qt Widgets Application project，here is the complete code.

#include "MainWidget.h"
#include <QHBoxlayout>
#include <Windows.h>
#include <qwindow.h>
#include <qpushbutton.h>

LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
    switch (message)
    {
    case WM_PAINT:
    {
        PAINTSTRUCT ps;
        HDC hdc = BeginPaint(hWnd, &ps);
        EndPaint(hWnd, &ps);
    }
    break;
    case WM_DESTROY:
        PostQuitMessage(0);
        break;
    default:
        return DefWindowProc(hWnd, message, wParam, lParam);
    }
    return 0;
}

MainWidget::MainWidget(QWidget *parent)
    : QWidget(parent)
{
    ui.setupUi(this);

    HINSTANCE hInstance = GetModuleHandle(NULL);
    WNDCLASSEXW wcex = { sizeof(WNDCLASSEX) };
    wcex.cbSize = sizeof(WNDCLASSEX);
    wcex.style = CS_HREDRAW | CS_VREDRAW;
    wcex.lpfnWndProc = WndProc;
    wcex.cbClsExtra = 0;
    wcex.cbWndExtra = 0;
    wcex.hInstance = hInstance;
    wcex.hCursor = LoadCursor(nullptr, IDC_ARROW);
    wcex.hbrBackground = (HBRUSH)(COLOR_WINDOW + 1);
    wcex.lpszMenuName = L"MyMenu";
    wcex.lpszClassName = L"RenderWindow";

    static ATOM wnd_class_ = RegisterClassExW(&wcex);
    qDebug() << "RegisterClassExW failed with " << GetLastError();
    HWND hwnd = ::CreateWindowExW(WS_EX_OVERLAPPEDWINDOW, L"RenderWindow", L"render", WS_OVERLAPPEDWINDOW,
        CW_USEDEFAULT, 0, CW_USEDEFAULT, 0, nullptr, nullptr, hInstance, nullptr);

    QWindow* render_wnd = QWindow::fromWinId((WId)hwnd);
    QWidget* renderWidget = QWidget::createWindowContainer(render_wnd);

    QHBoxLayout* mainLayout = new QHBoxLayout(this);
    mainLayout->setMargin(0);
    mainLayout->addWidget(renderWidget);
    this->setLayout(mainLayout);

    QPushButton* btn = new QPushButton(this);
    QHBoxLayout* renderLayout = new QHBoxLayout(this);
    renderLayout->setMargin(0);
    renderLayout->addWidget(btn);
    renderWidget->setLayout(renderLayout);

}

MainWidget::~MainWidget(){
}

gaojinhsu

@JonB Sad to hear that. BTW. adding Qt::WindowStaysOnTopHint to the QPushButton doesn't work.