7 files changed, 269 insertions, 35 deletions
diff --git a/src/plugins/platforms/wasm/CMakeLists.txt b/src/plugins/platforms/wasm/CMakeLists.txt
index 03cb0d52ca1..7e9beb7e832 100644
--- a/src/plugins/platforms/wasm/CMakeLists.txt
+++ b/src/plugins/platforms/wasm/CMakeLists.txt
@@ -33,6 +33,7 @@ qt_internal_add_plugin(QWasmIntegrationPlugin
         qwasmwindownonclientarea.cpp qwasmwindownonclientarea.h
         qwasminputcontext.cpp qwasminputcontext.h
         qwasmwindowstack.h
+        qwasmfiledialoghelper.cpp qwasmfiledialoghelper.h
     DEFINES
         QT_EGL_NO_X11
         QT_NO_FOREACH
diff --git a/src/plugins/platforms/wasm/qwasmdom.cpp b/src/plugins/platforms/wasm/qwasmdom.cpp
index 71efcee7887..eefd18154aa 100644
--- a/src/plugins/platforms/wasm/qwasmdom.cpp
+++ b/src/plugins/platforms/wasm/qwasmdom.cpp
@@ -10,6 +10,7 @@
 #include <QtCore/qrect.h>
 #include <QtGui/qimage.h>
 #include <private/qstdweb_p.h>
+#include <private/qwasmlocalfileengine_p.h>
 #include <QtCore/qurl.h>
 
 #include <utility>
@@ -112,11 +113,14 @@ void DataTransfer::toMimeDataWithFile(std::function<void(QMimeData *)> callback)
 
             m_callback(mimeData);
 
-            // Delete files; we expect that the user callback reads/copies
-            // file content before returning.
-            // Fixme: tie file lifetime to lifetime of the QMimeData?
-            for (QUrl fileUrl: fileUrls)
-                QFile(fileUrl.toLocalFile()).remove();
+            // Delete temporary files; we expect that the user callback reads/copies
+            // file content before returning.// Fixme: tie file lifetime to lifetime of the QMimeData?
+            // Note: QWasmFileEngine files (weblocalfile://) are managed by QWasmFileEngine
+            // and are not deleted here
+            for (QUrl fileUrl: fileUrls) {
+                if (!QWasmFileEngineHandler::isWasmFileName(fileUrl.toString()))
+                    QFile(fileUrl.toLocalFile()).remove();
+            }
 
             delete this;
         }
@@ -144,49 +148,56 @@ void DataTransfer::toMimeDataWithFile(std::function<void(QMimeData *)> callback)
         case ItemKind::File: {
             qstdweb::File webfile(item.call<emscripten::val>("getAsFile"));
 
-            if (webfile.size() > 1e+9) { // limit file size to 1 GB
-                qWarning() << "File is too large (> 1GB) and will be skipped. File size is" << webfile.size();
+            // Add a file access url for the local file. If asyncify is available,
+            // add a QWasmFileEngine managed url. Else fall back to placing a copy
+            // of the file at /tmp on Emsripten's in-memory file system.
+            if (qstdweb::haveAsyncify()) {
+                QUrl fileUrl(QWasmFileEngineHandler::addFile(webfile));
+                mimeContext->fileUrls.append(fileUrl);
                 mimeContext->deref();
-                continue;
-            }
+            } else {
+                // Limit in-memory file size to 1 GB
+                if (webfile.size() > 1e+9) {
+                    qWarning() << "File is too large (> 1GB) and will be skipped. File size is" << webfile.size();
+                    mimeContext->deref();
+                    continue;
+                }
 
-            QString mimeFormat = QString::fromStdString(webfile.type());
-            QString fileName = QString::fromStdString(webfile.name());
+                // Read file content
+                QByteArray fileContent(webfile.size(), Qt::Uninitialized);
+                webfile.stream(fileContent.data(), [=]() {
+                    QDir qtTmpDir("/qt/tmp/"); // "tmp": indicate that these files won't stay around
+                    qtTmpDir.mkpath(qtTmpDir.path());
+
+                    QUrl fileUrl = QUrl::fromLocalFile(qtTmpDir.filePath(QString::fromStdString(webfile.name())));
+                    mimeContext->fileUrls.append(fileUrl);
+
+                    QFile file(fileUrl.toLocalFile());
+                    if (!file.open(QFile::WriteOnly)) {
+                        qWarning() << "File was not opened";
+                        mimeContext->deref();
+                        return;
+                    }
+                    if (file.write(fileContent) < 0)
+                        qWarning() << "Write failed";
+                    file.close();
+                    mimeContext->deref();
+                });
 
-            // there's a file, now read it
-            QByteArray fileContent(webfile.size(), Qt::Uninitialized);
-            webfile.stream(fileContent.data(), [=]() {
-                
                 // If we get a single file, and that file is an image, then
                 // try to decode the image data. This handles the case where
                 // image data (i.e. not an image file) is pasted. The browsers
                 // will then create a fake "image.png" file which has the image
-                // data. As a side effect Qt will also decode the image for 
+                // data. As a side effect Qt will also decode the image for
                 // single-image-file drops, since there is no way to differentiate
                 // the fake "image.png" from a real one.
+                QString mimeFormat = QString::fromStdString(webfile.type());
                 if (fileCount == 1 && mimeFormat.contains("image/")) {
                     QImage image;
                     if (image.loadFromData(fileContent))
                         mimeContext->mimeData->setImageData(image);
                 }
-
-                QDir qtTmpDir("/qt/tmp/"); // "tmp": indicate that these files won't stay around
-                qtTmpDir.mkpath(qtTmpDir.path());
-
-                QUrl fileUrl = QUrl::fromLocalFile(qtTmpDir.filePath(QString::fromStdString(webfile.name())));
-                mimeContext->fileUrls.append(fileUrl);
-
-                QFile file(fileUrl.toLocalFile());
-                if (!file.open(QFile::WriteOnly)) {
-                    qWarning() << "File was not opened";
-                    mimeContext->deref();
-                    return;
-                }
-                if (file.write(fileContent) < 0)
-                    qWarning() << "Write failed";
-                file.close();
-                mimeContext->deref();
-            });
+            }
             break;
         }
         case ItemKind::String:
diff --git a/src/plugins/platforms/wasm/qwasmfiledialoghelper.cpp b/src/plugins/platforms/wasm/qwasmfiledialoghelper.cpp
new file mode 100644
index 00000000000..1e6e2b1f644
--- /dev/null
+++ b/src/plugins/platforms/wasm/qwasmfiledialoghelper.cpp
@@ -0,0 +1,157 @@
+// Copyright (C) 2025 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0-only
+
+#include "qwasmfiledialoghelper.h"
+
+#include <QtCore/QDebug>
+#include <QtCore/QUrl>
+#include <QtGui/private/qwasmlocalfileaccess_p.h>
+#include <QtCore/private/qwasmlocalfileengine_p.h>
+
+QT_BEGIN_NAMESPACE
+
+QWasmFileDialogHelper::QWasmFileDialogHelper()
+    : m_eventLoop(nullptr)
+{
+
+}
+
+QWasmFileDialogHelper::~QWasmFileDialogHelper()
+{
+
+}
+
+bool QWasmFileDialogHelper::defaultNameFilterDisables() const
+{
+    return false;
+}
+
+void QWasmFileDialogHelper::setDirectory(const QUrl &directory)
+{
+    Q_UNUSED(directory)
+}
+
+QUrl QWasmFileDialogHelper::directory() const
+{
+    return QUrl();
+}
+
+void QWasmFileDialogHelper::selectFile(const QUrl &file)
+{
+    m_selectedFiles.clear();
+    m_selectedFiles.append(file);
+}
+
+QList<QUrl> QWasmFileDialogHelper::selectedFiles() const
+{
+    return m_selectedFiles;
+}
+
+void QWasmFileDialogHelper::setFilter()
+{
+
+}
+
+void QWasmFileDialogHelper::selectNameFilter(const QString &filter)
+{
+    Q_UNUSED(filter);
+    // TODO
+}
+
+QString QWasmFileDialogHelper::selectedNameFilter() const
+{
+    return QString();
+}
+
+void QWasmFileDialogHelper::exec()
+{
+    QEventLoop eventLoop;
+    m_eventLoop = &eventLoop;
+    eventLoop.exec();
+    m_eventLoop = nullptr;
+}
+
+bool QWasmFileDialogHelper::show(Qt::WindowFlags flags, Qt::WindowModality modality, QWindow *parent)
+{
+    Q_UNUSED(flags)
+    Q_UNUSED(modality)
+    Q_UNUSED(parent)
+    showFileDialog();
+    return true;
+}
+
+void QWasmFileDialogHelper::hide()
+{
+
+}
+
+void QWasmFileDialogHelper::showFileDialog()
+{
+    if (options()->acceptMode() == QFileDialogOptions::AcceptOpen) {
+        // Use name filters from options
+        QString nameFilter = options()->nameFilters().join(";;");
+        if (nameFilter.isEmpty())
+            nameFilter = "*";
+
+        QWasmLocalFileAccess::showOpenFileDialog(nameFilter.toStdString(), [this](bool accepted, std::vector<qstdweb::File> files) {
+            onOpenDialogClosed(accepted, files);
+        });
+    } else if (options()->acceptMode() == QFileDialogOptions::AcceptSave) {
+        QString suggestion = m_selectedFiles.isEmpty() ? QString() : QUrl(m_selectedFiles.first()).fileName();
+        m_selectedFiles.clear();
+
+        QWasmLocalFileAccess::showSaveFileDialog(suggestion.toStdString(), [this](bool accepted, qstdweb::FileSystemFileHandle file){
+            onSaveDialogClosed(accepted, file);
+        });
+    }
+}
+
+void QWasmFileDialogHelper::onOpenDialogClosed(bool accepted, std::vector<qstdweb::File> files)
+{
+    m_selectedFiles.clear();
+
+    if (!accepted) {
+        emit reject();
+        return;
+    }
+
+    // Track opened files
+    for (const auto &file : files) {
+        QString wasmFileName = QWasmFileEngineHandler::addFile(file);
+        QUrl fileUrl(wasmFileName);
+        m_selectedFiles.append(fileUrl);
+    }
+
+    // Emit signals
+    if (m_selectedFiles.size() > 0) {
+        emit fileSelected(m_selectedFiles.first());
+        emit filesSelected(m_selectedFiles);
+    }
+    emit accept();
+
+    // exit exec() if in exec()
+    if (m_eventLoop)
+        m_eventLoop->quit();
+}
+
+void QWasmFileDialogHelper::onSaveDialogClosed(bool accepted, qstdweb::FileSystemFileHandle file)
+{
+    if (!accepted) {
+        emit reject();
+        return;
+    }
+
+    // Track save file
+    QString wasmFileName = QWasmFileEngineHandler::addFile(file);
+    QUrl fileUrl(wasmFileName);
+    m_selectedFiles.append(fileUrl);
+
+    // Emit signals
+    emit fileSelected(m_selectedFiles.first());
+    emit accept();
+
+    if (m_eventLoop)
+        m_eventLoop->quit();
+}
+
+QT_END_NAMESPACE
diff --git a/src/plugins/platforms/wasm/qwasmfiledialoghelper.h b/src/plugins/platforms/wasm/qwasmfiledialoghelper.h
new file mode 100644
index 00000000000..c5a5b57e518
--- /dev/null
+++ b/src/plugins/platforms/wasm/qwasmfiledialoghelper.h
@@ -0,0 +1,49 @@
+// Copyright (C) 2025 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0-only
+
+#ifndef QWASMFILEDIALOGHELPER_H
+#define QWASMFILEDIALOGHELPER_H
+
+#include <QtCore/QObject>
+#include <QtCore/QUrl>
+#include <QtCore/QEventLoop>
+#include <QtGui/qpa/qplatformdialoghelper.h>
+#include <QtGui/private/qwasmlocalfileaccess_p.h>
+
+QT_BEGIN_NAMESPACE
+
+class QWasmFileDialogHelper : public QPlatformFileDialogHelper
+{
+    Q_OBJECT
+public:
+    QWasmFileDialogHelper();
+    ~QWasmFileDialogHelper();
+public:
+    virtual void exec() override;
+    virtual bool show(Qt::WindowFlags windowFlags,
+                          Qt::WindowModality windowModality,
+                          QWindow *parent) override;
+    virtual void hide() override;
+    virtual bool defaultNameFilterDisables() const override;
+    virtual void setDirectory(const QUrl &directory) override;
+    virtual QUrl directory() const override;
+    virtual void selectFile(const QUrl &filename) override;
+    virtual QList<QUrl> selectedFiles() const override;
+    virtual void setFilter() override;
+    virtual void selectNameFilter(const QString &filter) override;
+    virtual QString selectedNameFilter() const override;
+    static QStringList cleanFilterList(const QString &filter);
+signals:
+    void fileDone(const QUrl &);
+private:
+    void showFileDialog();
+    void onOpenDialogClosed(bool accepted, std::vector<qstdweb::File> files);
+    void onSaveDialogClosed(bool accepted, qstdweb::FileSystemFileHandle file);
+
+    QList<QUrl> m_selectedFiles;
+    QEventLoop *m_eventLoop;
+};
+
+QT_END_NAMESPACE
+
+#endif // QWASMFILEDIALOGHELPER_H
diff --git a/src/plugins/platforms/wasm/qwasmtheme.cpp b/src/plugins/platforms/wasm/qwasmtheme.cpp
index b9340f31275..b1e5c208c6c 100644
--- a/src/plugins/platforms/wasm/qwasmtheme.cpp
+++ b/src/plugins/platforms/wasm/qwasmtheme.cpp
@@ -2,6 +2,7 @@
 // SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0-only
 
 #include "qwasmtheme.h"
+#include "qwasmfiledialoghelper.h"
 #include <QtCore/qvariant.h>
 #include <QFontDatabase>
 #include <QList>
@@ -127,6 +128,18 @@ const QFont *QWasmTheme::font(Font type) const
     return nullptr;
 }
 
+bool QWasmTheme::usePlatformNativeDialog(DialogType type) const
+{
+    return (type == DialogType::FileDialog);
+}
+
+QPlatformDialogHelper *QWasmTheme::createPlatformDialogHelper(DialogType type) const
+{
+    if (type == DialogType::FileDialog)
+        return new QWasmFileDialogHelper();
+    return nullptr;
+}
+
 void QWasmTheme::onColorSchemeChange()
 {
     auto colorScheme = getColorSchemeFromMedia();
diff --git a/src/plugins/platforms/wasm/qwasmtheme.h b/src/plugins/platforms/wasm/qwasmtheme.h
index 4eaad874c76..8b8dd6ebd97 100644
--- a/src/plugins/platforms/wasm/qwasmtheme.h
+++ b/src/plugins/platforms/wasm/qwasmtheme.h
@@ -57,6 +57,9 @@ public:
     Qt::ContrastPreference contrastPreference() const override;
     QVariant themeHint(ThemeHint hint) const override;
     const QFont *font(Font type) const override;
+    bool usePlatformNativeDialog(DialogType type) const override;
+    QPlatformDialogHelper *createPlatformDialogHelper(DialogType type) const override;
+
     QFont *fixedFont = nullptr;
 
     void onColorSchemeChange();
diff --git a/src/plugins/platforms/wasm/qwasmwindow.cpp b/src/plugins/platforms/wasm/qwasmwindow.cpp
index 6e8bd46ca58..7f1dd7eb34c 100644
--- a/src/plugins/platforms/wasm/qwasmwindow.cpp
+++ b/src/plugins/platforms/wasm/qwasmwindow.cpp
@@ -925,7 +925,7 @@ bool QWasmWindow::deliverPointerEvent(const PointerEvent &event)
                    std::back_inserter(touchPointList),
                    [](const QWindowSystemInterface::TouchPoint &val) { return val; });
 
-    if (event.type == EventType::PointerUp)
+    if (event.type == EventType::PointerUp || event.type == EventType::PointerCancel)
         m_pointerIdToTouchPoints.remove(event.pointerId);
 
     return event.type == EventType::PointerCancel