wasm: add support for drag into browser window

Drag and drop into the browser will work.
Drag and drop out of the browser will not.

Fixes: QTBUG-102242
Change-Id: Id9981ab6f9514535e1409bec18068790833a67a6
Reviewed-by: Morten Johan Sørvig <[email protected]>

src/plugins/platforms/wasm/CMakeLists.txt

@@ -27,6 +27,7 @@ qt_internal_add_plugin(QWasmIntegrationPlugin
         qwasmtheme.cpp qwasmtheme.h
         qwasmwindow.cpp qwasmwindow.h
         qwasminputcontext.cpp qwasminputcontext.h
+        qwasmdrag.cpp qwasmdrag.h
     DEFINES
         QT_EGL_NO_X11
         QT_NO_FOREACH

src/plugins/platforms/wasm/qwasmcompositor.cpp

@@ -136,6 +136,11 @@ void QWasmCompositor::deregisterEventHandlers()
     emscripten_set_touchend_callback(canvasSelector.constData(),  0, 0, NULL);
     emscripten_set_touchmove_callback(canvasSelector.constData(),  0, 0, NULL);
     emscripten_set_touchcancel_callback(canvasSelector.constData(),  0, 0, NULL);
+
+    val canvas = screen()->canvas();
+    canvas.call<void>("removeEventListener",
+        std::string("drop"),
+        val::module_property("qtDrop"), val(true));
 }
 
 void QWasmCompositor::destroy()
@@ -193,6 +198,13 @@ void QWasmCompositor::initEventHandlers()
     emscripten_set_touchend_callback(canvasSelector.constData(), (void *)this, 1, &touchCallback);
     emscripten_set_touchmove_callback(canvasSelector.constData(), (void *)this, 1, &touchCallback);
     emscripten_set_touchcancel_callback(canvasSelector.constData(), (void *)this, 1, &touchCallback);
+
+    val canvas = screen()->canvas();
+    canvas.call<void>("addEventListener",
+        std::string("drop"),
+        val::module_property("qtDrop"), val(true));
+    canvas.set("data-qtdropcontext", // ? unique
+                       emscripten::val(quintptr(reinterpret_cast<void *>(screen()))));
 }
 
 void QWasmCompositor::setEnabled(bool enabled)
@@ -1145,7 +1157,6 @@ bool QWasmCompositor::processMouse(int eventType, const EmscriptenMouseEvent *mo
 
     if (eventType == EMSCRIPTEN_EVENT_MOUSEDOWN && !accepted)
         QGuiApplicationPrivate::instance()->closeAllPopups();
-
     return accepted;
 }
 

src/plugins/platforms/wasm/qwasmdrag.cpp

@@ -0,0 +1,236 @@
+/****************************************************************************
+**
+** Copyright (C) 2022 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the plugins of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:GPL$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 3 or (at your option) any later version
+** approved by the KDE Free Qt Foundation. The licenses are as published by
+** the Free Software Foundation and appearing in the file LICENSE.GPL3
+** included in the packaging of this file. Please review the following
+** information to ensure the GNU General Public License requirements will
+** be met: https://www.gnu.org/licenses/gpl-3.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include "qwasmdrag.h"
+
+#include <iostream>
+#include <QMimeDatabase>
+
+#include <emscripten.h>
+#include <emscripten/html5.h>
+#include <emscripten/val.h>
+#include <emscripten/bind.h>
+#include <private/qstdweb_p.h>
+#include <qpa/qwindowsysteminterface.h>
+#include <private/qsimpledrag_p.h>
+#include "qwasmcompositor.h"
+#include "qwasmeventtranslator.h"
+#include <QtCore/QEventLoop>
+#include <QMimeData>
+#include <private/qshapedpixmapdndwindow_p.h>
+
+QT_BEGIN_NAMESPACE
+
+using namespace emscripten;
+
+static void getTextPlainCallback(val m_string)
+{
+    QWasmDrag *thisDrag = static_cast<QWasmDrag*>(QWasmIntegration::get()->drag());
+    thisDrag->m_mimeData->setText(QString::fromStdString(m_string.as<std::string>()));
+    thisDrag->qWasmDrop();
+}
+
+static void getTextUrlCallback(val m_string)
+{
+    QWasmDrag *thisDrag = static_cast<QWasmDrag*>(QWasmIntegration::get()->drag());
+    thisDrag->m_mimeData->setData(QStringLiteral("text/uri-list"),
+                                          QByteArray::fromStdString(m_string.as<std::string>()));
+
+    thisDrag->qWasmDrop();
+}
+
+static void getTextHtmlCallback(val m_string)
+{
+    QWasmDrag *thisDrag = static_cast<QWasmDrag*>(QWasmIntegration::get()->drag());
+    thisDrag->m_mimeData->setHtml(QString::fromStdString(m_string.as<std::string>()));
+
+    thisDrag->qWasmDrop();
+}
+
+static void dropEvent(val event)
+{
+    // someone dropped a file into the browser window
+    // event is dataTransfer object
+    // if drop event from outside browser, we do not get any mouse release, maybe mouse move
+    // after the drop event
+
+    // data-context thing was not working here :(
+    QWasmDrag *wasmDrag = static_cast<QWasmDrag*>(QWasmIntegration::get()->drag());
+
+    wasmDrag->m_wasmScreen =
+            reinterpret_cast<QWasmScreen*>(event["target"]["data-qtdropcontext"].as<quintptr>());
+
+    wasmDrag->m_mouseDropPoint = QPoint(event["x"].as<int>(), event["y"].as<int>());
+    if (wasmDrag->m_mimeData)
+        delete wasmDrag->m_mimeData;
+    wasmDrag->m_mimeData = new QMimeData;
+    int button = event["button"].as<int>();
+    wasmDrag->m_qButton = QWasmEventTranslator::translateMouseButton(button);
+
+    wasmDrag->m_keyModifiers = Qt::NoModifier;
+    if (event["altKey"].as<bool>())
+        wasmDrag->m_keyModifiers |= Qt::AltModifier;
+    if (event["ctrlKey"].as<bool>())
+        wasmDrag->m_keyModifiers |= Qt::ControlModifier;
+    if (event["metaKey"].as<bool>())
+        wasmDrag->m_keyModifiers |= Qt::MetaModifier;
+
+    event.call<void>("preventDefault"); // prevent browser from handling drop event
+
+    std::string dEffect = event["dataTransfer"]["dropEffect"].as<std::string>();
+
+    wasmDrag->m_dropActions = Qt::IgnoreAction;
+    if (dEffect == "copy")
+         wasmDrag->m_dropActions = Qt::CopyAction;
+    if (dEffect == "move")
+         wasmDrag->m_dropActions = Qt::MoveAction;
+    if (dEffect == "link")
+         wasmDrag->m_dropActions = Qt::LinkAction;
+
+    val dt = event["dataTransfer"]["items"]["length"];
+
+    val typesCount = event["dataTransfer"]["types"]["length"];
+
+    // handle mimedata
+    int count = dt.as<int>();
+    wasmDrag->m_mimeTypesCount = count;
+    // kind is file type: file or string
+    for (int i=0; i < count; i++) {
+        val item = event["dataTransfer"]["items"][i];
+        val kind = item["kind"];
+        val fileType = item["type"];
+
+        if (kind.as<std::string>() == "file") {
+            val m_file = item.call<val>("getAsFile");
+            if (m_file.isUndefined()) {
+                continue;
+            }
+
+            qstdweb::File file(m_file);
+
+            QString mimeFormat = QString::fromStdString(file.type());
+            QByteArray fileContent;
+            fileContent.resize(file.size());
+
+            file.stream(fileContent.data(), [=]() {
+                if (!fileContent.isEmpty()) {
+
+                    if (mimeFormat.contains("image")) {
+                        QImage image;
+                        image.loadFromData(fileContent, nullptr);
+                        wasmDrag->m_mimeData->setImageData(image);
+                    } else {
+                        wasmDrag->m_mimeData->setData(mimeFormat, fileContent.data());
+                    }
+                     wasmDrag->qWasmDrop();
+                }
+            });
+
+        } else { // string
+
+            if (fileType.as<std::string>() == "text/uri-list"
+                    || fileType.as<std::string>() == "text/x-moz-url") {
+                item.call<val>("getAsString", val::module_property("qtgetTextUrl"));
+            } else if (fileType.as<std::string>() == "text/html") {
+                item.call<val>("getAsString", val::module_property("qtgetTextHtml"));
+            } else { // handle everything else here as plain text
+                item.call<val>("getAsString", val::module_property("qtgetTextPlain"));
+            }
+        }
+    }
+}
+
+EMSCRIPTEN_BINDINGS(drop_module) {
+    function("qtDrop", &dropEvent);
+    function("qtgetTextPlain", &getTextPlainCallback);
+    function("qtgetTextUrl", &getTextUrlCallback);
+    function("qtgetTextHtml", &getTextHtmlCallback);
+}
+
+
+QWasmDrag::QWasmDrag()
+{
+    init();
+}
+
+QWasmDrag::~QWasmDrag()
+{
+    if (m_mimeData)
+        delete m_mimeData;
+}
+
+void QWasmDrag::init()
+{
+}
+
+void QWasmDrag::drop(const QPoint &globalPos, Qt::MouseButtons b, Qt::KeyboardModifiers mods)
+{
+    QSimpleDrag::drop(globalPos, b, mods);
+}
+
+void QWasmDrag::move(const QPoint &globalPos, Qt::MouseButtons b, Qt::KeyboardModifiers mods)
+{
+    QSimpleDrag::move(globalPos, b, mods);
+}
+
+void QWasmDrag::qWasmDrop()
+{
+    // collect mime
+    QWasmDrag *thisDrag = static_cast<QWasmDrag*>(QWasmIntegration::get()->drag());
+
+    if (thisDrag->m_mimeTypesCount != thisDrag->m_mimeData->formats().size())
+        return; // keep collecting mimetypes
+
+    // start drag enter
+    QWindowSystemInterface::handleDrag(thisDrag->m_wasmScreen->topLevelAt(thisDrag->m_mouseDropPoint),
+                                       thisDrag->m_mimeData,
+                                       thisDrag->m_mouseDropPoint,
+                                       thisDrag->m_dropActions,
+                                       thisDrag->m_qButton,
+                                       thisDrag->m_keyModifiers);
+
+    // drag drop
+    QWindowSystemInterface::handleDrop(thisDrag->m_wasmScreen->topLevelAt(thisDrag->m_mouseDropPoint),
+                                       thisDrag->m_mimeData,
+                                       thisDrag->m_mouseDropPoint,
+                                       thisDrag->m_dropActions,
+                                       thisDrag->m_qButton,
+                                       thisDrag->m_keyModifiers);
+
+    // drag leave
+    QWindowSystemInterface::handleDrag(thisDrag->m_wasmScreen->topLevelAt(thisDrag->m_mouseDropPoint),
+                                       nullptr,
+                                       QPoint(),
+                                       Qt::IgnoreAction, { }, { });
+
+    thisDrag->m_mimeData->clear();
+    thisDrag->m_mimeTypesCount = 0;
+}
+
+QT_END_NAMESPACE

src/plugins/platforms/wasm/qwasmdrag.h

@@ -0,0 +1,69 @@
+/****************************************************************************
+**
+** Copyright (C) 2022 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the plugins of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:GPL$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 3 or (at your option) any later version
+** approved by the KDE Free Qt Foundation. The licenses are as published by
+** the Free Software Foundation and appearing in the file LICENSE.GPL3
+** included in the packaging of this file. Please review the following
+** information to ensure the GNU General Public License requirements will
+** be met: https://www.gnu.org/licenses/gpl-3.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#ifndef QWASMDRAG_H
+#define QWASMDRAG_H
+
+#include <qpa/qplatformdrag.h>
+#include <private/qsimpledrag_p.h>
+#include <private/qstdweb_p.h>
+#include <QDrag>
+#include "qwasmscreen.h"
+
+QT_REQUIRE_CONFIG(draganddrop);
+
+QT_BEGIN_NAMESPACE
+
+class QWasmDrag : public QSimpleDrag
+{
+public:
+
+    QWasmDrag();
+    ~QWasmDrag();
+
+    void drop(const QPoint &globalPos, Qt::MouseButtons b, Qt::KeyboardModifiers mods) override;
+    void move(const QPoint &globalPos, Qt::MouseButtons b, Qt::KeyboardModifiers mods) override;
+
+    Qt::MouseButton m_qButton;
+    QPoint m_mouseDropPoint;
+    QFlags<Qt::KeyboardModifier> m_keyModifiers;
+    Qt::DropActions m_dropActions;
+    QWasmScreen *m_wasmScreen = nullptr;
+    int m_mimeTypesCount = 0;
+    QMimeData *m_mimeData = nullptr;
+    void qWasmDrop();
+
+private:
+    void init();
+};
+
+
+QT_END_NAMESPACE
+
+#endif // QWASMDRAG_H

src/plugins/platforms/wasm/qwasmintegration.cpp

@@ -57,7 +57,7 @@
 
 // this is where EGL headers are pulled in, make sure it is last
 #include "qwasmscreen.h"
-
+#include <private/qsimpledrag_p.h>
 using namespace emscripten;
 QT_BEGIN_NAMESPACE
 
@@ -176,6 +176,7 @@ QWasmIntegration::QWasmIntegration()
         visualViewport.call<void>("addEventListener", val("resize"),
                           val::module_property("qtResizeAllScreens"));
     }
+    m_drag = new QWasmDrag();
 }
 
 QWasmIntegration::~QWasmIntegration()
@@ -192,6 +193,7 @@ QWasmIntegration::~QWasmIntegration()
     delete m_desktopServices;
     if (m_platformInputContext)
         delete m_platformInputContext;
+    delete m_drag;
 
     for (const auto &elementAndScreen : m_screens)
         QWindowSystemInterface::handleScreenRemoved(elementAndScreen.second);
@@ -374,4 +376,11 @@ quint64 QWasmIntegration::getTimestamp()
     return emscripten_performance_now();
 }
 
+#if QT_CONFIG(draganddrop)
+QPlatformDrag *QWasmIntegration::drag() const
+{
+    return m_drag;
+}
+#endif // QT_CONFIG(draganddrop)
+
 QT_END_NAMESPACE