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Streamline reading of js DataTransfer object
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qwasmclipboard.cpp and qwasmdrag.cpp had the same logic that read
the js DataTransfer object implemented twice with small differences.
Use a single implementation in both.

This also introduces a clearer memory ownership model in the reader
code, and fixes a potential race condition by introducing a cancellation
flag.

Removed the useless QWasmDrag type which was in essence a SimpleDrag
and made the m_drag in QWasmIntegration a smart pointer.

Fixes: QTBUG-109626
Pick-to: 6.5
Change-Id: I5b76dd3b70ab2e5a8364d9a136c970ee8d4fae9c
Reviewed-by: Morten Johan Sørvig <[email protected]>
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@mboc-qt
mboc-qt committed Jan 18, 2023
1 parent 2e8b754 commit 16bf899
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Showing 9 changed files with 231 additions and 296 deletions.
114 changes: 114 additions & 0 deletions src/corelib/platform/wasm/qstdweb.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -5,6 +5,8 @@

#include <QtCore/qcoreapplication.h>
#include <QtCore/qfile.h>
#include <QtCore/qmimedata.h>

#include <emscripten/bind.h>
#include <emscripten/emscripten.h>
#include <emscripten/html5.h>
Expand Down Expand Up @@ -368,6 +370,111 @@ bool jsHaveAsyncify() { return false; }

#endif

struct DataTransferReader
{
public:
using DoneCallback = std::function<void(std::unique_ptr<QMimeData>)>;

static std::shared_ptr<CancellationFlag> read(emscripten::val webDataTransfer,
std::function<QVariant(QByteArray)> imageReader,
DoneCallback onCompleted)
{
auto cancellationFlag = std::make_shared<CancellationFlag>();
(new DataTransferReader(std::move(onCompleted), std::move(imageReader), cancellationFlag))
->read(webDataTransfer);
return cancellationFlag;
}

~DataTransferReader() = default;

private:
DataTransferReader(DoneCallback onCompleted, std::function<QVariant(QByteArray)> imageReader,
std::shared_ptr<CancellationFlag> cancellationFlag)
: mimeData(std::make_unique<QMimeData>()),
imageReader(std::move(imageReader)),
onCompleted(std::move(onCompleted)),
cancellationFlag(cancellationFlag)
{
}

void read(emscripten::val webDataTransfer)
{
enum class ItemKind {
File,
String,
};

const auto items = webDataTransfer["items"];
for (int i = 0; i < items["length"].as<int>(); ++i) {
const auto item = items[i];
const auto itemKind =
item["kind"].as<std::string>() == "string" ? ItemKind::String : ItemKind::File;
const auto itemMimeType = QString::fromStdString(item["type"].as<std::string>());

switch (itemKind) {
case ItemKind::File: {
++fileCount;

qstdweb::File file(item.call<emscripten::val>("getAsFile"));

QByteArray fileContent(file.size(), Qt::Uninitialized);
file.stream(fileContent.data(), [this, itemMimeType, fileContent]() {
if (!fileContent.isEmpty()) {
if (itemMimeType.startsWith("image/")) {
mimeData->setImageData(imageReader(fileContent));
} else {
mimeData->setData(itemMimeType, fileContent.data());
}
}
++doneCount;
onFileRead();
});
break;
}
case ItemKind::String:
if (itemMimeType.contains("STRING", Qt::CaseSensitive)
|| itemMimeType.contains("TEXT", Qt::CaseSensitive)) {
break;
}
QString a;
const QString data = QString::fromJsString(webDataTransfer.call<emscripten::val>(
"getData", emscripten::val(itemMimeType.toStdString())));

if (!data.isEmpty()) {
if (itemMimeType == "text/html")
mimeData->setHtml(data);
else if (itemMimeType.isEmpty() || itemMimeType == "text/plain")
mimeData->setText(data); // the type can be empty
else
mimeData->setData(itemMimeType, data.toLocal8Bit());
}
break;
}
}

onFileRead();
}

void onFileRead()
{
Q_ASSERT(doneCount <= fileCount);
if (doneCount < fileCount)
return;

std::unique_ptr<DataTransferReader> deleteThisLater(this);
if (!cancellationFlag.expired())
onCompleted(std::move(mimeData));
}

int fileCount = 0;
int doneCount = 0;
std::unique_ptr<QMimeData> mimeData;
std::function<QVariant(QByteArray)> imageReader;
DoneCallback onCompleted;

std::weak_ptr<CancellationFlag> cancellationFlag;
};

} // namespace

ArrayBuffer::ArrayBuffer(uint32_t size)
Expand Down Expand Up @@ -738,6 +845,13 @@ bool haveAsyncify()
return HaveAsyncify;
}

std::shared_ptr<CancellationFlag>
readDataTransfer(emscripten::val webDataTransfer, std::function<QVariant(QByteArray)> imageReader,
std::function<void(std::unique_ptr<QMimeData>)> onDone)
{
return DataTransferReader::read(webDataTransfer, std::move(imageReader), std::move(onDone));
}

} // namespace qstdweb

QT_END_NAMESPACE
21 changes: 18 additions & 3 deletions src/corelib/platform/wasm/qstdweb_p.h
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Expand Up @@ -16,15 +16,22 @@
//

#include <private/qglobal_p.h>
#include <QtCore/qglobal.h>
#include "QtCore/qhash.h"

#include <emscripten/val.h>

#include <cstdint>
#include <functional>
#include "initializer_list"
#include <QtCore/qglobal.h>
#include "QtCore/qhash.h"
#include <initializer_list>
#include <memory>
#include <string>
#include <utility>

QT_BEGIN_NAMESPACE

class QMimeData;

namespace qstdweb {
extern const char makeContextfulPromiseFunctionName[];

Expand Down Expand Up @@ -195,6 +202,14 @@ namespace qstdweb {
}

bool haveAsyncify();

struct CancellationFlag
{
};

std::shared_ptr<CancellationFlag>
readDataTransfer(emscripten::val webObject, std::function<QVariant(QByteArray)> imageReader,
std::function<void(std::unique_ptr<QMimeData>)> onDone);
}

QT_END_NAMESPACE
Expand Down
116 changes: 25 additions & 91 deletions src/plugins/platforms/wasm/qwasmclipboard.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -2,20 +2,18 @@
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0-only

#include "qwasmclipboard.h"
#include "qwasmdom.h"
#include "qwasmwindow.h"

#include <private/qstdweb_p.h>

#include <emscripten.h>
#include <emscripten/html5.h>
#include <emscripten/bind.h>
#include <emscripten/val.h>

#include <QCoreApplication>
#include <qpa/qwindowsysteminterface.h>
#include <QBuffer>
#include <QString>

#include <emscripten/val.h>

QT_BEGIN_NAMESPACE
using namespace emscripten;

Expand Down Expand Up @@ -67,93 +65,29 @@ static void qClipboardCopyTo(val event)
commonCopyEvent(event);
}

static void qWasmClipboardPaste(QMimeData *mData)
{
// Persist clipboard data so that the app can read it when handling the CTRL+V
QWasmIntegration::get()->clipboard()->
QPlatformClipboard::setMimeData(mData, QClipboard::Clipboard);

QWindowSystemInterface::handleKeyEvent(
0, QEvent::KeyPress, Qt::Key_V, Qt::ControlModifier, "V");
}

static void qClipboardPasteTo(val dataTransfer)
static void qClipboardPasteTo(val event)
{
enum class ItemKind {
File,
String,
};

struct Data
{
std::unique_ptr<QMimeData> data;
int fileCount = 0;
int doneCount = 0;
};

auto sharedData = std::make_shared<Data>();
sharedData->data = std::make_unique<QMimeData>();

auto continuation = [sharedData]() {
Q_ASSERT(sharedData->doneCount <= sharedData->fileCount);
if (sharedData->doneCount < sharedData->fileCount)
return;

if (!sharedData->data->formats().isEmpty())
qWasmClipboardPaste(sharedData->data.release());
};

const val clipboardData = dataTransfer["clipboardData"];
const val items = clipboardData["items"];
for (int i = 0; i < items["length"].as<int>(); ++i) {
const val item = items[i];
const auto itemKind =
item["kind"].as<std::string>() == "string" ? ItemKind::String : ItemKind::File;
const auto itemMimeType = QString::fromStdString(item["type"].as<std::string>());

switch (itemKind) {
case ItemKind::File: {
++sharedData->fileCount;

qstdweb::File file(item.call<emscripten::val>("getAsFile"));

QByteArray fileContent(file.size(), Qt::Uninitialized);
file.stream(fileContent.data(),
[continuation, itemMimeType, fileContent, sharedData]() {
if (!fileContent.isEmpty()) {
if (itemMimeType.startsWith("image/")) {
QImage image;
image.loadFromData(fileContent, nullptr);
sharedData->data->setImageData(image);
} else {
sharedData->data->setData(itemMimeType, fileContent.data());
}
}
++sharedData->doneCount;
continuation();
});
break;
}
case ItemKind::String:
if (itemMimeType.contains("STRING", Qt::CaseSensitive)
|| itemMimeType.contains("TEXT", Qt::CaseSensitive)) {
break;
}
const QString data = QString::fromJsString(
clipboardData.call<val>("getData", val(itemMimeType.toStdString())));

if (!data.isEmpty()) {
if (itemMimeType == "text/html")
sharedData->data->setHtml(data);
else if (itemMimeType.isEmpty() || itemMimeType == "text/plain")
sharedData->data->setText(data); // the type can be empty
else
sharedData->data->setData(itemMimeType, data.toLocal8Bit());
}
break;
}
}
continuation();
event.call<void>("preventDefault"); // prevent browser from handling drop event

static std::shared_ptr<qstdweb::CancellationFlag> readDataCancellation = nullptr;
readDataCancellation = qstdweb::readDataTransfer(
event["clipboardData"],
[](QByteArray fileContent) {
QImage image;
image.loadFromData(fileContent, nullptr);
return image;
},
[event](std::unique_ptr<QMimeData> data) {
if (data->formats().isEmpty())
return;

// Persist clipboard data so that the app can read it when handling the CTRL+V
QWasmIntegration::get()->clipboard()->QPlatformClipboard::setMimeData(
data.release(), QClipboard::Clipboard);

QWindowSystemInterface::handleKeyEvent(0, QEvent::KeyPress, Qt::Key_V,
Qt::ControlModifier, "V");
});
}

EMSCRIPTEN_BINDINGS(qtClipboardModule) {
Expand Down
5 changes: 5 additions & 0 deletions src/plugins/platforms/wasm/qwasmdom.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -3,14 +3,18 @@

#include "qwasmdom.h"

#include <QMimeData>
#include <QtCore/qpoint.h>
#include <QtCore/qrect.h>
#include <QtGui/qimage.h>
#include <private/qstdweb_p.h>

#include <utility>

QT_BEGIN_NAMESPACE

namespace dom {

void syncCSSClassWith(emscripten::val element, std::string cssClassName, bool flag)
{
if (flag) {
Expand All @@ -31,6 +35,7 @@ QPoint mapPoint(emscripten::val source, emscripten::val target, const QPoint &po
auto offset = sourceBoundingRect.topLeft() - targetBoundingRect.topLeft();
return (point + offset).toPoint();
}

} // namespace dom

QT_END_NAMESPACE
2 changes: 2 additions & 0 deletions src/plugins/platforms/wasm/qwasmdom.h
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Original file line number Diff line number Diff line change
Expand Up @@ -8,6 +8,8 @@

#include <emscripten/val.h>

#include <functional>
#include <memory>
#include <string>

QT_BEGIN_NAMESPACE
Expand Down
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