AuroraMiddleware/qt5base-lts
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

wasm: Move Blob creation code to qstdweb

Browse Source 
Add Uint8Array::copyFrom() and Blob::copyFrom(), which
constructs JS data containers with content copied from
the C heap.

These should not be confused with e.g. the Uint8Array(buffer, size)
constructor, which creates a Uint8Array which references
content on the heap, without making a copy.

Change-Id: Id7d25d8044ee3914d74698e5a15c93226568eaf3
Reviewed-by: David Skoland <david.skoland@qt.io>
Reviewed-by: Lorn Potter <lorn.potter@gmail.com>
This commit is contained in:
Morten Johan Sørvig 2021-11-09 13:14:41 +01:00
parent a0f9aef11b
commit 24134d5193
3 changed files with 56 additions and 21 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

45
src/corelib/platform/wasm/qstdweb.cpp
View File

@ -49,6 +49,11 @@ namespace qstdweb {
typedef double uint53_t; // see Number.MAX_SAFE_INTEGER
ArrayBuffer::ArrayBuffer(uint32_t size)
{
m_arrayBuffer = emscripten::val::global("ArrayBuffer").new_(size);
}
ArrayBuffer::ArrayBuffer(const emscripten::val &arrayBuffer)
:m_arrayBuffer(arrayBuffer)
{
@ -74,6 +79,23 @@ uint32_t Blob::size() const
return m_blob["size"].as<uint32_t>();
}
// Copies content from the given buffer into a Blob object
Blob Blob::copyFrom(const char *buffer, uint32_t size)
{
Uint8Array contentCopy = Uint8Array::copyFrom(buffer, size);
emscripten::val contentArray = emscripten::val::array();
contentArray.call<void>("push", contentCopy.m_uint8Array);
emscripten::val type = emscripten::val::object();
type.set("type","application/octet-stream");
return Blob(emscripten::val::global("Blob").new_(contentArray, type));
}
emscripten::val Blob::val()
{
return m_blob;
}
File::File(const emscripten::val &file)
:m_file(file)
{
@ -191,30 +213,41 @@ Uint8Array Uint8Array::heap()
return Uint8Array(heap_());
}
// Constructs a Uint8Array which references the given emscripten::val, which must contain a JS Unit8Array
Uint8Array::Uint8Array(const emscripten::val &uint8Array)
: m_uint8Array(uint8Array)
{
}
// Constructs a Uint8Array which references an ArrayBuffer
Uint8Array::Uint8Array(const ArrayBuffer &buffer)
: m_uint8Array(Uint8Array::constructor_().new_(buffer.m_arrayBuffer))
{
}
// Constructs a Uint8Array which references a view into an ArrayBuffer
Uint8Array::Uint8Array(const ArrayBuffer &buffer, uint32_t offset, uint32_t length)
: m_uint8Array(Uint8Array::constructor_().new_(buffer.m_arrayBuffer, offset, length))
{
}
Uint8Array::Uint8Array(char *buffer, uint32_t size)
// Constructs a Uint8Array which references an area on the heap.
Uint8Array::Uint8Array(const char *buffer, uint32_t size)
:m_uint8Array(Uint8Array::constructor_().new_(Uint8Array::heap().buffer().m_arrayBuffer, uint32_t(buffer), size))
{
}
// Constructs a Uint8Array which allocates and references a new ArrayBuffer with the given size.
Uint8Array::Uint8Array(uint32_t size)
: m_uint8Array(Uint8Array::constructor_().new_(size))
{
}
ArrayBuffer Uint8Array::buffer() const
{
return ArrayBuffer(m_uint8Array["buffer"]);
@ -230,16 +263,26 @@ void Uint8Array::set(const Uint8Array &source)
m_uint8Array.call<void>("set", source.m_uint8Array); // copies source content
}
// Copies the Uint8Array conent to a destination on the heap
void Uint8Array::copyTo(char *destination) const
{
Uint8Array(destination, length()).set(*this);
}
// Copies the Uint8Array conent to a destination on the heap
void Uint8Array::copy(char *destination, const Uint8Array &source)
{
Uint8Array(destination, source.length()).set(source);
}
// Copies content from a source on the heap to a new Uint8Array object
Uint8Array Uint8Array::copyFrom(const char *buffer, uint32_t size)
{
Uint8Array contentCopy(size);
contentCopy.set(Uint8Array(buffer, size));
return contentCopy;
}
emscripten::val Uint8Array::heap_()
{
return emscripten::val::module_property("HEAPU8");

8
src/corelib/platform/wasm/qstdweb_p.h
View File

@ -73,6 +73,7 @@ namespace qstdweb {
class ArrayBuffer {
public:
explicit ArrayBuffer(uint32_t size);
explicit ArrayBuffer(const emscripten::val &arrayBuffer);
uint32_t byteLength() const;
@ -85,6 +86,8 @@ namespace qstdweb {
public:
explicit Blob(const emscripten::val &blob);
uint32_t size() const;
static Blob copyFrom(const char *buffer, uint32_t size);
emscripten::val val();
private:
friend class FileReader;
@ -140,8 +143,9 @@ namespace qstdweb {
static Uint8Array heap();
explicit Uint8Array(const emscripten::val &uint8Array);
explicit Uint8Array(const ArrayBuffer &buffer);
explicit Uint8Array(uint32_t size);
Uint8Array(const ArrayBuffer &buffer, uint32_t offset, uint32_t length);
Uint8Array(char *buffer, uint32_t size);
Uint8Array(const char *buffer, uint32_t size);
ArrayBuffer buffer() const;
uint32_t length() const;
@ -149,7 +153,9 @@ namespace qstdweb {
void copyTo(char *destination) const;
static void copy(char *destination, const Uint8Array &source);
static Uint8Array copyFrom(const char *buffer, uint32_t size);
private:
friend class Blob;
static emscripten::val heap_();
static emscripten::val constructor_();
emscripten::val m_uint8Array = emscripten::val::undefined();

24
src/gui/platform/wasm/qwasmlocalfileaccess.cpp
View File

@ -129,27 +129,13 @@ void openFile(const std::string &accept,
void saveFile(const char *content, size_t size, const std::string &fileNameHint)
{
// Save a file by creating programmatically clicking a download
// link to an object url to a Blob containing the file content.
// File content is copied once, so that the passed in content
// buffer can be released as soon as this function returns - we
// don't know for how long the browser will retain the TypedArray
// view used to create the Blob.
// link to an object url to a Blob containing a copy of the file
// content. The copy is made so that the passed in content buffer
// can be released as soon as this function returns.
qstdweb::Blob contentBlob = qstdweb::Blob::copyFrom(content, size);
emscripten::val document = emscripten::val::global("document");
emscripten::val window = emscripten::val::global("window");
emscripten::val fileContentView = emscripten::val(emscripten::typed_memory_view(size, content));
emscripten::val fileContentCopy = emscripten::val::global("ArrayBuffer").new_(size);
emscripten::val fileContentCopyView = emscripten::val::global("Uint8Array").new_(fileContentCopy);
fileContentCopyView.call<void>("set", fileContentView);
emscripten::val contentArray = emscripten::val::array();
contentArray.call<void>("push", fileContentCopyView);
emscripten::val type = emscripten::val::object();
type.set("type","application/octet-stream");
emscripten::val contentBlob = emscripten::val::global("Blob").new_(contentArray, type);
emscripten::val contentUrl = window["URL"].call<emscripten::val>("createObjectURL", contentBlob);
emscripten::val contentUrl = window["URL"].call<emscripten::val>("createObjectURL", contentBlob.val());
emscripten::val contentLink = document.call<emscripten::val>("createElement", std::string("a"));
contentLink.set("href", contentUrl);
contentLink.set("download", fileNameHint);