I have found this piece of code showing how to call a blueprint function from C++:
UFUnction* Func = Obj->GetClass()->FindFunction(FName("FuncName"));
if(Func == nullptr){return;}
FStructOnScope FuncParam(Func);
UProperty* ReturnProp = nullptr;
for (TFieldIterator<UProperty> It(Func); It; ++It)
{
UProperty* Prop = *It;
if (Prop->HasAnyPropertyFlags(CPF_ReturnParm))
{
ReturnProp = Prop;
}
else
{
//FillParam here
}
}
Obj->ProcessEvent(Func, FuncParam.GetStructMemory());
But… I don’t know how to //Fillparam here.
How can I fill the FuncParam with the parameters that I need to pass?
Related
So I have a vector of objects
vector<Module*> moduleVector;
and I need to iterate through it and compare an attribute from the object to another attribute I'm pulling from a text file
I'm using an ifstream and getLine() to store the element that needs to be compared to the object's attribute (fileD is the opened file, markModId is the string variable)
getline(fileD, markModId, ' ');
But I am unsure of how I can refer to the object's attributes in an iterator. So my question is,
how do I compare the attribute from the file to the object using an iterator?
For reference here is my object constructor (id is the attribute I want to compare)
Module::Module(string id, string title, string lecturer, int
courseworkWeight)
{
code = id;
name = title;
lect = lecturer;
cwWeight = courseworkWeight;
exMark = 0; //ex mark initialised as 0
/*
Map to store coursework marks
*/
map<string, float> CWmarks;
//cwMarks.clear(); //cw marks map cleared
//create a map that stores
}
And exMark is the attribute that needs to be added to the object. All attributes in the Module constructor are private.
How do I compare the attribute from the file to the object using an
iterator?
Short answer: Suppose you have an iterator std::vector<Module*>::iterator iter you can access the public members of Module class like:
(*iter)->/*public member*/;
Long answer: First of all, you need a getter for private member id and one setter for exMark, by which you can get the id of each Module and compare to the id from the file and then set its exMark to some value.
std::string getId()const { return code; }
void setExMark(const double newMark) { exMark = newMark; }
If you want to change the first true instance of Module, you can use std::find_if for finding the Module:
std::string idFromFile = "two";
auto Condition = [&idFromFile](Module* element){ return element->getId() == idFromFile; };
auto iter = std::find_if(moduleVector.begin(), moduleVector.end(), Condition);
if(iter != moduleVector.end())
(*iter)->setExMark(10.0); // see this
// ^^^^^^^^^
See a sample code here
For multiple instances you can do:
for(auto iter = moduleVector.begin(); iter != moduleVector.end(); ++iter)
if ( (*iter)->getId() == idFromFile)
(*iter)->setExMark(10.0);
Note: In modern C++ you can use smart pointers, instead of raw pointers, which will delete the objects automatically as it goes out of scope.
Simply dereference the iterator to access its Module* pointer, then you can access the object using operator-> however you want, eg:
for (std::vector<Module*>::iterator iter = moduleVector.begin(), end = moduleVector.end(); iter != end; ++iter)
{
Module *m = *iter;
if (m->code == markModId)
m->exMark = ...;
}
Or, if you are using C++11 or later, let the compiler handle the iterator for you:
for (Module *m : moduleVector)
{
if (m->code == markModId)
m->exMark = ...;
}
Or, use a lambda with one of the standard iteration algorithms, eg:
std::for_each(moduleVector.begin(), moduleVector.end(),
[&](Module *m)
{
if (m->code == markModId)
m->exMark = ...;
}
);
If you are only interested in updating 1 Module, then break the loop when the the desired Module is found:
for (std::vector<Module*>::iterator iter = moduleVector.begin(), end = moduleVector.end(); iter != end; ++iter)
{
Module *m = *iter;
if (m->code == markModId)
{
m->exMark = ...;
break; // <-- add this
}
}
for (Module *m : moduleVector)
{
if (m->code == markModId)
{
m->exMark = ...;
break; // <-- add this
}
}
auto iter = std::find_if(moduleVector.begin(), moduleVector.end(),
[&](Module *m) { return (m->code == markModId); });
if (iter != moduleVector.end())
{
Module *m = *iter;
m->exMark = ...;
}
I am new to C++. I've wrote code in C# and PHP.Since I am using Unreal engine I am trying to learn C++. For my project I need to make a screenshot in-game and show it immediately so I want to get it as a texture.
I made a blueprint node which calls this function i've made:
void UMyBlueprintFunctionLibrary::TakeScreenshot()
{
FScreenshotRequest::RequestScreenshot(true);
if (GEngine)
GEngine->AddOnScreenDebugMessage(-1, 15.0f, FColor::Red, "Tried to take screenshot");
}
When I hover my mouse above RequestScreenshot I see the following pop-up:
"Screenshot can be read from memory by subscribing to the viewsport OnScreenshopCaptured delegate"
So that is what I try to do but I have no idea how I looked up this:
https://docs.unrealengine.com/latest/INT/API/Runtime/Engine/Engine/UGameViewportClient/OnScreenshotCaptured/
Can someone tell me how to implement this and how you see/know how to implement it?
I have an alternative, no delegate, but FRenderTarget::ReadPixel() to some buffer you allocated, by implementing your own UGameViewportClient (inherit it), and overriding Draw() function.
I'll show the essential codes, but not complete.
void UMyGameViewportClient::Draw(FViewport* Viewport, FCanvas* SceneCanvas)
{
Super::Draw(Viewport, SceneCanvas);
if (any_condition_you_need) {
CaptureFrame();
}
}
void UMyGameViewportClient::CaptureFrame()
{
if (!Viewport) {
return;
}
if (ViewportSize.X == 0 || ViewportSize.Y == 0) {
return;
}
ColorBuffer.Empty(); // Declare this in header as TArray<FColor>
if (!Viewport->ReadPixels(ColorBuffer, FReadSurfaceDataFlags(),
FIntRect(0, 0, ViewportSize.X, ViewportSize.Y)))
{
return;
}
SaveThumbnailImage();
}
void UMyGameViewportClient::SaveThumbnailImage()
{
IImageWrapperModule& wrappermodule = FModuleManager::LoadModuleChecked<IImageWrapperModule>(FName("ImageWrapper"));
auto wrapper_ptr = wrappermodule.CreateImageWrapper(EImageFormat::PNG);
for (int i = 0; i < ColorBuffer.Num(); i++)
{
auto ptr = &ColorBuffer[i];
auto r = ptr->R;
auto b = ptr->B;
ptr->R = b;
ptr->B = r;
ptr->A = 255;
} // not necessary, if you like bgra, just change the following function argument to ERGBFormat::BGRA
wrapper_ptr->SetRaw(&ColorBuffer[0], ColorBuffer.Num() * 4,
ViewportSize.X, ViewportSize.Y, ERGBFormat::RGBA, 8);
FFileHelper::SaveArrayToFile(wrapper_ptr->GetCompressed(), *ThumbnailFile);
}
I'm having some trouble with the following method and I need some help trying to figure out what I am doing wrong.
I want to return a reference to a Value in a document. I am passing the Document from outside the function so that when I read a json file into it I don't "lose it".
const rapidjson::Value& CTestManager::GetOperations(rapidjson::Document& document)
{
const Value Null(kObjectType);
if (m_Tests.empty())
return Null;
if (m_current > m_Tests.size() - 1)
return Null;
Test& the_test = m_Tests[m_current];
CMyFile fp(the_test.file.c_str()); // non-Windows use "r"
if (!fp.is_open())
return Null;
u32 operations_count = 0;
CFileBuffer json(fp);
FileReadStream is(fp.native_handle(), json, json.size());
if (document.ParseInsitu<kParseCommentsFlag>(json).HasParseError())
{
(...)
}
else
{
if (!document.IsObject())
{
(...)
}
else
{
auto tests = document.FindMember("td_tests");
if (tests != document.MemberEnd())
{
for (SizeType i = 0; i < tests->value.Size(); i++)
{
const Value& test = tests->value[i];
if (test["id"].GetInt() == the_test.id)
{
auto it = test.FindMember("operations");
if (it != test.MemberEnd())
{
//return it->value; is this legitimate?
return test["operations"];
}
return Null;
}
}
}
}
}
return Null;
}
Which I am calling like this:
Document document;
auto operations = TestManager().GetOperations(document);
When I inspect the value of test["operations"] inside the function I can see everything I would expect (debug code removed from the abode code).
When I inspect the returned value outside the function I can see that it's an array (which I expect). the member count int the array is correct as well, but when print it out, I only see garbage instead.
When I "print" the Value to a string inside the methods, I get what I expect (i.e. a well formated json), but when I do it outside all keys show up as "IIIIIIII" and values that aren't strings show up correctly.
rapidjson::StringBuffer strbuf2;
rapidjson::PrettyWriter<rapidjson::StringBuffer> writer2(strbuf2);
ops->Accept(writer2);
As this didn't work I decided to change the method to receive a Value as a parameter and do a deep copy into it like this
u32 CTestManager::GetOperationsEx(rapidjson::Document& document, rapidjson::Value& operations)
{
(...)
if (document.ParseInsitu<kParseCommentsFlag>(json).HasParseError())
{
(...)
}
else
{
if (!document.IsObject())
{
(...)
}
else
{
auto tests = document.FindMember("tests");
if (tests != document.MemberEnd())
{
for (SizeType i = 0; i < tests->value.Size(); i++)
{
const Value& test = tests->value[i];
if (test["id"].GetInt() == the_test.id)
{
const Value& opv = test["operations"];
Document::AllocatorType& allocator = document.GetAllocator();
operations.CopyFrom(opv, allocator); //would Swap work?
return operations.Size();
}
}
}
}
}
return 0;
}
Which I'm calling like this:
Document document;
Value operations(kObjectType);
u32 count = TestManager().GetOperationsEx(document, operations);
But... I get same thing!!!!
I know that it's going to be something silly but I can't put my hands on it!
Any ideas?
The problem in this case lies with the use of ParseInSitu. When any of the GetOperations exist the CFileBuffer loses scope and is cleaned up. Because the json is being parsed in-situ when the buffer to the file goes, so goes the data.
How to correct return created std::list through function argument? Now, I try so:
bool DatabaseHandler::tags(std::list<Tag> *tags)
{
QString sql = "SELECT * FROM " + Tag::TABLE_NAME + ";";
QSqlQueryModel model;
model.setQuery(sql);
if(model.lastError().type() != QSqlError::NoError) {
log(sql);
tags = NULL;
return false;
}
const int count = model.rowCount();
if(count > 0)
tags = new std::list<Tag>(count);
else
tags = new std::list<Tag>();
//some code
return true;
}
After I can use it:
std::list<Tag> tags;
mDB->tags(&tags);
Now, I fix my function:
bool DatabaseHandler::tags(std::list<Tag> **tags)
{
QString sql = "SELECT * FROM " + Tag::TABLE_NAME + ";";
QSqlQueryModel model;
model.setQuery(sql);
if(model.lastError().type() != QSqlError::NoError) {
log(sql);
*tags = NULL;
return false;
}
const int count = model.rowCount();
if(count > 0)
*tags = new std::list<Tag>(count);
else
*tags = new std::list<Tag>();
for(int i = 0; i < count; ++i) {
auto record = model.record(i);
Tag tag(record.value(Table::KEY_ID).toInt());
(*tags)->push_back(tag);
}
return true;
}
It works but list return size 4 although loop executes only 2 iterations and empty child objects (if I just called their default constructor). The Tag class hasn't copy constructor.
Since you passed an already instantiated list as a pointer to the function, there is no need to create another list.
In that sense, you question is pretty unclear. I'd suggest you read up a bit on pointers, references and function calls in general.
http://www.cplusplus.com/doc/tutorial/pointers/
http://www.cplusplus.com/doc/tutorial/functions/
UPDATE: I still strongly suggest you read up on the mentioned topics, since you don't know these fundamental points.
Anyway, this is what you probably want to do (event though I would suggest using references, here is the solution with pointers):
bool someFunc(std::list<Tag> **tags) {
// by default null the output argument
*tags = nullptr;
if (error) {
return false;
}
// dereference tags and assign it the address to a new instance of list<Tag>
*tags = new std::list<Tag>();
return true
}
std::list<Tag> *yourList;
if (someFunc(&yourList)) {
// then yourList is valid
} else {
// then you had an error and yourList == nullptr
}
However, this is not idiomatic C++. Please read a modern book or tutorial.
Use a reference.
bool DatabaseHandler::tags(std::list<Tag>& tags);
std::list<Tag> tags;
mDB->tags(tags);
You'll have to change all the -> to ., of course. Every operation done on the reference in the function will be done to the original tags list it was called with.
EDIT: If you want to create the list inside the function and return it, you have a couple options. The closest, I think, is to just return a list pointer, and return nullptr if the function fails.
//beware, pseudocode ahead
std::list<Tag>* DatabaseHandler::tags() //return new list
{
if (success)
return new std::list<Tag>(...); //construct with whatever
else
return nullptr; //null pointer return, didn't work
}
std::list<Tag> tags* = mDB->tags();
You could alternatively have it return an empty list instead, depending on how you want it to work. Taking a reference to a pointer would work the same way, too.
bool DatabaseHandler::tags(std::list<Tag>*&); //return true/false
std::list<Tag>* tags;
mDB->tags(tags); //tags will be set to point to a list if it worked
I'm work on next version of v8-profiler and now I want to simplify it.
I see that my class (ProfileNode) don't needs hidden link to internal object (v8::CpuProfileNode), because my class don't uses internal object methods.
Can I delete getter methods and replace it like the example below?
Is it wrong realisation?
Is it hight memory usage?
Or it's OK?
(I'm novice in c++ and v8 library)
(Please ignore version uncompatibility - it's not a part of question)
This is a part of current profile_node.cc
Persistent<ObjectTemplate> ProfileNode::node_template_;
void ProfileNode::Initialize() {
Local<ObjectTemplate> tpl = NanNewLocal<ObjectTemplate>(ObjectTemplate::New());
NanAssignPersistent(ObjectTemplate, node_template_, tpl);
tpl->SetInternalFieldCount(1);
tpl->SetAccessor(String::New("functionName"), ProfileNode::GetFunctionName);
...
}
NAN_GETTER(ProfileNode::GetFunctionName) {
NanScope();
Local<Object> self = args.Holder();
void* ptr = NanGetInternalFieldPointer(self, 0);
Handle<String> fname = static_cast<CpuProfileNode*>(ptr)->GetFunctionName();
NanReturnValue(fname);
}
...
Handle<Value> ProfileNode::New(const CpuProfileNode* node) {
NanScope();
if (node_template_.IsEmpty()) {
ProfileNode::Initialize();
}
if(!node) {
return Undefined();
}
else {
Local<Object> obj = NanPersistentToLocal(node_template_)->NewInstance();
NanSetInternalFieldPointer(obj, 0, const_cast<CpuProfileNode*>(node));
return obj;
}
}
After refactoring
//ProfileNode::Initialize deleted
//ProfileNode::GetFunctionName deleted
Handle<Value> ProfileNode::New(const CpuProfileNode* node) {
NanScope();
if(!node) {
return NanUndefined();
}
else {
//Create new simplest object, instead of new instance of object template
Local<Object> obj = NanNew<Object>();
//Append the value to this object
obj->Set(String::New("functionName"), node->GetFunctionName());
//Delete internal link.
//NanSetInternalFieldPointer(obj, 0, const_cast<CpuProfileNode*>(node));
return obj;
}
}