As the title says, I would like to apply one Texture object to multiples Sprites. The following is the main function where 10 Creature objects are created:
int main() {
...
// creates a Creature vector and fills it with 10 Creature objects
std::vector<Creature> creatureList;
for (int i = 0; i < 10; i++) {
creatureList.emplace_back();
}
...
}
The following is the Creature header file:
class Creature {
public:
Creature();
...
private:
...
sf::Texture bodyTexture;
sf::Sprite body;
};
And finally, the following is the source file:
Creature::Creature() {
...
bodyTexture.loadFromFile("square.png");
...
body.setColor(sf::Color(rgbDistribution(mt), rgbDistribution(mt),
rgbDistribution(mt)));
body.setTexture(bodyTexture);
}
The problem with this code is that it gives only the most recently created Creature object the actual texture, leading me to believe it keeps changing "possession" of the bodyTexture each time body.setTexture(bodyTexture); is called.
What am I missing here? I've tried experimenting with throwing around various pointers and other stuff, but to no avail.
Found an answer: I simply had to pass the texture as a reference so the "owner" of the texture wouldn't change each time I called body.setTexture(bodyTexture);
Related
Is it possible for QTextLayout to render several characters, but to process/handle it as one character. For example rendering a code point like: [U+202e], and when moving the caret/calculating positions, it is treated as one character.
Edited:
Please check this following issue, were I explain what I'm trying to do. It for the edbee Qt component. It's using QTextLayout for line rendering.
https://github.com/edbee/edbee-lib/issues/127
Possibly it isn't possible with QTextLayout, the documentation is quite limited.
According to Qt docs:
"The class has a rather low level API and unless you intend to implement your own text rendering for some specialized widget, you probably won't need to use it directly." - https://doc.qt.io/qt-5/qtextlayout.html#details
You should probably use a QLineEdit or a QTextEdit (each has a method called setReadOnly(bool)).
Before answering the question, I will point out that the CursorMode enum (https://doc.qt.io/qt-5/qtextlayout.html#CursorMode-enum) seems very promising for this problem, but to me, the documentation isn't clear on how to use it or set it.
Now to answer your question in regards to QLineEdit or QTextEdit, it's a bit complicated, but it's the same for QLineEdit and QTextEdit, so lets look at QTextEdit.
Firstly, mouse clicks: QTextEdit has a signal called cursorPositionChanged(), which will be helpful here. You'll want to connect that to a custom slot, which can make use of the function moveCursor(QTextCursor::MoveOperation operation, QTextCursor::MoveMode mode = QTextCursor::MoveAnchor) (https://doc.qt.io/qt-5/qtextedit.html#moveCursor). Notice that there are very helpful enumeration values for you here in QTextCursor::MoveOperation regarding word hopping (https://doc.qt.io/qt-5/qtextcursor.html#MoveOperation-enum). How do we put all of this together? Well, probably the right way to do it is to determine the width of the chars to the left of the cursor's position and the width of the chars to the right of the cursor's position when the cursorPositionChanged() signal is emitted and go to the side of the word that has less width. However, I'm not sure how to do that. At this point I'd settle with checking the number of chars to the left and right and going to the side with less.
Secondly, keyboard presses: This goes a bit out of my knowledge, but almost everything drawable and iteractable inherits from QWidget. Take a look at https://doc.qt.io/qt-5/qwidget.html#keyPressEvent and it's possible that overriding that in your own implementation of QTextEdit is necessary to get the left arrow and right arrow keypresses to jump words (once you get that part it's pretty easy, just use the same function as last section for moving the cursor, or in the case of QLineEdit, cursorWordForward()/cursorWordBackward()).
All this being said, I've so far been assuming that you're not deleting anything or selecting anything. Selection can be a real pain depending on if you allow multiple selections, but the functions are all there in the documentation to implement those things.
Example of mouse click impl:
myclass.hpp
#include <QTextEdit>
#include <QTextCursor>
#include <QObject>
#include <QString>
int distance_to_word_beginning_or_end(const QString &str, int index, bool beginning);
class MyClass {
MyClass();
~MyClass();
private:
QTextEdit *text_edit;
public slots:
void text_edit_changed_cursor_location();
};
myclass.cpp
#include "myclass.hpp"
int distance_to_word_beginning_or_end(const QString &str, int index, bool beginning)
{
// return the distance from the beginning or end of the word from the index given
int inc_or_dec = (beginning) ? -1 : 1;
int distance = 0;
while (index >= 0 && index < str.length())
{
if (str.at(index) == ' ' || str.at(index) == '\n' || str.at(index) == '\t')
{
return distance;
}
distance++;
index += inc_or_dec;
}
return --distance;
}
MyClass::MyClass()
{
text_edit = new QTextEdit();
QObject::connect(text_edit, &QTextEdit::cursorPositionChanged, this, &MyClass::text_edit_changed_cursor_location);
}
MyClass::~MyClass()
{
delete text_edit;
}
void MyClass::text_edit_changed_cursor_location()
{
QString text_edit_string = text_edit->text();
QTextCursor text_edit_cursor = text_edit->textCursor();
auto current_position = text_edit_cursor.position();
QTextCursor new_text_cursor;
int distance_to_beginning = distance_to_word_beginning_or_end(text_edit_string, current_position, true);
int distance_to_end = distance_to_word_beginning_or_end(text_edit_string, current_position, false);
auto movement_type;
if (distance_to_beginning > distance_to_end)
{
new_text_cursor.setPosition(current_position + distance_to_end);
} else {
new_text_cursor.setPosition(current_position - distance_to_beginning);
}
text_edit->setTextCursor(new_text_cursor);
}
I have been having a problem with this code for a while. The placement of recursive call of the function does not seem right.
i tried running the code and yes it does run into a infinite loop.
// I DEFINE HEAP STRUCTURE AS :
struct heap_array
{
int *array; // heap implementation using arrays(note : heap is atype of a tree).
int capacity; // how much the heap can hold.
int size; //how much size is currently occupied.
void MaxHeapify(struct heap_array *h,int loc) // note : loc is the location of element to be PERCOLATED DOWN.
{
int left,right,max_loc=loc;
left=left_loc_child(h,loc);
right=right_loc_child(h,loc);
if(left !=-1 && h->array[left]>h->array[loc])
{
max_loc=left;
}
if(right!=-1 && h->array[right]>h->array[max_loc])
{
max_loc=right;
}
if(max_loc!=loc) //i.e. if changes were made:
{
//swap the element at max_loc and loc
int temp=h->array[max_loc];
h->array[max_loc]=h->array[loc];
h->array[loc]=temp;
}
MaxHeapify(h,max_loc); // <-- i feel that this recursive call is misplaced. I have seen the exact same code in almost all the online videos and some books i referred to. ALSO I THINK THAT THE CALL SHOULD BE MADE WITHIN THE SCOPE OF condition if(max_loc!=loc).
//if no changes made, end the func right there.
}
In your current implementation, it looks like you don't have a base case for recursion to stop.
Remember that you need a base case in a recursive function (in this case, your MaxHeapify function), and it doesn't look like there is one.
Here is an example of MaxHeap which may be resourceful to look at
// A recursive function to max heapify the given
// subtree. This function assumes that the left and
// right subtrees are already heapified, we only need
// to fix the root.
private void maxHeapify(int pos)
{
if (isLeaf(pos))
return;
if (Heap[pos] < Heap[leftChild(pos)] ||
Heap[pos] < Heap[rightChild(pos)]) {
if (Heap[leftChild(pos)] > Heap[rightChild(pos)]) {
swap(pos, leftChild(pos));
maxHeapify(leftChild(pos));
}
else {
swap(pos, rightChild(pos));
maxHeapify(rightChild(pos));
}
}
}
Here, you can see the basecase of:
if (isLeaf(pos))
return;
You need to add a base case to your recursive function.
I am fairly new to Qt. It is the first framework I have worked with. I am writing a blackjack game using Qt. It seems to me that I should store the images of each card in a container class such as QVector. The container type would be of QImage. So I would have a declaration such as QVector<QImage> cards; Perhaps this is not the best way about approaching this problem so any alternative suggestion is of course welcomed. However, regardless, I would like to know if it is possible to initialize the container during the declaration. I have not been able to solve this so my solution is the following:
// Deck.h
class Deck
{
public:
Deck();
void shuffle(); // Creates new deck and shuffles it.
QImage &popCard(); // Removes first card off deck.
private:
void emptyDeck(); // Empty the deck so new cards can be added
QVector<QImage> cards;
QQueue<QImage> deck;
};
// Deck.cpp
Deck::Deck()
{
cards.push_back(QImage(":/PlayingCards/Clubs 1.png"));
cards.push_back(QImage(":/PlayingCards/Clubs 2.png"));
cards.push_back(QImage(":/PlayingCards/Clubs 3.png"));
cards.push_back(QImage(":/PlayingCards/Clubs 4.png"));
// continue process for entire deck of cards...
}
This seems to be painfully tedious especially if I consider adding a different style of playing cards later on, or if I give the user an option to change the style of the cards at run time. What would be an efficient design to this?
I would like to know if it is possible to initialize the container during the declaration
Yes you can since C++11:
QList<int> list{1, 2, 3, 4, 5};
Well about your question one of the way can be:
Create in resources all types of your images style calling like template, for example: "Name n.png", where n - number from 1 to 54 (cnt of cards with Jokers);
Create some QList<QImage> (I think it'll be better then QVector);
Create some QMap for searching correct template easy;
Create some enum class for template map;
Write a function that change images of your cards by selected enum.
However it is very light codding. I think there is more usefull ways and there is a lot of other more beauty ways to do this game and logic. But as part of your question here some code (can be not very right, cause write as is):
// Somewhere in global
enum class CardsTemplate: {
Clubs,
SomeTemp1,
SomeTemp2,
...
SomeTempN
}
.H file:
private:
QList<QImage> _images;
QMap<CardsTemplate, QString> _imagesMap {
{CardsTemplate::Clubs, QString("Clubs")},
{CardsTemplate::SomeTemp1, QString("SomeTemp1")},
{CardsTemplate::SomeTemp2, QString("SomeTemp2")},
...
{CardsTemplate::SomeTempN, QString("SomeTempN")}
}
public:
Deck(CardsTemplate temp);
void setNewTemplate(CardsTemplate temp);
.CPP file:
Deck::Deck(CardsTemplate temp){
for(int i = 1; i <= 54; i++)
_images << QImage(QString(":/Playing cards/%1 %2.png")
.arg(_imagesMap.value(temp)).arg(i));
}
void Deck::setNewTemplate(CardsTemplate temp) {
for(int i = 1; i <= _images.size(); i++)
_images[i] = QImage(QString(":/Playing cards/%1 %2.png")
.arg(_imagesMap.value(temp)).arg(i));
}
I have a Qt project, there I have an Object, which is going to be copied a lot of time. Therefor I would like to add move semantics.
#ifndef OBJECTTOCOPY_H
#define OBJECTTOCOPY_H
#include <QColor>
#include <QString>
#include <QDataStream>
namespace level_1 {
namespace level_2 {
class ObjectToCopy {
public:
explicit ObjectToCopy(const QString& _name = "", const QColor& colorBody = QColor() );
// MOVE
ObjectToCopy(ObjectToCopy && other);
static quint32 _valueInt32;
static quint16 _valueInt16;
QString _name;
QColor _colorBody;
private:
};
}
}
#endif // OBJECTTOCOPY_H
How do I steal the pointers of the member variables, since they are no pointers?
ObjectToCopy::ObjectToCopy (ObjectToCopy&& other)
: _valueInt32( other._valueInt32 )
, _valueInt16( other._valueInt16 )
, _name( other._name )
, _colorBody( other._colorBody )
{
other._valueInt32 = 0;
other._valueInt16 = 0;
other.name.clear();
other._colorBody = QColor();
}
Does that make sense for non-pointers?
Is it ok to reset QString 's like string.clear(); to mark that for the garbage collector?
How could I reset a QColor object?
You can add move semantics of course, but in your case there is no need in this at all. quint32, quint16 are moved by copying. QColor is wrapper around union and has no move constructor (and doesn't need one) and will also be moved by copying. QString is reference counted type in QT. It has move constructor in recent versions of library, but the difference in speed will be minimal (difference between swapping pointer and incrementing reference counter).
You are looking for std::move:
ObjectToCopy::ObjectToCopy (ObjectToCopy&& other)
: _valueInt32( other._valueInt32 )
, _valueInt16( other._valueInt16 )
, _name( std::move(other._name) )
, _colorBody( std::move(other._colorBody) )
{
other._valueInt32 = 0; //probably not necessary
other._valueInt16 = 0; //probably not necessary
//other.name.clear(); //not necessary
//other._colorBody = nullptr; //not necessary
}
It makes sense to move non-pointers. You are in the process of making such an object. Moving integers doesn't help, but doesn't hurt either, so you may as well do it for consistancy. Moving things that don't have a move constructor also works: If no move constructor is available the copy constructor is used (moving is not always better, but not worse either).
The implementation above says "move by copying the ints and moving the name and the _colorBody".
Make sure you do not read from variables you moved from.
It is ok, but not necessary. other is supposed to be a temporary that will get destroyed anyways. (C++ does not have a garbage collector in your sense)
Also once an object is moved from it tends to be in the cleared state like for QString, but that is not always the case.
You cannot really. You can assign a default constructed one like other._colorBody = QColor(); but that just means it sets the color to black. A QColor cannot be empty, it always has some color.
Also read What are move semantics?
I am doing one project in which I define a data types like below
typedef QVector<double> QFilterDataMap1D;
typedef QMap<double, QFilterDataMap1D> QFilterDataMap2D;
Then there is one class with the name of mono_data in which i have define this variable
QFilterMap2D valid_filters;
mono_data Scan_data // Class
Now i am reading one variable from a .mat file and trying to save it in to above "valid_filters" QMap.
Qt Code: Switch view
for(int i=0;i<1;i++)
{
for(int j=0;j<1;j++)
{
Scan_Data.valid_filters[i][j]=valid_filters[i][j];
printf("\nValid_filters=%f",Scan_Data.valid_filters[i][j]);
}
}
The transferring is done successfully but then it gives run-time error
Windows has triggered a breakpoint in SpectralDataCollector.exe.
This may be due to a corruption of the heap, and indicates a bug in
SpectralDataCollector.exe or any of the DLLs it has loaded.
The output window may have more diagnostic information
Can anyone help in solving this problem. It will be of great help to me.
Thanks
Different issues here:
1. Using double as key type for a QMap
Using a QMap<double, Foo> is a very bad idea. the reason is that this is a container that let you access a Foo given a double. For instance:
map[0.45] = foo1;
map[15.74] = foo2;
This is problematic, because then, to retrieve the data contained in map[key], you have to test if key is either equal, smaller or greater than other keys in the maps. In your case, the key is a double, and testing if two doubles are equals is not a "safe" operation.
2. Using an int as key while you defined it was double
Here:
Scan_Data.valid_filters[i][j]=valid_filters[i][j];
i is an integer, and you said it should be a double.
3. Your loop only test for (i,j) = (0,0)
Are you aware that
for(int i=0;i<1;i++)
{
for(int j=0;j<1;j++)
{
Scan_Data.valid_filters[i][j]=valid_filters[i][j];
printf("\nValid_filters=%f",Scan_Data.valid_filters[i][j]);
}
}
is equivalent to:
Scan_Data.valid_filters[0][0]=valid_filters[0][0];
printf("\nValid_filters=%f",Scan_Data.valid_filters[0][0]);
?
4. Accessing a vector with operator[] is not safe
When you do:
Scan_Data.valid_filters[i][j]
You in fact do:
QFilterDataMap1D & v = Scan_Data.valid_filters[i]; // call QMap::operator[](double)
double d = v[j]; // call QVector::operator[](int)
The first one is safe, and create the entry if it doesn't exist. The second one is not safe, the jth element in you vector must already exist otherwise it would crash.
Solution
It seems you in fact want a 2D array of double (i.e., a matrix). To do this, use:
typedef QVector<double> QFilterDataMap1D;
typedef QVector<QFilterDataMap1D> QFilterDataMap2D;
Then, when you want to transfer one in another, simply use:
Scan_Data.valid_filters = valid_filters;
Or if you want to do it yourself:
Scan_Data.valid_filters.clear();
for(int i=0;i<n;i++)
{
Scan_Data.valid_filters << QFilterDataMap1D();
for(int j=0;j<m;j++)
{
Scan_Data.valid_filters[i] << valid_filters[i][j];
printf("\nValid_filters=%f",Scan_Data.valid_filters[i][j]);
}
}
If you want a 3D matrix, you would use:
typedef QVector<QFilterDataMap2D> QFilterDataMap3D;