Image is not shown in QGraphicsScene - c++

Question

Description
I wrote following Qt code. And Make executable file for Windows (*.exe). But Image (JPG) is not shown in QGraphicsScene. And I had already checked whether the path to image is correct. In following code, MyQGraphicsScene is derived class inherits QGraphicsScene class.
I compiled same code in macOS. Then, Executable file (ELF) for macOS ran correctly. Image file was shown in its component. I feel starange that source code is same. But the result is different by environment.
Development environment
Windows 10
Qt version : 5.7.0
C++ Compiler : Microsoft Visual C++ Ver.14.0 (MSVC2015)
Source code
#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QGraphicsRectItem>
#include <QMessageBox>
#include <QIcon>
#include "TrainingData.h"
#include "trainingDataMaker.h"
MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::MainWindow)
{
QGraphicsItem *curGItem;
QListWidgetItem *listItem;
ui->setupUi(this);
scene = new MyQGraphicsScene(QRectF(0, 0, 400, 400));
ui->graphicsView->setScene(scene);
listItem = new QListWidgetItem();
listItem->setIcon(QIcon("data/000001.jpg"));
ui->imgListWidget->addItem(listItem);
listItem = new QListWidgetItem();
listItem->setIcon(QIcon("data/000276.jpg"));
ui->imgListWidget->addItem(listItem);
ui->imgListWidget->setIconSize(QSize(300,100));
QPixmap pixmap;
QImage img("data/000001.jpg");
QTransform transForm;
pixmap = QPixmap::fromImage(img);
QGraphicsPixmapItem *imgPixmap = new QGraphicsPixmapItem(pixmap);
transForm = QTransform();
transForm.scale(0.1, 0.1);
imgPixmap->setTransform(transForm);
scene->addItem(imgPixmap);
//connect(scene, SIGNAL(changed(const QList<QRectF> &)), imgPixmap, SLOT(chgSize(const QList<QRectF> &)));
}

Answer 1

I compiled same code in macOS. Then, Executable file (ELF) for macOS
ran correctly. Image file was shown in its component. I feel starange
that source code is same. But the result is different by environment.
Since it works under MacOS/X but not under Windows, one likely explanation is that it's a distribution/environmental problem. In particular, perhaps your program can't find Qt's imageformat plugin (e.g. qjpeg4.dll or qjpeg5.dll) under Windows, and that is why the image is not being displayed.
To test that theory, you could copy the qjpeg*.dll plugin file into the same folder as your .exe file, and then re-run your program and see if that makes it behave better. Alternatively, if you don't want to mess with image format plugins, you could convert your .jpg file to another file format that Qt includes native (i.e. non-plugin-based) support for, such as BMP or PNG, and use that instead.

Answer 2

As result, Cause of this issue is my misunderstanding of current directory in case that the application is launched from IDE. Current directory is (a) in following diagram.
Directory structure before
[Output directory is specified in build configuration] - (a)
|- debug - (b)
| |- test.exe // executable file of this application
| |- data
| |-000001.jpg
|- release
Therefore, I should have located "data" directory includes image files in directory (a) as following diagram. I'm feeling strange this specification of IDE. Of course, Current directory is same diretory of exe file in case that application launch directly(Doublu-clicking exe file) .
Directory structure after
[Output directory is specified in build configuration] - (a)
|- debug - (b)
| |- test.exe // executable file of this application
|- release
|- data
|-000001.jpg