For a file, how to obtain a QImage of the icon shown on explorer?

lqsa

When open explorer on Windows, an icon is shown for every file. How to obtain this icon in a QImage?

I've tried:

QFileIconProvider ip;
QFileInfo info(fileName);
QIcon icon = ip.icon(info);
QPixmap pixmap = icon.pixmap(QSize(32, 32));
QImage image = pixmap.toImage();

but pixmap is always invalid

JonB

@lqsa
I do not know whether this will affect the result. But because of Windows Explorer icon generation and caching, I would make sure the you view the particular file used in the code in Windows Explorer, so you know the icon has been generated.

Oh. I'm talking about thumbnail images for files like *.MP4, do you mean you see a different image for each file, or do you mean the generic icons Explorer uses for files, folders etc.?

lqsa

No, I'm not talking about thumbnail images, I'm talking about file type icon or application icon if it's an exe.

SGaist

Hi,

You can try the technique described here.

lqsa

The same, pixmap is invalid.

I'm not sure if the problem is in icon.pixmap method, because the ip.icon returns something on icon, and when call icon.availableSizes(), it returns a list with two QSize, 24x24 and 32x32.

hskoglund

Hi, just tried something similar to your code on my Windows 7; I created an empty vanilla widgets app and added this to mainwindow.cpp:

#include "QHBoxLayout"
#include "QLabel"
#include "qdir.h"
#include "qfileiconprovider.h"

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);

    auto b = new QHBoxLayout(ui->centralWidget);
    for (auto f : QDir("C:/Windows").entryInfoList(QDir::Files))
    {
        auto icon = QFileIconProvider().icon(f);
        auto l = new QLabel;
        l->setPixmap(icon.pixmap(icon.availableSizes().first()));
        b->addWidget(l);
    }
}

and got this:
works ok :-)

lqsa

I found it. The fileName was obtained from FileDialog, and it begins with file:///. After remove it, it works.

Thank you very much.

JonB

@lqsa
So OOI, your original call to QFileInfo info(fileName) did not indicate that the path was unacceptable?

lqsa

What method is used for this?

JonB

@lqsa
That's just the constructor. But afterwards info.exists() would be a start if the file is supposed to exist, and it's not finding it via file:/// or whatever you said. Or I presume something in the information in the QFileInfo can't be right if it can't find the file or get its correct information...

lqsa

Yes, info.exists() returns false if not finding it.

JonB

@lqsa So that was your clue to the original problem :)