Why my window doesn't show any QPixmap picture?

Question

I am trying to make a basic window that shows a .gif but it doesn't. I made sure that the file is in the same directory than my main.cpp . I tried with other file extensions but it still doesn't work.

#include <QApplication>
#include <QBoxLayout>
#include <QLabel>
#include <iostream>

int main(int argc, char *argv[])
{
QApplication a(argc, argv);

QWidget *window = new QWidget;
window->setFixedSize(640, 480);

QLabel *gif_anim = new QLabel();
QPixmap const *movie = new QPixmap("sea.gif");
gif_anim->setPixmap(*movie);

QHBoxLayout *layout = new QHBoxLayout;
layout->addWidget(gif_anim);

std::cout << movie->isNull() << std::endl;

window->setLayout(layout);
window->show();

return a.exec();
}

I tested with the isNull() method and it tells me that my QPixmap is null (I don't know why).

Your help is appreciated.

Answer 1

You have the following errors:

• QPixmap does not support the gif format, if you want to show a gif you must use QMovie.

• The path of the file is relative to the executable, not the source code, so in these I use a small command to copy files from the source code folder to the build folder.

Considering the above, the solution is:

*.pro

COPY_CONFIG = sea.gif
copy_cmd.input = COPY_CONFIG
copy_cmd.output = ${QMAKE_FILE_IN_BASE}${QMAKE_FILE_EXT}
copy_cmd.commands = $$QMAKE_COPY_DIR ${QMAKE_FILE_IN} ${QMAKE_FILE_OUT}
copy_cmd.CONFIG += no_link_no_clean
copy_cmd.variable_out = PRE_TARGETDEPS
QMAKE_EXTRA_COMPILERS += copy_cmd

main.cpp

QWidget window;
window.setFixedSize(640, 480);
QLabel *gif_anim = new QLabel();
QMovie *movie = new QMovie("sea.gif");
gif_anim->setMovie(movie);
movie->start();
QHBoxLayout *layout = new QHBoxLayout;
layout->addWidget(gif_anim);
window.setLayout(layout);
window.show();