The ImageEditor application

In this chapter, we will build an application that can be used to edit images, so we will name it ImageEditor. To edit an image with a GUI application, the first step is opening and viewing the image with that application, which is what we did in the previous chapter. Therefore, I decided to make a copy of the ImageViewer application and rename it ImageEditor, before adding the image editing features to it.

Let's start by copying the sources:

    $ mkdir Chapter-02
    $ cp -r Chapter-01/ImageViewer/ Chapter-02/ImageEditor
    $ ls Chapter-02
    ImageEditor
    $ cd Chapter-02/ImageEditor
    $ make clean
    $ rm -f ImageViewer

With these commands, we copy the ImageViewer directory under the Chapter-01 directory to Chapter-02/ImageEditor. Then, we can enter that directory, run make clean to clean all intermediate files that were generated in the compiling process, and remove the old target executable file using rm -f ImageViewer.

 Now that we have a cleaned project, let's rename some of it:

• The project directory is named with the new project name ImageEditor in the copying process, so we don't need to do anything here.
• The Qt project file, ImageViewer.pro, should be renamed to ImageEditor.pro. You can do this in your file manager or in a Terminal.
• In the ImageEditor.pro file, we should rename the TARGET to ImageEditor by changing the TARGET = ImageViewer line to TARGET = ImageEditor.
• In the source file, main.cpp, we should change the window title by changing the window.setWindowTitle("ImageViewer"); line to window.setWindowTitle("ImageEditor");.

Now that everything has been renamed, let's compile and run the new ImageEditor application, which has been copied from ImageViewer:

    $ qmake -makefile
    $ make
    g++ -c -pipe ...
    # output truncated
    # ...
    $ ls
    ImageEditor ImageEditor.pro main.cpp main.o mainwindow.cpp mainwindow.h
    mainwindow.o Makefile moc_mainwindow.cpp moc_mainwindow.o moc_predefs.h
    $ export LD_LIBRARY_PATH=/home/kdr2/programs/opencv/lib/
    $ ./ImageEditor

You will see that the window is exactly the same as the window of ImageViewer, except that it has a different window title, ImageEditor. Anyway, we have set our editor application up, even though it has no feature for image editing now. We will add a simple editing feature in the next chapter.