How to add an Icon to an application built with Eclipse Galileo C and MinGW?

In Windows, the icons as well as some other elements (cursors, bitmaps, …) have to be specified in a resource file, which once compiled will be linked to the program.

First an example on how to add an icon to a Windows program which will illustrate it’s use within Eclipse. Here is a simple program that just creates a window, look at the time we fill the WNDCLASSEX, the icon of the application is referenced there:

resources.h – this file may be used to assign a value to a resource identifier, and so use the value instead:

#define AppIcon 101

The next file is the resources file, you may create it manually or from within Eclipse as well, to create it in Eclipse, right click the directory you want it to be (in this case is src) and select New -> File. There write the name you want and click Finish. To edit it from within Eclipse right click it and select Open with -> Text Editor.

resources.rc – the icon will be specified here:

#include "resources.h"

// The icon path I used will be needed by Eclipse.
// If you want to use back-slashes you have to scape them (\\ instead of \):
AppIcon ICON "../src/icon.ico"

demoicon.c – the file containing the code of the program:

#include <windows.h>
#include "resources.h"

const char *ClassName = "DemoIcon";

// Declaration of the window procedure, to be used in the WNDCLASSEX struct:
LRESULT CALLBACK WindowProc(HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam);

int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrev, LPSTR lpCmdLine, int nShowCmd) {

    WNDCLASSEX wc;
    HWND hWnd;
    MSG msg;

    // Filling the structure:
    wc.cbSize = sizeof(WNDCLASSEX);
    wc.style = 0;
    wc.lpfnWndProc = WindowProc;
    wc.cbClsExtra = 0;
    wc.cbWndExtra = 0;
    wc.hInstance = hInstance;
    // Remember this just loads 32x32, use LoadImage() instead for other dimensions (16x16, 48x48, ...):
    wc.hIcon = LoadIcon(hInstance, MAKEINTRESOURCE(AppIcon));
    wc.hCursor = LoadCursor(NULL, IDC_ARROW);
    wc.hbrBackground = (HBRUSH)(COLOR_WINDOW);
    wc.lpszMenuName = NULL;
    wc.lpszClassName = ClassName;
    // Here we'll use LoadImage, as we need a 16x16 mini icon:
    wc.hIconSm = LoadImage(hInstance,MAKEINTRESOURCE(AppIcon),IMAGE_ICON,16,16, LR_DEFAULTCOLOR);

    // Registering the class:
    if(!RegisterClassEx(&wc)) {
        MessageBox(NULL,
                   "Could not register window.",
                   "Error",
                   MB_ICONEXCLAMATION | MB_OK);
        return -1;
    }

    // Create the window using the "MainWindow" class:
    hWnd = CreateWindowEx(WS_EX_WINDOWEDGE,
                          ClassName,
                          "Demo Icon",
                          WS_OVERLAPPEDWINDOW,
                          CW_USEDEFAULT,
                          CW_USEDEFAULT,
                          200,
                          150,
                          NULL,
                          NULL,
                          hInstance,
                          NULL);

    // If the window was not created show error and exit:
    if(hWnd == NULL) {
        MessageBox(NULL,
                   "Could not create window.",
                   "Error",
                   MB_ICONEXCLAMATION | MB_OK);
        return -1;
    }

    // Set the windows show state, to show it:
    ShowWindow(hWnd, nShowCmd);
    // Draw the window:
    UpdateWindow(hWnd);

    // Retrieve messages from the message queue:
    while(GetMessage(&msg, NULL, 0, 0) > 0) {
        TranslateMessage(&msg);
        DispatchMessage(&msg);
    }

    return msg.wParam;
}

// Implementation of the window procedure, will handle the messages:
LRESULT CALLBACK WindowProc(HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam) {

    switch(uMsg) {
        case WM_CLOSE:
            DestroyWindow(hWnd);
            break;
        case WM_DESTROY:
            PostQuitMessage(0);
            break;
        default:
            return DefWindowProc(hWnd, uMsg, wParam, lParam);
    }

    return 0;
}

Now, in your Eclipse project source directory make sure you have all the files (in the example the 3 files mentioned before and the icon file).

After that go to Project -> Properties.
There, go to C/C++ Build -> Settings -> Build Steps tab.
There you’ll see Pre-build steps -> Command. The command you fill in there will be executed before the compilation starts, so you’ll tell it to compile the resource file. As you are using MinGW the resource compiler is windres:

windres ../src/resources.rc -o ../Resources/resources.o

As you can see I’ll be placing the compiled resource file in a directory called Resources, you may leave it where you want (and so the name of the file, it doesn’t have to be named resources.rc).

Now go to the Tool Settings tab.
There, go to MinGW C Linker -> Miscellaneous, and in other objects add the object file created before, in this case you should add:

Resources/resources.o

As this is a Windows app, add the option -mwindows to the linker flags at the top of the same tab.

Done, when building your project Eclipse will compile the resource file first and then link the generated object as any other object file of your project.

I hope it’s clear enough to read through this.