LinuxQuestions.org - [SOLVED] C++ from C xmp.h function call: XpmCreatePixmapFromData

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C++ from C xmp.h function call: XpmCreatePixmapFromData

I am writing this little dockapp in C++ converting what I can from C using the, if you've heard of it, wmgeneral.c file to help create the dockapp window.

within it are a bunch of hand written functions that where using

Code:

char *something = "whatever";

getting,

Code:

ISO C++ forbids converting a string constant to 'char*'

so I changed everything to

Code:

char const *something = " whatever";

starting from the xpm file and modding it to this within the file.

Code:

static char const * bgmask_xpm[] = {

now I have an outside function call coming from xmp.h called.

Code:

 FUNC(XpmCreatePixmapFromData, int, (Display *display,

                                        Drawable d,

                                        char **data,

                                        Pixmap *pixmap_return,

                                        Pixmap *shapemask_return,

                                        XpmAttributes *attributes));

https://github.com/winlibs/libxpm/bl...lude/X11/xpm.h

how do I get that function to conform from a char **data to a char const **data without having to re-code their code?

I'm getting this

Code:



/home/userx/C++Projects/wmslideshow/wmgeneral.cpp|178|error: invalid conversion from 'const char**' to 'char**' [-fpermissive]|

/usr/include/X11/xpm.h|292|note:  initializing argument 3 of 'int XpmCreatePixmapFromData(Display*, Drawable, char**, Pixmap*, Pixmap*, XpmAttributes*)'|

which is the last error I got to get rid of before I can move on with this little endeavor.

( though I seen it pop open the header in codeblocks to show me what it's talking about. -- MAYBE just edit that one add const into its definition and cross my fingers? ;) )

UPDATE: casting didn't work...

Code:

 err = XpmCreatePixmapFromData(display, Root, (char **)pixmap_bytes, &(wmgen->pixmap), &(wmgen->mask), &(wmgen->attributes));

Code:

||=== Build: Debug in wmslideshow (compiler: GNU GCC Compiler) ===|

||error: ld returned 1 exit status|

||=== Build failed: 1 error(s), 0 warning(s) (0 minute(s), 0 second(s)) ===|

Quote:

Originally Posted by norobro (Post 5842416)

Here you go: http://en.cppreference.com/w/cpp/language/const_cast

I'm assuming this is correct, I got a good compile, with a seg fault, that shows progress. :D

Code:

static void GetXPM(XpmIcon *wmgen, char const *pixmap_bytes[]) {



    XWindowAttributes  attributes;

    int                err;



    char **pixmapy = const_cast<char **>(pixmap_bytes);



  // For the colormap

    XGetWindowAttributes(display, Root, &attributes);



    wmgen->attributes.valuemask |= (XpmReturnPixels | XpmReturnExtensions);



    err = XpmCreatePixmapFromData(display, Root, pixmapy /*  pixmap_bytes */, &(wmgen->pixmap), &(wmgen->mask), &(wmgen->attributes));



    if (err != XpmSuccess) {

        fprintf(stderr, "Not enough free colorcells.\n");

        exit(1);

    }

}

just got to weed out the seg fault now. Hopefully its nothing to do with the changes I made to the char to const char.

Got it! onward and upwards...