How to get permission for RandR outputs through xcb RandR extension?

Question

I am working on a project that already uses xcb and should get the resolution of the individual outputs, not the resolution of the combo screen. Can I do this with the RandR extension for xcb? If so, how can I use my object xcb_connection_tfor this.

Answer 1

I was also looking for an answer. I do not know if you succeeded or not, but since you did not answer this question, I think you did not.

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bartender: "OK, I'll get you a beer."
*bartender handles a ticket with an ID of the beer order to the client*
*client waits and waits and then he approaches bartender*
client   : "Dude, give me my beer finally, here your damn ticket"
*client handles the ticket to bartender, who looks for the order from the 
 ticket in his order book and when he finds it he replies*
bartender: "Here your beer, enjoy."

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#include <cstdio>
#include <xcb/xcb.h>
#include <xcb/randr.h>

int main()
{
    //Open connection to X server
    xcb_connection_t* XConnection = xcb_connect(0, 0);

    //Get the first X screen
    xcb_screen_t* XFirstScreen = xcb_setup_roots_iterator(
                               xcb_get_setup(XConnection)).data;
    //Generate ID for the X window
    xcb_window_t XWindowDummy = xcb_generate_id(XConnection);

    //Create dummy X window
    xcb_create_window(XConnection, 0, XWindowDummy, XFirstScreen->root,
                      0, 0, 1, 1, 0, 0, 0, 0, 0);

    //Flush pending requests to the X server
    xcb_flush(XConnection);

    //Send a request for screen resources to the X server
    xcb_randr_get_screen_resources_cookie_t screenResCookie = {};
    screenResCookie = xcb_randr_get_screen_resources(XConnection, 
                                                     XWindowDummy);

    //Receive reply from X server
    xcb_randr_get_screen_resources_reply_t* screenResReply = {};
    screenResReply = xcb_randr_get_screen_resources_reply(XConnection,
                     screenResCookie, 0);

    int crtcs_num = 0;
    xcb_randr_crtc_t* firstCRTC;

    //Get a pointer to the first CRTC and number of CRTCs
    //It is crucial to notice that you are in fact getting
    //an array with firstCRTC being the first element of
    //this array and crtcs_length - length of this array
    if(screenResReply)
    {
        crtcs_num = xcb_randr_get_screen_resources_crtcs_length(screenResReply);

        firstCRTC = xcb_randr_get_screen_resources_crtcs(screenResReply);
    }
    else
        return -1;

    //Array of requests to the X server for CRTC info
    xcb_randr_get_crtc_info_cookie_t* crtcResCookie = new   
               xcb_randr_get_crtc_info_cookie_t[crtcs_num];
    for(int i = 0; i < crtcs_num; i++)
        crtcResCookie[i] = xcb_randr_get_crtc_info(XConnection, 
                                            *(firstCRTC+i), 0);
    //Array of pointers to replies from X server
    xcb_randr_get_crtc_info_reply_t** crtcResReply = new 
               xcb_randr_get_crtc_info_reply_t*[crtcs_num];
    for(int i = 0; i < crtcs_num; i++)
        crtcResReply[i] = xcb_randr_get_crtc_info_reply(XConnection,
                                             crtcResCookie[i], 0);
    //Self-explanatory
    for(int i = 0; i < crtcs_num; i++)
    {
        if(crtcResReply[i])
        {
            printf("CRTC[%i] INFO:\n", i);
            printf("x-off\t: %i\n", crtcResReply[i]->x);
            printf("y-off\t: %i\n", crtcResReply[i]->y);
            printf("width\t: %i\n", crtcResReply[i]->width);
            printf("height\t: %i\n\n", crtcResReply[i]->height);
        }
    }

    xcb_disconnect(XConnection);

    return 0;
}

:

CRTC[0] INFO:
x-off   : 1920
y-off   : 0
width   : 1920
height  : 1200

CRTC[1] INFO:
x-off   : 0
y-off   : 0
width   : 1920
height  : 1200

CRTC[2] INFO:
x-off   : 0
y-off   : 0
width   : 0
height  : 0

CRTC[3] INFO:
x-off   : 0
y-off   : 0
width   : 0
height  : 0

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• XCB ( )
• XCB API ( , RandR API)