nx_x11_get_image.nx

nx_x11_get_image.nx -- bits-up X11 GetImage opcode + reply read. Part of the Nishi-troubleshoots-Nishi self-closing-loop arc. Pulls pixel data BACK from a drawable so we can save it to disk + diff/inspect off-line. GetImage (opcode 73): byte 0: 73 byte 1: format (1 = XYPixmap, 2 = ZPixmap) bytes 2-3: request_length = 5 bytes 4-7: drawable bytes 8-9: x bytes 10-11: y bytes 12-13: width bytes 14-15: height bytes 16-19: plane_mask (0xFFFFFFFF for all planes) Reply (32-byte header + data): byte 0: 1 (Reply marker) byte 1: depth bytes 2-3: sequence bytes 4-7: reply_length (4-byte units; tells us pixel-data size) bytes 8-11: visual bytes 12-31: pad bytes 32+: pixel data For ZPixmap on a 24-bit visual, the server typically returns 32-bit-per-pixel data (BGRX or XBGR). Total data bytes = reply_length * 4. Caller allocates a buffer of width*height*4 + some slack and we copy the result there. license_tier: ORIGINAL genealogy_id: international-research-sources/x_org/xproto_v11_r0 lineage_id: nishi_x11_get_image_q10