_i_n_M_e_a_s_u_r_e_C_h_a_r_s Specifies whether to compute metrics only for the string
or for the characters as well.
_i_n_S_t_r_i_n_g Specifies a zero-terminated array of characters.
DDDDEEEESSSSCCCCRRRRIIIIPPPPTTTTIIIIOOOONNNN
ggggllllccccMMMMeeeeaaaassssuuuurrrreeeeSSSSttttrrrriiiinnnngggg measures the layout that would result from rendering a
string and stores the measurements in the GLC measurement buffer.
ggggllllccccMMMMeeeeaaaassssuuuurrrreeeeSSSSttttrrrriiiinnnngggg is identical to ggggllllccccMMMMeeeeaaaassssuuuurrrreeeeCCCCoooouuuunnnntttteeeeddddSSSSttttrrrriiiinnnngggg except that
_i_n_S_t_r_i_n_g is zero-terminated, not counted.
EEEERRRRRRRROOOORRRRSSSS
GGGGLLLLCCCC____PPPPAAAARRRRAAAAMMMMEEEETTTTEEEERRRR____EEEERRRRRRRROOOORRRR is generated if _i_n_M_e_a_s_u_r_e_C_h_a_r_s is less than zero.
GGGGLLLLCCCC____SSSSTTTTAAAATTTTEEEE____EEEERRRRRRRROOOORRRR is generated if the issuing thread has no current GLC