home *** CD-ROM | disk | FTP | other *** search
XXXXmmmmeeeeRRRReeeessssoooollllvvvveeeePPPPaaaarrrrttttOOOOffffffffsssseeeettttssss((((3333XXXX)))) UUUUNNNNIIIIXXXX SSSSyyyysssstttteeeemmmm VVVV XXXXmmmmeeeeRRRReeeessssoooollllvvvveeeePPPPaaaarrrrttttOOOOffffffffsssseeeettttssss((((3333XXXX)))) NNNNAAAAMMMMEEEE XXXXmmmmeeeeRRRReeeessssoooollllvvvveeeePPPPaaaarrrrttttOOOOffffffffsssseeeettttssss - Allows writing of upward-compatible applications and widgets SSSSYYYYNNNNOOOOPPPPSSSSIIIISSSS #include <Xm/XmP.h> vvvvooooiiiidddd XXXXmmmmeeeeRRRReeeessssoooollllvvvveeeePPPPaaaarrrrttttOOOOffffffffsssseeeettttssss( WWWWiiiiddddggggeeeettttCCCCllllaaaassssssss wwwwiiiiddddggggeeeetttt____ccccllllaaaassssssss, XXXXmmmmOOOOffffffffsssseeeettttPPPPttttrrrr ****ooooffffffffsssseeeetttt, XXXXmmmmOOOOffffffffsssseeeettttPPPPttttrrrr ****ccccoooonnnnssssttttrrrraaaaiiiinnnntttt____ooooffffffffsssseeeetttt); VVVVEEEERRRRSSSSIIIIOOOONNNN This page documents Motif 2.1. DDDDEEEESSSSCCCCRRRRIIIIPPPPTTTTIIIIOOOONNNN The use of offset records requires two extra global variables per widget class. The variables consist of pointers to arrays of offsets into the widget record and constraint record for each part of the widget structure. The XXXXmmmmeeeeRRRReeeessssoooollllvvvveeeePPPPaaaarrrrttttOOOOffffffffsssseeeettttssss function allocates the offset records needed by an application to guarantee upward- compatible access to widget instance and constraint records by applications and widgets. These offset records are used by the widget to access all of the widget's variables. A widget needs to take the steps described in the following paragraphs. Instead of creating a resource list, the widget creates an offset resource list. To accomplish this, use the XXXXmmmmPPPPaaaarrrrttttRRRReeeessssoooouuuurrrrcccceeeestructure and the XXXXmmmmPPPPaaaarrrrttttOOOOffffffffsssseeeetttt macro. The XXXXmmmmPPPPaaaarrrrttttRRRReeeessssoooouuuurrrrcccceeee data structure looks just like a resource list, but, instead of having one integer for its offset, it has two shorts. This structure is put into the class record as if it were a normal resource list. Instead of using XXXXttttOOOOffffffffsssseeeetttt for the offset, the widget uses XXXXmmmmPPPPaaaarrrrttttOOOOffffffffsssseeeetttt. If the widget is a subclass of the CCCCoooonnnnssssttttrrrraaaaiiiinnnntttt class and it defines additional constraint resources, create an offset resource list for the constraint part as well. Instead of using XXXXttttOOOOffffffffsssseeeetttt for the offset, the widget uses XXXXmmmmCCCCoooonnnnssssttttrrrraaaaiiiinnnnttttPPPPaaaarrrrttttOOOOffffffffsssseeeettttin the constraint resource list. Do not create parts that do not preserve alignment (for example, a widget part containing a single Boolean). XmPartResource resources[] = { { BarNxyz, BarCXyz, XmRBoolean, sizeof(Boolean), XmPartOffset(Bar,xyz), XmRImmediate, (XtPointer)False } }; XmPartResource constraints[] = { { BarNmaxWidth, BarNMaxWidth, XmRDimension, sizeof(Dimension), XmConstraintPartOffset(Bar,max_width), Page 1 (printed 10/3/02) XXXXmmmmeeeeRRRReeeessssoooollllvvvveeeePPPPaaaarrrrttttOOOOffffffffsssseeeettttssss((((3333XXXX)))) UUUUNNNNIIIIXXXX SSSSyyyysssstttteeeemmmm VVVV XXXXmmmmeeeeRRRReeeessssoooollllvvvveeeePPPPaaaarrrrttttOOOOffffffffsssseeeettttssss((((3333XXXX)))) XmRImmediate, (XtPointer)100 } }; Instead of putting the widget size in the class record, the widget puts the widget part size in the same field. If the widget is a subclass of the CCCCoooonnnnssssttttrrrraaaaiiiinnnntttt class, instead of putting the widget constraint record size in the class record, the widget puts the widget constraint part size in the same field. Instead of putting XXXXttttVVVVeeeerrrrssssiiiioooonnnn in the class record, the widget puts XXXXttttVVVVeeeerrrrssssiiiioooonnnnDDDDoooonnnnttttCCCChhhheeeecccckkkk in the class record. Define a variable of type XXXXmmmmOOOOffffffffsssseeeettttPPPPttttrrrr to point to the offset record. If the widget is a subclass of the CCCCoooonnnnssssttttrrrraaaaiiiinnnntttt class, define a variable of type XXXXmmmmOOOOffffffffsssseeeettttPPPPttttrrrr to point to the constraint offset record. These can be part of the widget's class record or separate global variables. In class initialization, the widget calls XXXXmmmmeeeeRRRReeeessssoooollllvvvveeeePPPPaaaarrrrttttOOOOffffffffsssseeeettttssss, passing it pointers to the class record, the address of the offset record, and the address of the constraint offset record. If the widget is not a subclass of the CCCCoooonnnnssssttttrrrraaaaiiiinnnntttt class, it should pass _N_U_L_L as the address of the CCCCoooonnnnssssttttrrrraaaaiiiinnnntttt offset record. This does several things: +o Adds the superclass (which, by definition, has already been initialized) size field to the part size field +o If the widget is a subclass of the CCCCoooonnnnssssttttrrrraaaaiiiinnnntttt class, adds the superclass constraint size field to the constraint size field +o Allocates an array based upon the number of superclasses +o If the widget is a subclass of the CCCCoooonnnnssssttttrrrraaaaiiiinnnntttt class, allocates an array for the constraint offset record +o Fills in the offsets of all the widget parts and constraint parts with the appropriate values, which can be determined by examining the size fields of all superclass records +o Uses the part offset array to modify the offset entries in the resource list to be real offsets, in place The widget defines a constant that will be the index to its part structure in the offsets array. The value should be 1 greater than the index of the widget's superclass. Constants defined for all Xm widgets can be found in header Page 2 (printed 10/3/02) XXXXmmmmeeeeRRRReeeessssoooollllvvvveeeePPPPaaaarrrrttttOOOOffffffffsssseeeettttssss((((3333XXXX)))) UUUUNNNNIIIIXXXX SSSSyyyysssstttteeeemmmm VVVV XXXXmmmmeeeeRRRReeeessssoooollllvvvveeeePPPPaaaarrrrttttOOOOffffffffsssseeeettttssss((((3333XXXX)))) file XXXXmmmm////XXXXmmmmPPPP....hhhh. #define BarIndex (XmBulletinBIndex + 1) Instead of accessing fields directly, the widget must always go through the offset table. The XXXXmmmmFFFFiiiieeeelllldddd and XXXXmmmmCCCCoooonnnnssssttttrrrraaaaiiiinnnnttttFFFFiiiieeeelllldddd macros help you access these fields. Because the XXXXmmmmPPPPaaaarrrrttttOOOOffffffffsssseeeetttt, XXXXmmmmCCCCoooonnnnssssttttrrrraaaaiiiinnnnttttPPPPaaaarrrrttttOOOOffffffffsssseeeetttt, XXXXmmmmFFFFiiiieeeelllldddd, and XXXXmmmmCCCCoooonnnnssssttttrrrraaaaiiiinnnnttttFFFFiiiieeeellllddddmacros concatenate things, you must ensure that there is no space after the part argument. For example, the following macros do not work because of the space after the part (Label) argument: XmField(w, offset, Label, text, char *) XmPartOffset(Label, text). You must not have any spaces after the part (Label) argument, illustrated as follows: XmField(w, offset, Label, text, char *) XmPartOffset(Label, text). You can define macros for each field to make this easier. For example, the following shows how to define a macro for an enumerated field _x_y_z in widget BBBBaaaarrrr: #define BarXyz(w) \ XmField(w,offsets,Bar,xyz,XtEnum) Define a macro for constraint field _m_a_x__w_i_d_t_h as follows: #define BarMaxWidth(w) \ XmConstraintField(w,constraint_offsets,Bar,max_width,Dimension) The arguments for XXXXmmmmeeeeRRRReeeessssoooollllvvvveeeePPPPaaaarrrrttttOOOOffffffffsssseeeettttssss are as follows: _w_i_d_g_e_t__c_l_a_s_s Specifies the widget class pointer for the created widget. _o_f_f_s_e_t Returns the offset record. _c_o_n_s_t_r_a_i_n_t__o_f_f_s_e_t Returns the constraint offset record. RRRREEEELLLLAAAATTTTEEEEDDDD IIIINNNNFFFFOOOORRRRMMMMAAAATTTTIIIIOOOONNNN XXXXmmmmRRRReeeessssoooollllvvvveeeeAAAAllllllllPPPPaaaarrrrttttOOOOffffffffsssseeeettttssss(3). Page 3 (printed 10/3/02) 
