How PutCopyBox Determines Window Size in 7.00/7.10 UI ToolBox (65926)

SUMMARY

The User-Interface (UI) ToolBox uses three assembler routines to "Get a window from the screen" (GetCopyBox), "Put a window to the screen" (PutCopyBox), and "Change the attributes of a window" (AttrBox). The source code for these three assembler routines are located in the UIASM.ASM file.

GetCopyBox and PutCopyBox are complimentary routines, except for the parameters that they use. GetCopyBox needs five parameters; four to define the rectangle of the window and one for the string to store the information. PutCopyBox uses only three parameters; two for the upper-left corner and one for the string where the information will come from.

PutCopyBox determines the size of the rectangle by the window width and window height stored in the first four bytes of the string. GetCopyBox stores this information in the string as the first four bytes, then places the contents of the window following the height and width of the window.

The window width is the first two bytes and the window height is the next two bytes.

This information applies to Microsoft Basic Professional Development System (PDS) versions 7.00 and 7.10 for MS-DOS.

MORE INFORMATION

The following is an extraction of code from UIASM.ASM used by the UI ToolBox routines to preserve and restore a window on the screen.

The sections of code listed below that refer to "si,offset" are moving the data from memory to the string. The references to "di,offset" are moving the data from the string to memory.

Sample Code

get_setstr:
        mov     al,x1
        sub     al,x0                   ;find width of box
        mov     bwidth,al               ;and save
        add     al,1                    ;add one to width
        mov     ah,0                    ;to find # words to move
        mov     movword,ax              ;MovWord = (width+1)
        mov     al,y1
        sub     al,y0                   ;find height of box
        mov     height,al               ;and save
        mov     es,strdseg
        mov     di,strdoff              ;string is the destination

        ; Place the Windows Width in the first word of the string
        ; The first and second bytes of the string

        mov     si,offset bwidth        ;point to width
        movsb                           ;put width in string

        ; Place the Windows Height in the second word of the string
        ; The third and fourth bytes of the string

        mov     si,offset height
        movsb                           ;and the height, too


put_setstr:
        push    ds
        pop     es                      ;equate ES to DS

        mov     si,strdoff              ;point DS:SI to string mem
        push    ds
        mov     ds,strdseg

        ; Get the Windows Width from the string

        mov     di,offset bwidth
        movsb                           ;get width

        ; Get the Windows Height from the string

        mov     di,offset height
        movsb                           ;and height out of string

        pop     ds