HP OpenVMS Systems Documentation

1. The client assigns window width and height the value of 600 (pixels) each.
2. The client specifies the position of the window using two display information routines, DISPLAY WIDTH and DISPLAY HEIGHT. The WINDOW_1X and WINDOW_1Y coordinates define the top left outside corner of the window borders relative to the inside of the parent border. In this case, the parent is the root window, which does not have a border.
3. The CREATE SIMPLE WINDOW routine call has the following format:

   window_id = X$CREATE_SIMPLE_WINDOW(display, parent_id, x_coord, y_coord, width, height, border_width, border_id, background_id)

   
   The client specifies a black border ten pixels wide, a white background, and a size of 600 by 600 pixels.
   The window manager overrides border width and color.
   CREATE SIMPLE WINDOW returns a unique identifier, WINDOW_1, used in subsequent calls related to the window.

To create a window whose attributes are different from the parent window, use the CREATE WINDOW routine. The CREATE WINDOW routine enables clients to specify the following window attributes when creating an input-output window:

• Default contents of an input-output window
• Border of an input-output window
• Treatment of the window when it or its relative is obscured
• Treatment of the window when it or its relative is moved
• Information the window receives about operations associated with other windows
• Color
• Cursor

Clients creating input-only windows can define the following attributes:

• Treatment of the window when it or its relative is moved
• Information the window receives about operations associated with other windows
• Cursor

Specifying other attributes for an input-only window causes the server to generate an error. Input-only windows cannot have input-output windows as children.

Use the following method to define window attributes:

• Assign values to the relevant members of a set window attributes data structure.
• Indicate the defined attribute by specifying the appropriate flag and in the value_mask argument of the CREATE WINDOW routine. If more than one attribute is to be defined, indicate the attributes by doing a bitwise OR on the appropriate flags and passing the result in the value_mask argument of the CREATE WINDOW routine.

Figure 3-5 illustrates the set window attributes data structure.

Figure 3-5 Set Window Attributes Data Structure

Xlib provides routines that the client can use to set or read the WM_NORMAL_HINTS property for a given window. These routines use the size hints data structure to communicate to the window manager about the size and position of windows in their normal and iconic startup states.

Use the SET WM NORMAL HINTS routine to set a window's X$C_XA_WM_NORMAL_HINTS property. Use the GET WM NORMAL HINTS routine to read a window's X$C_XA_WM_NORMAL_HINTS property.

Table 3-9 lists the flags used in the size hints data structure.

Figure 3-9 illustrates the size hints data structure. Table 3-10 describes the members of the data structure.

Figure 3-9 Size Hints Data Structure

Xlib provides an additional routine to set a window name. The STORE NAME routine assigns a name to a window and displays it in a prominent place such as the title bar. Example 1-1 in Chapter 1 uses the STORE NAME routine to define the name of its parent window, as follows:

To define and get the class of a specified window, use the SET CLASS HINT and GET CLASS HINT routines. The routines refer to the class hint data structure. Figure 3-11 illustrates the class hint data structure. Table 3-12 describes the members of the data structure.

Figure 3-11 Class Hint Data Structure

The client can change the hierarchical position of a window in relation to all windows in the stack or to a specified sibling. If the client changes the size, position, and stacking order of the window by calling CONFIGURE WINDOW, the server restacks the window based on its final, not initial, size and position. Table 3-14 lists constants and definitions for restacking windows.

Xlib assigns a symbol to the flag associated with each member of the data structure (Table 3-15).

Example 3-5 illustrates using CONFIGURE WINDOW to change the position, size, and stacking order of a window when the user presses a button.

C
C       This program changes the position, size, and stacking
C       order of SUBWINDOW_1

        RECORD /X$WINDOW_CHANGES/ XWC
                    .
                    .
                    .

(1)      WCHG_MASK = X$M_CW_X .OR. X$M_CW_Y .OR. X$M_CW_WIDTH .OR.
        1       X$M_CW_HEIGHT .OR. X$M_CW_SIBLING .OR. X$M_CW_STACK_MODE

(2)      XWC.X$L_WCHG_X = 200
        XWC.X$L_WCHG_Y = 350
        XWC.X$L_WCHG_WIDTH = 200
        XWC.X$L_WCHG_HEIGHT = 50
        XWC.X$L_WCHG_SIBLING = SUBWINDOW_2
        XWC.X$L_WCHG_STACK_MODE = X$C_ABOVE

(3)      CALL X$CONFIGURE_WINDOW(DPY, SUBWINDOW_1, WCHG_MASK, XWC)

1. Specify the members of the window changes data structure that have assigned values. Create a mask by performing a bitwise OR operation on relevant flags that indicate which members of WINDOW CHANGES the client will define.
2. Assign values to relevant members of the window changes data structure. Because the client identifies a sibling (SUBWINDOW_1), it must also choose a mode for stacking operations.
3. The call to reconfigure SUBWINDOW_1. The CONFIGURE WINDOW routine call has the following format:

   X$CONFIGURE_WINDOW(display, window_id, change_mask, values)

Figure 3-13 illustrates how the windows look after being reconfigured.

Figure 3-13 Reconfigured Window

Table 3-16 lists routines to change individual window characteristics.

It is important to know how reconfiguring windows affects graphics and text drawn in them by the client. (See Chapter 6 for a description of working with graphics and Chapter 8 for a description of writing text.) When a client resizes a window, window contents are either moved or lost, depending on the bit gravity of the window. Bit gravity indicates that a designated region of the window should be relocated when the window is resized. Resizing also causes the server to resize children of the changed window.

To control how the server moves children when a parent is resized, set the window gravity attribute. Table 3-17 lists choices for retaining window contents and controlling how the server relocates children.

Figure 3-14 illustrates how the server moves the contents of a reconfigured window when the bit gravity is set to the constant x$c_east_gravity.

Figure 3-15 illustrates how the server moves a child window if its parent is resized and its window gravity is set to the constant x$c_north_west_gravity.

Figure 3-14 East Bit Gravity

Figure 3-15 Northwest Window Gravity

Xlib provides routines that alter the window stacking order in the following ways:

• A specified window moves to either the top or the bottom of the stack.
• The lowest mapped child obscured by a sibling moves to the top of the stack.
• The highest mapped child that obscures a sibling moves to the bottom of the stack.

Use the RAISE WINDOW and LOWER WINDOW routines to move a specified window to either the top or the bottom of the stack, respectively.

To raise the lowest mapped child of an obscured window to the top of the stack, call CIRCULATE SUBWINDOWS UP. To lower the highest mapped child that obscures another child, call CIRCULATE SUBWINDOWS DOWN. The CIRCULATE SUBWINDOWS routine enables the client to perform these operations by specifying either the constant x$c_raise_lowest or the constant x$c_lower_highest.

To change the order of the window stack, use RESTACK WINDOW, which changes the window stack to a specified order. Reordered windows must have a common parent. If the first window the client specifies has other unspecified siblings, its order relative to those siblings remains unchanged.