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4 <TITLE>XsMDICanvas Class</TITLE>
5 <LINK REV="made" HREF="mailto:ssadler@cisco.com">
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8 <H2>
9 The XsMDICanvas Class
10 </H2>
11
12 <P>
13 This section describes how to build and manipulate an MDI using the
14 <I>XsMDICanvas</I> class. Minimally, you must perform the following actions
15 to build and display an MDI canvas:
16
17 <OL>
18 <LI>Create the <I>XsMDICanvas</I> object.</LI>
19 <LI>Create the documents as instances of subclasses of <I>XsMDIWindow</I>.</LI>
20 <LI>Add the documents to the canvas</LI>
21 <LI>Show the canvas</LI>
22 </OL>
23
24 <P>
25 <B>Constructor and Destructor:</B>
26
27 <P>
28 The <I>XsMDICanvas</I> accepts two arguments:
29
30 <DL>
31 <DD>XsMDICanvas (const char *name, Widget parent)</DD>
32 </DL>
33
34 <P>
35 The <I>name</I> parameter specifies the name of the canvas and is used
36 as the widget name for the underlying implementation. The <I>parent</I>
37 parameter specifies the widget that is to be used as the parent of the
38 canvas.
39
40 <P>
41 The <I>XsMDICanvas</I> destructor destroys the canvas, but it <B>does not</B>
42 destroy any of the underlying documents. It is up to the application to
43 destroy these.
44
45 <P>
46 <B>Adding and removing documents:</B>
47
48 <P>
49 After the documents are created, they must be added to the canvas. The
50 <I>XsMDICanvas::add()</I> member-function adds documents to the canvas:
51
52 <DL>
53 <DD>virtual void add (XsMDIWindow *window)</DD>
54 </DL>
55
56 <P>
57 The behavior of adding the same document to the canvas more than once
58 is undefined. Documents can be removed from the canvas by using:
59
60 <DL>
61 <DD>virtual void remove (XsMDIWindow *window)</DD>
62 </DL>
63
64 <P>
65 Additionally, all documents can be removed from the canvas with:
66
67 <DL>
68 <DD>void removeAll ( )</DD>
69 </DL>
70
71 <P>
72 The number of documents currently installed in the canvas can be
73 retrieved with:
74
75 <DL>
76 <DD>int numWindows ( ) const</DD>
77 </DL>
78
79 <P>
80 <B>Showing the canvas:</B>
81
82 <P>
83 In order to show (manage) the canvas call the <I>show</I> member function:
84
85 <DL>
86 <DD>virtual void show ( )</DD>
87 </DL>
88
89 This member-function is responsible for cycling all of the installed documents
90 and calling their respective <I>XsMDIWindow::_buildClientArea()</I>
91 member-functions. After each document has been created, <I>show</I> will then
92 manage each document and, finally, itself.
93
94 <P>
95 <B>Window Placement:</B>
96
97 <P>
98 The current implementation of <I>XsMDICanvas</I> uses a very simple algorithm
99 to place the documents on the canvas. In order to implement a more specific
100 placement algorithm, derive a class from <I>XsMDICanvas</I> and override
101 the member-function:
102
103 <DL>
104 <DD>virtual void _placeWindow (XsMDIWindow *win)</DD>
105 </DL>
106
107 <P>
108 This member-function is called for each document in the canvas to compute
109 the location of the document. Please refer to the code (<I>XsMDICanvas.C</I>)
110 for more details.
111
112 <P>
113 <B>Canvas Behavior:</B>
114
115 <P>
116 The <I>XsMDICanvas</I> is implemented as an <I>XmScrolledWindow</I> with an
117 <I>XmDrawingArea</I> work-window. The instance name for the work-window
118 is <I>canvas</I>. Internal callbacks in the canvas class force the work-window
119 to be at-least the size of the clip-window. This prevents documents from
120 being clipped as they are moved around.
121
122 <P>
123 By default, the <I>XmDrawingArea</I> work-window has its <I>XmNresizePolicy</I>
124 set to <I>XmRESIZE_GROW</I>. This will allow the work-area to grow to
125 whatever size necessary, but it will not automatically shrink as windows
126 are manipulated. If different behavior is desired, the <I>XmNresizePolicy</I>
127 resource on the work-area can be set to <I>XmRESIZE_ANY</I>. This will
128 force the work-window to recompute its size as windows are manipulated, and
129 it will grow and shrink as necessary. However, the <I>XsMDICanvas</I> will
130 still force the work-area to be at-least the size of the clip-window.
131
132 <P>To change the default behavior, add the following resource:
133
134 <DL>
135 <DD>&ltXsMDICanvas name&gt*canvas.resizePolicy: XmRESIZE_ANY</DD>
136 </DL>
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