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1.1 root 1: .NH 2
2: Line Drawing and Fill Operations
3: .FD
4: .IN "Definitions" "XLine"
5: .IN "XLine"
6: .IN "Line" "Drawing"
7: XLine (w, x1, y1, x2, y2, width, height, pixel, func, planes)
8: Window w;
9: int width, height; /* brush */
10: int x1, y1, x2, y2; /* beginning and end points */
11: int pixel; /* pixel value */
12: int func; /* display function */
13: int planes; /* plane mask */
14: .FN
15: \fIXLine\fP draws a line from pixel (\fIx1\fP,\fIy1\fP) to pixel
16: (\fIx2\fP,\fIy2\fP) inclusive
17: in the specified window, using the specified display function \fIfunc\fP.
18: .PP
19: The line will be drawn in the color specified by the \fIpixel\fP value.
20: .PP
21: \fIWidth\fP and \fIheight\fP
22: specify the size of a brush to be drawn along the line.
23: See the description of brushes at the beginning of this section.
24: .PP
25: The plane mask \fIplanes\fP
26: specifies which planes of the display will be modified.
27: .FD
28: .IN "Definitions" "XDraw"
29: .IN "XDraw"
30: .IN "Line" "Drawing"
31: XDraw (w, vlist, vcount, width, height, pixel, func, planes)
32: Window w;
33: int vcount; /* number of vertices */
34: Vertex *vlist;
35: int height, width; /* brush */
36: int pixel; /* pixel value */
37: int func; /* display function */
38: int planes; /* plane mask */
39: .FN
40: \fIXDraw\fP draws an arbitrary polygon or curve using the specified function.
41: The figure drawn is defined by the list of Vertexes \fIvlist\fP
42: that the caller supplies.
43: The points will be connected by lines as specified in the flags
44: in the vertex structure.
45: .PP
46: \fIWidth\fP and \fIheight\fP
47: specify the size of a brush to be drawn along the line.
48: See the description of brushes at the beginning of this section.
49: .PP
50: The plane mask \fIplanes\fP
51: specifies which planes of the display will be modified.
52: .PP
53: .IN "File" "<X/X.h>"
54: Each Vertex is a structure (defined in \fI<X/X.h>\fP):
55: .IN "Data Structures" "Vertex"
56: .IN "Vertex"
57: .nf
58: .sp
59: typedef struct _Vertex {
60: short x, y;
61: unsigned short flags;
62: } Vertex;
63: .fi
64: .LP
65: \fIX\fP and \fIy\fP are the coordinates of the vertex,
66: relative to either the upper
67: .IN "Vertex" "Flags"
68: left inside corner of the window (if the \fIVertexRelative\fP
69: bit in \fIflags\fP
70: is 0) or
71: the previous vertex (if \fIVertexRelative\fP is 1).
72: .PP
73: .IN "File" "<X/X.h>"
74: .IN "Vertex" "Flags"
75: The flags, as defined in \fI<X/X.h>\fP, are as follows:
76: .LP
77: .TS
78: center;
79: l c l.
80: VertexRelative 0x0001 else absolute
81: VertexDontDraw 0x0002 else draw
82: VertexCurved 0x0004 else straight
83: VertexStartClosed 0x0008 else not
84: VertexEndClosed 0x0010 else not
85: VertexDrawLastPoint 0x0020 else don't
86: .TE
87: .IN "VertexRelative"
88: \fIVertexRelative\fP is described above.
89: If bit 0 is not set, the coordinates are absolute (relative to the window).
90: The first vertex must be an absolute vertex.
91: .PP
92: .IN "VertexDontDraw"
93: If the \fIVertexDontDraw\fP bit is 1, no line or curve is drawn from the previous
94: vertex to this one. This is analogous to picking up the pen and moving
95: to another place before drawing another line.
96: .PP
97: .IN "VertexCurved"
98: If the \fIVertexCurved\fP bit is 1, a spline algorithm is used to draw a smooth
99: curve from the previous vertex, through this one, to the next vertex.
100: Otherwise, a straight line is drawn from the previous vertex.
101: It makes
102: sense to set \fIVertexCurved\fP to 1 only if a previous and next vertex are
103: both defined (either explicitly in the array, or through the definition
104: of a closed curve--see below.)
105: .PP
106: It is permissible for \fIVertexDontDraw\fP
107: bits and \fIVertexCurved\fP bits to both be 1;
108: this is useful if you want to define the `previous point' for the smooth
109: curve, but don't want an actual curve drawing to start until this
110: point.
111: .PP
112: .IN "VertexStartClosed"
113: If \fIVertexStartClosed\fP bit is 1, then this point marks the beginning of a
114: closed curve.
115: This vertex MUST be followed later in the array by
116: another vertex whose absolute coordinates are identical, and which has
117: .IN "VertexEndClosed"
118: \fIVertexEndClosed\fP bit of 1.
119: The points in between form a cycle for the purpose
120: of determining predecessor and successor vertices for the spline
121: algorithm.
122: It makes sense to set \fIVertexStartClosed\fP bit or \fIVertexEndClosed\fP bit
123: to 1 only if \fIVertexCurved\fP is also 1.
124: .PP
125: Normally, the end point of a curve or line is not drawn, since it is
126: probably the beginning point of the next curve or line.
127: .IN "Display Functions"
128: This is important if
129: a display function such as \fIGXinvert\fP or \fIGXxor\fP
130: is used, since drawing a
131: point twice with such a function produces a different result than
132: drawing it just once.
133: If \fIVertexDrawLastPoint\fP is 1, the end point is drawn.
134: .PP
135: .PP
136: The line will be drawn in the color specified by the pixel value.
137: .FD
138: .IN "Definitions" "XAppendVertex"
139: .IN "XAppendVertex"
140: int XAppendVertex(vertices,nvert)
141: Vertex vertices[];
142: int nvert;
143: .FN
144: This function appends \fIvertices\fP to the output buffer.
145: It is the responsibility of higher level subroutines to determine
146: if the previous draw command was of the same type.
147: This subroutine is NOT intended for normal users of this library,
148: but as a hook for certain libraries built on this library.
149: This function returns a 0 if there is no Draw command currently in
150: the output buffer, -1 if the vertices would not fit before the end of
151: the buffer, or \fInvert\fP if it was successful at appending the vertices.
152: .FD
153: .IN "Definitions" "XClearVertexFlag"
154: .IN "XClearVertexFlag"
155: XClearVertexFlag()
156: .FN
157: This routine clears the state of the flag marking if it is safe to
158: append vertices.
159: Again, this is principally for use of more sophisticated libraries.
160: .sp 2
161: .PP
162: When drawing lines, one may want to draw `dashed' or `dotted' lines.
163: This means you want to be able to some how specify the length of the
164: dashes, and the distance between them.
165: These functions therefore take a `pattern' specifier.
166: .PP
167: .IN "Macro" "DashedLine"
168: .IN "Macro" "DottedLine"
169: .IN "Macro" "SolidLine"
170: \fIXlib.h\fP has some predefined pattern values (actually macro invocations)
171: of \fIDashedLine\fP, \fIDottedLine\fP,
172: \fISolidLine\fP.
173: .IN "Definitions" "Patterns"
174: .IN "Patterns"
175: Since these predefined patterns are macro invocations and evaluate
176: to an integer,
177: you can use the predefined patterns to initialize static data.
178: .FD
179: .IN "Definitions" "XMakePattern"
180: .IN "XMakePattern"
181: .IN "Patterns"
182: Pattern XMakePattern(pattern, length, multiplier)
183: int pattern, length, multiplier;
184: .FN
185: In this macro, \fIpattern\fP is a bit string of the specified \fIlength\fP (at
186: most 16 bits).
187: The \fImultiplier\fP specifies how many times each bit in the
188: string should be repeated before moving to the next bit.
189: It cannot be more than 4096.
190: The bits are used least significant bit first, and repeated as many times
191: as needed.
192: .FD
193: .IN "Definitions" "XDrawPatterned"
194: .IN "Definitions" "XDrawDashed"
195: .IN "XDrawPatterned"
196: .IN "XDrawDashed"
197: .IN "Patterns"
198: XDrawPatterned (w, vlist, vcount, width, height, pixel, altpix, pattern, func, planes)
199: int altpix;
200:
201: XDrawDashed (w, vlist, vcount, width, height, pixel, pattern, func, planes)
202: Window w;
203: int pixel; /* pixel value */
204: int height, width; /* brush size */
205: int vcount; /* number of vertices */
206: Vertex *vlist;
207: Pattern pattern; /* pattern specification */
208: int func; /* display function */
209: int planes; /* plane mask */
210: .FN
211: .IN "XDraw"
212: These functions are similar to \fIXDraw\fP,
213: except they draw a dashed rather than a
214: solid line.
215: The pattern is a value encoding the pattern to be used.
216: .PP
217: For a dashed line, the destination is only updated when the pattern bit
218: is one.
219: .PP
220: For a patterned line,
221: the alternate source pixel value is used when the pattern bit is zero.
222: .FD
223: .IN "Definitions" "XDrawTiled"
224: .IN "Definitions" "XDrawFilled"
225: .IN "XDrawTiled"
226: .IN "XDrawFilled"
227: XDrawTiled (w, vlist, vcount, tile, func, planes)
228: Pixmap tile;
229:
230: XDrawFilled (w, vlist, vcount, pixel, func, planes)
231: Window w;
232: Vertex *vlist;
233: int vcount; /* number of vertices */
234: int pixel; /* pixel value */
235: int func; /* display function */
236: int planes; /* plane mask */
237: .FN
238: .IN "Polygons"
239: \fIXDrawFilled\fP draws arbitrary polygons or curves and fills them with
240: the specified \fIpixel\fP value.
241: .IN "Filled Polygons"
242: XDrawTiled draws arbitrary polygons or curves and fills them with
243: the specified \fItile\fP Pixmap.
244: .IN "XDraw"
245: The \fIvlist\fP, \fIvcount\fP, \fIfunc\fP and \fIplanes\fP
246: arguments are identical to \fIXDraw\fP.
247: Note that there may be implementation restrictions on the
248: nature of the \fItile\fP Pixmap.
249: (See \fIXQueryTileShape\fP.)
250: The vertex list should consist only of one or more closed regions.
251: A point is defined to be inside a region if an infinite ray with the point
252: as an origin crosses the path of the region an odd number of times.
253: .IN "XQueryTileShape"
254: .FD
255: .IN "Definitions" "XQueryBrushShape"
256: .IN "XQueryBrushShape"
257: .IN "Limitations" "Brush Shape"
258: XQueryBrushShape (width, height, cwidth, height)
259: int width, height;
260: int *cwidth, *cheight; /* RETURN of `closest' legal size */
261: .FN
262: This function returns the `closest' shape actually supported by the
263: display hardware for brushes, since not all hardware is capable of supporting
264: arbitrary size brushes.
265: Painting lines using brushes of widths not supported by the hardware
266: has unpredictable results.
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