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| Rev 1892 | Rev 3959 | ||
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| Line 36... | Line 36... | ||
| 36 | 36 | ||
| Line 37... | Line 37... | ||
| 37 | #include "cairoint.h" |
37 | #include "cairoint.h" |
| Line -... | Line 38... | ||
| - | 38 | ||
| - | 39 | #include "cairo-arc-private.h" |
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| 38 | 40 | ||
| Line 39... | Line 41... | ||
| 39 | #include "cairo-arc-private.h" |
41 | #define MAX_FULL_CIRCLES 65536 |
| Line 40... | Line 42... | ||
| 40 | 42 | ||
| Line 129... | Line 131... | ||
| 129 | (R * cos(B) + h * sin(B), R * sin(B) - h * cos (B)) |
131 | (R * cos(B) + h * sin(B), R * sin(B) - h * cos (B)) |
| 130 | (R * cos(B), R * sin(B)) |
132 | (R * cos(B), R * sin(B)) |
| Line 131... | Line 133... | ||
| 131 | 133 | ||
| Line 132... | Line 134... | ||
| 132 | for some value of h. |
134 | for some value of h. |
| 133 | 135 | ||
| 134 | "Approximation of circular arcs by cubic poynomials", Michael |
136 | "Approximation of circular arcs by cubic polynomials", Michael |
| Line 135... | Line 137... | ||
| 135 | Goldapp, Computer Aided Geometric Design 8 (1991) 227-238, provides |
137 | Goldapp, Computer Aided Geometric Design 8 (1991) 227-238, provides |
| Line 136... | Line 138... | ||
| 136 | various values of h along with error analysis for each. |
138 | various values of h along with error analysis for each. |
| Line 137... | Line 139... | ||
| 137 | 139 | ||
| 138 | From that paper, a very practical value of h is: |
140 | From that paper, a very practical value of h is: |
| 139 | 141 | ||
| 140 | h = 4/3 * tan(angle/4) |
142 | h = 4/3 * R * tan(angle/4) |
| Line 182... | Line 184... | ||
| 182 | cairo_direction_t dir) |
184 | cairo_direction_t dir) |
| 183 | { |
185 | { |
| 184 | if (cairo_status (cr)) |
186 | if (cairo_status (cr)) |
| 185 | return; |
187 | return; |
| Line -... | Line 188... | ||
| - | 188 | ||
| - | 189 | assert (angle_max >= angle_min); |
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| - | 190 | ||
| 186 | 191 | if (angle_max - angle_min > 2 * M_PI * MAX_FULL_CIRCLES) { |
|
| 187 | while (angle_max - angle_min > 4 * M_PI) |
192 | angle_max = fmod (angle_max - angle_min, 2 * M_PI); |
| - | 193 | angle_min = fmod (angle_min, 2 * M_PI); |
|
| - | 194 | angle_max += angle_min + 2 * M_PI * MAX_FULL_CIRCLES; |
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| Line 188... | Line 195... | ||
| 188 | angle_max -= 2 * M_PI; |
195 | } |
| 189 | 196 | ||
| 190 | /* Recurse if drawing arc larger than pi */ |
197 | /* Recurse if drawing arc larger than pi */ |
| 191 | if (angle_max - angle_min > M_PI) { |
198 | if (angle_max - angle_min > M_PI) { |
| Line 208... | Line 215... | ||
| 208 | dir); |
215 | dir); |
| 209 | } |
216 | } |
| 210 | } else if (angle_max != angle_min) { |
217 | } else if (angle_max != angle_min) { |
| 211 | cairo_matrix_t ctm; |
218 | cairo_matrix_t ctm; |
| 212 | int i, segments; |
219 | int i, segments; |
| 213 | double angle, angle_step; |
220 | double step; |
| Line 214... | Line 221... | ||
| 214 | 221 | ||
| 215 | cairo_get_matrix (cr, &ctm); |
222 | cairo_get_matrix (cr, &ctm); |
| 216 | segments = _arc_segments_needed (angle_max - angle_min, |
223 | segments = _arc_segments_needed (angle_max - angle_min, |
| 217 | radius, &ctm, |
224 | radius, &ctm, |
| 218 | cairo_get_tolerance (cr)); |
225 | cairo_get_tolerance (cr)); |
| - | 226 | step = (angle_max - angle_min) / segments; |
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| Line 219... | Line 227... | ||
| 219 | angle_step = (angle_max - angle_min) / (double) segments; |
227 | segments -= 1; |
| - | 228 | ||
| - | 229 | if (dir == CAIRO_DIRECTION_REVERSE) { |
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| 220 | 230 | double t; |
|
| 221 | if (dir == CAIRO_DIRECTION_FORWARD) { |
231 | |
| 222 | angle = angle_min; |
232 | t = angle_min; |
| - | 233 | angle_min = angle_max; |
|
| 223 | } else { |
234 | angle_max = t; |
| 224 | angle = angle_max; |
235 | |
| Line 225... | Line 236... | ||
| 225 | angle_step = - angle_step; |
236 | step = -step; |
| 226 | } |
237 | } |
| 227 | - | ||
| 228 | for (i = 0; i < segments; i++, angle += angle_step) { |
- | |
| 229 | _cairo_arc_segment (cr, xc, yc, |
238 | |
| 230 | radius, |
239 | for (i = 0; i < segments; i++, angle_min += step) { |
| - | 240 | _cairo_arc_segment (cr, xc, yc, radius, |
|
| - | 241 | angle_min, angle_min + step); |
|
| - | 242 | } |
|
| 231 | angle, |
243 | |
| 232 | angle + angle_step); |
244 | _cairo_arc_segment (cr, xc, yc, radius, |
| 233 | } |
245 | angle_min, angle_max); |
| 234 | } else { |
246 | } else { |
| 235 | cairo_line_to (cr, |
247 | cairo_line_to (cr, |
| 236 | xc + radius * cos (angle_min), |
248 | xc + radius * cos (angle_min), |
| Line 237... | Line 249... | ||
| 237 | yc + radius * sin (angle_min)); |
249 | yc + radius * sin (angle_min)); |
| 238 | } |
250 | } |
| 239 | } |
251 | } |
| 240 | 252 | ||
| 241 | /** |
253 | /** |
| 242 | * _cairo_arc_path |
254 | * _cairo_arc_path: |
| 243 | * @cr: a cairo context |
255 | * @cr: a cairo context |