209 lines
6.7 KiB
C++
209 lines
6.7 KiB
C++
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// mapnik
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#include <mapnik/markers_placement.hpp>
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#include <mapnik/geometry.hpp>
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#include <mapnik/ctrans.hpp>
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#include <mapnik/label_collision_detector.hpp>
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// agg
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#include "agg_basics.h"
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// stl
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#include <cmath>
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namespace mapnik
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{
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/** Constructor for markers_placement object.
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* \param locator Path along which markers are placed (type: vertex source)
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* \param size Size of the marker
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* \param detector Collision detection
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* \param spacing Distance between markers. If the value is negative it is
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* converted to a positive value with similar magnitude, but
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* choosen to optimize marker placement. 0 = no markers
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*/
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template <typename Locator, typename Detector> markers_placement<Locator, Detector>::markers_placement(
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Locator &locator, box2d<double> size, Detector &detector, double spacing, double max_error, bool allow_overlap)
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: locator_(locator), size_(size), detector_(detector), max_error_(max_error), allow_overlap_(allow_overlap)
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{
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if (spacing >= 0)
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{
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spacing_ = spacing;
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} else if (spacing < 0)
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{
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spacing_ = find_optimal_spacing(-spacing);
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}
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rewind();
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}
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/** Automatically chooses spacing. */
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template <typename Locator, typename Detector> double markers_placement<Locator, Detector>::find_optimal_spacing(double s)
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{
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rewind();
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//Calculate total path length
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unsigned cmd = agg::path_cmd_move_to;
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double length = 0;
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while (!agg::is_stop(cmd))
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{
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double dx = next_x - last_x;
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double dy = next_y - last_y;
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length += std::sqrt(dx * dx + dy * dy);
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last_x = next_x;
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last_y = next_y;
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while (agg::is_move_to(cmd = locator_.vertex(&next_x, &next_y)))
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{
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//Skip over "move" commands
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last_x = next_x;
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last_y = next_y;
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}
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}
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unsigned points = round(length / s);
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if (points == 0) return 0.0; //Path to short
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return length / points;
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}
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/** Start again at first marker.
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* \note Returning the same list of markers only works when they were NOT added
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* to the detector.
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*/
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template <typename Locator, typename Detector> void markers_placement<Locator, Detector>::rewind()
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{
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locator_.rewind(0);
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//Get first point
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done_ = agg::is_stop(locator_.vertex(&next_x, &next_y)) || spacing_ < size_.width();
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last_x = next_x;
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last_y = next_y; // Force request of new segment
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error_ = 0;
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marker_nr_ = 0;
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}
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/** Get a point where the marker should be placed.
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* Each time this function is called a new point is returned.
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* \param x Return value for x position
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* \param y Return value for x position
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* \param angle Return value for rotation angle
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* \param add_to_detector Add selected position to detector
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* \return True if a place is found, false if none is found.
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*/
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template <typename Locator, typename Detector> bool markers_placement<Locator, Detector>::get_point(
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double *x, double *y, double *angle, bool add_to_detector)
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{
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if (done_) return false;
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unsigned cmd;
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double spacing_left;
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if (marker_nr_++ == 0)
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{
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//First marker
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spacing_left = spacing_ / 2;
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} else
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{
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spacing_left = spacing_;
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}
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spacing_left -= error_;
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error_ = 0;
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while (true)
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{
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//Loop exits when a position is found or when no more segments are available
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if (spacing_left < size_.width()/2)
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{
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//Do not place markers to close to the beginning of a segment
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error_ += size_.width()/2 - spacing_left;
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spacing_left = size_.width()/2;
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}
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if (abs(error_) > max_error_ * spacing_)
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{
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spacing_left += spacing_ - error_;
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error_ = 0;
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}
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double dx = next_x - last_x;
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double dy = next_y - last_y;
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double d = std::sqrt(dx * dx + dy * dy);
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if (d <= spacing_left)
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{
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//Segment is to short to place marker. Find next segment
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spacing_left -= d;
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last_x = next_x;
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last_y = next_y;
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while (agg::is_move_to(cmd = locator_.vertex(&next_x, &next_y)))
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{
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//Skip over "move" commands
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last_x = next_x;
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last_y = next_y;
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}
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if (agg::is_stop(cmd))
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{
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done_ = true;
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return false;
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}
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continue; //Try again
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}
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//Check if marker really fits in this segment
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if (d < size_.width())
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{
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//Segment to short => Skip this segment
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error_ += d + size_.width()/2 - spacing_left;
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spacing_left = d + size_.width()/2;
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continue;
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} else if (d - spacing_left < size_.width()/2)
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{
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//Segment is long enough, but we are to close to the end
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//Note: This function moves backwards. This could lead to an infinite
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// loop when another function adds a positive offset. Therefore we
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// only move backwards when there is no offset
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if (error_ == 0)
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{
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error_ += d - size_.width()/2 - spacing_left;
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spacing_left = d - size_.width()/2;
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} else
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{
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//Skip this segment
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error_ += d + size_.width()/2 - spacing_left;
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spacing_left = d + size_.width()/2;
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}
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continue; //Force checking of max_error constraint
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}
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*angle = atan2(dy, dx);
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*x = last_x + dx * (spacing_left / d);
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*y = last_y + dy * (spacing_left / d);
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box2d<double> box = perform_transform(*angle, *x, *y);
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if (!allow_overlap_ && !detector_.has_placement(box))
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{
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//10.0 is choosen arbitrarily
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error_ += spacing_ * max_error_ / 10.0;
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spacing_left += spacing_ * max_error_ / 10.0;
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continue;
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}
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if (add_to_detector) detector_.insert(box);
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last_x = *x;
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last_y = *y;
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return true;
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}
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}
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/** Rotates the size_ box and translates the position. */
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template <typename Locator, typename Detector> box2d<double> markers_placement<Locator, Detector>::perform_transform(double angle, double dx, double dy)
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{
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double c = cos(angle), s = sin(angle);
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double x1 = size_.minx();
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double x2 = size_.maxx();
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double y1 = size_.miny();
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double y2 = size_.maxy();
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double x1_ = dx + x1 * c - y1 * s;
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double y1_ = dy + x1 * s + y1 * c;
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double x2_ = dx + x2 * c - y2 * s;
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double y2_ = dy + x2 * s + y2 * c;
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return box2d<double>(x1_, y1_, x2_, y2_);
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}
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typedef coord_transform2<CoordTransform,geometry_type> path_type;
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template class markers_placement<path_type, label_collision_detector4>;
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} //ns mapnik
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