/********************************************************************** * File: coutln.c (Formerly coutline.c) * Description: Code for the C_OUTLINE class. * Author: Ray Smith * Created: Mon Oct 07 16:01:57 BST 1991 * * (C) Copyright 1991, Hewlett-Packard Ltd. ** Licensed under the Apache License, Version 2.0 (the "License"); ** you may not use this file except in compliance with the License. ** You may obtain a copy of the License at ** http://www.apache.org/licenses/LICENSE-2.0 ** Unless required by applicable law or agreed to in writing, software ** distributed under the License is distributed on an "AS IS" BASIS, ** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. ** See the License for the specific language governing permissions and ** limitations under the License. * **********************************************************************/ #include #ifdef __UNIX__ #include #endif #include "coutln.h" #include "allheaders.h" #include "blobs.h" #include "normalis.h" // Include automatically generated configuration file if running autoconf. #ifdef HAVE_CONFIG_H #include "config_auto.h" #endif ELISTIZE (C_OUTLINE) ICOORD C_OUTLINE::step_coords[4] = { ICOORD (-1, 0), ICOORD (0, -1), ICOORD (1, 0), ICOORD (0, 1) }; /** * @name C_OUTLINE::C_OUTLINE * * Constructor to build a C_OUTLINE from a CRACKEDGE LOOP. * @param startpt outline to convert * @param bot_left bounding box * @param top_right bounding box * @param length length of loop */ C_OUTLINE::C_OUTLINE(CRACKEDGE* startpt, ICOORD bot_left, ICOORD top_right, inT16 length) : box(bot_left, top_right), start(startpt->pos), offsets(NULL) { inT16 stepindex; //index to step CRACKEDGE *edgept; //current point stepcount = length; //no of steps if (length == 0) { steps = NULL; return; } //get memory steps = (uinT8 *) alloc_mem (step_mem()); memset(steps, 0, step_mem()); edgept = startpt; for (stepindex = 0; stepindex < length; stepindex++) { //set compact step set_step (stepindex, edgept->stepdir); edgept = edgept->next; } } /** * @name C_OUTLINE::C_OUTLINE * * Constructor to build a C_OUTLINE from a C_OUTLINE_FRAG. */ C_OUTLINE::C_OUTLINE ( //constructor //steps to copy ICOORD startpt, DIR128 * new_steps, inT16 length //length of loop ):start (startpt), offsets(NULL) { inT8 dirdiff; //direction difference DIR128 prevdir; //previous direction DIR128 dir; //current direction DIR128 lastdir; //dir of last step TBOX new_box; //easy bounding inT16 stepindex; //index to step inT16 srcindex; //source steps ICOORD pos; //current position pos = startpt; stepcount = length; // No. of steps. ASSERT_HOST(length >= 0); steps = static_cast(alloc_mem(step_mem())); // Get memory. memset(steps, 0, step_mem()); lastdir = new_steps[length - 1]; prevdir = lastdir; for (stepindex = 0, srcindex = 0; srcindex < length; stepindex++, srcindex++) { new_box = TBOX (pos, pos); box += new_box; //copy steps dir = new_steps[srcindex]; set_step(stepindex, dir); dirdiff = dir - prevdir; pos += step (stepindex); if ((dirdiff == 64 || dirdiff == -64) && stepindex > 0) { stepindex -= 2; //cancel there-and-back prevdir = stepindex >= 0 ? step_dir (stepindex) : lastdir; } else prevdir = dir; } ASSERT_HOST (pos.x () == startpt.x () && pos.y () == startpt.y ()); do { dirdiff = step_dir (stepindex - 1) - step_dir (0); if (dirdiff == 64 || dirdiff == -64) { start += step (0); stepindex -= 2; //cancel there-and-back for (int i = 0; i < stepindex; ++i) set_step(i, step_dir(i + 1)); } } while (stepindex > 1 && (dirdiff == 64 || dirdiff == -64)); stepcount = stepindex; ASSERT_HOST (stepcount >= 4); } /** * @name C_OUTLINE::C_OUTLINE * * Constructor to build a C_OUTLINE from a rotation of a C_OUTLINE. * @param srcline outline to rotate * @param rotation rotate to coord */ C_OUTLINE::C_OUTLINE(C_OUTLINE* srcline, FCOORD rotation) : offsets(NULL) { TBOX new_box; //easy bounding inT16 stepindex; //index to step inT16 dirdiff; //direction change ICOORD pos; //current position ICOORD prevpos; //previous dest point ICOORD destpos; //destination point inT16 destindex; //index to step DIR128 dir; //coded direction uinT8 new_step; stepcount = srcline->stepcount * 2; if (stepcount == 0) { steps = NULL; box = srcline->box; box.rotate(rotation); return; } //get memory steps = (uinT8 *) alloc_mem (step_mem()); memset(steps, 0, step_mem()); for (int iteration = 0; iteration < 2; ++iteration) { DIR128 round1 = iteration == 0 ? 32 : 0; DIR128 round2 = iteration != 0 ? 32 : 0; pos = srcline->start; prevpos = pos; prevpos.rotate (rotation); start = prevpos; box = TBOX (start, start); destindex = 0; for (stepindex = 0; stepindex < srcline->stepcount; stepindex++) { pos += srcline->step (stepindex); destpos = pos; destpos.rotate (rotation); // tprintf("%i %i %i %i ", destpos.x(), destpos.y(), pos.x(), pos.y()); while (destpos.x () != prevpos.x () || destpos.y () != prevpos.y ()) { dir = DIR128 (FCOORD (destpos - prevpos)); dir += 64; //turn to step style new_step = dir.get_dir (); // tprintf(" %i\n", new_step); if (new_step & 31) { set_step(destindex++, dir + round1); prevpos += step(destindex - 1); if (destindex < 2 || ((dirdiff = step_dir (destindex - 1) - step_dir (destindex - 2)) != -64 && dirdiff != 64)) { set_step(destindex++, dir + round2); prevpos += step(destindex - 1); } else { prevpos -= step(destindex - 1); destindex--; prevpos -= step(destindex - 1); set_step(destindex - 1, dir + round2); prevpos += step(destindex - 1); } } else { set_step(destindex++, dir); prevpos += step(destindex - 1); } while (destindex >= 2 && ((dirdiff = step_dir (destindex - 1) - step_dir (destindex - 2)) == -64 || dirdiff == 64)) { prevpos -= step(destindex - 1); prevpos -= step(destindex - 2); destindex -= 2; // Forget u turn } //ASSERT_HOST(prevpos.x() == destpos.x() && prevpos.y() == destpos.y()); new_box = TBOX (destpos, destpos); box += new_box; } } ASSERT_HOST (destpos.x () == start.x () && destpos.y () == start.y ()); dirdiff = step_dir (destindex - 1) - step_dir (0); while ((dirdiff == 64 || dirdiff == -64) && destindex > 1) { start += step (0); destindex -= 2; for (int i = 0; i < destindex; ++i) set_step(i, step_dir(i + 1)); dirdiff = step_dir (destindex - 1) - step_dir (0); } if (destindex >= 4) break; } ASSERT_HOST(destindex <= stepcount); stepcount = destindex; destpos = start; for (stepindex = 0; stepindex < stepcount; stepindex++) { destpos += step (stepindex); } ASSERT_HOST (destpos.x () == start.x () && destpos.y () == start.y ()); } // Build a fake outline, given just a bounding box and append to the list. void C_OUTLINE::FakeOutline(const TBOX& box, C_OUTLINE_LIST* outlines) { C_OUTLINE_IT ol_it(outlines); // Make a C_OUTLINE from the bounds. This is a bit of a hack, // as there is no outline, just a bounding box, but it works nicely. CRACKEDGE start; start.pos = box.topleft(); C_OUTLINE* outline = new C_OUTLINE(&start, box.topleft(), box.botright(), 0); ol_it.add_to_end(outline); } /** * @name C_OUTLINE::area * * Compute the area of the outline. */ inT32 C_OUTLINE::area() const { int stepindex; //current step inT32 total_steps; //steps to do inT32 total; //total area ICOORD pos; //position of point ICOORD next_step; //step to next pix // We aren't going to modify the list, or its contents, but there is // no const iterator. C_OUTLINE_IT it(const_cast(&children)); pos = start_pos (); total_steps = pathlength (); total = 0; for (stepindex = 0; stepindex < total_steps; stepindex++) { //all intersected next_step = step (stepindex); if (next_step.x () < 0) total += pos.y (); else if (next_step.x () > 0) total -= pos.y (); pos += next_step; } for (it.mark_cycle_pt (); !it.cycled_list (); it.forward ()) total += it.data ()->area ();//add areas of children return total; } /** * @name C_OUTLINE::perimeter * * Compute the perimeter of the outline and its first level children. */ inT32 C_OUTLINE::perimeter() const { inT32 total_steps; // Return value. // We aren't going to modify the list, or its contents, but there is // no const iterator. C_OUTLINE_IT it(const_cast(&children)); total_steps = pathlength(); for (it.mark_cycle_pt(); !it.cycled_list(); it.forward()) total_steps += it.data()->pathlength(); // Add perimeters of children. return total_steps; } /** * @name C_OUTLINE::outer_area * * Compute the area of the outline. */ inT32 C_OUTLINE::outer_area() const { int stepindex; //current step inT32 total_steps; //steps to do inT32 total; //total area ICOORD pos; //position of point ICOORD next_step; //step to next pix pos = start_pos (); total_steps = pathlength (); if (total_steps == 0) return box.area(); total = 0; for (stepindex = 0; stepindex < total_steps; stepindex++) { //all intersected next_step = step (stepindex); if (next_step.x () < 0) total += pos.y (); else if (next_step.x () > 0) total -= pos.y (); pos += next_step; } return total; } /** * @name C_OUTLINE::count_transitions * * Compute the number of x and y maxes and mins in the outline. * @param threshold winding number on size */ inT32 C_OUTLINE::count_transitions(inT32 threshold) { BOOL8 first_was_max_x; //what was first BOOL8 first_was_max_y; BOOL8 looking_for_max_x; //what is next BOOL8 looking_for_min_x; BOOL8 looking_for_max_y; //what is next BOOL8 looking_for_min_y; int stepindex; //current step inT32 total_steps; //steps to do //current limits inT32 max_x, min_x, max_y, min_y; inT32 initial_x, initial_y; //initial limits inT32 total; //total changes ICOORD pos; //position of point ICOORD next_step; //step to next pix pos = start_pos (); total_steps = pathlength (); total = 0; max_x = min_x = pos.x (); max_y = min_y = pos.y (); looking_for_max_x = TRUE; looking_for_min_x = TRUE; looking_for_max_y = TRUE; looking_for_min_y = TRUE; first_was_max_x = FALSE; first_was_max_y = FALSE; initial_x = pos.x (); initial_y = pos.y (); //stop uninit warning for (stepindex = 0; stepindex < total_steps; stepindex++) { //all intersected next_step = step (stepindex); pos += next_step; if (next_step.x () < 0) { if (looking_for_max_x && pos.x () < min_x) min_x = pos.x (); if (looking_for_min_x && max_x - pos.x () > threshold) { if (looking_for_max_x) { initial_x = max_x; first_was_max_x = FALSE; } total++; looking_for_max_x = TRUE; looking_for_min_x = FALSE; min_x = pos.x (); //reset min } } else if (next_step.x () > 0) { if (looking_for_min_x && pos.x () > max_x) max_x = pos.x (); if (looking_for_max_x && pos.x () - min_x > threshold) { if (looking_for_min_x) { initial_x = min_x; //remember first min first_was_max_x = TRUE; } total++; looking_for_max_x = FALSE; looking_for_min_x = TRUE; max_x = pos.x (); } } else if (next_step.y () < 0) { if (looking_for_max_y && pos.y () < min_y) min_y = pos.y (); if (looking_for_min_y && max_y - pos.y () > threshold) { if (looking_for_max_y) { initial_y = max_y; //remember first max first_was_max_y = FALSE; } total++; looking_for_max_y = TRUE; looking_for_min_y = FALSE; min_y = pos.y (); //reset min } } else { if (looking_for_min_y && pos.y () > max_y) max_y = pos.y (); if (looking_for_max_y && pos.y () - min_y > threshold) { if (looking_for_min_y) { initial_y = min_y; //remember first min first_was_max_y = TRUE; } total++; looking_for_max_y = FALSE; looking_for_min_y = TRUE; max_y = pos.y (); } } } if (first_was_max_x && looking_for_min_x) { if (max_x - initial_x > threshold) total++; else total--; } else if (!first_was_max_x && looking_for_max_x) { if (initial_x - min_x > threshold) total++; else total--; } if (first_was_max_y && looking_for_min_y) { if (max_y - initial_y > threshold) total++; else total--; } else if (!first_was_max_y && looking_for_max_y) { if (initial_y - min_y > threshold) total++; else total--; } return total; } /** * @name C_OUTLINE::operator< * * @return TRUE if the left operand is inside the right one. * @param other other outline */ BOOL8 C_OUTLINE::operator<(const C_OUTLINE& other) const { inT16 count = 0; //winding count ICOORD pos; //position of point inT32 stepindex; //index to cstep if (!box.overlap (other.box)) return FALSE; //can't be contained if (stepcount == 0) return other.box.contains(this->box); pos = start; for (stepindex = 0; stepindex < stepcount && (count = other.winding_number (pos)) == INTERSECTING; stepindex++) pos += step (stepindex); //try all points if (count == INTERSECTING) { //all intersected pos = other.start; for (stepindex = 0; stepindex < other.stepcount && (count = winding_number (pos)) == INTERSECTING; stepindex++) //try other way round pos += other.step (stepindex); return count == INTERSECTING || count == 0; } return count != 0; } /** * @name C_OUTLINE::winding_number * * @return the winding number of the outline around the given point. * @param point point to wind around */ inT16 C_OUTLINE::winding_number(ICOORD point) const { inT16 stepindex; //index to cstep inT16 count; //winding count ICOORD vec; //to current point ICOORD stepvec; //step vector inT32 cross; //cross product vec = start - point; //vector to it count = 0; for (stepindex = 0; stepindex < stepcount; stepindex++) { stepvec = step (stepindex); //get the step //crossing the line if (vec.y () <= 0 && vec.y () + stepvec.y () > 0) { cross = vec * stepvec; //cross product if (cross > 0) count++; //crossing right half else if (cross == 0) return INTERSECTING; //going through point } else if (vec.y () > 0 && vec.y () + stepvec.y () <= 0) { cross = vec * stepvec; if (cross < 0) count--; //crossing back else if (cross == 0) return INTERSECTING; //illegal } vec += stepvec; //sum vectors } return count; //winding number } /** * C_OUTLINE::turn_direction * * @return the sum direction delta of the outline. */ inT16 C_OUTLINE::turn_direction() const { //winding number DIR128 prevdir; //previous direction DIR128 dir; //current direction inT16 stepindex; //index to cstep inT8 dirdiff; //direction difference inT16 count; //winding count if (stepcount == 0) return 128; count = 0; prevdir = step_dir (stepcount - 1); for (stepindex = 0; stepindex < stepcount; stepindex++) { dir = step_dir (stepindex); dirdiff = dir - prevdir; ASSERT_HOST (dirdiff == 0 || dirdiff == 32 || dirdiff == -32); count += dirdiff; prevdir = dir; } ASSERT_HOST (count == 128 || count == -128); return count; //winding number } /** * @name C_OUTLINE::reverse * * Reverse the direction of an outline. */ void C_OUTLINE::reverse() { //reverse drection DIR128 halfturn = MODULUS / 2; //amount to shift DIR128 stepdir; //direction of step inT16 stepindex; //index to cstep inT16 farindex; //index to other side inT16 halfsteps; //half of stepcount halfsteps = (stepcount + 1) / 2; for (stepindex = 0; stepindex < halfsteps; stepindex++) { farindex = stepcount - stepindex - 1; stepdir = step_dir (stepindex); set_step (stepindex, step_dir (farindex) + halfturn); set_step (farindex, stepdir + halfturn); } } /** * @name C_OUTLINE::move * * Move C_OUTLINE by vector * @param vec vector to reposition OUTLINE by */ void C_OUTLINE::move(const ICOORD vec) { C_OUTLINE_IT it(&children); // iterator box.move (vec); start += vec; for (it.mark_cycle_pt (); !it.cycled_list (); it.forward ()) it.data ()->move (vec); // move child outlines } /** * Returns true if *this and its children are legally nested. * The outer area of a child should have the opposite sign to the * parent. If not, it means we have discarded an outline in between * (probably due to excessive length). */ bool C_OUTLINE::IsLegallyNested() const { if (stepcount == 0) return true; int parent_area = outer_area(); // We aren't going to modify the list, or its contents, but there is // no const iterator. C_OUTLINE_IT child_it(const_cast(&children)); for (child_it.mark_cycle_pt(); !child_it.cycled_list(); child_it.forward()) { const C_OUTLINE* child = child_it.data(); if (child->outer_area() * parent_area > 0 || !child->IsLegallyNested()) return false; } return true; } /** * If this outline is smaller than the given min_size, delete this and * remove from its list, via *it, after checking that *it points to this. * Otherwise, if any children of this are too small, delete them. * On entry, *it must be an iterator pointing to this. If this gets deleted * then this is extracted from *it, so an iteration can continue. * @param min_size minimum size for outline * @param it outline iterator */ void C_OUTLINE::RemoveSmallRecursive(int min_size, C_OUTLINE_IT* it) { if (box.width() < min_size || box.height() < min_size) { ASSERT_HOST(this == it->data()); delete it->extract(); // Too small so get rid of it and any children. } else if (!children.empty()) { // Search the children of this, deleting any that are too small. C_OUTLINE_IT child_it(&children); for (child_it.mark_cycle_pt(); !child_it.cycled_list(); child_it.forward()) { C_OUTLINE* child = child_it.data(); child->RemoveSmallRecursive(min_size, &child_it); } } } // Factored out helpers below are used only by ComputeEdgeOffsets to operate // on data from an 8-bit Pix, and assume that any input x and/or y are already // constrained to be legal Pix coordinates. /** * Helper computes the local 2-D gradient (dx, dy) from the 2x2 cell centered * on the given (x,y). If the cell would go outside the image, it is padded * with white. */ static void ComputeGradient(const l_uint32* data, int wpl, int x, int y, int width, int height, ICOORD* gradient) { const l_uint32* line = data + y * wpl; int pix_x_y = x < width && y < height ? GET_DATA_BYTE(line, x) : 255; int pix_x_prevy = x < width && y > 0 ? GET_DATA_BYTE(line - wpl, x) : 255; int pix_prevx_prevy = x > 0 && y > 0 ? GET_DATA_BYTE(line - wpl, x - 1) : 255; int pix_prevx_y = x > 0 && y < height ? GET_DATA_BYTE(line, x - 1) : 255; gradient->set_x(pix_x_y + pix_x_prevy - (pix_prevx_y + pix_prevx_prevy)); gradient->set_y(pix_x_prevy + pix_prevx_prevy - (pix_x_y + pix_prevx_y)); } /** * Helper evaluates a vertical difference, (x,y) - (x,y-1), returning true if * the difference, matches diff_sign and updating the best_diff, best_sum, * best_y if a new max. */ static bool EvaluateVerticalDiff(const l_uint32* data, int wpl, int diff_sign, int x, int y, int height, int* best_diff, int* best_sum, int* best_y) { if (y <= 0 || y >= height) return false; const l_uint32* line = data + y * wpl; int pixel1 = GET_DATA_BYTE(line - wpl, x); int pixel2 = GET_DATA_BYTE(line, x); int diff = (pixel2 - pixel1) * diff_sign; if (diff > *best_diff) { *best_diff = diff; *best_sum = pixel1 + pixel2; *best_y = y; } return diff > 0; } /** * Helper evaluates a horizontal difference, (x,y) - (x-1,y), where y is implied * by the input image line, returning true if the difference matches diff_sign * and updating the best_diff, best_sum, best_x if a new max. */ static bool EvaluateHorizontalDiff(const l_uint32* line, int diff_sign, int x, int width, int* best_diff, int* best_sum, int* best_x) { if (x <= 0 || x >= width) return false; int pixel1 = GET_DATA_BYTE(line, x - 1); int pixel2 = GET_DATA_BYTE(line, x); int diff = (pixel2 - pixel1) * diff_sign; if (diff > *best_diff) { *best_diff = diff; *best_sum = pixel1 + pixel2; *best_x = x; } return diff > 0; } /** * Adds sub-pixel resolution EdgeOffsets for the outline if the supplied * pix is 8-bit. Does nothing otherwise. * Operation: Consider the following near-horizontal line: * @verbatim * _________ * |________ * |________ * @endverbatim * At *every* position along this line, the gradient direction will be close * to vertical. Extrapoaltion/interpolation of the position of the threshold * that was used to binarize the image gives a more precise vertical position * for each horizontal step, and the conflict in step direction and gradient * direction can be used to ignore the vertical steps. */ void C_OUTLINE::ComputeEdgeOffsets(int threshold, Pix* pix) { if (pixGetDepth(pix) != 8) return; const l_uint32* data = pixGetData(pix); int wpl = pixGetWpl(pix); int width = pixGetWidth(pix); int height = pixGetHeight(pix); bool negative = flag(COUT_INVERSE); delete [] offsets; offsets = new EdgeOffset[stepcount]; ICOORD pos = start; ICOORD prev_gradient; ComputeGradient(data, wpl, pos.x(), height - pos.y(), width, height, &prev_gradient); for (int s = 0; s < stepcount; ++s) { ICOORD step_vec = step(s); TPOINT pt1(pos); pos += step_vec; TPOINT pt2(pos); ICOORD next_gradient; ComputeGradient(data, wpl, pos.x(), height - pos.y(), width, height, &next_gradient); // Use the sum of the prev and next as the working gradient. ICOORD gradient = prev_gradient + next_gradient; // best_diff will be manipulated to be always positive. int best_diff = 0; // offset will be the extrapolation of the location of the greyscale // threshold from the edge with the largest difference, relative to the // location of the binary edge. int offset = 0; if (pt1.y == pt2.y && abs(gradient.y()) * 2 >= abs(gradient.x())) { // Horizontal step. diff_sign == 1 indicates black above. int diff_sign = (pt1.x > pt2.x) == negative ? 1 : -1; int x = MIN(pt1.x, pt2.x); int y = height - pt1.y; int best_sum = 0; int best_y = y; EvaluateVerticalDiff(data, wpl, diff_sign, x, y, height, &best_diff, &best_sum, &best_y); // Find the strongest edge. int test_y = y; do { ++test_y; } while (EvaluateVerticalDiff(data, wpl, diff_sign, x, test_y, height, &best_diff, &best_sum, &best_y)); test_y = y; do { --test_y; } while (EvaluateVerticalDiff(data, wpl, diff_sign, x, test_y, height, &best_diff, &best_sum, &best_y)); offset = diff_sign * (best_sum / 2 - threshold) + (y - best_y) * best_diff; } else if (pt1.x == pt2.x && abs(gradient.x()) * 2 >= abs(gradient.y())) { // Vertical step. diff_sign == 1 indicates black on the left. int diff_sign = (pt1.y > pt2.y) == negative ? 1 : -1; int x = pt1.x; int y = height - MAX(pt1.y, pt2.y); const l_uint32* line = pixGetData(pix) + y * wpl; int best_sum = 0; int best_x = x; EvaluateHorizontalDiff(line, diff_sign, x, width, &best_diff, &best_sum, &best_x); // Find the strongest edge. int test_x = x; do { ++test_x; } while (EvaluateHorizontalDiff(line, diff_sign, test_x, width, &best_diff, &best_sum, &best_x)); test_x = x; do { --test_x; } while (EvaluateHorizontalDiff(line, diff_sign, test_x, width, &best_diff, &best_sum, &best_x)); offset = diff_sign * (threshold - best_sum / 2) + (best_x - x) * best_diff; } offsets[s].offset_numerator = static_cast(ClipToRange(offset, -MAX_INT8, MAX_INT8)); offsets[s].pixel_diff = static_cast(ClipToRange(best_diff, 0 , MAX_UINT8)); if (negative) gradient = -gradient; // Compute gradient angle quantized to 256 directions, rotated by 64 (pi/2) // to convert from gradient direction to edge direction. offsets[s].direction = Modulo(FCOORD::binary_angle_plus_pi(gradient.angle()) + 64, 256); prev_gradient = next_gradient; } } /** * Adds sub-pixel resolution EdgeOffsets for the outline using only * a binary image source. * * Runs a sliding window of 5 edge steps over the outline, maintaining a count * of the number of steps in each of the 4 directions in the window, and a * sum of the x or y position of each step (as appropriate to its direction.) * Ignores single-count steps EXCEPT the sharp U-turn and smoothes out the * perpendicular direction. Eg * @verbatim * ___ ___ Chain code from the left: * |___ ___ ___| 222122212223221232223000 * |___| |_| Corresponding counts of each direction: * 0 00000000000000000123 * 1 11121111001111100000 * 2 44434443443333343321 * 3 00000001111111112111 * Count of direction at center 41434143413313143313 * Step gets used? YNYYYNYYYNYYNYNYYYyY (y= U-turn exception) * Path redrawn showing only the used points: * ___ ___ * ___ ___ ___| * ___ _ * @endverbatim * Sub-pixel edge position cannot be shown well with ASCII-art, but each * horizontal step's y position is the mean of the y positions of the steps * in the same direction in the sliding window, which makes a much smoother * outline, without losing important detail. */ void C_OUTLINE::ComputeBinaryOffsets() { delete [] offsets; offsets = new EdgeOffset[stepcount]; // Count of the number of steps in each direction in the sliding window. int dir_counts[4]; // Sum of the positions (y for a horizontal step, x for vertical) in each // direction in the sliding window. int pos_totals[4]; memset(dir_counts, 0, sizeof(dir_counts)); memset(pos_totals, 0, sizeof(pos_totals)); ICOORD pos = start; ICOORD tail_pos = pos; // tail_pos is the trailing position, with the next point to be lost from // the window. tail_pos -= step(stepcount - 1); tail_pos -= step(stepcount - 2); // head_pos is the leading position, with the next point to be added to the // window. ICOORD head_pos = tail_pos; // Set up the initial window with 4 points in [-2, 2) for (int s = -2; s < 2; ++s) { increment_step(s, 1, &head_pos, dir_counts, pos_totals); } for (int s = 0; s < stepcount; pos += step(s++)) { // At step s, s in in the middle of [s-2, s+2]. increment_step(s + 2, 1, &head_pos, dir_counts, pos_totals); int dir_index = chain_code(s); ICOORD step_vec = step(s); int best_diff = 0; int offset = 0; // Use only steps that have a count of >=2 OR the strong U-turn with a // single d and 2 at d-1 and 2 at d+1 (mod 4). if (dir_counts[dir_index] >= 2 || (dir_counts[dir_index] == 1 && dir_counts[Modulo(dir_index - 1, 4)] == 2 && dir_counts[Modulo(dir_index + 1, 4)] == 2)) { // Valid step direction. best_diff = dir_counts[dir_index]; int edge_pos = step_vec.x() == 0 ? pos.x() : pos.y(); // The offset proposes that the actual step should be positioned at // the mean position of the steps in the window of the same direction. // See ASCII art above. offset = pos_totals[dir_index] - best_diff * edge_pos; } offsets[s].offset_numerator = static_cast(ClipToRange(offset, -MAX_INT8, MAX_INT8)); offsets[s].pixel_diff = static_cast(ClipToRange(best_diff, 0 , MAX_UINT8)); // The direction is just the vector from start to end of the window. FCOORD direction(head_pos.x() - tail_pos.x(), head_pos.y() - tail_pos.y()); offsets[s].direction = direction.to_direction(); increment_step(s - 2, -1, &tail_pos, dir_counts, pos_totals); } } /** * Renders the outline to the given pix, with left and top being * the coords of the upper-left corner of the pix. */ void C_OUTLINE::render(int left, int top, Pix* pix) const { ICOORD pos = start; for (int stepindex = 0; stepindex < stepcount; ++stepindex) { ICOORD next_step = step(stepindex); if (next_step.y() < 0) { pixRasterop(pix, 0, top - pos.y(), pos.x() - left, 1, PIX_NOT(PIX_DST), NULL, 0, 0); } else if (next_step.y() > 0) { pixRasterop(pix, 0, top - pos.y() - 1, pos.x() - left, 1, PIX_NOT(PIX_DST), NULL, 0, 0); } pos += next_step; } } /** * Renders just the outline to the given pix (no fill), with left and top * being the coords of the upper-left corner of the pix. * @param left coord * @param top coord * @param pix the pix to outline */ void C_OUTLINE::render_outline(int left, int top, Pix* pix) const { ICOORD pos = start; for (int stepindex = 0; stepindex < stepcount; ++stepindex) { ICOORD next_step = step(stepindex); if (next_step.y() < 0) { pixSetPixel(pix, pos.x() - left, top - pos.y(), 1); } else if (next_step.y() > 0) { pixSetPixel(pix, pos.x() - left - 1, top - pos.y() - 1, 1); } else if (next_step.x() < 0) { pixSetPixel(pix, pos.x() - left - 1, top - pos.y(), 1); } else if (next_step.x() > 0) { pixSetPixel(pix, pos.x() - left, top - pos.y() - 1, 1); } pos += next_step; } } /** * @name C_OUTLINE::plot * * Draw the outline in the given colour. * @param window window to draw in * @param colour colour to draw in */ #ifndef GRAPHICS_DISABLED void C_OUTLINE::plot(ScrollView* window, ScrollView::Color colour) const { inT16 stepindex; // index to cstep ICOORD pos; // current position DIR128 stepdir; // direction of step pos = start; // current position window->Pen(colour); if (stepcount == 0) { window->Rectangle(box.left(), box.top(), box.right(), box.bottom()); return; } window->SetCursor(pos.x(), pos.y()); stepindex = 0; while (stepindex < stepcount) { pos += step(stepindex); // step to next stepdir = step_dir(stepindex); stepindex++; // count steps // merge straight lines while (stepindex < stepcount && stepdir.get_dir() == step_dir(stepindex).get_dir()) { pos += step(stepindex); stepindex++; } window->DrawTo(pos.x(), pos.y()); } } /** * Draws the outline in the given colour, normalized using the given denorm, * making use of sub-pixel accurate information if available. */ void C_OUTLINE::plot_normed(const DENORM& denorm, ScrollView::Color colour, ScrollView* window) const { window->Pen(colour); if (stepcount == 0) { window->Rectangle(box.left(), box.top(), box.right(), box.bottom()); return; } const DENORM* root_denorm = denorm.RootDenorm(); ICOORD pos = start; // current position FCOORD f_pos = sub_pixel_pos_at_index(pos, 0); FCOORD pos_normed; denorm.NormTransform(root_denorm, f_pos, &pos_normed); window->SetCursor(IntCastRounded(pos_normed.x()), IntCastRounded(pos_normed.y())); for (int s = 0; s < stepcount; pos += step(s++)) { int edge_weight = edge_strength_at_index(s); if (edge_weight == 0) { // This point has conflicting gradient and step direction, so ignore it. continue; } FCOORD f_pos = sub_pixel_pos_at_index(pos, s); FCOORD pos_normed; denorm.NormTransform(root_denorm, f_pos, &pos_normed); window->DrawTo(IntCastRounded(pos_normed.x()), IntCastRounded(pos_normed.y())); } } #endif /** * @name C_OUTLINE::operator= * * Assignment - deep copy data * @param source assign from this */ C_OUTLINE& C_OUTLINE::operator=(const C_OUTLINE& source) { box = source.box; start = source.start; if (steps != NULL) free_mem(steps); stepcount = source.stepcount; steps = (uinT8 *) alloc_mem (step_mem()); memmove (steps, source.steps, step_mem()); if (!children.empty ()) children.clear (); children.deep_copy(&source.children, &deep_copy); delete [] offsets; if (source.offsets != NULL) { offsets = new EdgeOffset[stepcount]; memcpy(offsets, source.offsets, stepcount * sizeof(*offsets)); } else { offsets = NULL; } return *this; } /** * Helper for ComputeBinaryOffsets. Increments pos, dir_counts, pos_totals * by the step, increment, and vertical step ? x : y position * increment * at step s Mod stepcount respectively. Used to add or subtract the * direction and position to/from accumulators of a small neighbourhood. */ void C_OUTLINE::increment_step(int s, int increment, ICOORD* pos, int* dir_counts, int* pos_totals) const { int step_index = Modulo(s, stepcount); int dir_index = chain_code(step_index); dir_counts[dir_index] += increment; ICOORD step_vec = step(step_index); if (step_vec.x() == 0) pos_totals[dir_index] += pos->x() * increment; else pos_totals[dir_index] += pos->y() * increment; *pos += step_vec; } ICOORD C_OUTLINE::chain_step(int chaindir) { return step_coords[chaindir % 4]; }