Image: Eliminate VLAs from polygon fill algorithm implementation
This commit is contained in:
Peter Keresztes Schmidt
parent
a335e740f3
commit
6642ca4515
132
src/zm_image.cpp
132
src/zm_image.cpp
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@ -2458,7 +2458,7 @@ void Image::Outline( Rgb colour, const Polygon &polygon ) {
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} // end foreach coordinate in the polygon
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}
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/* RGB32 compatible: complete */
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// Polygon filling is based on the Scan-line Polygon filling algorithm
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void Image::Fill(Rgb colour, int density, const Polygon &polygon) {
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if (!(colours == ZM_COLOUR_GRAY8 || colours == ZM_COLOUR_RGB24 || colours == ZM_COLOUR_RGB32)) {
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Panic("Attempt to fill image with unexpected colours %d", colours);
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@ -2468,115 +2468,91 @@ void Image::Fill(Rgb colour, int density, const Polygon &polygon) {
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colour = rgb_convert(colour, subpixelorder);
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size_t n_coords = polygon.GetVertices().size();
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int n_global_edges = 0;
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Edge global_edges[n_coords];
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std::vector<Edge> global_edges;
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global_edges.reserve(n_coords);
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for (size_t j = 0, i = n_coords - 1; j < n_coords; i = j++) {
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const Vector2 &p1 = polygon.GetVertices()[i];
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const Vector2 &p2 = polygon.GetVertices()[j];
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int x1 = p1.x_;
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int x2 = p2.x_;
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int y1 = p1.y_;
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int y2 = p2.y_;
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//Debug( 9, "x1:%d,y1:%d x2:%d,y2:%d", x1, y1, x2, y2 );
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if ( y1 == y2 )
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// Do not add horizontal edges to the global edge table.
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if (p1.y_ == p2.y_)
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continue;
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double dx = x2 - x1;
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double dy = y2 - y1;
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Vector2 d = p2 - p1;
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global_edges[n_global_edges].min_y = y1<y2?y1:y2;
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global_edges[n_global_edges].max_y = y1<y2?y2:y1;
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global_edges[n_global_edges].min_x = y1<y2?x1:x2;
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global_edges[n_global_edges]._1_m = dx/dy;
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n_global_edges++;
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}
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std::sort(global_edges, global_edges + n_global_edges, Edge::CompareYX);
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global_edges.emplace_back(std::min(p1.y_, p2.y_),
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std::max(p1.y_, p2.y_),
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p1.y_ < p2.y_ ? p1.x_ : p2.x_,
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d.x_ / static_cast<double>(d.y_));
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#ifndef ZM_DBG_OFF
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if ( logLevel() >= Logger::DEBUG9 ) {
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for ( int i = 0; i < n_global_edges; i++ ) {
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Debug(9, "%d: min_y: %d, max_y:%d, min_x:%.2f, 1/m:%.2f",
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i, global_edges[i].min_y, global_edges[i].max_y, global_edges[i].min_x, global_edges[i]._1_m);
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}
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}
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#endif
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std::sort(global_edges.begin(), global_edges.end(), Edge::CompareYX);
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int n_active_edges = 0;
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Edge active_edges[n_global_edges];
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int y = global_edges[0].min_y;
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do {
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for ( int i = 0; i < n_global_edges; i++ ) {
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if ( global_edges[i].min_y == y ) {
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Debug(9, "Moving global edge");
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active_edges[n_active_edges++] = global_edges[i];
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if ( i < (n_global_edges-1) ) {
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memmove(&global_edges[i], &global_edges[i + 1], sizeof(*global_edges) * (n_global_edges - i - 1));
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i--;
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}
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n_global_edges--;
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std::vector<Edge> active_edges;
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active_edges.reserve(global_edges.size());
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int32 scan_line = global_edges[0].min_y;
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while (!global_edges.empty() || !active_edges.empty()) {
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// Deactivate edges with max_y < current scan line
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for (auto it = active_edges.begin(); it != active_edges.end();) {
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if (scan_line >= it->max_y) {
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it = active_edges.erase(it);
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} else {
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break;
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it->min_x += it->_1_m;
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++it;
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}
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}
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std::sort(active_edges, active_edges + n_active_edges, Edge::CompareX);
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#ifndef ZM_DBG_OFF
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if ( logLevel() >= Logger::DEBUG9 ) {
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for ( int i = 0; i < n_active_edges; i++ ) {
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Debug(9, "%d - %d: min_y: %d, max_y:%d, min_x:%.2f, 1/m:%.2f",
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y, i, active_edges[i].min_y, active_edges[i].max_y, active_edges[i].min_x, active_edges[i]._1_m );
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// Activate edges with min_y == current scan line
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for (auto it = global_edges.begin(); it != global_edges.end();) {
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if (it->min_y == scan_line) {
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active_edges.emplace_back(*it);
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it = global_edges.erase(it);
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} else {
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++it;
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}
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}
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#endif
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if ( !(y%density) ) {
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//Debug( 9, "%d", y );
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for ( int i = 0; i < n_active_edges; ) {
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int lo_x = int(round(active_edges[i++].min_x));
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int hi_x = int(round(active_edges[i++].min_x));
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std::sort(active_edges.begin(), active_edges.end(), Edge::CompareX);
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if (!(scan_line % density)) {
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for (auto it = active_edges.begin(); it != active_edges.end(); ++it) {
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int32 lo_x = static_cast<int32>(it->min_x);
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int32 hi_x = static_cast<int32>(std::next(it)->min_x);
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if (colours == ZM_COLOUR_GRAY8) {
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unsigned char *p = &buffer[(y*width)+lo_x];
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for ( int x = lo_x; x <= hi_x; x++, p++) {
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uint8 *p = &buffer[(scan_line * width) + lo_x];
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for (int32 x = lo_x; x <= hi_x; x++, p++) {
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if (!(x % density)) {
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//Debug( 9, " %d", x );
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*p = colour;
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}
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}
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} else if (colours == ZM_COLOUR_RGB24) {
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unsigned char *p = &buffer[colours*((y*width)+lo_x)];
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for ( int x = lo_x; x <= hi_x; x++, p += 3) {
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constexpr uint8 bytesPerPixel = 3;
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uint8 *ptr = &buffer[((scan_line * width) + lo_x) * bytesPerPixel];
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for (int32 x = lo_x; x <= hi_x; x++, ptr += bytesPerPixel) {
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if (!(x % density)) {
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RED_PTR_RGBA(p) = RED_VAL_RGBA(colour);
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GREEN_PTR_RGBA(p) = GREEN_VAL_RGBA(colour);
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BLUE_PTR_RGBA(p) = BLUE_VAL_RGBA(colour);
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RED_PTR_RGBA(ptr) = RED_VAL_RGBA(colour);
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GREEN_PTR_RGBA(ptr) = GREEN_VAL_RGBA(colour);
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BLUE_PTR_RGBA(ptr) = BLUE_VAL_RGBA(colour);
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}
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}
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} else if (colours == ZM_COLOUR_RGB32) {
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Rgb *p = (Rgb*)&buffer[((y*width)+lo_x)<<2];
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for ( int x = lo_x; x <= hi_x; x++, p++) {
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constexpr uint8 bytesPerPixel = 4;
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Rgb *ptr = reinterpret_cast<Rgb *>(&buffer[((scan_line * width) + lo_x) * bytesPerPixel]);
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for (int32 x = lo_x; x <= hi_x; x++, ptr++) {
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if (!(x % density)) {
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/* Fast, copies the entire pixel in a single pass */
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*p = colour;
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*ptr = colour;
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}
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}
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}
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}
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}
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y++;
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for ( int i = n_active_edges-1; i >= 0; i-- ) {
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if ( y >= active_edges[i].max_y ) {
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// Or >= as per sheets
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Debug(9, "Deleting active_edge");
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if ( i < (n_active_edges-1) ) {
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//memcpy( &active_edges[i], &active_edges[i+1], sizeof(*active_edges)*(n_active_edges-i) );
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memmove( &active_edges[i], &active_edges[i+1], sizeof(*active_edges)*(n_active_edges-i) );
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scan_line++;
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}
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n_active_edges--;
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} else {
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active_edges[i].min_x += active_edges[i]._1_m;
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}
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}
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} while ( n_global_edges || n_active_edges );
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}
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void Image::Fill(Rgb colour, const Polygon &polygon) {
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@ -23,11 +23,10 @@
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#include "zm_box.h"
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#include <vector>
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struct Edge {
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int min_y;
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int max_y;
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double min_x;
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double _1_m;
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class Edge {
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public:
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Edge() = default;
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Edge(int32 min_y, int32 max_y, double min_x, double _1_m) : min_y(min_y), max_y(max_y), min_x(min_x), _1_m(_1_m) {}
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static bool CompareYX(const Edge &e1, const Edge &e2) {
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if (e1.min_y == e2.min_y)
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@ -38,6 +37,12 @@ struct Edge {
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static bool CompareX(const Edge &e1, const Edge &e2) {
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return e1.min_x < e2.min_x;
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}
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public:
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int32 min_y;
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int32 max_y;
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double min_x;
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double _1_m;
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};
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// This class represents convex or concave non-self-intersecting polygons.
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