127 lines
4.0 KiB
C++
127 lines
4.0 KiB
C++
#include "editor/EntityCutoutUtils.h"
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#include <algorithm>
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#include <cmath>
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#include <QPainter>
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#include <QPolygonF>
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#include <QTransform>
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namespace entity_cutout {
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QPainterPath pathFromWorldPolygon(const QVector<QPointF>& poly) {
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QPainterPath path;
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if (poly.size() < 3) {
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return path;
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}
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path.addPolygon(QPolygonF(poly));
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path.closeSubpath();
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return path;
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}
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QPointF polygonCentroid(const QVector<QPointF>& poly) {
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if (poly.size() < 3) {
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return {};
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}
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double a2 = 0.0;
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double cx6a = 0.0;
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double cy6a = 0.0;
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for (int i = 0; i < poly.size(); ++i) {
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const QPointF p0 = poly[i];
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const QPointF p1 = poly[(i + 1) % poly.size()];
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const double cross = static_cast<double>(p0.x()) * static_cast<double>(p1.y()) -
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static_cast<double>(p1.x()) * static_cast<double>(p0.y());
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a2 += cross;
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cx6a += (static_cast<double>(p0.x()) + static_cast<double>(p1.x())) * cross;
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cy6a += (static_cast<double>(p0.y()) + static_cast<double>(p1.y())) * cross;
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}
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if (std::abs(a2) < 1e-6) {
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const QRectF bb = pathFromWorldPolygon(poly).boundingRect();
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return bb.center();
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}
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const double inv6a = 1.0 / (3.0 * a2);
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return QPointF(cx6a * inv6a, cy6a * inv6a);
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}
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QRect clampRectToImage(const QRect& r, const QSize& size) {
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QRect out = r.normalized();
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if (out.isNull()) {
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return {};
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}
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out.setLeft(std::max(0, out.left()));
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out.setTop(std::max(0, out.top()));
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out.setRight(std::min(size.width() - 1, out.right()));
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out.setBottom(std::min(size.height() - 1, out.bottom()));
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if (out.width() <= 0 || out.height() <= 0) {
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return {};
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}
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return out;
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}
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QImage extractEntityImage(const QImage& bg, const QVector<QPointF>& polyWorld, QPointF& outTopLeftWorld) {
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if (bg.isNull() || polyWorld.size() < 3) {
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outTopLeftWorld = {};
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return {};
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}
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const QPainterPath path = pathFromWorldPolygon(polyWorld);
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if (path.isEmpty()) {
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outTopLeftWorld = {};
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return {};
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}
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// bbox 必须只由顶点 min/max 推导，不能依赖 QPainterPath::boundingRect()：
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// 在坐标含小数时，boundingRect 的浮点误差会造成稳定的“右下”偏移。
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double minX = polyWorld.front().x();
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double minY = polyWorld.front().y();
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double maxX = polyWorld.front().x();
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double maxY = polyWorld.front().y();
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for (const auto& p : polyWorld) {
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minX = std::min(minX, double(p.x()));
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minY = std::min(minY, double(p.y()));
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maxX = std::max(maxX, double(p.x()));
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maxY = std::max(maxY, double(p.y()));
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}
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const int left = std::clamp(int(std::floor(minX)), 0, bg.width());
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const int top = std::clamp(int(std::floor(minY)), 0, bg.height());
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const int right = std::clamp(int(std::ceil(maxX)), 0, bg.width() - 1);
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const int bottom = std::clamp(int(std::ceil(maxY)), 0, bg.height() - 1);
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const QRect bbox = clampRectToImage(QRect(QPoint(left, top), QPoint(right, bottom)), bg.size());
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if (bbox.isNull()) {
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outTopLeftWorld = {};
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return {};
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}
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outTopLeftWorld = bbox.topLeft();
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QImage out(bbox.size(), QImage::Format_ARGB32_Premultiplied);
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out.fill(Qt::transparent);
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QPainter p(&out);
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p.setRenderHint(QPainter::Antialiasing, true);
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QTransform tr;
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tr.translate(-bbox.left(), -bbox.top());
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const QPainterPath localPath = tr.map(path);
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p.setClipPath(localPath);
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p.drawImage(QPoint(0, 0), bg, bbox);
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p.end();
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return out;
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}
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void applyBlackFillToBackground(QImage& bgCutout, const QVector<QPointF>& polyWorld) {
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if (bgCutout.isNull() || polyWorld.size() < 3) {
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return;
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}
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QPainterPath path = pathFromWorldPolygon(polyWorld);
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if (path.isEmpty()) {
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return;
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}
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QPainter p(&bgCutout);
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p.setRenderHint(QPainter::Antialiasing, true);
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p.setPen(Qt::NoPen);
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p.setBrush(QColor(0, 0, 0, 255));
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p.drawPath(path);
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p.end();
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}
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} // namespace entity_cutout
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