mirror of
https://github.com/openharmony/graphic_utils.git
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liuyuxiang-bear
3e7f661383
Signed-off-by: liuyuxiang-bear <liuyuxiang7@huawei.com> Change-Id: I624ffb8b26d745daf13e4ed6f9563b05390fbc46
236 lines
7.8 KiB
C++
236 lines
7.8 KiB
C++
/*
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* Copyright (c) 2020-2022 Huawei Device Co., Ltd.
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include "gfx_utils/geometry2d.h"
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#include "securec.h"
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namespace OHOS {
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/* return point of intersection of two lines when it is sure a and b is intersected */
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bool Intersect(const Line& a, const Line& b, Vector2<int16_t>& out)
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{
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Vector2<int16_t> aA = a[0];
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Vector2<int16_t> aB = a[1];
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Vector2<int16_t> bA = b[0];
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Vector2<int16_t> bB = b[1];
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int32_t den = static_cast<int32_t>(aA.x_ - aB.x_) * (bA.y_ - bB.y_) -
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static_cast<int32_t>(aA.y_ - aB.y_) * (bA.x_ - bB.x_);
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if (den == 0) {
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return false;
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}
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int32_t xNum = (static_cast<int32_t>(aA.x_) * aB.y_ - static_cast<int32_t>(aA.y_) * aB.x_) * (bA.x_ - bB.x_) -
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(aA.x_ - aB.x_) * (static_cast<int32_t>(bA.x_) * bB.y_ - static_cast<int32_t>(bA.y_) * bB.x_);
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int32_t yNum = (static_cast<int32_t>(aA.x_) * aB.y_ - static_cast<int32_t>(aA.y_) * aB.x_) * (bA.y_ - bB.y_) -
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(aA.y_ - aB.y_) * (static_cast<int32_t>(bA.x_) * bB.y_ - static_cast<int32_t>(bA.y_) * bB.x_);
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out.x_ = xNum / den;
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out.y_ = yNum / den;
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return true;
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}
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/* check two line intersect if intersect return true, else false */
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bool IsIntersect(const Line& a, const Line& b)
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{
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Vector2<int16_t> aA = a[0];
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Vector2<int16_t> aB = a[1];
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Vector2<int16_t> bA = b[0];
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Vector2<int16_t> bB = b[1];
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int32_t iPos = static_cast<int32_t>(aB.x_ - aA.x_) * (bA.y_ - aA.y_) -
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static_cast<int32_t>(aB.y_ - aA.y_) * (bA.x_ - aA.x_);
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int32_t kPos = static_cast<int32_t>(aB.x_ - aA.x_) * (bB.y_ - aA.y_) -
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static_cast<int32_t>(aB.y_ - aA.y_) * (bB.x_ - aA.x_);
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if (static_cast<int64_t>(iPos) * kPos <= 0) {
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return true;
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}
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return false;
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}
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/* This functions clips all the edges w.r.t one clip edge of clipping area */
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void Clip(Polygon& poly, const Line& line)
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{
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uint8_t vertexNum = poly.GetVertexNum();
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Polygon newPoly;
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int16_t iX;
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int16_t iY;
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int16_t kX;
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int16_t kY;
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int16_t x1;
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int16_t y1;
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int16_t x2;
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int16_t y2;
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int8_t k;
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int32_t iPos;
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int32_t kPos;
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/* (iX, iY), (kX, kY) are the co-ordinate values of the points */
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for (int8_t i = 0; i < vertexNum; i++) {
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/* i and k form a line in polygon */
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k = (i + 1) % vertexNum;
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iX = poly[i].x_;
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iY = poly[i].y_;
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kX = poly[k].x_;
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kY = poly[k].y_;
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x1 = line[0].x_;
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y1 = line[0].y_;
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x2 = line[1].x_;
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y2 = line[1].y_;
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/* Calculating position of first point w.r.t. clipper line */
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iPos = static_cast<int32_t>(x2 - x1) * (iY - y1) - static_cast<int32_t>(y2 - y1) * (iX - x1);
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/* Calculating position of second point w.r.t. clipper line */
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kPos = static_cast<int32_t>(x2 - x1) * (kY - y1) - static_cast<int32_t>(y2 - y1) * (kX - x1);
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uint8_t newVertexNum = newPoly.GetVertexNum();
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if (iPos < 0 && kPos < 0) {
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/* Case 1 : When both points are inside */
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newPoly[newVertexNum].x_ = kX;
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newPoly[newVertexNum].y_ = kY;
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newVertexNum++;
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} else if (iPos >= 0 && kPos < 0) {
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/* Case 2: When only first point is outside */
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Vector2<int16_t> intersectPoint;
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bool intersect = Intersect(Line(x1, y1, x2, y2), Line(iX, iY, kX, kY), intersectPoint);
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if (!intersect) {
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continue;
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}
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newPoly[newVertexNum].x_ = intersectPoint.x_;
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newPoly[newVertexNum].y_ = intersectPoint.y_;
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newVertexNum++;
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newPoly[newVertexNum].x_ = kX;
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newPoly[newVertexNum].y_ = kY;
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newVertexNum++;
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} else if (iPos < 0 && kPos >= 0) {
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/* Case 3: When only second point is outside Only point of intersection with edge is added */
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Vector2<int16_t> intersectPoint;
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bool intersect = Intersect(Line(x1, y1, x2, y2), Line(iX, iY, kX, kY), intersectPoint);
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if (!intersect) {
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continue;
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}
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newPoly[newVertexNum].x_ = intersectPoint.x_;
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newPoly[newVertexNum].y_ = intersectPoint.y_;
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newVertexNum++;
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}
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newPoly.SetVertexNum(newVertexNum);
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}
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/* Copying new points into original array and changing the no. of vertices */
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poly = newPoly;
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}
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/* Implements Sutherland–Hodgman algorithm for polygon clipping */
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Polygon SuthHodgClip(const Rect& clipRect, const Polygon& polygon)
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{
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Polygon newPolygon(polygon);
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Clip(newPolygon, Line(clipRect.GetLeft(), clipRect.GetTop(), clipRect.GetRight(), clipRect.GetTop()));
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Clip(newPolygon, Line(clipRect.GetRight(), clipRect.GetTop(), clipRect.GetRight(), clipRect.GetBottom()));
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Clip(newPolygon, Line(clipRect.GetRight(), clipRect.GetBottom(), clipRect.GetLeft(), clipRect.GetBottom()));
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Clip(newPolygon, Line(clipRect.GetLeft(), clipRect.GetBottom(), clipRect.GetLeft(), clipRect.GetTop()));
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return newPolygon;
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}
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/* the max cross point is two when a line cross a convex polygon */
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void Clip(const Line& line, const Polygon& poly, Vector2<int16_t>* pOut, uint8_t *pNum)
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{
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if (pOut == nullptr || pNum == nullptr) {
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return;
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}
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uint8_t vertexNum = poly.GetVertexNum();
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int16_t iX;
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int16_t iY;
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int16_t kX;
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int16_t kY;
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int16_t x1;
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int16_t y1;
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int16_t x2;
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int16_t y2;
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int8_t k;
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int32_t iPos;
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int32_t kPos;
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/* (iX, iY), (kX, kY) are the co-ordinate values of the points */
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for (int8_t i = 0; i < vertexNum; i++) {
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/* i and k form a line in polygon */
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k = (i + 1) % vertexNum;
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iX = poly[i].x_;
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iY = poly[i].y_;
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kX = poly[k].x_;
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kY = poly[k].y_;
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x1 = line[0].x_;
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y1 = line[0].y_;
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x2 = line[1].x_;
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y2 = line[1].y_;
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/* Calculating position of first point w.r.t. clipper line */
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iPos = static_cast<int32_t>(x2 - x1) * (iY - y1) - static_cast<int32_t>(y2 - y1) * (iX - x1);
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/* Calculating position of second point w.r.t. clipper line */
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kPos = static_cast<int32_t>(x2 - x1) * (kY - y1) - static_cast<int32_t>(y2 - y1) * (kX - x1);
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if ((iPos >= 0 && kPos < 0) || (iPos < 0 && kPos >= 0)) {
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Vector2<int16_t> intersectPoint;
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Intersect(Line(x1, y1, x2, y2), Line(iX, iY, kX, kY), intersectPoint);
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(*pOut) = intersectPoint;
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(*pNum)++;
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}
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}
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}
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Polygon::Polygon(const Vector2<int16_t>* vertexes, const uint8_t vertexNum)
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{
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ASSERT(vertexNum <= MAX_VERTEX_NUM);
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if (memcpy_s(vertexes_, MAX_VERTEX_NUM * sizeof(Vector2<int16_t>),
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vertexes, vertexNum * sizeof(Vector2<int16_t>)) != EOK) {
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ASSERT(0);
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}
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vertexNum_ = vertexNum;
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}
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Rect Polygon::MakeAABB() const
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{
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int16_t minX = vertexes_[0].x_;
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int16_t maxX = vertexes_[0].x_;
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int16_t minY = vertexes_[0].y_;
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int16_t maxY = vertexes_[0].y_;
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for (uint8_t i = 1; i < vertexNum_; i++) {
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if (minX > vertexes_[i].x_) {
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minX = vertexes_[i].x_;
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}
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if (maxX < vertexes_[i].x_) {
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maxX = vertexes_[i].x_;
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}
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if (minY > vertexes_[i].y_) {
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minY = vertexes_[i].y_;
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}
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if (maxY < vertexes_[i].y_) {
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maxY = vertexes_[i].y_;
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}
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}
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return Rect(minX, minY, maxX, maxY);
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}
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}
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