最近在做相册的图片编辑功能，遇到一个bug，插入文字后旋转文字区域，点击文字区域无法触发，分析原因是判断时认定为点没在RectF内。如图：
如果只是通过rect.contains(x, y)来判断，那么实际区域则是绿色区域的部分，则有部分无法点击，如下图： 因此需要将矩形框旋转。
如果通过matrix.mapRect(rect)来获取转换后的区域，再通过rect.contains(x, y)来判断是否落在区域内，那么实际区域如下图绿色区域，则点击非区域内的位置仍会触发文字区域的点击，如下图：
Matrix matrix = new Matrix(); matrix.setRotate(roatetAngle, mHelpBoxRect.centerX(), mHelpBoxRect.centerY()); matrix.mapRect(mHelpBoxRect);因此，无法通过rect.contains(x, y)来判断点是否落在区域内。需要将原矩形四个顶点旋转，将转换后的矩形四个顶点重新构成四边形，再判断点是否落在该四边形内。
public boolean clickHelpBoxRect(float x, float y) { if (mHelpBoxRect == null || mHelpBoxRect.isEmpty()) { return false; } boolean isClickHelpBoxRect; if (roatetAngle != 0) { // 旋转后判断点是否在四边形内 Matrix matrix = new Matrix(); matrix.setRotate(roatetAngle, mHelpBoxRect.centerX(), mHelpBoxRect.centerY()); PointF curPoint = new PointF(x, y); PointF pointLT = getMapPoints(matrix, mHelpBoxRect.left, mHelpBoxRect.top); PointF pointRT = getMapPoints(matrix, mHelpBoxRect.right, mHelpBoxRect.top); PointF pointLB = getMapPoints(matrix, mHelpBoxRect.left, mHelpBoxRect.bottom); PointF pointRB = getMapPoints(matrix, mHelpBoxRect.right, mHelpBoxRect.bottom); isClickHelpBoxRect = pointInRect(curPoint, pointLT, pointRT, pointLB, pointRB); } else { isClickHelpBoxRect = mHelpBoxRect.contains(x, y); } return isClickHelpBoxRect; } /** * 获取旋转后的坐标点 * * @param matrix 转换矩阵 * @param x 左坐标 * @param y 右坐标 * @return */ private PointF getMapPoints(Matrix matrix, float x, float y) { float[] floats = new float[]{x, y}; matrix.mapPoints(floats); return new PointF(floats[0], floats[1]); } /** * 点是否落在四边形内 * * @param curPoint 点击位置 * @param pointLT 左上顶点 * @param pointRT 右上顶点 * @param pointLB 左下顶点 * @param pointRB 右下顶点 * @return true 在四边形内；false 不在四边形内 */ private boolean pointInRect(PointF curPoint, PointF pointLT, PointF pointRT, PointF pointLB, PointF pointRB) { int nCount = 4; PointF[] rectPoints = new PointF[]{pointLT, pointLB, pointRB, pointRT}; int nCross = 0; for (int i = 0; i < nCount; i++) { //依次取相邻的两个点 PointF pStart = rectPoints[i]; PointF pEnd = rectPoints[(i + 1) % nCount]; //相邻的两个点是平行于x轴的，肯定不相交，忽略 if (pStart.y == pEnd.y) continue; //交点在pStart,pEnd的延长线上，pCur肯定不会与pStart.pEnd相交，忽略 if (curPoint.y < Math.min(pStart.y, pEnd.y) || curPoint.y > Math.max(pStart.y, pEnd.y)) continue; //求当前点和x轴的平行线与pStart,pEnd直线的交点的x坐标 double x = (double) (curPoint.y - pStart.y) * (double) (pEnd.x - pStart.x) / (double) (pEnd.y - pStart.y) + pStart.x; //若x坐标大于当前点的坐标，则有交点 if (x > curPoint.x) nCross++; } // 单边交点为偶数，点在多边形之外 return (nCross % 2 == 1); }