Photoshop中的套索工具通过鼠标多次点击可以选中一个任意多边形的区域，然后单独对这块区域进行编辑，下面就使用OpenCV实现一个简单的功能，模拟Photoshop中的套索工具。
这里的套索工具通过鼠标左键在图片上多次点击创建任意多个点，右键点击后将这些点连成封闭的多边形，形成一块待编辑的区域，键盘方向键控制该区域的移动，从而将该区域内的图像复制到原图像的其他地方。
首先定义下列全局变量
const char* winName = "TaoSuoTool";//窗口名称
cv::Mat resultImg;//最终在OpenCV窗口上显示的图像
cv::Mat foregroundImg;//编辑前的图像
cv::Mat areaMask;//蒙版，多边形区域实际绘制在该蒙版上
cv::Point maskLocation;//蒙版位置，通过方向键移动后蒙版位置随之变化
std::vector<cv::Point> drawingPoints;//区域完成前正在点击的所有点
std::vector<cv::Point> areaPoints;//区域完成后其多边形顶点
main函数
int main(int argc, char **arv)
{
foregroundImg = cv::imread("test.webp");
foregroundImg.copyTo(resultImg);
areaMask = cv::Mat::zeros(foregroundImg.size(), CV_8U);
cv::imshow(winName, resultImg);
maskLocation.x = maskLocation.y = 0;
cv::setMouseCallback(winName, OnMouseEvent);
int key = cv::waitKeyEx(0);
while (key != VK_ESCAPE)
{
key = cv::waitKeyEx(0);
}
return 0;
}
在鼠标回调函数OnMouseEvent中处理三个消息：鼠标左键按下，鼠标右键按下和鼠标移动
void OnMouseEvent(int event, int x, int y, int flags, void* userdata)
{
if (event == cv::EVENT_LBUTTONDOWN)
{
OnLeftMouseButtonDown(x,y);
}
else if (event == cv::EVENT_RBUTTONDOWN)
{
OnRightMouseButtonDown(x,y);
}
if (event == cv::EVENT_MOUSEMOVE)
{
OnMouseMove(x,y);
}
}
在编写鼠标事件前先定义一个函数
void OnCompleteArea(bool bDrawOutline);
它表示完成当前区域的编辑，包括右键点击完成封闭多边形、移动区域以及合成最终图片。参数bDrawOutline表示绘制区域多边形的外轮廓，右键点击完成封闭多边形和移动区域过程中都要显示轮廓(bDrawOutline=true)，合成最终图片后就不需要显示轮廓了(bDrawOutline=false)。
鼠标左键按下事件：先判断是否有前一个区域存在，存在则先完成前一个区域并且不显示区域轮廓，然后开始绘制新的区域多边形的点，点与点之间用蓝色线连接，点位置处绘制一个4X4的红色矩形。
void OnLeftMouseButtonDown(int x,int y)
{
if (drawingPoints.empty() && areaPoints.size() > 0)
{
OnCompleteArea(false);
}
drawingPoints.push_back(cv::Point(x, y));
cv::rectangle(resultImg, cv::Rect(x - 2, y - 2, 4, 4), CV_RGB(255, 0, 0), -1);
if (drawingPoints.size() >= 2)
{
cv::line(resultImg, drawingPoints[drawingPoints.size() - 2], cv::Point(x, y), CV_RGB(0, 0, 255), 1);
}
cv::imshow(winName, resultImg);
}
鼠标移动事件：判断drawingPoints是否为空，如果已经存在点则绘制线和点，并且还要绘制一根连接到鼠标当前位置的线。
void OnMouseMove(int x,int y)
{
if (drawingPoints.size() > 0)
{
foregroundImg.copyTo(resultImg);
for (int i = 0; i < drawingPoints.size() - 1; i++)
{
cv::rectangle(resultImg, cv::Rect(drawingPoints[i].x - 2, drawingPoints[i].y - 2, 4, 4), CV_RGB(255, 0, 0), -1);
cv::line(resultImg, drawingPoints[i], drawingPoints[i + 1], CV_RGB(0, 0, 255), 1);
}
cv::rectangle(resultImg, cv::Rect(drawingPoints[drawingPoints.size() - 1].x - 2, drawingPoints[drawingPoints.size() - 1].y - 2, 4, 4), CV_RGB(255, 0, 0), -1);
cv::line(resultImg, drawingPoints[drawingPoints.size() - 1], cv::Point(x, y), CV_RGB(0, 0, 255), 1);
cv::imshow(winName, resultImg);
}
}
鼠标右键按下事件：如果点个数少于2，不能形成有效区域则不做处理（不考虑多个点共线），否则就在蒙版Area上绘制一个多边形区域，然后调用OnCompleteArea完成区域编辑，这里需要画多边形轮廓，参数传入true。
void OnRightMouseButtonDown(int x,int y)
{
if (drawingPoints.size() >= 3)
{
areaPoints = drawingPoints;
std::vector<std::vector<cv::Point>> polys;
polys.push_back(areaPoints);
cv::fillPoly(areaMask, polys, cv::Scalar::all(255));
OnCompleteArea(true);
}
else
{
foregroundImg.copyTo(resultImg);
}
drawingPoints.clear();
cv::imshow(winName, resultImg);
}
下面是OnCompleteArea函数的实现，其中MergeImages函数通过蒙版以及蒙版的位置合成最终的图像，蒙版中区域内的像素值大于0，其他像素值都为0，默认图像是三通道(destImg.at<cv::Vec3b>)
void MergeImages(cv::Mat& destImg, const cv::Mat& srcImg, const cv::Mat& maskImg, int x, int y)
{
int top = y > 0 ? y : 0;
int left = x > 0 ? x : 0;
int right = destImg.cols > x + srcImg.cols ? x + srcImg.cols : destImg.cols;
int bottom = destImg.rows > y + srcImg.rows ? y + srcImg.rows : destImg.rows;
for (int i = top; i < bottom; i++)
{
for (int j = left; j < right; j++)
{
int destIndex = i * destImg.cols + j;
int srcIndex = (i - top)*srcImg.cols + j - left;
int channel = destImg.channels();
if (maskImg.at<uchar>(i - y, j - x) > 0)
{
destImg.at<cv::Vec3b>(i, j)[0] = srcImg.at<cv::Vec3b>(i - y, j - x)[0];
destImg.at<cv::Vec3b>(i, j)[1] = srcImg.at<cv::Vec3b>(i - y, j - x)[1];
destImg.at<cv::Vec3b>(i, j)[2] = srcImg.at<cv::Vec3b>(i - y, j - x)[2];
}
}
}
}
void OnCompleteArea(bool bDrawOutline)
{
foregroundImg.copyTo(resultImg);
MergeImages(resultImg, foregroundImg, areaMask, maskLocation.x, maskLocation.y);
if (bDrawOutline)
{
if (areaPoints.size() >= 3)
{
std::vector<std::vector<cv::Point>> polys;
polys.push_back(areaPoints);
cv::polylines(resultImg, polys, true, cv::Scalar::all(255));
}
}
else
{
resultImg.copyTo(foregroundImg);
areaPoints.clear();
memset(areaMask.data, 0, areaMask.rows*areaMask.cols*areaMask.elemSize());
maskLocation.x = maskLocation.y = 0;
}
}
绘制区域之后就可以通过方向按键控制区域图像的移动了（也可以实现为鼠标左键按下拖动来移动区域），移动主要是更新maskLocation和areaPoints的坐标值，然后调用OnCompleteArea(true)，依然显示区域的轮廓。
void OnDirectionKeyDown(short keyCode)
{
int x = keyCode == VK_LEFT ? -2 : (keyCode == VK_RIGHT ? 2 : 0);
int y = keyCode == VK_UP ? -2 : (keyCode == VK_DOWN ? 2 : 0);
maskLocation.x += x;
maskLocation.y += y;
for (int i = 0; i < areaPoints.size(); i++)
{
areaPoints[i].x += x;
areaPoints[i].y += y;
}
OnCompleteArea(true);
cv::imshow(winName, resultImg);
}
将上面函数在主函数的按键循环中调用，方向按键通过key的高16位判断，在Windows下可以使用虚拟键码宏表示。 同时为了能看到最终合成的图片加入Enter按键消息处理，将图像合成并去掉轮廓。
int key = cv::waitKeyEx(0);
short lowKey = key;
short highKey = key >> 16;
while (key != VK_ESCAPE)
{
if (key == VK_RETURN)//Enter
{
OnCompleteArea(false);
cv::imshow(winName, resultImg);
}
else if (lowKey == 0 && (highKey == VK_UP || highKey == VK_DOWN || highKey == VK_LEFT || highKey == VK_RIGHT))
{
OnDirectionKeyDown(highKey);
}
key = cv::waitKeyEx(0);
lowKey = key;
highKey = key >> 16;
}
这样一个简单的套索工具功能就做好了（上面的代码都是简化处理，还有很多可以优化的地方，从而使编辑更加流畅）
完整代码
#include<iostream>
#include"opencv2/opencv.hpp"
#include<windows.h>
const char* winName = "TaoSuoTool";
cv::Point maskLocation;
cv::Mat resultImg;
cv::Mat foregroundImg;
cv::Mat areaMask;
std::vector<cv::Point> drawingPoints;
std::vector<cv::Point> areaPoints;
void MergeImages(cv::Mat& destImg, const cv::Mat& srcImg, const cv::Mat& maskImg, int x, int y)
{
int top = y > 0 ? y : 0;
int left = x > 0 ? x : 0;
int right = destImg.cols > x + srcImg.cols ? x + srcImg.cols : destImg.cols;
int bottom = destImg.rows > y + srcImg.rows ? y + srcImg.rows : destImg.rows;
for (int i = top; i < bottom; i++)
{
for (int j = left; j < right; j++)
{
int destIndex = i * destImg.cols + j;
int srcIndex = (i - top)*srcImg.cols + j - left;
int channel = destImg.channels();
if (maskImg.at<uchar>(i - y, j - x) > 0)
{
destImg.at<cv::Vec3b>(i, j)[0] = srcImg.at<cv::Vec3b>(i - y, j - x)[0];
destImg.at<cv::Vec3b>(i, j)[1] = srcImg.at<cv::Vec3b>(i - y, j - x)[1];
destImg.at<cv::Vec3b>(i, j)[2] = srcImg.at<cv::Vec3b>(i - y, j - x)[2];
}
}
}
}
void OnCompleteArea(bool bDrawOutline)
{
foregroundImg.copyTo(resultImg);
MergeImages(resultImg, foregroundImg, areaMask, maskLocation.x, maskLocation.y);
if (bDrawOutline)
{
if (areaPoints.size() >= 3)
{
std::vector<std::vector<cv::Point>> polys;
polys.push_back(areaPoints);
cv::polylines(resultImg, polys, true, cv::Scalar::all(255));
}
}
else
{
resultImg.copyTo(foregroundImg);
areaPoints.clear();
memset(areaMask.data, 0, areaMask.rows*areaMask.cols*areaMask.elemSize());
maskLocation.x = maskLocation.y = 0;
}
}
void OnLeftMouseButtonDown(int x,int y)
{
if (drawingPoints.empty() && areaPoints.size() > 0)
{
OnCompleteArea(false);
}
drawingPoints.push_back(cv::Point(x, y));
cv::rectangle(resultImg, cv::Rect(x - 2, y - 2, 4, 4), CV_RGB(255, 0, 0), -1);
if (drawingPoints.size() >= 2)
{
cv::line(resultImg, drawingPoints[drawingPoints.size() - 2], cv::Point(x, y), CV_RGB(0, 0, 255), 1);
}
cv::imshow(winName, resultImg);
}
void OnRightMouseButtonDown(int x,int y)
{
if (drawingPoints.size() >= 3)
{
areaPoints = drawingPoints;
std::vector<std::vector<cv::Point>> polys;
polys.push_back(areaPoints);
cv::fillPoly(areaMask, polys, cv::Scalar::all(255));
OnCompleteArea(true);
}
else
{
foregroundImg.copyTo(resultImg);
}
drawingPoints.clear();
cv::imshow(winName, resultImg);
}
void OnMouseMove(int x,int y)
{
if (drawingPoints.size() > 0)
{
foregroundImg.copyTo(resultImg);
for (int i = 0; i < drawingPoints.size() - 1; i++)
{
cv::rectangle(resultImg, cv::Rect(drawingPoints[i].x - 2, drawingPoints[i].y - 2, 4, 4), CV_RGB(255, 0, 0), -1);
cv::line(resultImg, drawingPoints[i], drawingPoints[i + 1], CV_RGB(0, 0, 255), 1);
}
cv::rectangle(resultImg, cv::Rect(drawingPoints[drawingPoints.size() - 1].x - 2, drawingPoints[drawingPoints.size() - 1].y - 2, 4, 4), CV_RGB(255, 0, 0), -1);
cv::line(resultImg, drawingPoints[drawingPoints.size() - 1], cv::Point(x, y), CV_RGB(0, 0, 255), 1);
cv::imshow(winName, resultImg);
}
}
void OnMouseEvent(int event, int x, int y, int flags, void* userdata)
{
if (event == cv::EVENT_LBUTTONDOWN)
{
OnLeftMouseButtonDown(x,y);
}
else if (event == cv::EVENT_RBUTTONDOWN)
{
OnRightMouseButtonDown(x,y);
}
if (event == cv::EVENT_MOUSEMOVE)
{
OnMouseMove(x,y);
}
}
void OnDirectionKeyDown(short keyCode)
{
int x = keyCode == VK_LEFT ? -2 : (keyCode == VK_RIGHT ? 2 : 0);
int y = keyCode == VK_UP ? -2 : (keyCode == VK_DOWN ? 2 : 0);
maskLocation.x += x;
maskLocation.y += y;
for (int i = 0; i < areaPoints.size(); i++)
{
areaPoints[i].x += x;
areaPoints[i].y += y;
}
OnCompleteArea(true);
cv::imshow(winName, resultImg);
}
int main(int argc, char **arv)
{
foregroundImg = cv::imread("test.webp");
foregroundImg.copyTo(resultImg);
areaMask = cv::Mat::zeros(foregroundImg.size(), CV_8U);
cv::imshow(winName, resultImg);
maskLocation.x = maskLocation.y = 0;
cv::setMouseCallback(winName, OnMouseEvent);
int key = cv::waitKeyEx(0);
short lowKey = key;
short highKey = key >> 16;
while (key != VK_ESCAPE)
{
if (key == VK_RETURN)//Enter
{
OnCompleteArea(false);
cv::imshow(winName, resultImg);
}
else if (lowKey == 0 && (highKey == VK_UP || highKey == VK_DOWN || highKey == VK_LEFT || highKey == VK_RIGHT))
{
OnDirectionKeyDown(highKey);
}
key = cv::waitKeyEx(0);
lowKey = key;
highKey = key >> 16;
}
return 0;
}
