我想让 setmousecallback 函数在仍然按下鼠标左键时连续传递坐标
I want to make setmousecallback function to pass the coordinate continuously when mouse left button is still pressed
我的代码工作正常,但当鼠标左键仍被按下时,它不能连续传递坐标。它确实在鼠标移动时传递坐标。
抱歉,我没有添加 mouse_callback 功能,我现在已经添加了。
任何帮助都会有所帮助。
代码:
#include <stdio.h>
#include <opencv2/opencv.hpp>
#include <opencv2/highgui.hpp>
#include <opencv2/imgproc.hpp>
#include <iostream>
using namespace cv;
using namespace std;
Point pt(-1, -1);
bool newCoords = false;
void mouse_callback(int event, int x, int y, int flag, void *param)
{
if (event == EVENT_LBUTTONDOWN)
{
pt.x = x;
pt.y = y;
newCoords = true;
}
else if (flag == EVENT_FLAG_LBUTTON && event == EVENT_MOUSEMOVE) {
pt.x = x;
pt.y = y;
newCoords = true;
}
}
int main(int argc, char** argv)
{
String WindowName = "Original Feed";
namedWindow(WindowName, CV_WINDOW_AUTOSIZE);
Mat oriImg;
int Frame_Width = 720;
int Frame_Height = 540;
VideoCapture cap(0);
setMouseCallback(WindowName, mouse_callback);
cap.set(CV_CAP_PROP_FRAME_WIDTH, Frame_Width);
cap.set(CV_CAP_PROP_FRAME_HEIGHT, Frame_Height);
while (waitKey(30) != 27) {
cap.read(oriImg);
if (pt.x != -1 && pt.y != -1)
{
circle(oriImg, pt, 3, Scalar(0, 0, 255));
if (newCoords)
{
std::cout << "Clicked coordinates: " << pt << std::endl;
newCoords = false;
}
}
imshow(WindowName, oriImg);
}
return 0;
}
每当 OS/GUI 生成鼠标事件时调用回调。只要鼠标的状态(按钮、滚轮、位置等)发生变化,就会生成此类事件——如果没有任何变化,则您已经知道(可以知道)当前状态。
如果您想在多次迭代中以某种方式响应鼠标的稳定状态(例如,在静止时按住按钮),您将不得不自己处理。
我对你的问题的理解是这样的:只要按住左键,在显示的每一帧光标最近的位置画一个圆
由于我们 运行 的帧速率不错,我们可以保持简单,并且仅根据前一帧的 click/position 信息更新当前帧。用户将无法观察到这种轻微的延迟。
为了后代:图像正在显示,鼠标回调仅在 cv::waitKey
函数为 运行.
时调用
下面列举了我们在每次迭代中可能遇到的情况,以及我们应该如何在下面的框架中应对:
- LMB 未在
waitKey
的进出处持有
- LMB 从未被释放(因此从未按下)-> 无事可做
- LMB 至少被按住和释放一次(因此被按下了多次)-> 在最后一次按下的位置画圆圈
- LMB 未在入口处持有,但在
waitKey
出口处持有
- 按住 LMB -> 在最后报告的鼠标位置画圆圈
- LMB 在进入时持有,但在
waitKey
退出时未持有
- LMB 至少被按住和释放一次(并且少按一次)-> 在最后一次按下的位置画圆圈
- LMB 在
waitKey
的进出处举行
- 按住 LMB -> 在最后报告的鼠标位置画圆圈
基于此,我们需要跟踪:
- 最后一次按下或释放 LMB 的位置。
- LMB 当前是否被按住
- LMB 是否在上一次迭代中被释放(即它被按住,即使它不再是)
我们可以使用 struct
来保存此信息(由于用户数据参数,我们让回调使用它):
struct mouse_state
{
mouse_state()
: position(-1, -1)
, left_button_held(false)
, left_button_clicked(false)
{}
void new_iteration()
{
left_button_clicked = false;
}
cv::Point2i position; // Last position where the LMB was down
bool left_button_held; // Is the LMB down right now?
bool left_button_clicked; // Was the LMB down in the last iteration?
};
鼠标回调会负责更新上面的struct
.
- 当用户按下 LMB 时,记录位置并按住设置按钮
- 当用户松开鼠标左键时,记录位置,设置按钮被点击,设置按钮未按住
- 当鼠标移动并按住 LMB 时,记录位置
带有一些原始调试跟踪的回调实现示例如下所示:
void mouse_callback(int event, int x, int y, int flag, void* param)
{
mouse_state* state(static_cast<mouse_state*>(param));
if (event == cv::EVENT_LBUTTONDOWN) {
std::cout << "LMB down @ (" << x << "," << y << ")\n";
state->position = cv::Point2i(x, y);
state->left_button_held = true;
} else if (event == cv::EVENT_LBUTTONUP) {
std::cout << "LMB up @(" << x << "," << y << ")\n";
state->position = cv::Point2i(x, y);
state->left_button_held = false;
state->left_button_clicked = true;
} else if ((flag == cv::EVENT_FLAG_LBUTTON) && (event == cv::EVENT_MOUSEMOVE)) {
std::cout << "LMB held, mouse moved to (" << x << "," << y << ")\n";
state->position = cv::Point2i(x, y);
}
}
然后可以通过以下方式注册回调:
mouse_state ms;
cv::setMouseCallback(WINDOW_NAME, mouse_callback, &ms);
处理循环将非常简单:
- 读取新帧,失败时退出循环
- 检查鼠标的最后状态。如果按住或单击 LMB,则在记录的位置绘制圆圈。
- 重置每次迭代鼠标状态标志
- 显示图像,更新鼠标状态信息
这可能如下所示:
for (;;) {
// We can have `image` here, since `cap.read` always gives us
// a reference to its internal buffer
cv::Mat image;
if (!cap.read(image)) {
std::cerr << "Failed to read image, exiting...\n";
break; // Failed to read image, nothing else to do
}
if (ms.left_button_clicked || ms.left_button_held) {
std::cout << "Current position: " << ms.position << "\n";
cv::circle(image, ms.position, 3, cv::Scalar(0, 0, 255));
cv::circle(image, ms.position, 10, cv::Scalar(0, 0, 255), 2);
}
ms.new_iteration();
cv::imshow(WINDOW_NAME, image);
if (cv::waitKey(30) == 27) {
std::cout << "Esc pressed, exiting...\n";
break;
}
}
示例程序
#include <opencv2/opencv.hpp>
#include <iostream>
struct mouse_state
{
mouse_state()
: position(-1, -1)
, left_button_held(false)
, left_button_clicked(false)
{}
void new_iteration()
{
left_button_clicked = false;
}
cv::Point2i position; // Last position where the LMB was down
bool left_button_held; // Is the LMB down right now?
bool left_button_clicked; // Was the LMB down in the last iteration?
};
void mouse_callback(int event, int x, int y, int flag, void* param)
{
mouse_state* state(static_cast<mouse_state*>(param));
if (event == cv::EVENT_LBUTTONDOWN) {
std::cout << "LMB down @ (" << x << "," << y << ")\n";
state->position = cv::Point2i(x, y);
state->left_button_held = true;
} else if (event == cv::EVENT_LBUTTONUP) {
std::cout << "LMB up @(" << x << "," << y << ")\n";
state->position = cv::Point2i(x, y);
state->left_button_held = false;
state->left_button_clicked = true;
} else if ((flag == cv::EVENT_FLAG_LBUTTON) && (event == cv::EVENT_MOUSEMOVE)) {
std::cout << "LMB held, mouse moved to (" << x << "," << y << ")\n";
state->position = cv::Point2i(x, y);
}
}
int main(int argc, char** argv)
{
cv::String const WINDOW_NAME("Original Feed");
cv::namedWindow(WINDOW_NAME, CV_WINDOW_AUTOSIZE);
mouse_state ms;
cv::setMouseCallback(WINDOW_NAME, mouse_callback, &ms);
int const FRAME_WIDTH(720);
int const FRAME_HEIGHT(540);
cv::VideoCapture cap(0);
if (!cap.isOpened()) {
std::cerr << "Unable to open camera, exiting...\n";
return -1;
}
cap.set(CV_CAP_PROP_FRAME_WIDTH, FRAME_WIDTH);
cap.set(CV_CAP_PROP_FRAME_HEIGHT, FRAME_HEIGHT);
for (;;) {
// We can have `image` here, since `cap.read` always gives us
// a reference to its internal buffer
cv::Mat image;
if (!cap.read(image)) {
std::cerr << "Failed to read image, exiting...\n";
break; // Failed to read image, nothing else to do
}
if (ms.left_button_clicked || ms.left_button_held) {
std::cout << "Current position: " << ms.position << "\n";
cv::circle(image, ms.position, 3, cv::Scalar(0, 0, 255));
cv::circle(image, ms.position, 10, cv::Scalar(0, 0, 255), 2);
}
ms.new_iteration();
cv::imshow(WINDOW_NAME, image);
if (cv::waitKey(30) == 27) {
std::cout << "Esc pressed, exiting...\n";
break;
}
}
return 0;
}
我的代码工作正常,但当鼠标左键仍被按下时,它不能连续传递坐标。它确实在鼠标移动时传递坐标。
抱歉,我没有添加 mouse_callback 功能,我现在已经添加了。 任何帮助都会有所帮助。 代码:
#include <stdio.h>
#include <opencv2/opencv.hpp>
#include <opencv2/highgui.hpp>
#include <opencv2/imgproc.hpp>
#include <iostream>
using namespace cv;
using namespace std;
Point pt(-1, -1);
bool newCoords = false;
void mouse_callback(int event, int x, int y, int flag, void *param)
{
if (event == EVENT_LBUTTONDOWN)
{
pt.x = x;
pt.y = y;
newCoords = true;
}
else if (flag == EVENT_FLAG_LBUTTON && event == EVENT_MOUSEMOVE) {
pt.x = x;
pt.y = y;
newCoords = true;
}
}
int main(int argc, char** argv)
{
String WindowName = "Original Feed";
namedWindow(WindowName, CV_WINDOW_AUTOSIZE);
Mat oriImg;
int Frame_Width = 720;
int Frame_Height = 540;
VideoCapture cap(0);
setMouseCallback(WindowName, mouse_callback);
cap.set(CV_CAP_PROP_FRAME_WIDTH, Frame_Width);
cap.set(CV_CAP_PROP_FRAME_HEIGHT, Frame_Height);
while (waitKey(30) != 27) {
cap.read(oriImg);
if (pt.x != -1 && pt.y != -1)
{
circle(oriImg, pt, 3, Scalar(0, 0, 255));
if (newCoords)
{
std::cout << "Clicked coordinates: " << pt << std::endl;
newCoords = false;
}
}
imshow(WindowName, oriImg);
}
return 0;
}
每当 OS/GUI 生成鼠标事件时调用回调。只要鼠标的状态(按钮、滚轮、位置等)发生变化,就会生成此类事件——如果没有任何变化,则您已经知道(可以知道)当前状态。
如果您想在多次迭代中以某种方式响应鼠标的稳定状态(例如,在静止时按住按钮),您将不得不自己处理。
我对你的问题的理解是这样的:只要按住左键,在显示的每一帧光标最近的位置画一个圆
由于我们 运行 的帧速率不错,我们可以保持简单,并且仅根据前一帧的 click/position 信息更新当前帧。用户将无法观察到这种轻微的延迟。
为了后代:图像正在显示,鼠标回调仅在 cv::waitKey
函数为 运行.
下面列举了我们在每次迭代中可能遇到的情况,以及我们应该如何在下面的框架中应对:
- LMB 未在
waitKey
的进出处持有- LMB 从未被释放(因此从未按下)-> 无事可做
- LMB 至少被按住和释放一次(因此被按下了多次)-> 在最后一次按下的位置画圆圈
- LMB 未在入口处持有,但在
waitKey
出口处持有- 按住 LMB -> 在最后报告的鼠标位置画圆圈
- LMB 在进入时持有,但在
waitKey
退出时未持有- LMB 至少被按住和释放一次(并且少按一次)-> 在最后一次按下的位置画圆圈
- LMB 在
waitKey
的进出处举行- 按住 LMB -> 在最后报告的鼠标位置画圆圈
基于此,我们需要跟踪:
- 最后一次按下或释放 LMB 的位置。
- LMB 当前是否被按住
- LMB 是否在上一次迭代中被释放(即它被按住,即使它不再是)
我们可以使用 struct
来保存此信息(由于用户数据参数,我们让回调使用它):
struct mouse_state
{
mouse_state()
: position(-1, -1)
, left_button_held(false)
, left_button_clicked(false)
{}
void new_iteration()
{
left_button_clicked = false;
}
cv::Point2i position; // Last position where the LMB was down
bool left_button_held; // Is the LMB down right now?
bool left_button_clicked; // Was the LMB down in the last iteration?
};
鼠标回调会负责更新上面的struct
.
- 当用户按下 LMB 时,记录位置并按住设置按钮
- 当用户松开鼠标左键时,记录位置,设置按钮被点击,设置按钮未按住
- 当鼠标移动并按住 LMB 时,记录位置
带有一些原始调试跟踪的回调实现示例如下所示:
void mouse_callback(int event, int x, int y, int flag, void* param)
{
mouse_state* state(static_cast<mouse_state*>(param));
if (event == cv::EVENT_LBUTTONDOWN) {
std::cout << "LMB down @ (" << x << "," << y << ")\n";
state->position = cv::Point2i(x, y);
state->left_button_held = true;
} else if (event == cv::EVENT_LBUTTONUP) {
std::cout << "LMB up @(" << x << "," << y << ")\n";
state->position = cv::Point2i(x, y);
state->left_button_held = false;
state->left_button_clicked = true;
} else if ((flag == cv::EVENT_FLAG_LBUTTON) && (event == cv::EVENT_MOUSEMOVE)) {
std::cout << "LMB held, mouse moved to (" << x << "," << y << ")\n";
state->position = cv::Point2i(x, y);
}
}
然后可以通过以下方式注册回调:
mouse_state ms;
cv::setMouseCallback(WINDOW_NAME, mouse_callback, &ms);
处理循环将非常简单:
- 读取新帧,失败时退出循环
- 检查鼠标的最后状态。如果按住或单击 LMB,则在记录的位置绘制圆圈。
- 重置每次迭代鼠标状态标志
- 显示图像,更新鼠标状态信息
这可能如下所示:
for (;;) {
// We can have `image` here, since `cap.read` always gives us
// a reference to its internal buffer
cv::Mat image;
if (!cap.read(image)) {
std::cerr << "Failed to read image, exiting...\n";
break; // Failed to read image, nothing else to do
}
if (ms.left_button_clicked || ms.left_button_held) {
std::cout << "Current position: " << ms.position << "\n";
cv::circle(image, ms.position, 3, cv::Scalar(0, 0, 255));
cv::circle(image, ms.position, 10, cv::Scalar(0, 0, 255), 2);
}
ms.new_iteration();
cv::imshow(WINDOW_NAME, image);
if (cv::waitKey(30) == 27) {
std::cout << "Esc pressed, exiting...\n";
break;
}
}
示例程序
#include <opencv2/opencv.hpp>
#include <iostream>
struct mouse_state
{
mouse_state()
: position(-1, -1)
, left_button_held(false)
, left_button_clicked(false)
{}
void new_iteration()
{
left_button_clicked = false;
}
cv::Point2i position; // Last position where the LMB was down
bool left_button_held; // Is the LMB down right now?
bool left_button_clicked; // Was the LMB down in the last iteration?
};
void mouse_callback(int event, int x, int y, int flag, void* param)
{
mouse_state* state(static_cast<mouse_state*>(param));
if (event == cv::EVENT_LBUTTONDOWN) {
std::cout << "LMB down @ (" << x << "," << y << ")\n";
state->position = cv::Point2i(x, y);
state->left_button_held = true;
} else if (event == cv::EVENT_LBUTTONUP) {
std::cout << "LMB up @(" << x << "," << y << ")\n";
state->position = cv::Point2i(x, y);
state->left_button_held = false;
state->left_button_clicked = true;
} else if ((flag == cv::EVENT_FLAG_LBUTTON) && (event == cv::EVENT_MOUSEMOVE)) {
std::cout << "LMB held, mouse moved to (" << x << "," << y << ")\n";
state->position = cv::Point2i(x, y);
}
}
int main(int argc, char** argv)
{
cv::String const WINDOW_NAME("Original Feed");
cv::namedWindow(WINDOW_NAME, CV_WINDOW_AUTOSIZE);
mouse_state ms;
cv::setMouseCallback(WINDOW_NAME, mouse_callback, &ms);
int const FRAME_WIDTH(720);
int const FRAME_HEIGHT(540);
cv::VideoCapture cap(0);
if (!cap.isOpened()) {
std::cerr << "Unable to open camera, exiting...\n";
return -1;
}
cap.set(CV_CAP_PROP_FRAME_WIDTH, FRAME_WIDTH);
cap.set(CV_CAP_PROP_FRAME_HEIGHT, FRAME_HEIGHT);
for (;;) {
// We can have `image` here, since `cap.read` always gives us
// a reference to its internal buffer
cv::Mat image;
if (!cap.read(image)) {
std::cerr << "Failed to read image, exiting...\n";
break; // Failed to read image, nothing else to do
}
if (ms.left_button_clicked || ms.left_button_held) {
std::cout << "Current position: " << ms.position << "\n";
cv::circle(image, ms.position, 3, cv::Scalar(0, 0, 255));
cv::circle(image, ms.position, 10, cv::Scalar(0, 0, 255), 2);
}
ms.new_iteration();
cv::imshow(WINDOW_NAME, image);
if (cv::waitKey(30) == 27) {
std::cout << "Esc pressed, exiting...\n";
break;
}
}
return 0;
}