I have a code in C language that uses the cvopen Library.
Here is the code:
#include <stdio.h>
#include <opencv2\highgui\highgui_c.h>
int main(void)
{
int i;
cvNamedWindow("Display window", CV_WINDOW_AUTOSIZE); //create a window
//create an image
IplImage* image = cvLoadImage("C:\\Users\\magshimim\\Desktop\\Mummy.png", 1);
if (!image)//The image is empty.
{
printf("could not open image\n");
}
else
{
cvShowImage("Display window", image);
cvWaitKey(0);
system("pause");
cvReleaseImage(&image);
}
getchar();
return 0;
}
In line 17 "cvShowImage("Display window", image);" the system throws exception that says:
Exception thrown at 0xAD76406A in Q4.exe: 0xC0000008: An invalid handle was specified
The cvopen pack is fine, and other function works. but this code (which works on other computers) just crushes every time.
How can i fix this?
cvShowImage is part of the old C-style naming convention in OpenCV. This old convention has been fully depreciated and is not compatible with OpenCV 3.0 and up.
Instead of cvShowImage try using imshow
imshow("Display Window", image);
Related
So I am developing a set of wrapping utilities for SDL2 but have come across a strange issue. Whenever I poll for errors using SDL_GetError at the end of a frame, if I am touching the trackpad I get the following strange error message: Unknown touch device id -1, cannot reset. This error in quotes only shows one result on google and it seems to be an issue with macOS though with only one occurrence it's hard to be sure.
Here's a minimum reproducible example:
#include <SDL2/SDL.h>
#include <stdio.h>
int main() {
SDL_Init(SDL_INIT_VIDEO);
SDL_Window* window = SDL_CreateWindow("Window", SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED, 100, 100, SDL_WINDOW_SHOWN);
while(1) {
SDL_Event e;
while(SDL_PollEvent(&e))
switch(e.type) {
case SDL_QUIT: {
SDL_DestroyWindow(window);
SDL_Quit();
exit(0);
break;
}
}
const char* err = SDL_GetError();
if(err[0]) {
printf("%s", err);
exit(-1);
}
}
}
I understand that this is a strange issue(and a potentially unanswerable one) so I really appreciate any answers or suggestions.
I am using a MacBook Pro 13-inch Mid 2012 running macOS Catalina(10.15.6). Compiled using clang 12.0.0
EDIT: I have downloaded the SDL2 source code to look for the error and the root cause seems to be this function:
static int
SDL_GetTouchIndex(SDL_TouchID id)
{
int index;
SDL_Touch *touch;
for (index = 0; index < SDL_num_touch; ++index) {
touch = SDL_touchDevices[index];
if (touch->id == id) {
return index;
}
}
return -1;
}
I am in the process of looking for why exactly this error is triggered and will update this post for any future people who encounter this error as well as filing a bug report to the SDL dev team
I want to get the full version number for Windows, just like CMD does:
I ended up with this MS doc that says:
To obtain the full version number for the operating system, call the
GetFileVersionInfo function on one of the system DLLs, such as
Kernel32.dll, then call VerQueryValue to obtain the
\StringFileInfo\\ProductVersion subblock of the file version
information.
So I tried to use those functions with this code:
#include <Windows.h>
#include <wchar.h>
#pragma comment(lib, "Mincore.lib")
int wmain(int argc, wchar_t* argv[])
{
// GetFileVersionInfoW
LPCWSTR fileName = L"C:\\Windows\\System32\\kernel32.dll";
DWORD fileInfoSize;
fileInfoSize = GetFileVersionInfoSizeW(fileName, NULL);
if (fileInfoSize == 0)
{
fwprintf(stderr, L"\nError code: %u\n", GetLastError());
return;
}
// GetFileVersionInfoW
VOID* pFileVerInfo = malloc(fileInfoSize);
if (pFileVerInfo == NULL)
{
fwprintf(stderr, L"Failed allocating!\n");
return;
}
if (!GetFileVersionInfoW(fileName, 0, fileInfoSize, pFileVerInfo))
{
fwprintf(stderr, L"Error code: %u\n", GetLastError());
free(pFileVerInfo);
return;
}
// VerQueryValueW
LPCWSTR subBlock = L"\\StringFileInfo\\\\ProductVersion";
VS_FIXEDFILEINFO * pFileInfo;
UINT pLen = 0;
if (!VerQueryValueW(pFileVerInfo, subBlock, (LPVOID*)& pFileInfo, &pLen))
{
fwprintf(stderr, L"Error code: %u\n", GetLastError());
return;
}
return 0;
}
However, the VerQueryValueW function fails with code 1813 and I have no idea why. I also have no idea how I can show the full version after calling the function.
Can you help me?
L"\\StringFileInfo\\\\ProductVersion" is not correct. There must be a Language ID in the middle. On my Windows 10 installation, a working string is: L"\\StringFileInfo\\040904B0\\ProductVersion". But maybe this would differ on other systems.
As suggested by Jonathan Potter in comments, you could find the ID by querying \\VarFileInfo\\Translation.
Simpler options to achieve the goal include:
Query VS_FIXEDFILEINFO instead of StringFileInfo
Read the OS version from the Windows API instead of querying a random DLL.
I have some C code trying to use libharu. Although I can use every function of this library (even UTF8) I can hardly draw images. Here is some very basic code:
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <math.h>
#include <setjmp.h>
#include "hpdf.h"
jmp_buf env;
#ifdef HPDF_DLL
void __stdcall
#else
void
#endif
error_handler (HPDF_STATUS error_no,
HPDF_STATUS detail_no,
void *user_data)
{
printf ("ERROR: error_no=%04X, detail_no=%u\n", (HPDF_UINT)error_no,
(HPDF_UINT)detail_no);
longjmp(env, 1);
}
int main (int argc, char **argv)
{
HPDF_Doc pdf;
HPDF_Font font;
HPDF_Page page;
char fname[256];
HPDF_Image image;
strcpy (fname, argv[0]);
strcat (fname, ".pdf");
pdf = HPDF_New (error_handler, NULL);
if (!pdf) {
printf ("error: cannot create PdfDoc object\n");
return 1;
}
/* error-handler */
if (setjmp(env)) {
HPDF_Free (pdf);
return 1;
}
font = HPDF_GetFont (pdf, "Helvetica", NULL);
page = HPDF_AddPage (pdf);
HPDF_Page_SetWidth (page, 550);
HPDF_Page_SetHeight (page, 500);
image = HPDF_LoadPngImageFromFile (pdf, "img.png");
HPDF_SaveToFile (pdf, fname);
HPDF_Free (pdf);
return 0;
}
When I compile this I have ERROR: error_no=1015, detail_no=0. I have found a similar post in stackoverflow: this. However although original poster said the problem is solved it hardly helped mine. I moved img.png to a folder and recompiled the file. Changed the code that says /home/name/path/to/img.png which is the direct path to image. Nothing works. I "always" have the same error, but when I change the name of file I have ERROR: error_no=1017, detail_no=2 which basicly means program cannot find image (according to reference of libharu) So I deduce that program finds img.png; but, it's strange but, cannot allocate the necessary memory. Which is weird because I cannot see any reason for this program not to allocate memory. I have every kind of permission.
I am using GCC 4.7.2 under Ubuntu Quantal Quetzal and libharu 2.3.0 RC2. Thank you for your help.
Hello Equalities of polynomials .
I also encountered the same problem when i integrated the haru sdk in my macOS environment.
The error_handler returned ERROR: error_no=1017, detail_no=2,and then i checked the official document for haru at http://libharu.sourceforge.net/error_handling.html query 0x1017 indicates that the file failed to open, so i suspect that the second parameter of the HPDF_LoadPngImageFromFile method needs to pass an exact png image file path, so after I modified it, the problem was solved, and I hope to help you.
code ad follow:
char filename1[255];
strcpy(filename1, "/Users/xx/Downloads/lusaceg.com.png");
image = HPDF_LoadPngImageFromFile (pdf, filename1);
Faithfully yours.
I am trying to get this screen shot program to work (below) which saves a picture of the screen as a bmp file and when I try to compile it using gcc, I get the following error:
/tmp/ccetmoRd.o:Screenshot.c:(.text+0x128): undefined reference to _GetDIBits#28'
/tmp/ccetmoRd.o:Screenshot.c:(.text+0x1e1): undefined reference to_GetDIBits#28'
collect2: ld returned 1 exit status
Any ideas why this may be?
Thanks a lot.
code:
#include <stdlib.h>
#include <windows.h>
#include <stdio.h>
void TakeScreenShot(char* filename);
int main()
{
TakeScreenShot("c:\\Screenshot.bmp");
return 0;
}
//
// Side Effects:N/A
//
//This code is copyrighted and has// limited warranties.Please see http://
// www.Planet-Source-Code.com/vb/scripts/Sh
// owCode.asp?txtCodeId=10754&lngWId=3//for details.//**************************************
//
void TakeScreenShot(char* filename)
{
keybd_event(VK_SNAPSHOT, 0x45, KEYEVENTF_EXTENDEDKEY, 0);
keybd_event(VK_SNAPSHOT, 0x45, KEYEVENTF_EXTENDEDKEY | KEYEVENTF_KEYUP, 0);
HBITMAP h;
OpenClipboard(NULL);
h = (HBITMAP)GetClipboardData(CF_BITMAP);
CloseClipboard();
HDC hdc=NULL;
FILE*fp=NULL;
LPVOID pBuf=NULL;
BITMAPINFO bmpInfo;
BITMAPFILEHEADER bmpFileHeader;
do
{
hdc=GetDC(NULL);
ZeroMemory(&bmpInfo,sizeof(BITMAPINFO));
bmpInfo.bmiHeader.biSize=sizeof(BITMAPINFOHEADER);
GetDIBits(hdc,h,0,0,NULL,&bmpInfo,DIB_RGB_COLORS);
if(bmpInfo.bmiHeader.biSizeImage<=0)
bmpInfo.bmiHeader.biSizeImage=bmpInfo.bmiHeader.biWidth*abs(bmpInfo.bmiHeader.biHeight)*(bmpInfo.bmiHeader.biBitCount+7)/8;
if((pBuf = malloc(bmpInfo.bmiHeader.biSizeImage))==NULL)
{
MessageBox( NULL, "Unable to Allocate Bitmap Memory", "Error", MB_OK|MB_ICONERROR);
break;
}
bmpInfo.bmiHeader.biCompression=BI_RGB;
GetDIBits(hdc,h,0,bmpInfo.bmiHeader.biHeight,pBuf, &bmpInfo, DIB_RGB_COLORS);
if((fp = fopen(filename,"wb"))==NULL)
{
MessageBox(NULL, "Unable to Create Bitmap File", "Error", MB_OK|MB_ICONERROR);
break;
}
bmpFileHeader.bfReserved1=0;
bmpFileHeader.bfReserved2=0;
bmpFileHeader.bfSize=sizeof(BITMAPFILEHEADER)+sizeof(BITMAPINFOHEADER)+bmpInfo.bmiHeader.biSizeImage;
bmpFileHeader.bfType='MB';
bmpFileHeader.bfOffBits=sizeof(BITMAPFILEHEADER)+sizeof(BITMAPINFOHEADER);
fwrite(&bmpFileHeader,sizeof(BITMAPFILEHEADER),1,fp);
fwrite(&bmpInfo.bmiHeader,sizeof(BITMAPINFOHEADER),1,fp);
fwrite(pBuf,bmpInfo.bmiHeader.biSizeImage,1,fp);
}
while(0);
if(hdc)
ReleaseDC(NULL,hdc);
if(pBuf)
free(pBuf);
if(fp)
fclose(fp);
}
Since feature requests to mark a comment as an answer remain declined, I copy the above solution here.
SOLVED: Downloaded gdi32 library and it resolved the issue. Thanks for the tip! – Jeremy
Working on a Windows 7 servicepack 1 environment with cygwin gcc compiler.
The following program is supposed to take a screenshot and save the file as a .bmp to the file specified. It compiles fine and seems to give a .bmp file in the desired directory but when run seems to create only a 1kb file with no screenshot data in it. If the while loop is given a starting value of while(1), it gives the "Unable to Create Bitmap File" error. I am new to this kind of programming and cannot seem to see why this is.
Any ideas?
(has to be compiled with -lgdi32)
code:
#include <stdlib.h>
#include <windows.h>
#include <stdio.h>
void TakeScreenShot(char* filename);
int main()
{
TakeScreenShot("c:\\Screenshot.bmp");
return 0;
}
//
// Side Effects:N/A
//
//This code is copyrighted and has// limited warranties.Please see http://
// www.Planet-Source-Code.com/vb/scripts/Sh
// owCode.asp?txtCodeId=10754&lngWId=3//for details.//**************************************
//
void TakeScreenShot(char* filename)
{
keybd_event(VK_SNAPSHOT, 0x45, KEYEVENTF_EXTENDEDKEY, 0);
keybd_event(VK_SNAPSHOT, 0x45, KEYEVENTF_EXTENDEDKEY | KEYEVENTF_KEYUP, 0);
HBITMAP h;
OpenClipboard(NULL);
h = (HBITMAP)GetClipboardData(CF_BITMAP);
CloseClipboard();
HDC hdc=NULL;
FILE*fp=NULL;
LPVOID pBuf=NULL;
BITMAPINFO bmpInfo;
BITMAPFILEHEADER bmpFileHeader;
do
{
hdc=GetDC(NULL);
ZeroMemory(&bmpInfo,sizeof(BITMAPINFO));
bmpInfo.bmiHeader.biSize=sizeof(BITMAPINFOHEADER);
GetDIBits(hdc,h,0,0,NULL,&bmpInfo,DIB_RGB_COLORS);
if(bmpInfo.bmiHeader.biSizeImage<=0)
bmpInfo.bmiHeader.biSizeImage=bmpInfo.bmiHeader.biWidth*abs(bmpInfo.bmiHeader.biHeight)*(bmpInfo.bmiHeader.biBitCount+7)/8;
if((pBuf = malloc(bmpInfo.bmiHeader.biSizeImage))==NULL)
{
MessageBox( NULL, "Unable to Allocate Bitmap Memory", "Error", MB_OK|MB_ICONERROR);
break;
}
bmpInfo.bmiHeader.biCompression=BI_RGB;
GetDIBits(hdc,h,0,bmpInfo.bmiHeader.biHeight,pBuf, &bmpInfo, DIB_RGB_COLORS);
if((fp = fopen(filename,"wb"))==NULL)
{
MessageBox(NULL, "Unable to Create Bitmap File", "Error", MB_OK|MB_ICONERROR);
break;
}
bmpFileHeader.bfReserved1=0;
bmpFileHeader.bfReserved2=0;
bmpFileHeader.bfSize=sizeof(BITMAPFILEHEADER)+sizeof(BITMAPINFOHEADER)+bmpInfo.bmiHeader.biSizeImage;
bmpFileHeader.bfType='MB';
bmpFileHeader.bfOffBits=sizeof(BITMAPFILEHEADER)+sizeof(BITMAPINFOHEADER);
fwrite(&bmpFileHeader,sizeof(BITMAPFILEHEADER),1,fp);
fwrite(&bmpInfo.bmiHeader,sizeof(BITMAPINFOHEADER),1,fp);
fwrite(pBuf,bmpInfo.bmiHeader.biSizeImage,1,fp);
}
while(0);
if(hdc)
ReleaseDC(NULL,hdc);
if(pBuf)
free(pBuf);
if(fp)
fclose(fp);
}
The program apparently saves bitmap data it gets from the clipboard. If there is no data on the clipboard, I assume it only saves an empty bitmap. And it writes a file called "Screenshot.bmp", not a .png file.
To put bitmap data on the clipboard, I assume you must press the print screen button first. This saves a screenshot to the clipboard. Now the program can be used to save this clipboard data to a file.