EvilZone

Hello you guys. I'm working a bit on improving my C++ so I decided to mess around with screenshots. it's windows based an uses gdiplus and windows api. It gets your window with the windows api then handles the bitmap that it generates with gdiplus and saves it to a file.

The screenshot header file

Code: [Select]

#include <Windows.h>
#include <gdiplus.h>


#pragma comment(lib, "gdiplus.lib")
#pragma once

class Screenshot
{
public:
    Screenshot();
    ~Screenshot();
    void makeScreenshot(const WCHAR*);
private:
    ULONG_PTR token;
    int GetEncoderClsid(const WCHAR*, CLSID*);
};

The screenshot class

Code: [Select]

#include "Screenshot.h"

ULONG_PTR gdiToken;

Screenshot::Screenshot()
{
    Gdiplus::GdiplusStartupInput StartupInput;
    Gdiplus::GdiplusStartup(&gdiToken, &StartupInput, NULL);
}


Screenshot::~Screenshot()
{
    Gdiplus::GdiplusShutdown(gdiToken);
}

int Screenshot::GetEncoderClsid(const WCHAR* format, CLSID* pClsid) {
    UINT num = 0;
    UINT size = 0;

    Gdiplus::ImageCodecInfo* pImageCodecInfo = NULL;
    Gdiplus::GetImageEncodersSize(&num, &size);
   
    if (size == 0)
        return -1;

    pImageCodecInfo = (Gdiplus::ImageCodecInfo*)(malloc(size));

    if (pImageCodecInfo == NULL)
        return -1;

    Gdiplus::GetImageEncoders(num, size, pImageCodecInfo);

    for (UINT codec = 0; codec < num; ++codec)
    {
        if (wcscmp(pImageCodecInfo[codec].MimeType, format) == 0)
        {
            *pClsid = pImageCodecInfo[codec].Clsid;
            free(pImageCodecInfo);
            return codec;
        }
    }

    free(pImageCodecInfo);
    return -1;
}

void Screenshot::makeScreenshot(const WCHAR* filename) {
    int screenHeight = GetSystemMetrics(SM_CYSCREEN);
    int screenWidth = GetSystemMetrics(SM_CXSCREEN);

    HWND desktopWindow = GetDesktopWindow();

    HDC desktopDC = GetDC(desktopWindow);
    HDC captureDC = CreateCompatibleDC(desktopDC);

    HBITMAP captureBitmap = CreateCompatibleBitmap(desktopDC, screenWidth, screenHeight);
    SelectObject(captureDC, captureBitmap);
    BitBlt(captureDC, 0, 0, screenWidth, screenHeight, desktopDC, 0, 0, SRCCOPY | CAPTUREBLT);

    Gdiplus::Bitmap *bitmap = new Gdiplus::Bitmap(captureBitmap, NULL);
    CLSID clsId;

    int retVal = this->GetEncoderClsid(L"image/png", &clsId);
    bitmap->Save(filename, &clsId, NULL);
   
    ReleaseDC(desktopWindow, desktopDC);
    DeleteDC(captureDC);
    DeleteObject(captureBitmap);
}


Hi buddy,
                  i just compiled your code in gcc compiler by using following command
"g++ filename.cpp  screenshot.h -o filename.exe"
That is give  undefined reference says lot .what i will do to overcome this problem


thanks 

It's good to break down the problems you have into simpler ones. Then try to solve one after another. My point is, although this problem is simple enough, you know that you have to sort an array. That's something to start with. Google and learn to sort arrays, implement it in your program, and then continue with whatever is next.

It's best if you could sit down and learn C/C++ from the beginning. You're trying to solve something without knowing the right tools and that's why you're stuck. But however, if you prefer to tackle a problem right away, break it down to specific tasks and learn how to do them separately.

You're using iostream for input and stdio.h for output for some reason. In C you should use stdio.h, iostream is a C++ library.

Printing "k" is pointless because k by itself is actually a pointer to the beginning of that array. You want to print elements of it.

My hints are:
1. First, read all the elements in one loop.
2. Rearrange the array so it fits your criteria. You want ascending order so every element should be greater than all of those before it, not some temp element. Not sure what your idea was with that one too.
3. Print the array correctly.

You should really go learn the basics of the language from the beginning, and not ask people to help you with your homework. And if you do, there are plenty of other places you can do so, this one is primarily for learning.

You have a long way to go, kid. I use vim, without any plugins to code in the language I want. If you can't code without autocomplete, you seriously need to work hard on your skills.
I can understand coding Java with autocomplete as you seriously need to type all the class.function name but not in C, C++ -_-

I can understand coding Java with autocomplete as you seriously need to type all the class.function name but not in C, C++ -_-

Just for fun

Code: [Select]

```
 ~/fun  cat test.c
#include <stdlib.h>
#include <stdio.h>
#include <string.h>


char** split(char *s,const char *delim) {
        int delims = 0; char *p = strtok(s,delim), **res = NULL;
    while(p) {
       res = realloc(res,sizeof(char*) * ++delims); // allocating memory
           if ( res == NULL ) exit(-1); // there is no more memory , allocation is failed
           res[delims-1] = p;
       p = strtok(NULL,delim);
    }
        // adding last element because of the null 
        res = realloc(res,sizeof(char*) * ++delims);
        res[delims-1] = 0;
        return res;
   
}

int main () {
  char buf[] ="it is just a simple example for fun";
  char** data = split(buf," ");
  for(int i=0; data[i]; i++)
     printf("%d = %s\n",i, data[i] );
  free(data);
}

```


Well, as much as I hate to admit it , you're correct about sizeof(char), it's definitely equal to one according to the standard.*  I see what you mean about the chkret macro now, not freeing what it should, good catch.

*I took some time to do a little more research into the subject and even if a "char" is 32 bits, sizeof(char) will always return 1.  You can also find the number of bits contained in a char by looking at CHAR_BITS in <limits.h>. Source: (ctrl+f) for section 6.5.3.4