/*
1 - Get a bmp image from hard drive( i have it).
 
2 - Copy it to byte array, or get its internal array, i have tested both ways (method1 and method2 in comments).
 
3 - Prepare a PicutreBox and obtain from it my context device.
 
4 - Use BitBlt function to copy only first 50 lines of the initial bitmap.
 
5 - Display it in a windows form.
*/
 
#include "stdafx.h"
#include <Windows.h>
#include "MyForm.h"
#include "string.h"
 
using namespace System;
using namespace System::Runtime::InteropServices;
using namespace System::Runtime::CompilerServices;
using namespace System::IO;
using namespace System::Windows::Forms;
using namespace System::Drawing;
using namespace System::Drawing::Imaging;
 
using namespace ConsoleApplication1;
 
[DllImport("gdi32.dll", CallingConvention = CallingConvention::StdCall, SetLastError = true)]
extern bool BitBlt(IntPtr hdcDest, int nXDest, int nYDest, int nWidth, int nHeight,
	IntPtr hdcSrc, int nXSrc, int nYSrc, long dwRop);
 
int main(array<System::String ^> ^args){
	Graphics ^gph = nullptr;
	try{
		//Get a test image and it's parameters
		Bitmap ^image = gcnew Bitmap("./img/Simple_tux0.bmp");
		int iWidth = image->Width;
		int iHeigth = image->Height;
		PixelFormat pxF = image->PixelFormat;
 
 
		//Prepare a PictureBo, whici will be given as parameter to Windows Form.
		PictureBox ^pb = gcnew PictureBox();
		pb->SizeMode = PictureBoxSizeMode::StretchImage;
		pb->Size = Drawing::Size(iWidth + 10, iHeigth + 10);
		pb->Location = Drawing::Point(3, 3);
 
		//Get bitmap 
		IntPtr prueba = image->GetHbitmap();
 
		//Create my device context, where i will paint my lines.
		gph = pb->CreateGraphics();
		IntPtr deviceContext = gph->GetHdc();
 
 
		//Paint only 50 lines of the source Bitmap.
		BOOL b = BitBlt((HDC)deviceContext.ToPointer(), 0, 0, iWidth, 50,
			(HDC)prueba.ToPointer(), 0, 0, SRCCOPY);
 
		//Get the error:
		unsigned long err = GetLastError();
		Console::WriteLine("error: {0}", err);	//error 6 : Invalid Handle
 
		//Create windows form with the PictureBox to display my 50 lines.
		MyForm ^f = gcnew MyForm(pb);
		Application::Run(f);
		Application::Exit();
	}
	finally{
		if (gph != nullptr){
			gph->ReleaseHdc();
			delete gph;
		}
 
	}
	return 0;
}
 

[DllImport("coredll.dll", EntryPoint = "CreateCompatibleDC")]
extern IntPtr CreateCompatibleDC(IntPtr hdc);
 
[DllImport("coredll.dll", EntryPoint = "GetDC")]
extern IntPtr GetDC(IntPtr hwnd);
 
int main(){
//...
//...
IntPtr dc = GetDC(deviceContext);
IntPtr compDc = CreateCompatibleDC(dc);
 
//Paint only 50 lines of the source Bitmap.
BOOL b = BitBlt((HDC)compDc.ToPointer(), 0, 0, iWidth, 50,
	(HDC)prueba.ToPointer(), 0, 0, SRCCOPY);
 

(HDC)deviceContext.ToPointer()