[C++] Visualizzare Bitmap su un Form

[emi81]

ciao a tutti,
ho creato un porgramma che apre un form (ID_FORM).

su questo form vorrei visualizzare un immagine bmp (img1.bmp)

Qualcuno sa dirmi come devo fare?

Grazie a tutti!

[frarugi87]

che compilatore usi? perchè molti hanno come strumento una imagebox p simile che ti permette di inserire direttamente un'immagine...
se no gliela fai disegnare pixel per pixel...

[emi81]

utilizzo visual c++ 6.

io ho trovato un modo in rete, solo che non riesco a utilizzarlo nel mio lavoro.

il metodo che ho trovato è questo :

// *************************************************************
//                       BMP LOAD EXAMPLE
//         Written by Juan Soulie <jsoulie@cplusplus.com>
// *************************************************************

#include <windows.h>
#include <fstream.h>

char szAppName [] = "BMPLoad";

LRESULT CALLBACK WindowProc (HWND, UINT, WPARAM, LPARAM);

// **********
// class CRaster
//   - Generic class for BMP raster images.
class CRaster {
	public:
		int Width,Height;		// Dimensions
		int BPP;				// Bits Per Pixel.
		char * Raster;			// Bits of the Image.
		RGBQUAD * Palette;		// RGB Palette for the image.
		int BytesPerRow;		// Row Width (in bytes).
		BITMAPINFO * pbmi;		// BITMAPINFO structure

		// Member functions (defined later):
		int LoadBMP (char * szFile);
		int GDIPaint (HDC hdc,int x,int y);
};

// **********
// Windows Main Function. 
//   - Here starts our demo program
int WINAPI WinMain ( HINSTANCE hInstance, HINSTANCE hPrevInstance,
					LPSTR lpCmdLine, int nCmdShow )
{
	HWND hwnd;
	MSG msg;

	WNDCLASS wc;
	wc.style = CS_HREDRAW|CS_VREDRAW;
	wc.lpfnWndProc = WindowProc;
	wc.cbClsExtra = 0;
	wc.cbWndExtra = 0;
	wc.hInstance = hInstance;
	wc.hIcon = LoadIcon (NULL, IDI_APPLICATION);
	wc.hCursor = LoadCursor (NULL, IDC_ARROW);
	wc.hbrBackground = (HBRUSH) (COLOR_WINDOW+1);
	wc.lpszMenuName = NULL;
	wc.lpszClassName = szAppName;

	RegisterClass (&wc);

	hwnd = CreateWindow (szAppName,"BMP Load",WS_OVERLAPPEDWINDOW,
		CW_USEDEFAULT,CW_USEDEFAULT,CW_USEDEFAULT,CW_USEDEFAULT,
		0,0,hInstance,0);

	ShowWindow (hwnd,nCmdShow);
	UpdateWindow (hwnd);

	while (GetMessage(&msg,0,0,0))
	{
		TranslateMessage (&msg);
		DispatchMessage (&msg);
	}

	return msg.wParam;
}

// **********
// Main Window Procedure.
//   - Processes Window Messages
LRESULT CALLBACK WindowProc
	(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
	static CRaster bmp;
	HDC hdc;
	PAINTSTRUCT ps;

	switch (message)
	{
		case WM_CREATE:
			bmp.LoadBMP ("example.bmp");
			return 0;
		case WM_PAINT:
			hdc=BeginPaint (hwnd,&ps);
			bmp.GDIPaint (hdc,10,10);
			EndPaint (hwnd,&ps);
			return 0;
		case WM_DESTROY:
			PostQuitMessage (0);
			return 0;
	}
	return DefWindowProc (hwnd,message,wParam,lParam);
}

// **********
// CRaster::LoadBMPFile (FileName);
//   - loads a BMP file into a CRaster object
//   * supports non-RLE-compressed files of 1, 2, 4, 8 & 24 bits-per-pixel
int CRaster::LoadBMP (char * szFile)
{
	BITMAPFILEHEADER bmfh;
	BITMAPINFOHEADER bmih;

	// Open file.
	ifstream bmpfile (szFile , ios::in | ios::binary);
	if (! bmpfile.is_open()) return 1;		// Error opening file

	// Load bitmap fileheader & infoheader
	bmpfile.read ((char*)&bmfh,sizeof (BITMAPFILEHEADER));
	bmpfile.read ((char*)&bmih,sizeof (BITMAPINFOHEADER));

	// Check filetype signature
	if (bmfh.bfType!='MB') return 2;		// File is not BMP

	// Assign some short variables:
	BPP=bmih.biBitCount;
	Width=bmih.biWidth;
	Height= (bmih.biHeight>0) ? bmih.biHeight : -bmih.biHeight; // absoulte value
	BytesPerRow = Width * BPP / 8;
	BytesPerRow += (4-BytesPerRow%4) % 4;	// int alignment

	// If BPP aren't 24, load Palette:
	if (BPP==24) pbmi=(BITMAPINFO*)new char [sizeof(BITMAPINFO)];
	else
	{
		pbmi=(BITMAPINFO*) new char[sizeof(BITMAPINFOHEADER)+(1<<BPP)*sizeof(RGBQUAD)];
		Palette=(RGBQUAD*)((char*)pbmi+sizeof(BITMAPINFOHEADER));
		bmpfile.read ((char*)Palette,sizeof (RGBQUAD) * (1<<BPP));
	}
	pbmi->bmiHeader=bmih;

	// Load Raster
	bmpfile.seekg (bmfh.bfOffBits,ios::beg);

	Raster= new char[BytesPerRow*Height];

	// (if height is positive the bmp is bottom-up, read it reversed)
	if (bmih.biHeight>0)
		for (int n=Height-1;n>=0;n--)
			bmpfile.read (Raster+BytesPerRow*n,BytesPerRow);
	else
		bmpfile.read (Raster,BytesPerRow*Height);

	// so, we always have a up-bottom raster (that is negative height for windows):
	pbmi->bmiHeader.biHeight=-Height;

	bmpfile.close();

	return 0;
}

// **********
// CRaster::GDIPaint (hdc,x,y);
// * Paints Raster to a Windows DC.
int CRaster::GDIPaint (HDC hdc,int x=0,int y=0)
{
	// Paint the image to the device.
	return SetDIBitsToDevice (hdc,x,y,Width,Height,0,0,
		0,Height,(LPVOID)Raster,pbmi,0);
}

cosi è perfetto, apre una finestra e mostra l'immagine.
il mio problema è che io ho creato un prog con view multiple. ho una classe per ogni view, nella quale carico un form.
io non riesco a recuperare l'handle di questp form, per poipoter chiamare correttamente :
hdc=BeginPaint (hwnd,&ps);
e quindi non riesco a disegnare l'immagine..

[frarugi87]

non conosco la programmazione ad oggetti.. mi dispiace...

qualcun altro sa qualcosa per dare una mano?

[oregon]

Originariamente inviato da emi81
il mio problema è che io ho creato un prog con view multiple. ho una classe per ogni view, nella quale carico un form.

Come le hai create? Quale classe hai usato? Quale libreria?

[emi81]

la classe di una vie è questa :

FormPres.cpp

#include "stdafx.h"
#include "WiDemo.h"
#include "FormPres.h"

#ifdef _DEBUG
#define new DEBUG_NEW
#undef THIS_FILE
static char THIS_FILE[] = __FILE__;
#endif

extern CWiDemoApp theApp;

/////////////////////////////////////////////////////////////////////////////
IMPLEMENT_DYNCREATE(CFormPres, CColorFormView)

CFormPres::CFormPres()
	: CColorFormView(CFormPres::IDD, RGB(255, 255, 255)) //white
{
	//{{AFX_DATA_INIT(CFormPres)
		// NOTE: the ClassWizard will add member initialization here
	//}}AFX_DATA_INIT
}

CFormPres::~CFormPres()
{
	TRACE("destructing CFormPres\n");
}

void CFormPres:: DoDataExchange(CDataExchange* pDX)
{
	CFormView:: DoDataExchange(pDX);
	//{{AFX_DATA_MAP(CFormPres)
		// NOTE: the ClassWizard will add DDX and DDV calls here
	//}}AFX_DATA_MAP
}

BEGIN_MESSAGE_MAP(CFormPres, CColorFormView)
	//{{AFX_MSG_MAP(CFormPres)

	//}}AFX_MSG_MAP
END_MESSAGE_MAP()

/////////////////////////////////////////////////////////////////////////////
// CFormPres diagnostics
#ifdef _DEBUG
void CFormPres::AssertValid() const
{
	CFormView::AssertValid();
}

void CFormPres:: Dump(CDumpContext& dc) const
{
	CFormView:: Dump(dc);
}

#endif //_DEBUG
/////////////////////////////////////////////////////////////////////////////

FormPres.h

#if !defined(AFX_CFormPres_H__CB97F4D2_1752_11D2_B134_00C04FB9CA2B__INCLUDED_)
#define AFX_CFormPres_H__CB97F4D2_1752_11D2_B134_00C04FB9CA2B__INCLUDED_

#if _MSC_VER >= 1000
#pragma once
#endif // _MSC_VER >= 1000
// FormPres.h : header file
//
#include "ColorFormView.h"

/////////////////////////////////////////////////////////////////////////////
// CFormPres form view

#ifndef __AFXEXT_H__
#include <afxext.h>
#endif

class CFormPres : public CColorFormView
{
protected:
	CFormPres();           // protected constructor used by dynamic creation
	DECLARE_DYNCREATE(CFormPres)

// Form Data
public:
	//{{AFX_DATA(CFormPres)
	enum { IDD = IDD_FORMPRES };
		// NOTE: the ClassWizard will add data members here
	//}}AFX_DATA

// Attributes
public:

// Operations
public:

// Overrides
	// ClassWizard generated virtual function overrides
	//{{AFX_VIRTUAL(CFormPres)
	protected:
	virtual void DoDataExchange(CDataExchange* pDX);    // DDX/DDV support
	//}}AFX_VIRTUAL

// Implementation
protected:
	virtual ~CFormPres();
#ifdef _DEBUG
	virtual void AssertValid() const;
	virtual void Dump(CDumpContext& dc) const;
#endif

	// Generated message map functions
	//{{AFX_MSG(CFormPres)
	
	//}}AFX_MSG
	DECLARE_MESSAGE_MAP()
};

/////////////////////////////////////////////////////////////////////////////

//{{AFX_INSERT_LOCATION}}
// Microsoft Developer Studio will insert additional declarations immediately before the previous line.

#endif // !defined(AFX_CFormPres_H__CB97F4D2_1752_11D2_B134_00C04FB9CA2B__INCLUDED_)

Mentre la funzione con la quale le chiamo è questa :

/////////////////////////////////////////////////////////////////////////////
//This function displays a view that is chosen from the menu.
void CMainFrame::OnChooseView(UINT nCmdID) 
{
	if(nCmdID == m_nCurrentView)
		return; //view is already selected, so don't need to destroy it and then create it again

	CWnd* pWnd;
	CWnd* pWndToDelete;

	//The use of EnumChildWindows below is to find a child window that is derived from CView.
	//GetActiveView() will return NULL if no view has focus, so we can't use it here.
	//GetActiveDocument() also can't be used because it calls GetActiveView().
	EnumChildWindows(m_hWnd, MyWndEnumProc, (LPARAM)&(pWnd));

	if(pWnd == NULL)
	{
		AfxMessageBox("Problem: CMainFrame::OnChooseView can not find any views!");
		return;
	}

	//Now that we've found a view, search up the parent tree until we come to the CMainFrame 
	//window. Then set pWndToDelete to the CWnd that is the immediate child of CMainFrame. 
	//This is done to find the most senior view (which may or may not have children views). 
	//CMainFrame also has children, such as the toolbar, that we don't want to delete.
	while( lstrcmp(pWnd->GetRuntimeClass()->m_lpszClassName, "CMainFrame") )
	{
		pWndToDelete = pWnd;
		pWnd = pWnd->GetParent();
	}

	CRuntimeClass* pNewViewRTClass;
	switch(nCmdID)
	{
		case ID_WORKS_SEQUENTIAL:
			pNewViewRTClass = RUNTIME_CLASS(CFormSeq);
			break;
		case ID_WORKS_SINGLEDOC:
			pNewViewRTClass = RUNTIME_CLASS(CFormSing);
			break;
		case IDD_FORMPRES:
			pNewViewRTClass = RUNTIME_CLASS(CFormPres);
			break;
		default:
			ASSERT(0);
			return;
	}
	
	//Create the new view:
	CCreateContext context;
	context.m_pNewViewClass = pNewViewRTClass;

	m_pNewView = STATIC_DOWNCAST(CView, CreateView(&context));
	if(m_pNewView != NULL)
	{
		m_nCurrentView = nCmdID; 

		//destroy the old view:
		pWndToDelete->DestroyWindow(); 

		//OnInitialUpdate() is not called as a result of calling CreateView() above. 
		//It is not always called by the framework, so it is called here:
		m_pNewView->OnInitialUpdate(); 

		//Show and activate view:
		m_pNewView->ShowWindow(SW_SHOW); 
		SetActiveView(m_pNewView);
		RecalcLayout();
	}
	else
	{
		AfxMessageBox("problem creating a view in CMainFrame::OnChooseView()");
	}
}

[alka]

Originariamente inviato da emi81
Qualcuno sa dirmi come devo fare?

In futuro, evitare di aprire discussioni duplicate, dato che avevi già aperto una discussione analoga qui.