www.pudn.com > jpg.zip > f_main.cpp

//--------------------------------------------------------------------------- 
#include  
#pragma hdrstop 
 
#include  
#define HAVE_BOOLEAN 
#include "jpglib/jpeglib.h" 
#include "f_main.h" 
//--------------------------------------------------------------------------- 
#pragma package(smart_init) 
#pragma resource "*.dfm" 
TForm1 *Form1; 
//--------------------------------------------------------------------------- 
__fastcall TForm1::TForm1(TComponent* Owner) 
	: TForm(Owner) 
{ 
} 
//--------------------------------------------------------------------------- 
 
 
void TForm1::ReadJPEGBitmap(const char * file_name, Graphics::TBitmap *bitmap) 
{ 
	jpeg_decompress_struct cinfo; 
    jpeg_error_mgr jerr; 
    FILE *input_file; 
 
    input_file = fopen(file_name, "rb"); 
    if (input_file == NULL) 
    	throw "Can't open file"; 
 
	/* Initialize the JPEG decompression object with default error handling. */ 
	cinfo.err = jpeg_std_error(&jerr); 
	jpeg_create_decompress(&cinfo); 
 
    jpeg_stdio_src(&cinfo, input_file); 
    if (!jpeg_read_header(&cinfo, TRUE)) 
    	throw "Jpeg header do not match"; 
 
    jpeg_start_decompress(&cinfo); 
    bitmap->HandleType = bmDIB; 
    bitmap->PixelFormat = pf24bit; 
    bitmap->Width = cinfo.output_width; 
    bitmap->Height = cinfo.output_height; 
    while (cinfo.output_scanline < cinfo.output_height) 
    { 
        unsigned char *scanline = (unsigned char *)bitmap->ScanLine[cinfo.output_scanline]; 
    	int num_scanlines = jpeg_read_scanlines(&cinfo, &scanline, 1); 
        if (num_scanlines != 1) 
        	throw "Error while decompressing Jpeg file"; 
        // exchange the order of R & B 
        for (unsigned int i=0; iExecute()) 
    { 
    	Graphics::TBitmap *bitmap = new Graphics::TBitmap; 
    	ReadJPEGBitmap(OpenDialog1->FileName.c_str(), bitmap); 
        PaintBox1->Canvas->Draw(0, 0, bitmap); 
        delete bitmap; 
    } 
} 
//---------------------------------------------------------------------------