bmplib.cpp

#ifdef _WIN32
#include "boinc_win.h"
#else
#include "config.h"
#endif

#include "bmplib.h"

// Returns true for success -- false otherwise
bool DIB_BITMAP::set_size(int width, int height, int channels)	
{
 
	// If DIB_BITMAP has already been set -- clear it out first
	FreeDIB_BMP();

	// Create a temporary compatible device context
	HDC temp_hdc = CreateCompatibleDC(NULL);
		
		// Error Check
		if(!temp_hdc)
			return false;

	bmp_width = width; // Set the width
	bmp_height = height; // Set the height
	bmp_channels = channels; // Set the channels (3 == 24-bit, 4 == 32-bit)
	
	// Set stride -- The stride is the TRUE number of bytes in a line of pixels
	// Windows makes all the .bmps DWORD aligned (divisible evenly by 4)
	// So if you bitmap say was 103x103 pixels, Windows would add 1 "padding byte" to it
	// so in memory it would be 104x103 pixels.  The "padding bytes" do not get blit (drawn)
	// to the screen, they're just there so again everything is DWORD aligned which makes 
	// blitting (drawing to the screen) easier for the OS
	bmp_stride = bmp_width * bmp_channels;

	while((bmp_stride % 4) != 0) // Ensure bmp_stride is DWORD aligned
		bmp_stride++;
		
	BITMAPINFO bmp_info = {0};

	// Initialize the parameters that we care about
	bmp_info.bmiHeader.biSize = sizeof(BITMAPINFOHEADER);
	bmp_info.bmiHeader.biWidth = width;
	bmp_info.bmiHeader.biHeight = height;
	bmp_info.bmiHeader.biPlanes = 1; // Always equal 1
	bmp_info.bmiHeader.biBitCount = channels * 8;
	bmp_info.bmiHeader.biCompression = BI_RGB; // No compression
	bmp_info.bmiHeader.biClrUsed = 0; // Always equals 0 with a 24 or 32-bit .bmp

	// Create a DIBSection -- This returns us two things, an HBITMAP handle and
	// a memory pointer (pointer to the pixels) in surface_bits
	hbitmap = CreateDIBSection(temp_hdc, &bmp_info, DIB_RGB_COLORS,
							   (void**)&surface_bits, 0, 0);

	// Release our temporary HDC
	DeleteDC(temp_hdc);

		// Error Check -- Make sure the call to CreateDIBSection() DID NOT fail
		if(!hbitmap)
			return false;		
		
	return true; // We're sized :)

} // end of set_size(int width, int height, int channels)

bool DIB_BITMAP::loadBMP(const char *file_name)
{
	// If DIB_BITMAP has already been set -- clear it out first
	FreeDIB_BMP();

		// Error Check -- Make sure they passed in a valid file name