SimpleBMP

SimpleBMP is a small, simple, self-contained and cross-platform C++ library for loading, saving and handling BMP (Bitmap) image files.

The only thing that SimpleBMP uses/requires is the standard library header <fstream>.

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SimpleBMP is a young library, so any feedback for improvements and/or missing features are welcome!

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Why SimpleBMP?

Before making SimpleBMP I was looking for a simple and upfront library for loading and saving BMP files. The only thing that I found was cluttered and complex libraries. BMP files are and they should have a simple library, when having to deal with them!

SimpleBMP mainly has two functions SimpleBMP::load() and SimpleBMP::save(). SimpleBMP then also offers a class which is built around those two functions.

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Examples

There are a lot of examples on how SimpleBMP can be used, in the "examples" directory!

• Generating a Gradient
• Apply Grayscale Effect to an Image
• OpenGL Load Texture
• OpenGL Save Screenshot
• Error Codes
• Packed RGB Values

But basically there are two general ways of using SimpleBMP.

The following example, is for loading an image, applying the grayscale effect to the loaded image and then save it again!

The first way is, where you store and maintain the width, height and pixels.

int width = 0, height = 0;
unsigned char *pixels = nullptr;

SimpleBMP::load(&width, &height, &pixels, "input.bmp");

for (int i = 0; i < width; i++)
{
	for (int j = 0; j < height; j++)
	{
		unsigned char red = 0, green = 0, blue = 0;

		SimpleBMP::getPixel(width, height, pixels, i, j, &red, &green, &blue);

		unsigned char gray = (red + green + blue) / 3;

		SimpleBMP::setPixel(width, height, pixels, i, j, gray, gray, gray);
	}
}

SimpleBMP::save(width, height, pixels, "output.bmp");

The second way, is where you use and instanciate a SimpleBMP object.

SimpleBMP bmp;
bmp.load("input.bmp");

for (int i = 0; i < bmp.width; i++)
{
	for (int j = 0; j < bmp.height; j++)
	{
		unsigned char red = 0, green = 0, blue = 0;

		bmp.getPixel(i, j, &red, &green, &blue);

		unsigned char gray = (red + green + blue) / 3;

		bmp.setPixel(i, j, gray, gray, gray);
	}
}

bmp.save("output.bmp");

SimpleBMP + OpenGL

SimpleBMP also has a simple wrapper function for use with OpenGL. But before you can use it, you need to define SIMPLEBMP_OPENGL before you include simplebmp.h.

#define SIMPLEBMP_OPENGL
#include "simplebmp\simplebmp.h"

Again you can both use it with or without having to instanciate a SimpleBMP object.

SimpleBMP::glTexImage2D(width, height, pixels);

or

bmp.glTexImage2D();

Complete OpenGL Example

// Always remember that the texture must have
// a width and height of Power of Two
//
// http://en.wikipedia.org/wiki/Power_of_two

GLuint texture_handle;
glGenTextures(1, &texture_handle);
glBindTexture(GL_TEXTURE_2D, texture_handle);

bmp.glTexImage2D();

OpenGL Save Screenshot

SimpleBMP also allows for an easy way to save a screenshot!

const char *path = "screenshot.bmp";

// The width and the height, would be the width
// and height of your current scene.
const int width = 1280;
const int height = 720;

SimpleBMP bmp(width, height);

bmp.glReadPixels();

if (!bmp.save(path))
{
	printf("Successfully Saved! <%s>\n", path);
}
else
{
	printf("Save Failed! <%s>\n", path);
}

Error Codes

The save and load functions, return error codes. It is guaranteed that 0 (SIMPLEBMP_NO_ERROR) is returned when no error has happened!

#define SIMPLEBMP_NO_ERROR 0
#define SIMPLEBMP_FOPEN_ERROR 1

#define SIMPLEBMP_INVALID_SIGNATURE 2
#define SIMPLEBMP_INVALID_BITS_PER_PIXEL 3