screengrab.c

#include "screengrab.h"
#include "bmp_io.h"
#include "endian.h"
#include <stdlib.h> /* malloc() */

#if defined(IS_MACOSX)
	#include <OpenGL/OpenGL.h>
	#include <OpenGL/gl.h>
	#include <ApplicationServices/ApplicationServices.h>
#elif defined(USE_X11)
	#include <X11/Xlib.h>
	#include <X11/Xutil.h>
	#include "xdisplay.h"
#elif defined(IS_WINDOWS)
	#include <string.h>
#endif

MMBitmapRef copyMMBitmapFromDisplayInRect(MMRect rect)
{
#if defined(IS_MACOSX)

	MMBitmapRef bitmap = NULL;
	uint8_t *buffer = NULL;
	size_t bufferSize = 0;

	CGDirectDisplayID displayID = CGMainDisplayID();

	CGImageRef image = CGDisplayCreateImageForRect(displayID,
		CGRectMake(rect.origin.x,
			rect.origin.y,
			rect.size.width,
			rect.size.height));

	if (!image) { return NULL; }

	CFDataRef imageData = CGDataProviderCopyData(CGImageGetDataProvider(image));

	if (!imageData) { return NULL; }

	bufferSize = CFDataGetLength(imageData);
	buffer = malloc(bufferSize);

	CFDataGetBytes(imageData, CFRangeMake(0,bufferSize), buffer);

	bitmap = createMMBitmap(buffer,
		CGImageGetWidth(image),
		CGImageGetHeight(image),
		CGImageGetBytesPerRow(image),
		CGImageGetBitsPerPixel(image),
		CGImageGetBitsPerPixel(image) / 8);

	CFRelease(imageData);

	CGImageRelease(image);

	return bitmap;

#elif defined(USE_X11)
	MMBitmapRef bitmap;

	Display *display = XOpenDisplay(NULL);
	XImage *image = XGetImage(display,
	                          XDefaultRootWindow(display),
	                          (int)rect.origin.x,
	                          (int)rect.origin.y,
	                          (unsigned int)rect.size.width,
	                          (unsigned int)rect.size.height,
	                          AllPlanes, ZPixmap);
	XCloseDisplay(display);
	if (image == NULL) return NULL;

	bitmap = createMMBitmap((uint8_t *)image->data,
	                        rect.size.width,
	                        rect.size.height,
	                        (size_t)image->bytes_per_line,
	                        (uint8_t)image->bits_per_pixel,
	                        (uint8_t)image->bits_per_pixel / 8);
	image->data = NULL; /* Steal ownership of bitmap data so we don't have to
	                     * copy it. */
	XDestroyImage(image);

	return bitmap;
#elif defined(IS_WINDOWS)
	MMBitmapRef bitmap;
	void *data;
	HDC screen = NULL, screenMem = NULL;
	HBITMAP dib;
	BITMAPINFO bi;

	/* Initialize bitmap info. */
	bi.bmiHeader.biSize = sizeof(bi.bmiHeader);
   	bi.bmiHeader.biWidth = (long)rect.size.width;
   	bi.bmiHeader.biHeight = -(long)rect.size.height; /* Non-cartesian, please */
   	bi.bmiHeader.biPlanes = 1;
   	bi.bmiHeader.biBitCount = 32;
   	bi.bmiHeader.biCompression = BI_RGB;
   	bi.bmiHeader.biSizeImage = (DWORD)(4 * rect.size.width * rect.size.height);
	bi.bmiHeader.biXPelsPerMeter = 0;
	bi.bmiHeader.biYPelsPerMeter = 0;
	bi.bmiHeader.biClrUsed = 0;
	bi.bmiHeader.biClrImportant = 0;

	screen = GetDC(NULL); /* Get entire screen */
	if (screen == NULL) return NULL;

	/* Get screen data in display device context. */
   	dib = CreateDIBSection(screen, &bi, DIB_RGB_COLORS, &data, NULL, 0);

	/* Copy the data into a bitmap struct. */
	if ((screenMem = CreateCompatibleDC(screen)) == NULL ||
	    SelectObject(screenMem, dib) == NULL ||
	    !BitBlt(screenMem,
	            (int)0,
	            (int)0,
	            (int)rect.size.width,
	            (int)rect.size.height,
				screen,
				rect.origin.x,
				rect.origin.y,
				SRCCOPY)) {
		
		/* Error copying data. */
		ReleaseDC(NULL, screen);
		DeleteObject(dib);
		if (screenMem != NULL) DeleteDC(screenMem);

		return NULL;
	}

	bitmap = createMMBitmap(NULL,
	                        rect.size.width,
	                        rect.size.height,
	                        4 * rect.size.width,
	                        (uint8_t)bi.bmiHeader.biBitCount,
	                        4);

	/* Copy the data to our pixel buffer. */
	if (bitmap != NULL) {
		bitmap->imageBuffer = malloc(bitmap->bytewidth * bitmap->height);
		memcpy(bitmap->imageBuffer, data, bitmap->bytewidth * bitmap->height);
	}

	ReleaseDC(NULL, screen);
	DeleteObject(dib);
	DeleteDC(screenMem);

	return bitmap;
#endif
}