Easy win32 GDI Print API interface with callbacks.

cbprint.c

#ifndef _PRINTER_PAGE_H_
#define _PRINTER_PAGE_H_

#include <windows.h>

/* compile with flags -lgdi32 and -lwinspool */

int PrintPage(wchar_t *printer_name, void (*callback)(HDC printer, void *userdata), void *userdata) {
	HDC printer;
	DOCINFOA docinfo;
	
	if (callback == NULL) return 0;
	
	if (printer_name == NULL || *printer_name == '\0') {
		unsigned long size;
		GetDefaultPrinterW(NULL, &size);
		
		printer_name = (wchar_t*) malloc(size * sizeof(wchar_t));
		if (printer_name == NULL) return 0;
		
		if (GetDefaultPrinterW(printer_name, &size) == 0) {
			free(printer_name);
			return 0;
		}
		
		printer = CreateDCW(L"WINSPOOL", printer_name, NULL, NULL);
		free(printer_name);
	}
	else {
		printer = CreateDCW(L"WINSPOOL", printer_name, NULL, NULL);
	}
	
	if (printer == NULL) return 0;
	
	memset(&docinfo, 0, sizeof(docinfo));
	docinfo.cbSize = sizeof(docinfo);

	if (StartDoc(printer, (const DOCINFO*)&docinfo) <= 0) goto error;
	if (StartPage(printer) <= 0) goto error;
	
	callback(printer, userdata);
	
	if (EndPage(printer) <= 0) goto error;
	if (EndDoc(printer) <= 0) goto error;
	DeleteDC(printer);
	
	return 1;
error:

	DeleteDC(printer);
	return 0;
}
#endif /* _PRINTER_PAGE_H_ */

/*///////////////////////////////////
	
          	Testing:
		
///////////////////////////////////*/

#include <stdio.h>
#include <stdlib.h>

void ScreenshotOut(HDC printer, int x, int y) {
	int *pixels;
	BITMAPINFO bitmapinfo;
	HDC screen = GetDC(0);
	int width = GetSystemMetrics(SM_CXSCREEN);
	int height = GetSystemMetrics(SM_CYSCREEN);
	
	HDC memoryDC = CreateCompatibleDC(screen);
	HBITMAP memoryBMP = CreateCompatibleBitmap(screen, width, height);
	SelectObject(memoryDC, memoryBMP);
	
	bitmapinfo.bmiHeader.biSize = sizeof(BITMAPINFOHEADER);
	bitmapinfo.bmiHeader.biWidth = width;
	bitmapinfo.bmiHeader.biHeight = height;
	bitmapinfo.bmiHeader.biPlanes = 1;
	bitmapinfo.bmiHeader.biBitCount = 32;
	bitmapinfo.bmiHeader.biCompression = BI_RGB;
	
	pixels = (int*)malloc(sizeof(int) * width * height);
	if (pixels == NULL) {
		DeleteObject(memoryBMP);
		DeleteDC(memoryDC);
		return;
	}
	
	BitBlt(memoryDC, 0, 0, width, height, screen, x, y, SRCCOPY);
	GetDIBits(memoryDC, memoryBMP, 0, height, pixels, &bitmapinfo, DIB_RGB_COLORS);
	StretchDIBits(printer, x, y, width, height, 0, 0, width, height, pixels, &bitmapinfo, DIB_RGB_COLORS, SRCCOPY);
	
	free(pixels);
	DeleteObject(memoryBMP);
	DeleteDC(memoryDC);
}

void callback(HDC printer, void *userdata) {
	(void)userdata;
	
	{
		wchar_t *msg = L"SCREENSHOT:"; 
		TextOutW(printer, 0, 0, msg, wcslen(msg));
	}
	
	{
		ScreenshotOut(printer, 0, 150);
	}
}

int main(void) {
	PrintPage(NULL, callback, NULL);
	return 0;
}