1 files changed, 90 insertions, 0 deletions
diff --git a/Plugins/screen.c b/Plugins/screen.c
new file mode 100644
index 0000000..76fd6bd
--- /dev/null
+++ b/Plugins/screen.c
@@ -0,0 +1,90 @@
+//
+//  screen - screen of two images
+//  
+//	written by Olaf Matthes <olaf.matthes@gmx.de>
+//
+//  This program is free software; you can redistribute it and/or modify
+//  it under the terms of the GNU General Public License as published by
+//  the Free Software Foundation; either version 2 of the License, or
+//  (at your option) any later version.
+//
+//  This program is distributed in the hope that it will be useful,
+//  but WITHOUT ANY WARRANTY; without even the implied warranty of
+//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+//  GNU General Public License for more details.
+//
+//  You should have received a copy of the GNU General Public License
+//  along with this program; if not, write to the Free Software
+//  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+//   
+//  usage: screen
+//
+
+#include <stdlib.h>
+#include "plugin.h"
+
+void perform_effect(struct frame f, struct args a)
+{
+	printf("Using screen as effect does nothing!\n");
+}
+
+void perform_copy(struct frame f1, struct frame f2, struct args a)
+{
+	short x, y, w, h;
+	pixel16 *pix1_16, *pix2_16;
+	pixel24 *pix1_24, *pix2_24;
+	pixel32 *pix1_32, *pix2_32;
+	byte r, g, b;
+
+	w = f1.width<f2.width ? f1.width : f2.width;
+	h = f1.height<f2.height ? f1.height : f2.height;
+
+	printf("difference\n");
+
+	switch(f1.pixelformat)
+	{
+		case 16:
+			// compare images pixel by pixel
+			for(y = 0; y < h; y++) 
+			{
+				pix1_16 = scanline16(f1, y);
+				pix2_16 = scanline16(f2, y);
+				for(x = 0; x < w; x++)
+				{
+					r = klamp255(255 - ( (255-r16(pix1_16[x])) * (255-r16(pix2_16[x]) ) / 255 ));
+					g = klamp255(255 - ( (255-g16(pix1_16[x])) * (255-g16(pix2_16[x]) ) / 255 ));
+					b = klamp255(255 - ( (255-b16(pix1_16[x])) * (255-b16(pix2_16[x]) ) / 255 ));
+					pix2_16[x] = rgbtocolor16(r, g, b);
+				}
+			}
+			break;
+		case 24:
+			for(y = 0; y < h; y++) 
+			{
+				pix1_24 = scanline24(f1, y);
+				pix2_24 = scanline24(f2, y);
+				for(x = 0; x < w; x++)
+				{
+					r = klamp255(255 - ( (255-r24(pix1_24[x])) * (255-r24(pix2_24[x]) ) / 255 ));
+					g = klamp255(255 - ( (255-g24(pix1_24[x])) * (255-g24(pix2_24[x]) ) / 255 ));
+					b = klamp255(255 - ( (255-b24(pix1_24[x])) * (255-b24(pix2_24[x]) ) / 255 ));
+					pix2_24[x] = rgbtocolor24(r, g, b);
+				}
+			}
+			break;
+		case 32:
+			for(y = 0; y < h; y++) 
+			{
+				pix1_32 = scanline32(f1, y);
+				pix2_32 = scanline32(f2, y);
+				for(x = 0; x < w; x++)
+				{
+					r = klamp255(255 - ( (255-r32(pix1_32[x])) * (255-r32(pix2_32[x]) ) / 255 ));
+					g = klamp255(255 - ( (255-g32(pix1_32[x])) * (255-g32(pix2_32[x]) ) / 255 ));
+					b = klamp255(255 - ( (255-b32(pix1_32[x])) * (255-b32(pix2_32[x]) ) / 255 ));
+					pix2_32[x] = rgbtocolor32(r, g, b);
+				}
+			}
+			break;
+	}
+}