poll_events: fix and de-macroify CLIP_EVENT_AREA

I don't know why the author was so obsessed with macros where they served
to only make impossible to read and maintain, bringing zero benefit.

This turned out to have some bugs so I rewrote some of it while converting
to a function.

2 files changed, 59 insertions, 45 deletions

diff --git a/recordmydesktop/src/rmd_macro.h b/recordmydesktop/src/rmd_macro.h
index 37c032d..2f1ac88 100644
--- a/recordmydesktop/src/rmd_macro.h
+++ b/recordmydesktop/src/rmd_macro.h
@@ -76,5 +76,8 @@
 #define Y_UNIT_WIDTH    0x0010
 #define UV_UNIT_WIDTH   0x0008
 
+#define MAX(a, b) ((a) < (b)) ? (b) : (a)
+#define MIN(a, b) ((a) > (b)) ? (b) : (a)
+
 #endif
 
diff --git a/recordmydesktop/src/rmd_poll_events.c b/recordmydesktop/src/rmd_poll_events.c
index 9745889..12ff87e 100644
--- a/recordmydesktop/src/rmd_poll_events.c
+++ b/recordmydesktop/src/rmd_poll_events.c
@@ -42,43 +42,58 @@
 #include <pthread.h>
 
 
-#define CLIP_EVENT_AREA(e,brwin,xrect) {\
-    if (((e)->area.x<=(brwin)->rrect.x)&&((e)->area.y<=(brwin)->rrect.y)&&\
-        ((e)->area.width>=(brwin)->rrect.width)&&\
-        ((e)->area.height<(brwin)->rrect.height)) {\
-        (xrect)->x=(brwin)->rrect.x;\
-        (xrect)->y=(brwin)->rrect.y;\
-        (xrect)->width=(brwin)->rrect.width;\
-        (xrect)->height=(brwin)->rrect.height;\
-    }\
-    else{\
-        (xrect)->x=((((e)->area.x+(e)->area.width>=(brwin)->rrect.x)&&\
-        ((e)->area.x<=(brwin)->rrect.x+(brwin)->rrect.width))?\
-        (((e)->area.x<=(brwin)->rrect.x)?(brwin)->rrect.x:(e)->area.x):-1);\
-    \
-        (xrect)->y=((((e)->area.y+(e)->area.height>=(brwin)->rrect.y)&&\
-        ((e)->area.y<=(brwin)->rrect.y+(brwin)->rrect.height))?\
-        (((e)->area.y<=(brwin)->rrect.y)?(brwin)->rrect.y:(e)->area.y):-1);\
-    \
-        (xrect)->width=((e)->area.x<=(brwin)->rrect.x)?\
-        (e)->area.width-((brwin)->rrect.x-(e)->area.x):\
-        ((e)->area.x<=(brwin)->rrect.x+(brwin)->rrect.width)?\
-        (((brwin)->rrect.width-(e)->area.x+(brwin)->rrect.x<(e)->area.width)?\
-        (brwin)->rrect.width-(e)->area.x+(brwin)->rrect.x:e->area.width):0;\
-    \
-        (xrect)->height=((e)->area.y<=(brwin)->rrect.y)?\
-        (e)->area.height-((brwin)->rrect.y-(e)->area.y):\
-        ((e)->area.y<=(brwin)->rrect.y+(brwin)->rrect.height)?\
-        (((brwin)->rrect.height-(e)->area.y+\
-         (brwin)->rrect.y<(e)->area.height)?\
-         (brwin)->rrect.height-(e)->area.y+\
-         (brwin)->rrect.y:(e)->area.height):0;\
-    \
-        if ((xrect)->width>(brwin)->rrect.width)\
-            (xrect)->width=(brwin)->rrect.width;\
-        if ((xrect)->height>(brwin)->rrect.height)\
-            (xrect)->height=(brwin)->rrect.height;\
-    }\
+static int clip_event_area(XDamageNotifyEvent *e, XRectangle *cliprect, XRectangle *res)
+{
+
+#if 0
+	printf("got area %x,%x %x,%x\n",
+		e->area.x,
+		e->area.y,
+		e->area.width,
+		e->area.height);
+#endif
+
+	if (	e->area.x <= cliprect->x &&
+		e->area.y <= cliprect->y &&
+		e->area.width >= cliprect->width &&
+		e->area.height >= cliprect->height) {
+
+		/* area completely covers cliprect, cliprect becomes the area */
+		res->x = cliprect->x;
+		res->y = cliprect->y;
+		res->width = cliprect->width;
+		res->height = cliprect->height;
+
+	} else if (	e->area.x + e->area.width < cliprect->x ||
+			e->area.x + e->area.width > cliprect->x + cliprect->width ||
+			e->area.y + e->area.height < cliprect->y ||
+			e->area.y + e->area.height > cliprect->y + cliprect->height) {
+
+		/* area has at least one axis with zero overlap, so they can't overlap */
+		return 0;
+
+	} else {
+
+		/* areas partially overlap */
+		res->x = MAX(e->area.x, cliprect->x);
+		res->width = MIN(e->area.x + e->area.width, cliprect->x + cliprect->width) - res->x;
+
+		res->y = MAX(e->area.y, cliprect->y);
+		res->height = MIN(e->area.y + e->area.height, cliprect->y + cliprect->height) - res->y;
+
+		if (!res->width || !res->height)
+			return 0;
+	}
+
+#if 0
+	printf("clipped to %x,%x %x,%x\n",
+		res->x,
+		res->y,
+		res->width,
+		res->height);
+#endif
+
+	return 1;
 }
 
 
@@ -181,15 +196,11 @@ void rmdEventLoop(ProgData *pdata) {
 								XDamageReportRawRectangles);
 				}
 			} else if (event.type == pdata->damage_event + XDamageNotify ) {
-				XDamageNotifyEvent *e =(XDamageNotifyEvent *)( &event );
-				XRectangle xrect;
-				CLIP_EVENT_AREA(e,&(pdata->brwin),&xrect);
-				if ((xrect.x>=0)&&(xrect.y>=0)&&
-				   (xrect.width>0)&&(xrect.height>0)) {
+				XDamageNotifyEvent	*e = (XDamageNotifyEvent *)&event;
+				XRectangle		xrect;
 
-					inserts+=rmdRectInsert(&pdata->rect_root,&xrect);
-
-				}
+				if (clip_event_area(e, &pdata->brwin.rrect, &xrect))
+					inserts += rmdRectInsert(&pdata->rect_root,&xrect);
 			}
 		}