more flood speedups

libvips/inplace/flood.c

@@ -187,27 +187,12 @@ buffer_add( Buffer *buf, Flood *flood, int x1, int x2, int y, int dir )
 /* Is p "connected"? ie. is equal to or not equal to flood->edge, depending on
  * whether we are flooding to the edge boundary or flooding edge-coloured
  * pixels.
- *
- * If test and mark are different images, we also need to check ink to make
- * sure we haven't painted this pixel before. Otherwise we can get stuck in
- * loops.
  */
 static inline gboolean
-flood_connected( Flood *flood, PEL *tp, PEL *mp )
+flood_connected( Flood *flood, PEL *tp )
 {
  	int j;
 
-	if( flood->test != flood->mark ) {
-		for( j = 0; j < flood->msize; j++ ) 
-			if( mp[j] != flood->ink[j] ) 
-				break;
-
-		if( j == flood->msize )
-			/* We've painted this before, can't be connected now.
-			 */
-			return( FALSE );
-	}
-
 	for( j = 0; j < flood->tsize; j++ ) 
 		if( tp[j] != flood->edge[j] ) 
 			break;
@@ -217,6 +202,20 @@ flood_connected( Flood *flood, PEL *tp, PEL *mp )
 	return( flood->equal ^ (j < flood->tsize) );
 }
 
+/* Is p painted?
+ */
+static inline gboolean
+flood_painted( Flood *flood, PEL *mp )
+{
+ 	int j;
+
+	for( j = 0; j < flood->msize; j++ ) 
+		if( mp[j] != flood->ink[j] ) 
+			break;
+
+	return( j == flood->msize );
+}
+
 /* Faster than memcpy for n < about 20.
  */
 static inline void
@@ -229,7 +228,7 @@ flood_paint( Flood *flood, PEL *q )
 }
 
 /* Fill left and right, return the endpoints. The start point (x, y) must be 
- * connected.
+ * connected and unpainted.
  */
 static void 
 flood_scanline( Flood *flood, int x, int y, int *x1, int *x2 )
@@ -239,33 +238,43 @@ flood_scanline( Flood *flood, int x, int y, int *x1, int *x2 )
 	PEL *tp;
 	PEL *mp;
 	int i;
+	int j;
 
 	g_assert( flood_connected( flood, 
-		(PEL *) IM_IMAGE_ADDR( flood->test, x, y ),
+		(PEL *) IM_IMAGE_ADDR( flood->test, x, y ) ) );
+	g_assert( !flood_painted( flood, 
 		(PEL *) IM_IMAGE_ADDR( flood->mark, x, y ) ) );
 
-	/* Fill this pixel and to the right.
+	/* Search to the right for the first non-connected pixel. If the start
+	 * pixel is unpainted, we know all the intervening pixels must be
+	 * unpainted too.
 	 */
 	tp = (PEL *) IM_IMAGE_ADDR( flood->test, x, y );
-	mp = (PEL *) IM_IMAGE_ADDR( flood->mark, x, y );
+	for( i = x; i < width; i++ ) {
-	for( i = x; i < width && flood_connected( flood, tp, mp ); i++ ) {
+		if( !flood_connected( flood, tp ) )
-		flood_paint( flood, mp );
+			break;
 		tp += flood->tsize;
-		mp += flood->msize;
 	}
 	*x2 = i - 1;
 
-	/* Fill to the left.
+	/* Search left.
 	 */
 	tp = (PEL *) IM_IMAGE_ADDR( flood->test, x - 1, y );
-	mp = (PEL *) IM_IMAGE_ADDR( flood->mark, x - 1, y );
+	for( i = x - 1; i > 0; i-- ) {
-	for( i = x - 1; i > 0 && flood_connected( flood, tp, mp ); i-- ) {
+		if( !flood_connected( flood, tp ) )
-		flood_paint( flood, mp );
+			break;
 		tp -= flood->tsize;
-		mp -= flood->msize;
 	}
 	*x1 = i + 1;
 
+	/* Paint the range we discovered.
+	 */
+	mp = (PEL *) IM_IMAGE_ADDR( flood->mark, x, y );
+	for( i = *x1; i <= *x2; i++ ) {
+		flood_paint( flood, mp );
+		mp += flood->msize;
+	}
+
 	if( flood->dout ) {
 		flood->left = IM_MIN( flood->left, *x1 );
 		flood->right = IM_MAX( flood->right, *x2 );
@@ -285,18 +294,29 @@ flood_scanline( Flood *flood, int x, int y, int *x1, int *x2 )
 static void
 flood_around( Flood *flood, Scan *scan )
 {
+	PEL *tp;
 	int x;
 
 	g_assert( scan->dir == 1 || scan->dir == -1 );
 
+	tp = (PEL *) IM_IMAGE_ADDR( flood->test, scan->x1, scan->y );
 	for( x = scan->x1; x <= scan->x2; x++ ) {
-		PEL *tp = (PEL *) IM_IMAGE_ADDR( flood->test, x, scan->y );
+		if( flood_connected( flood, tp ) ) {
-		PEL *mp = (PEL *) IM_IMAGE_ADDR( flood->mark, x, scan->y );
-
-		if( flood_connected( flood, tp, mp ) ) {
 			int x1a;
 			int x2a;
 
+			/* If mark and test are different images, we also need
+			 * to check for painted. Otherwise we can get stuck in
+			 * connected loops.
+			 */
+			if( flood->mark != flood->test ) {
+				PEL *mp = (PEL *) IM_IMAGE_ADDR( 
+					flood->mark, x, scan->y );
+
+				if( flood_painted( flood, mp ) )
+					continue;
+			}
+
 			flood_scanline( flood, x, scan->y, &x1a, &x2a );
 
 			/* Our new scanline can have up to three more
@@ -316,7 +336,10 @@ flood_around( Flood *flood, Scan *scan )
 				scan->dir );
 
 			x = x2a;
+			tp = (PEL *) IM_IMAGE_ADDR( flood->test, x, scan->y );
 		}
+
+		tp += flood->tsize;
 	}
 }
 
@@ -341,8 +364,7 @@ flood_all( Flood *flood, int x, int y )
 	/* Test start pixel ... nothing to do?
 	 */
 	if( flood_connected( flood, 
-		(PEL *) IM_IMAGE_ADDR( flood->test, x, y ),
+		(PEL *) IM_IMAGE_ADDR( flood->test, x, y ) ) ) {
-		(PEL *) IM_IMAGE_ADDR( flood->mark, x, y ) ) ) {
 		int x1, x2;
 
 		flood_scanline( flood, x, y, &x1, &x2 );