Change to pass structures by reference rather than value.

This is faster on ARM in particular. The primary changes involve
fz_matrix, fz_rect and fz_bbox.

Rather than passing 'fz_rect r' into a function, we now consistently
pass 'const fz_rect *r'. Where a rect is passed in and modified, we
miss the 'const' off. Where possible, we return the pointer to the
modified structure to allow 'chaining' of expressions.

The basic upshot of this work is that we do far fewer copies of
rectangle/matrix structures, and all the copies we do are explicit.

This has opened the way to other optimisations, also performed in
this commit.

Rather than using expressions like:

   fz_concat(fz_scale(sx, sy), fz_translate(tx, ty))

we now have fz_pre_{scale,translate,rotate} functions. These
can be implemented much more efficiently than doing the fully
fledged matrix multiplication that fz_concat requires.

We add fz_rect_{min,max} functions to return pointers to the
min/max points of a rect. These can be used to in transformations
to directly manipulate values.

With a little casting in the path transformation code we can avoid
more needless copying.

We rename fz_widget_bbox to the more consistent fz_bound_widget.

1 files changed, 41 insertions, 37 deletions

diff --git a/draw/draw_edge.c b/draw/draw_edge.c
index 6c22aa73..dca6a648 100644
--- a/draw/draw_edge.c
+++ b/draw/draw_edge.c
@@ -203,7 +203,7 @@ fz_new_gel(fz_context *ctx)
 }
 
 void
-fz_reset_gel(fz_gel *gel, fz_bbox clip)
+fz_reset_gel(fz_gel *gel, const fz_bbox *clip)
 {
 	fz_aa_context *ctxaa = gel->ctx->aa;
 
@@ -213,10 +213,10 @@ fz_reset_gel(fz_gel *gel, fz_bbox clip)
 		gel->clip.x1 = gel->clip.y1 = BBOX_MIN;
 	}
 	else {
-		gel->clip.x0 = clip.x0 * fz_aa_hscale;
-		gel->clip.x1 = clip.x1 * fz_aa_hscale;
-		gel->clip.y0 = clip.y0 * fz_aa_vscale;
-		gel->clip.y1 = clip.y1 * fz_aa_vscale;
+		gel->clip.x0 = clip->x0 * fz_aa_hscale;
+		gel->clip.x1 = clip->x1 * fz_aa_hscale;
+		gel->clip.y0 = clip->y0 * fz_aa_vscale;
+		gel->clip.y1 = clip->y1 * fz_aa_vscale;
 	}
 
 	gel->bbox.x0 = gel->bbox.y0 = BBOX_MAX;
@@ -235,17 +235,21 @@ fz_free_gel(fz_gel *gel)
 	fz_free(gel->ctx, gel);
 }
 
-fz_bbox
-fz_bound_gel(fz_gel *gel)
+fz_bbox *
+fz_bound_gel(const fz_gel *gel, fz_bbox *bbox)
 {
-	fz_bbox bbox;
 	fz_aa_context *ctxaa = gel->ctx->aa;
 	if (gel->len == 0)
-		return fz_empty_bbox;
-	bbox.x0 = fz_idiv(gel->bbox.x0, fz_aa_hscale);
-	bbox.y0 = fz_idiv(gel->bbox.y0, fz_aa_vscale);
-	bbox.x1 = fz_idiv(gel->bbox.x1, fz_aa_hscale) + 1;
-	bbox.y1 = fz_idiv(gel->bbox.y1, fz_aa_vscale) + 1;
+	{
+		*bbox = fz_empty_bbox;
+	}
+	else
+	{
+		bbox->x0 = fz_idiv(gel->bbox.x0, fz_aa_hscale);
+		bbox->y0 = fz_idiv(gel->bbox.y0, fz_aa_vscale);
+		bbox->x1 = fz_idiv(gel->bbox.x1, fz_aa_hscale) + 1;
+		bbox->y1 = fz_idiv(gel->bbox.y1, fz_aa_vscale) + 1;
+	}
 	return bbox;
 }
 
@@ -666,7 +670,7 @@ static inline void blit_aa(fz_pixmap *dst, int x, int y,
 }
 
 static void
-fz_scan_convert_aa(fz_gel *gel, int eofill, fz_bbox clip,
+fz_scan_convert_aa(fz_gel *gel, int eofill, const fz_bbox *clip,
 	fz_pixmap *dst, unsigned char *color)
 {
 	unsigned char *alphas;
@@ -682,14 +686,14 @@ fz_scan_convert_aa(fz_gel *gel, int eofill, fz_bbox clip,
 
 	int xofs = xmin * fz_aa_hscale;
 
-	int skipx = clip.x0 - xmin;
-	int clipn = clip.x1 - clip.x0;
+	int skipx = clip->x0 - xmin;
+	int clipn = clip->x1 - clip->x0;
 
 	if (gel->len == 0)
 		return;
 
-	assert(clip.x0 >= xmin);
-	assert(clip.x1 <= xmax);
+	assert(clip->x0 >= xmin);
+	assert(clip->x1 <= xmax);
 
 	alphas = fz_malloc_no_throw(ctx, xmax - xmin + 1);
 	deltas = fz_malloc_no_throw(ctx, (xmax - xmin + 1) * sizeof(int));
@@ -719,7 +723,7 @@ fz_scan_convert_aa(fz_gel *gel, int eofill, fz_bbox clip,
 	yd = fz_idiv(y, fz_aa_vscale);
 
 	/* Quickly skip to the start of the clip region */
-	while (yd < clip.y0 && (gel->alen > 0 || e < gel->len))
+	while (yd < clip->y0 && (gel->alen > 0 || e < gel->len))
 	{
 		/* rh = remaining height = number of subscanlines left to be
 		 * inserted into the current scanline, which will be plotted
@@ -738,14 +742,14 @@ fz_scan_convert_aa(fz_gel *gel, int eofill, fz_bbox clip,
 			yd++;
 		}
 		/* Skip any whole scanlines we can */
-		while (yd < clip.y0 && h0 >= fz_aa_vscale)
+		while (yd < clip->y0 && h0 >= fz_aa_vscale)
 		{
 			h0 -= fz_aa_vscale;
 			yd++;
 		}
 		/* If we haven't hit the start of the clip region, then we
 		 * have less than a scanline left. */
-		if (yd < clip.y0)
+		if (yd < clip->y0)
 		{
 			h0 = 0;
 		}
@@ -770,7 +774,7 @@ fz_scan_convert_aa(fz_gel *gel, int eofill, fz_bbox clip,
 			memset(deltas, 0, (skipx + clipn) * sizeof(int));
 		}
 		yd = yc;
-		if (yd >= clip.y1)
+		if (yd >= clip->y1)
 			break;
 
 		/* height = The number of subscanlines with identical edge
@@ -792,7 +796,7 @@ fz_scan_convert_aa(fz_gel *gel, int eofill, fz_bbox clip,
 				blit_aa(dst, xmin + skipx, yd, alphas + skipx, clipn, color);
 				memset(deltas, 0, (skipx + clipn) * sizeof(int));
 				yd++;
-				if (yd >= clip.y1)
+				if (yd >= clip->y1)
 					break;
 				h0 -= rh;
 			}
@@ -812,7 +816,7 @@ fz_scan_convert_aa(fz_gel *gel, int eofill, fz_bbox clip,
 					 * to recalculate deltas here. */
 					blit_aa(dst, xmin + skipx, yd, alphas + skipx, clipn, color);
 					yd++;
-					if (yd >= clip.y1)
+					if (yd >= clip->y1)
 						goto clip_ended;
 					h0 -= fz_aa_vscale;
 				}
@@ -836,7 +840,7 @@ advance:
 		y += height;
 	}
 
-	if (yd < clip.y1)
+	if (yd < clip->y1)
 	{
 		undelta_aa(ctxaa, alphas, deltas, skipx + clipn);
 		blit_aa(dst, xmin + skipx, yd, alphas + skipx, clipn, color);
@@ -851,7 +855,7 @@ clip_ended:
  */
 
 static inline void blit_sharp(int x0, int x1, int y,
-	fz_bbox clip, fz_pixmap *dst, unsigned char *color)
+	const fz_bbox *clip, fz_pixmap *dst, unsigned char *color)
 {
 	unsigned char *dp;
 	x0 = fz_clampi(x0, dst->x, dst->x + dst->w);
@@ -867,7 +871,7 @@ static inline void blit_sharp(int x0, int x1, int y,
 }
 
 static inline void non_zero_winding_sharp(fz_gel *gel, int y,
-	fz_bbox clip, fz_pixmap *dst, unsigned char *color)
+	const fz_bbox *clip, fz_pixmap *dst, unsigned char *color)
 {
 	int winding = 0;
 	int x = 0;
@@ -883,7 +887,7 @@ static inline void non_zero_winding_sharp(fz_gel *gel, int y,
 }
 
 static inline void even_odd_sharp(fz_gel *gel, int y,
-	fz_bbox clip, fz_pixmap *dst, unsigned char *color)
+	const fz_bbox *clip, fz_pixmap *dst, unsigned char *color)
 {
 	int even = 0;
 	int x = 0;
@@ -899,7 +903,7 @@ static inline void even_odd_sharp(fz_gel *gel, int y,
 }
 
 static void
-fz_scan_convert_sharp(fz_gel *gel, int eofill, fz_bbox clip,
+fz_scan_convert_sharp(fz_gel *gel, int eofill, const fz_bbox *clip,
 	fz_pixmap *dst, unsigned char *color)
 {
 	int e = 0;
@@ -909,16 +913,16 @@ fz_scan_convert_sharp(fz_gel *gel, int eofill, fz_bbox clip,
 	gel->alen = 0;
 
 	/* Skip any lines before the clip region */
-	if (y < clip.y0)
+	if (y < clip->y0)
 	{
 		while (gel->alen > 0 || e < gel->len)
 		{
 			height = insert_active(gel, y, &e);
 			y += height;
-			if (y >= clip.y0)
+			if (y >= clip->y0)
 			{
-				height -= y - clip.y0;
-				y = clip.y0;
+				height -= y - clip->y0;
+				y = clip->y0;
 				break;
 			}
 		}
@@ -934,8 +938,8 @@ fz_scan_convert_sharp(fz_gel *gel, int eofill, fz_bbox clip,
 		else
 		{
 			int h;
-			if (height >= clip.y1 - y)
-				height = clip.y1 - y;
+			if (height >= clip->y1 - y)
+				height = clip->y1 - y;
 
 			h = height;
 			while (h--)
@@ -947,7 +951,7 @@ fz_scan_convert_sharp(fz_gel *gel, int eofill, fz_bbox clip,
 				y++;
 			}
 		}
-		if (y >= clip.y1)
+		if (y >= clip->y1)
 			break;
 
 		advance_active(gel, height);
@@ -955,7 +959,7 @@ fz_scan_convert_sharp(fz_gel *gel, int eofill, fz_bbox clip,
 }
 
 void
-fz_scan_convert(fz_gel *gel, int eofill, fz_bbox clip,
+fz_scan_convert(fz_gel *gel, int eofill, const fz_bbox *clip,
 	fz_pixmap *dst, unsigned char *color)
 {
 	fz_aa_context *ctxaa = gel->ctx->aa;