Patch by GSR #7628, I also added alpha for text background.

The list of changes (some are fixes):
- Properly horizontally centered tags in all fields (bug?).
- File area does not have trailing space and has leading "File " at
start instead (probably a bug).
- Small separation between to time related fields, space saving.
- Removed colons, for consistency and space saving again.
- Frame field is zero aligned for higher visual stability.
- Marker name shows a rarer name, "<none>" (using <> is typical for cases
in which there is nothing: <none>, <empty>, <blank>, etc).
- Top area for misc info that can be really long (file, note and render date).
- Bottom area for more constantly changing but short ones (marker, SMPTE,
frame, camera and scene).
- Only render date moves a line (when note field is not used), and frame one
moves if no SMPTE (still in same line, so no big jump), for extra visual
stability (marker is fixed, assuming most people would show frame and or
SMPTE).
- ISO 8601 date format for render date, localization independant.

Comparision images:
http://www.infernal-iceberg.com/blender/stamp-original.png
http://www.infernal-iceberg.com/blender/stamp-cleanup.png

4 files changed, 109 insertions, 75 deletions

diff --git a/source/blender/blenkernel/intern/image.c b/source/blender/blenkernel/intern/image.c
index 278af464b82..56fd15cedb1 100644
--- a/source/blender/blenkernel/intern/image.c
+++ b/source/blender/blenkernel/intern/image.c
@@ -823,16 +823,67 @@ void BKE_stamp(struct ImBuf *ibuf)
 	
 	IMB_imginfo_change_field (ibuf, "File", G.sce);
 	if (G.scene->r.stamp & R_STAMP_DRAW) {
-		x = 1;
-		y = ibuf->y - font_height;
-		sprintf(text, "File: %s", G.sce);
+		/* Top left corner */
+		x = 1; /* Inits for everyone */
+		y = ibuf->y - font_height; /* Also inits for everyone */
+		sprintf(text, "File %s", G.sce);
 		text_width = BMF_GetStringWidth(font, text);
 		IMB_rectfill_area(ibuf, G.scene->r.bg_stamp, x-1, y-1, x+text_width+text_pad+1, y+font_height+1);
-		BMF_DrawStringBuf(font, G.sce, x, y, G.scene->r.fg_stamp, (unsigned char *)ibuf->rect, ibuf->rect_float, ibuf->x, ibuf->y);
-		x = 1;
+		BMF_DrawStringBuf(font, text, x+(text_pad/2), y, G.scene->r.fg_stamp, (unsigned char *)ibuf->rect, ibuf->rect_float, ibuf->x, ibuf->y);
 		y -= font_height+1;
 	}
 
+	if (G.scene->r.stamp & R_STAMP_NOTE) {
+		IMB_imginfo_change_field (ibuf, "Note", G.scene->r.stamp_udata);
+ 
+		if (G.scene->r.stamp & R_STAMP_DRAW) {
+			/* Top left corner, below File */
+			text_width = BMF_GetStringWidth(font, G.scene->r.stamp_udata);
+			IMB_rectfill_area(ibuf, G.scene->r.bg_stamp, x-1, y-1, x+text_width+text_pad+1, y+font_height+1);
+			BMF_DrawStringBuf(font, G.scene->r.stamp_udata, x+(text_pad/2), y, G.scene->r.fg_stamp, (unsigned char *)ibuf->rect, ibuf->rect_float, ibuf->x, ibuf->y);
+			y -= font_height+1;
+		}
+	}
+	
+	if (G.scene->r.stamp & R_STAMP_DATE) {
+#ifdef WIN32
+		_strdate (sdate);
+		sprintf (infotext, "%s", sdate);
+#else
+		t = time (NULL);
+		tl = localtime (&t);
+		sprintf (infotext, "%04d-%02d-%02d", tl->tm_year+1900, tl->tm_mon+1, tl->tm_mday);
+#endif /* WIN32 */
+		IMB_imginfo_change_field (ibuf, "Date", infotext);
+
+		if (G.scene->r.stamp & R_STAMP_DRAW) {
+			/* Top left corner, below File (or Note) */
+			sprintf (text, "Date %s", infotext);
+			text_width = BMF_GetStringWidth(font, text);
+			IMB_rectfill_area(ibuf, G.scene->r.bg_stamp, x-1, y-1, x+text_width+text_pad+1, y+font_height+1);
+			BMF_DrawStringBuf(font, text, x+(text_pad/2), y, G.scene->r.fg_stamp, (unsigned char *)ibuf->rect, ibuf->rect_float, ibuf->x, ibuf->y);
+		}
+	}
+
+
+	if (G.scene->r.stamp & R_STAMP_MARKER) {
+		TimeMarker *marker = get_frame_marker(CFRA);
+ 		
+		if (marker) strcpy(infotext, marker->name);
+		else 		strcpy(infotext, "<none>");
+ 		
+		IMB_imginfo_change_field (ibuf, "Marker", infotext);
+		
+		if (G.scene->r.stamp & R_STAMP_DRAW) {
+			/* Bottom left corner, leaving space for timing */
+			x = 1;
+			y = font_height+1;
+			sprintf (text, "Marker %s", infotext);
+			text_width = BMF_GetStringWidth(font, text);
+			IMB_rectfill_area(ibuf, G.scene->r.bg_stamp, x-1, y-1, x+text_width+text_pad+1, y+font_height+1);
+ 			BMF_DrawStringBuf(font, text, x+(text_pad/2), y, G.scene->r.fg_stamp, (unsigned char *)ibuf->rect, ibuf->rect_float, ibuf->x, ibuf->y);
+		}
+	}
 
 	if (G.scene->r.stamp & R_STAMP_TIME) {
 		h= m= s= f= 0;
@@ -857,11 +908,14 @@ void BKE_stamp(struct ImBuf *ibuf)
 		IMB_imginfo_change_field (ibuf, "Time", infotext);
 		
 		if (G.scene->r.stamp & R_STAMP_DRAW) {
+			/* Left bottom corner */
+			x = 1;
+			y = 1;
 			sprintf (text, "Time %s", infotext);
 			text_width = BMF_GetStringWidth(font, text);
 			IMB_rectfill_area(ibuf, G.scene->r.bg_stamp, x-1, y-1, x+text_width+text_pad+1, y+font_height+1);
-			BMF_DrawStringBuf(font, text, x, y, G.scene->r.fg_stamp, (unsigned char *)ibuf->rect, ibuf->rect_float, ibuf->x, ibuf->y);
-			x += text_width;
+			BMF_DrawStringBuf(font, text, x+(text_pad/2), y, G.scene->r.fg_stamp, (unsigned char *)ibuf->rect, ibuf->rect_float, ibuf->x, ibuf->y);
+			x += text_width+text_pad;
 		}
 	}
 
@@ -870,47 +924,35 @@ void BKE_stamp(struct ImBuf *ibuf)
 		IMB_imginfo_change_field (ibuf, "Frame", infotext);
 
 		if (G.scene->r.stamp & R_STAMP_DRAW) {
-			sprintf (text, "    Frame %s", infotext);
-			text_width = BMF_GetStringWidth(font, text);
-			IMB_rectfill_area(ibuf, G.scene->r.bg_stamp, x-1, y-1, x+text_width+text_pad+1, y+font_height+1);
-			BMF_DrawStringBuf(font, text, x, y, G.scene->r.fg_stamp, (unsigned char *)ibuf->rect, ibuf->rect_float, ibuf->x, ibuf->y);
-			x += BMF_GetStringWidth(font, text);
-		}
-	}
-
-	if (G.scene->r.stamp & R_STAMP_DATE) {
-#ifdef WIN32
-		_strdate (sdate);
-		sprintf (infotext, "%s", sdate);
-#else
-		t = time (NULL);
-		tl = localtime (&t);
-		sprintf (infotext, "%02d-%02d-%02d", tl->tm_mon+1, tl->tm_mday, tl->tm_year-100);
-#endif /* WIN32 */
-		IMB_imginfo_change_field (ibuf, "Date", infotext);
+			char format[32];
 
-		if (G.scene->r.stamp & R_STAMP_DRAW) {
-			x = 1;
-			y = 1;
-			sprintf (text, "Date %s", infotext);
+			/* First build "Frame %03i" for anims ending in frame 100-999, etc */
+			sprintf(format, "Frame %%0%di\n", 1 + (int) log10(G.scene->r.efra));
+			sprintf (text, format, G.scene->r.cfra);
 			text_width = BMF_GetStringWidth(font, text);
+			/* Left bottom corner (after SMPTE if exists) */
+			if (!(G.scene->r.stamp & R_STAMP_TIME)) {
+				x = 1;
+			}
+			y = 1;
 			IMB_rectfill_area(ibuf, G.scene->r.bg_stamp, x-1, y-1, x+text_width+text_pad+1, y+font_height+1);
-			BMF_DrawStringBuf(font, text, x, y, G.scene->r.fg_stamp, (unsigned char *)ibuf->rect, ibuf->rect_float, ibuf->x, ibuf->y);
-			x += text_width;
+			BMF_DrawStringBuf(font, text, x+(text_pad/2), y, G.scene->r.fg_stamp, (unsigned char *)ibuf->rect, ibuf->rect_float, ibuf->x, ibuf->y);
 		}
 	}
 
+
 	if (G.scene->r.stamp & R_STAMP_CAMERA) {
 		sprintf(infotext, ((Camera *) G.scene->camera)->id.name+2);
 		IMB_imginfo_change_field (ibuf, "Camera", infotext);
 
 		if (G.scene->r.stamp & R_STAMP_DRAW) {
-			sprintf (text, "Camera: %s", infotext);
+			sprintf (text, "Camera %s", infotext);
 			text_width = BMF_GetStringWidth(font, text);
+			/* Center of bottom edge */
 			x = (ibuf->x/2) - (BMF_GetStringWidth(font, text)/2);
 			y = 1;
 			IMB_rectfill_area(ibuf, G.scene->r.bg_stamp, x-1, y-1, x+text_width+text_pad+1, y+font_height+1);
-			BMF_DrawStringBuf(font, text, x, y, G.scene->r.fg_stamp, (unsigned char *)ibuf->rect, ibuf->rect_float, ibuf->x, ibuf->y);
+			BMF_DrawStringBuf(font, text, x+(text_pad/2), y, G.scene->r.fg_stamp, (unsigned char *)ibuf->rect, ibuf->rect_float, ibuf->x, ibuf->y);
 		}
 	}
 
@@ -919,41 +961,13 @@ void BKE_stamp(struct ImBuf *ibuf)
 		IMB_imginfo_change_field (ibuf, "Scene", infotext);
 
 		if (G.scene->r.stamp & R_STAMP_DRAW) {
-			sprintf (text, "Scene: %s", infotext);
+			sprintf (text, "Scene %s", infotext);
 			text_width = BMF_GetStringWidth(font, text);
+			/* Bottom right corner */
 			x = ibuf->x - (BMF_GetStringWidth(font, text)+1+text_pad);
+			y = 1;
 			IMB_rectfill_area(ibuf, G.scene->r.bg_stamp, x-1, y-1, x+text_width+text_pad+1, y+font_height+1);
-			BMF_DrawStringBuf(font, text, x, y, G.scene->r.fg_stamp, (unsigned char *)ibuf->rect, ibuf->rect_float, ibuf->x, ibuf->y);
-		}
-	}
-	
-	if (G.scene->r.stamp & R_STAMP_NOTE) {
-		IMB_imginfo_change_field (ibuf, "Note", G.scene->r.stamp_udata);
- 
-		if (G.scene->r.stamp & R_STAMP_DRAW) {
-			x = 1;
-			y = font_height+1;
-			text_width = BMF_GetStringWidth(font, G.scene->r.stamp_udata);
-			IMB_rectfill_area(ibuf, G.scene->r.bg_stamp, x-1, y-1, x+text_width+text_pad+1, y+font_height+1);
-			BMF_DrawStringBuf(font, G.scene->r.stamp_udata, x, y, G.scene->r.fg_stamp, (unsigned char *)ibuf->rect, ibuf->rect_float, ibuf->x, ibuf->y);
-		}
-	}
-	
-	if (G.scene->r.stamp & R_STAMP_MARKER) {
-		TimeMarker *marker = get_frame_marker(CFRA);
- 		
-		if (marker) strcpy(infotext, marker->name);
-		else 		strcpy(infotext, "None");
- 		
-		IMB_imginfo_change_field (ibuf, "Marker", infotext);
-		
-		if (G.scene->r.stamp & R_STAMP_DRAW) {
-			sprintf (text, "Marker: %s", infotext);
-			x = 1;
-			y = ibuf->y - (font_height+1)*3;
-			text_width = BMF_GetStringWidth(font, text);
-			IMB_rectfill_area(ibuf, G.scene->r.bg_stamp, x-1, y-1, x+text_width+text_pad+1, y+font_height+1);
- 			BMF_DrawStringBuf(font, text, x, y, G.scene->r.fg_stamp, (unsigned char *)ibuf->rect, ibuf->rect_float, ibuf->x, ibuf->y);
+			BMF_DrawStringBuf(font, text, x+(text_pad/2), y, G.scene->r.fg_stamp, (unsigned char *)ibuf->rect, ibuf->rect_float, ibuf->x, ibuf->y);
 		}
 	}
 }
diff --git a/source/blender/blenloader/intern/readfile.c b/source/blender/blenloader/intern/readfile.c
index 0b8500e6228..fc5214572f4 100644
--- a/source/blender/blenloader/intern/readfile.c
+++ b/source/blender/blenloader/intern/readfile.c
@@ -6781,6 +6781,8 @@ static void do_versions(FileData *fd, Library *lib, Main *main)
 		Scene *sce;
 		for(sce= main->scene.first; sce; sce=sce->id.next) {
 			sce->r.fg_stamp[0] = sce->r.fg_stamp[1] = sce->r.fg_stamp[2] = 0.8;
+			sce->r.fg_stamp[3] = 1.0; /* dont use text alpha yet */
+			sce->r.bg_stamp[3] = 0.25; /* make sure the background has full alpha */
 		}
 	}
 
diff --git a/source/blender/imbuf/intern/rectop.c b/source/blender/imbuf/intern/rectop.c
index 55cd4b9b6a1..591ab066c57 100644
--- a/source/blender/imbuf/intern/rectop.c
+++ b/source/blender/imbuf/intern/rectop.c
@@ -524,7 +524,7 @@ void IMB_rectfill(struct ImBuf *drect, float col[4])
 void IMB_rectfill_area(struct ImBuf *ibuf, float *col, int x1, int y1, int x2, int y2)
 {
 	int i, j;
-	
+	float a, ai;
 	if ((!ibuf) || (!col))
 		return;
 	
@@ -538,6 +538,9 @@ void IMB_rectfill_area(struct ImBuf *ibuf, float *col, int x1, int y1, int x2, i
 	if (y1>y2) SWAP(int,y1,y2);
 	if (x1==x2 || y1==y2) return;
 	
+	a = col[3];
+	ai = 1-a;
+	
 	if (ibuf->rect) {
 		unsigned char *img, *pixel; 
 		unsigned char chr, chg, chb;
@@ -550,9 +553,16 @@ void IMB_rectfill_area(struct ImBuf *ibuf, float *col, int x1, int y1, int x2, i
 		for (j = 0; j < y2-y1; j++) {
 			for (i = 0; i < x2-x1; i++) {
 				pixel = img + 4 * (((y1 + j) * ibuf->x) + (x1 + i));
-				pixel[0] = chr;
-				pixel[1] = chg;
-				pixel[2] = chb;
+				if (a == 1.0) {
+					pixel[0] = chr;
+					pixel[1] = chg;
+					pixel[2] = chb;
+				} else {
+					pixel[0] = (char)((chr*a) + (pixel[0]*ai));
+					pixel[1] = (char)((chg*a) + (pixel[1]*ai));
+					pixel[2] = (char)((chb*a) + (pixel[2]*ai));
+				}
+				
 			}
 		}
 	}
@@ -563,9 +573,15 @@ void IMB_rectfill_area(struct ImBuf *ibuf, float *col, int x1, int y1, int x2, i
 		for (j = 0; j < y2-y1; j++) {
 			for (i = 0; i < x2-x1; i++) {
 				pixel = img + 4 * (((y1 + j) * ibuf->x) + (x1 + i));
-				pixel[0] = col[0];
-				pixel[1] = col[1];
-				pixel[2] = col[2];
+				if (a == 1.0) {
+					pixel[0] = col[0];
+					pixel[1] = col[1];
+					pixel[2] = col[2];
+				} else {
+					pixel[0] = (col[0]*a) + (pixel[0]*ai);
+					pixel[1] = (col[1]*a) + (pixel[1]*ai);
+					pixel[2] = (col[2]*a) + (pixel[2]*ai);
+				}
 			}
 		}
 	}
diff --git a/source/blender/src/buttons_scene.c b/source/blender/src/buttons_scene.c
index d61268b2064..7232698a7a8 100644
--- a/source/blender/src/buttons_scene.c
+++ b/source/blender/src/buttons_scene.c
@@ -1570,12 +1570,14 @@ static void render_panel_stamp(void)
 			
 			/* draw fg/bg next to the scene */
 			yofs -= 25;
-			uiDefBut(block, LABEL, 0, "Text Color", xofs+110, yofs, 80, 19, 0, 0, 0, 0, 0, "");
-			uiDefBut(block, LABEL, 0, "Background", xofs+205, yofs, 80, 19, 0, 0, 0, 0, 0, "");
+			uiDefBut(block, LABEL, B_NOP, "Text Color", xofs+110, yofs, 80, 19, 0, 0, 0, 0, 0, "");
+			uiDefBut(block, LABEL, B_NOP, "Background", xofs+205, yofs, 80, 19, 0, 0, 0, 0, 0, "");
 			yofs -= 20;
 			uiDefButF(block, COL, B_NOP, "", xofs+110, yofs, 90, 19, G.scene->r.fg_stamp, 0, 0, 0, 0, "Foreground text color");
 			uiDefButF(block, COL, B_NOP, "", xofs+210, yofs, 90, 19, G.scene->r.bg_stamp, 0, 0, 0, 0, "Background color");
-			yofs += 75;
+			yofs -= 30;
+			uiDefButF(block, NUMSLI, B_NOP, "A", xofs+110, yofs, 180, 19, &G.scene->r.bg_stamp[3], 0, 1.0, 0, 0, "Alpha for text background");
+			yofs += 105;
 		} else {
 			yofs += 30;
 		}