From d34f67dae3caa277bfebe0aa9f60e83a22bce0eb Mon Sep 17 00:00:00 2001
From: Eli Zaretskii <eliz@gnu.org>
Date: Wed, 19 Feb 2014 19:32:29 +0200
Subject: [PATCH] Fix bug #16806 with horizontal scrolling of images when
 fringes are disabled.

 src/xdisp.c (display_line): Fix horizontal scrolling of large images
 when fringes are turned off.  This comes at a price of not
 displaying the truncation/continuation glyphs in this case.
---
 src/ChangeLog |  5 +++++
 src/xdisp.c   | 41 ++++++++++++++++++++++++++++-------------
 2 files changed, 33 insertions(+), 13 deletions(-)

diff --git a/src/ChangeLog b/src/ChangeLog
index cbc48a7546..f89f7e084f 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,5 +1,10 @@
 2014-02-19  Eli Zaretskii  <eliz@gnu.org>
 
+	* xdisp.c (display_line): Fix horizontal scrolling of large images
+	when fringes are turned off.  This comes at a price of not
+	displaying the truncation/continuation glyphs in this case.
+	(Bug#16806)
+
 	* image.c (x_create_x_image_and_pixmap) [HAVE_NTGUI]: If
 	CreateDIBSection returns an error indication, zero out *ximg after
 	destroying the image.  This avoids crashes in memory allocations
diff --git a/src/xdisp.c b/src/xdisp.c
index d941c7b108..b9908c6c9c 100644
--- a/src/xdisp.c
+++ b/src/xdisp.c
@@ -20119,7 +20119,12 @@ display_line (struct it *it)
       /* If we truncate lines, we are done when the last displayed
 	 glyphs reach past the right margin of the window.  */
       if (it->line_wrap == TRUNCATE
-	  && (FRAME_WINDOW_P (it->f) && WINDOW_RIGHT_FRINGE_WIDTH (it->w)
+	  && ((FRAME_WINDOW_P (it->f)
+	       /* Images are preprocessed in produce_image_glyph such
+		  that they are cropped at the right edge of the
+		  window, so an image glyph will always end exactly at
+		  last_visible_x, even if there's no right fringe.  */
+	       && (WINDOW_RIGHT_FRINGE_WIDTH (it->w) || it->what == IT_IMAGE))
 	      ? (it->current_x >= it->last_visible_x)
 	      : (it->current_x > it->last_visible_x)))
 	{
@@ -20152,19 +20157,26 @@ display_line (struct it *it)
 		  i = row->used[TEXT_AREA] - (i + 1);
 		}
 
-	      it->current_x = x_before;
-	      if (!FRAME_WINDOW_P (it->f))
+	      /* produce_special_glyphs overwrites the last glyph, so
+		 we don't want that if we want to keep that last
+		 glyph, which means it's an image.  */
+	      if (it->current_x > it->last_visible_x)
 		{
-		  for (n = row->used[TEXT_AREA]; i < n; ++i)
+		  it->current_x = x_before;
+		  if (!FRAME_WINDOW_P (it->f))
+		    {
+		      for (n = row->used[TEXT_AREA]; i < n; ++i)
+			{
+			  row->used[TEXT_AREA] = i;
+			  produce_special_glyphs (it, IT_TRUNCATION);
+			}
+		    }
+		  else
 		    {
 		      row->used[TEXT_AREA] = i;
 		      produce_special_glyphs (it, IT_TRUNCATION);
 		    }
-		}
-	      else
-		{
-		  row->used[TEXT_AREA] = i;
-		  produce_special_glyphs (it, IT_TRUNCATION);
+		  it->hpos = hpos_before;
 		}
 	    }
 	  else if (IT_OVERFLOW_NEWLINE_INTO_FRINGE (it))
@@ -20183,13 +20195,13 @@ display_line (struct it *it)
 		  goto at_end_of_line;
 		}
 	      it->current_x = x_before;
+	      it->hpos = hpos_before;
 	    }
 
 	  row->truncated_on_right_p = 1;
 	  it->continuation_lines_width = 0;
 	  reseat_at_next_visible_line_start (it, 0);
 	  row->ends_at_zv_p = FETCH_BYTE (IT_BYTEPOS (*it) - 1) != '\n';
-	  it->hpos = hpos_before;
 	  break;
 	}
     }
@@ -20203,9 +20215,12 @@ display_line (struct it *it)
       && IT_CHARPOS (*it) != CHARPOS (row->start.pos))
     {
       if (!FRAME_WINDOW_P (it->f)
-	  || (row->reversed_p
-	      ? WINDOW_RIGHT_FRINGE_WIDTH (it->w)
-	      : WINDOW_LEFT_FRINGE_WIDTH (it->w)) == 0)
+	  || (((row->reversed_p
+		? WINDOW_RIGHT_FRINGE_WIDTH (it->w)
+		: WINDOW_LEFT_FRINGE_WIDTH (it->w)) == 0)
+	      /* Don't let insert_left_trunc_glyphs overwrite the
+		 first glyph of the row if it is an image.  */
+	      && row->glyphs[TEXT_AREA]->type != IMAGE_GLYPH))
 	insert_left_trunc_glyphs (it);
       row->truncated_on_left_p = 1;
     }
-- 
2.20.1