[gtkhtml] Bug 537825 - Text cursor not erased when moved to new position

[Milan Crha <mcrha src gnome org>]

commit e8a17114bafd2a677bd89894ceb6249475f0e0c7
Author: Owen W. Taylor <otaylor fishsoup net>
Date:   Tue Oct 7 18:45:30 2014 +0200

    Bug 537825 - Text cursor not erased when moved to new position
    
    When we repaint and the cursor is visible, draw the cursor to the
    main cairo context we are using, rather than separately. This makes
    sure that we draw the cursor on top of the content and clipped to
    the redraw area, and thus preserve the shown/hidden state properly.
    
    Some combination of redraw ordering or drawing outside the clipped
    area caused the shown/hidden state of the cursor to be flipped
    on redraw, causing a left-over cursor on next cursor move.

 gtkhtml/htmlengine-edit-cursor.c |   28 ++++++++++++++++++++++++++--
 gtkhtml/htmlengine.c             |    3 ++-
 2 files changed, 28 insertions(+), 3 deletions(-)
---
diff --git a/gtkhtml/htmlengine-edit-cursor.c b/gtkhtml/htmlengine-edit-cursor.c
index bac61a7..68f0c34 100644
--- a/gtkhtml/htmlengine-edit-cursor.c
+++ b/gtkhtml/htmlengine-edit-cursor.c
@@ -28,6 +28,7 @@
 #include "htmlengine-edit-cursor.h"
 #include "htmlengine-edit-table.h"
 #include "htmlengine-edit-tablecell.h"
+#include "htmlgdkpainter.h"
 #include "htmlimage.h"
 #include "htmlobject.h"
 #include "htmltable.h"
@@ -357,7 +358,26 @@ html_engine_draw_cursor_in_area (HTMLEngine *engine,
 
        if (clip_cursor (engine, x, y, width, height, &x1, &y1, &x2, &y2)) {
                cairo_t *cr;
-               cr = gdk_cairo_create (engine->window);
+               gboolean using_painter_cr;
+
+               using_painter_cr = engine->painter &&
+                   HTML_IS_GDK_PAINTER (engine->painter) &&
+                   HTML_GDK_PAINTER (engine->painter)->cr != NULL;
+
+               if (using_painter_cr) {
+                       HTMLGdkPainter *gdk_painter = HTML_GDK_PAINTER (engine->painter);
+
+                       cr = gdk_painter->cr;
+                       cairo_save (cr);
+
+                       x1 -= gdk_painter->x1;
+                       y1 -= gdk_painter->y1;
+                       x2 -= gdk_painter->x1;
+                       y2 -= gdk_painter->y1;
+               } else {
+                       cr = gdk_cairo_create (engine->window);
+               }
+
                cairo_set_source_rgb (cr, 1, 1, 1);
                cairo_set_operator (cr, CAIRO_OPERATOR_DIFFERENCE);
                cairo_set_line_cap (cr, CAIRO_LINE_CAP_SQUARE);
@@ -365,7 +385,11 @@ html_engine_draw_cursor_in_area (HTMLEngine *engine,
                cairo_line_to (cr, x2 + 0.5, y2 - 0.5);
                cairo_set_line_width (cr, 1);
                cairo_stroke (cr);
-               cairo_destroy (cr);
+
+               if (using_painter_cr)
+                       cairo_restore (cr);
+               else
+                       cairo_destroy (cr);
        }
 }
 
diff --git a/gtkhtml/htmlengine.c b/gtkhtml/htmlengine.c
index b47f920..3c56cce 100644
--- a/gtkhtml/htmlengine.c
+++ b/gtkhtml/htmlengine.c
@@ -5290,11 +5290,12 @@ html_engine_draw_real (HTMLEngine *e,
                e->clue->y = html_engine_get_top_border (e) + e->clue->ascent;
                html_object_draw (e->clue, e->painter, x1, y1, x2 - x1, y2 - y1, 0, 0);
        }
-       html_painter_end (e->painter);
 
        if (e->editable || e->caret_mode)
                html_engine_draw_cursor_in_area (e, x1, y1, x2 - x1, y2 - y1);
 
+       html_painter_end (e->painter);
+
        e->expose = FALSE;
 }