[hitori] interface: Improve rendering of externals borders

[Philip Withnall <pwithnall src gnome org>]

commit 46705840468b19602067d2019143eacd839f7608
Author: Philip Withnall <philip tecnocode co uk>
Date:   Mon Mar 6 00:18:08 2017 +0000

    interface: Improve rendering of externals borders
    
    Fix the rendering so that half of the external border lines are not
    chopped off due to the fact that the lines are drawn centred on the
    coordinates given to Cairo. This is possible by considering the whole
    rendering area as needing to be BORDER_LEFT (the width) wider than it
    actually is, and ensuring that all the cell size calculations are done
    as floating point so as to not introduce rounding errors.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=732776

 src/interface.c |   29 ++++++++++++++++++-----------
 src/main.h      |    4 ++--
 2 files changed, 20 insertions(+), 13 deletions(-)
---
diff --git a/src/interface.c b/src/interface.c
index 795d5d5..cab918e 100644
--- a/src/interface.c
+++ b/src/interface.c
@@ -257,7 +257,7 @@ hitori_draw_cb (GtkWidget *drawing_area, cairo_t *cr, Hitori *hitori)
        gint area_width, area_height;
        HitoriVector iter;
        guint board_width, board_height;
-       gfloat cell_size;
+       gdouble cell_size;
        gdouble x_pos, y_pos;
        GtkStyleContext *style_context;
 
@@ -274,14 +274,17 @@ hitori_draw_cb (GtkWidget *drawing_area, cairo_t *cr, Hitori *hitori)
                board_height = area_width;
        }
 
+       board_width -= BORDER_LEFT;
+       board_height -= BORDER_LEFT;
+
        /* Work out the cell size and scale all text accordingly */
-       cell_size = board_width / hitori->board_size;
+       cell_size = (gdouble) board_width / (gdouble) hitori->board_size;
        pango_font_description_set_absolute_size (hitori->normal_font_desc, cell_size * NORMAL_FONT_SCALE * 
0.8 * PANGO_SCALE);
        pango_font_description_set_absolute_size (hitori->painted_font_desc, cell_size * PAINTED_FONT_SCALE * 
0.8 * PANGO_SCALE);
 
        /* Centre the board */
-       hitori->drawing_area_x_offset = (area_width - board_width) / 2;
-       hitori->drawing_area_y_offset = (area_height - board_height) / 2;
+       hitori->drawing_area_x_offset = (area_width - board_width) / 2.0;
+       hitori->drawing_area_y_offset = (area_height - board_height) / 2.0;
        cairo_translate (cr, hitori->drawing_area_x_offset, hitori->drawing_area_y_offset);
 
        /* Draw the unpainted cells first. */
@@ -324,7 +327,7 @@ gboolean
 hitori_button_release_cb (GtkWidget *drawing_area, GdkEventButton *event, Hitori *hitori)
 {
        gint width, height;
-       gfloat cell_size;
+       gdouble cell_size;
        HitoriVector pos;
        HitoriUndo *undo;
        gboolean recheck = FALSE;
@@ -339,7 +342,7 @@ hitori_button_release_cb (GtkWidget *drawing_area, GdkEventButton *event, Hitori
        if (height < width)
                width = height;
 
-       cell_size = width / hitori->board_size;
+       cell_size = (gdouble) width / (gdouble) hitori->board_size;
 
        /* Determine the cell in which the button was released */
        pos.x = (guchar) ((event->x - hitori->drawing_area_x_offset) / cell_size);
@@ -456,8 +459,9 @@ static gboolean
 hitori_update_hint (Hitori *hitori)
 {
        gint area_width, area_height;
-       guint board_width, board_height, drawing_area_x_offset, drawing_area_y_offset;
-       gfloat cell_size;
+       guint board_width, board_height;
+       gdouble drawing_area_x_offset, drawing_area_y_offset;
+       gdouble cell_size;
 
        /* Check to see if hinting's been stopped by a cell being changed (race condition) */
        if (hitori->hint_status == HINT_DISABLED)
@@ -481,10 +485,13 @@ hitori_update_hint (Hitori *hitori)
                board_height = area_width;
        }
 
-       cell_size = board_width / hitori->board_size;
+       board_width -= BORDER_LEFT;
+       board_height -= BORDER_LEFT;
+
+       cell_size = (gdouble) board_width / (gdouble) hitori->board_size;
 
-       drawing_area_x_offset = (area_width - board_width) / 2;
-       drawing_area_y_offset = (area_height - board_height) / 2;
+       drawing_area_x_offset = (area_width - board_width) / 2.0;
+       drawing_area_y_offset = (area_height - board_height) / 2.0;
 
        /* Redraw the cell */
        gtk_widget_queue_draw_area (hitori->drawing_area, drawing_area_x_offset + hitori->hint_position.x * 
cell_size,
diff --git a/src/main.h b/src/main.h
index ad62752..e9ee576 100644
--- a/src/main.h
+++ b/src/main.h
@@ -84,8 +84,8 @@ typedef struct {
        gdouble drawing_area_width;
        gdouble drawing_area_height;
 
-       guint drawing_area_x_offset;
-       guint drawing_area_y_offset;
+       gdouble drawing_area_x_offset;
+       gdouble drawing_area_y_offset;
 
        PangoFontDescription *normal_font_desc;
        PangoFontDescription *painted_font_desc;