[simple-scan] add buttons to change orientation of even/odd pages - usecase for RADF scanners

[Bartosz <bkosiorek src gnome org>]

commit 85032a55b9cd7e95b802b113c762f49a3bc60b11
Author: Bernhard Schuster <bernhard+gitlab gnome ahoi io>
Date:   Thu Sep 22 07:55:50 2022 +0000

    add buttons to change orientation of even/odd pages -  usecase for RADF scanners

 src/app-window.vala | 34 ++++++++++++++++++++++++++++++----
 src/book.vala       | 20 ++++++++++++++++++++
 src/page-icon.vala  | 21 +++++++++++++++++++--
 3 files changed, 69 insertions(+), 6 deletions(-)
---
diff --git a/src/app-window.vala b/src/app-window.vala
index cea6837d..fe54315b 100644
--- a/src/app-window.vala
+++ b/src/app-window.vala
@@ -1343,6 +1343,27 @@ public class AppWindow : Hdy.ApplicationWindow
         b.visible = true;
         g.attach (b, 1, 2, 1, 1);
 
+        /* Label on button for keeping the ordering, but flip every second upside down */
+        b = make_reorder_button (_("Flip odd pages upside-down"), "R1U2R3U4R5U6-R1R2R3R4R5R6");
+        b.clicked.connect (() =>
+        {
+            book.flip_every_second(false);
+            dialog.destroy ();
+        });
+        b.visible = true;
+        g.attach (b, 0, 3, 1, 1);
+
+
+        /* Label on button for keeping the ordering, but flip every second upside down */
+        b = make_reorder_button (_("Flip even pages upside-down"), "U1R2U3R4U5R6-R1R2R3R4R5R6");
+        b.clicked.connect (() =>
+        {
+            book.flip_every_second(true);
+            dialog.destroy ();
+        });
+        b.visible = true;
+        g.attach (b, 1, 3, 1, 1);
+
         dialog.present ();
     }
 
@@ -1401,10 +1422,15 @@ public class AppWindow : Hdy.ApplicationWindow
                 page_box.visible = true;
                 box.add (page_box);
             }
-
-            var icon = new PageIcon (side, items[i] - '1');
-            icon.visible = true;
-            page_box.add (icon);
+            if (side == 'U') {
+                var icon = new PageIcon (side, items[i] - '1', 180);
+                icon.visible = true;
+                page_box.add (icon);
+            } else {
+                var icon = new PageIcon (side, items[i] - '1', 0);
+                icon.visible = true;
+                page_box.add (icon);
+            }
         }
 
         return box;
diff --git a/src/book.vala b/src/book.vala
index d2aa54da..b0ffc3fb 100644
--- a/src/book.vala
+++ b/src/book.vala
@@ -99,6 +99,26 @@ public class Book : Object
         changed ();
     }
 
+    public void flip_every_second (bool flip_first)
+    {
+        var new_pages = new List<Page> ();
+        for (var i = 0; i < n_pages; i++)
+        {
+            var page = pages.nth_data (i);
+            if (i % 2 == (int)flip_first) {
+                new_pages.append (page);
+            } else {
+                page.rotate_left();
+                page.rotate_left();
+                new_pages.append (page);
+            }
+        }
+        pages = (owned) new_pages;
+
+        reordered ();
+        changed ();
+    }
+
     public void combine_sides_reverse ()
     {
         var new_pages = new List<Page> ();
diff --git a/src/page-icon.vala b/src/page-icon.vala
index f1a25ead..3e3fa93a 100644
--- a/src/page-icon.vala
+++ b/src/page-icon.vala
@@ -14,12 +14,14 @@ public class PageIcon : Gtk.DrawingArea
 {
     private char side;
     private int position;
+    private int angle;
     private const int MINIMUM_WIDTH = 20;
 
-    public PageIcon (char side, int position)
+    public PageIcon (char side, int position, int angle)
     {
         this.side = side;
         this.position = position;
+        this.angle = angle;
     }
 
     public override void get_preferred_width (out int minimum_width, out int natural_width)
@@ -73,6 +75,14 @@ public class PageIcon : Gtk.DrawingArea
             /* Orange 3 */
             rgba.parse ("#ff7800");
             break;
+        case 'U':
+            /* green 4 */
+            rgba.parse ("#5cc02e");
+            break;
+        case 'R':
+            /* blue 4 */
+            rgba.parse ("#0deee7");
+            break;
         default:
             /* Yellow 3 to Red 2 */
             Gdk.RGBA start = {}, end = {};
@@ -109,8 +119,15 @@ public class PageIcon : Gtk.DrawingArea
 
         var text = @"$(position + 1)";
         Cairo.TextExtents extents;
+
+        var rad =  Math.PI / 180.0 * angle;
         c.text_extents (text, out extents);
-        c.translate ((w - extents.width) * 0.5 - 0.5, (h + extents.height) * 0.5 - 0.5);
+        c.translate ((w - extents.width) * 0.5 - 0.5, extents.height + (h - extents.height) * 0.5 - 0.5);
+        c.rotate(rad);
+        //  only correct for 0 and 180 degree
+        var tx = (1.0 - Math.sin(rad)) * extents.width / 2;
+        var ty = (1.0 - Math.sin(rad)) * extents.height / 2;
+        c.translate(-tx, +ty);
         c.show_text (text);
 
         return true;