OMEMO: Make QR code fixed-resolution and the quiet zone ISO-conformant

4 files changed, 34 insertions, 24 deletions

diff --git a/main/data/theme.css b/main/data/theme.css
index 3e076248..059585b7 100644
--- a/main/data/theme.css
+++ b/main/data/theme.css
@@ -369,4 +369,8 @@ box.dino-input-error label.input-status-highlight-once {
 
 .dino-call-window .own-video {
     box-shadow: 0 0 2px 0 rgba(0,0,0,0.5);
-}
\ No newline at end of file
+}
+
+.qrcode-container {
+    background: white;  /* Color of the quiet zone. MUST have the same "reflectance" as light modules of the QR code. */
+}
diff --git a/plugins/omemo/data/contact_details_dialog.ui b/plugins/omemo/data/contact_details_dialog.ui
index 188bf06e..62aded6b 100644
--- a/plugins/omemo/data/contact_details_dialog.ui
+++ b/plugins/omemo/data/contact_details_dialog.ui
@@ -278,7 +278,6 @@
         <child>
             <object class="GtkBox">
                 <property name="visible">True</property>
-                <property name="margin">10</property>
                 <child>
                     <object class="GtkImage" id="qrcode_image">
                         <property name="visible">True</property>
diff --git a/plugins/omemo/src/ui/contact_details_dialog.vala b/plugins/omemo/src/ui/contact_details_dialog.vala
index b268cc13..18884784 100644
--- a/plugins/omemo/src/ui/contact_details_dialog.vala
+++ b/plugins/omemo/src/ui/contact_details_dialog.vala
@@ -92,20 +92,14 @@ public class ContactDetailsDialog : Gtk.Dialog {
             copy_button.clicked.connect(() => {Clipboard.get_default(get_display()).set_text(fingerprint, fingerprint.length);});
 
             int sid = plugin.db.identity.row_with(plugin.db.identity.account_id, account.id)[plugin.db.identity.device_id];
-            Pixbuf qr_pixbuf = new QRcode(@"xmpp:$(account.bare_jid)?omemo-sid-$(sid)=$(fingerprint)", 2).to_pixbuf();
-            qr_pixbuf = qr_pixbuf.scale_simple(150, 150, InterpType.NEAREST);
-
-            Pixbuf pixbuf = new Pixbuf(
-                qr_pixbuf.colorspace,
-                qr_pixbuf.has_alpha,
-                qr_pixbuf.bits_per_sample,
-                170,
-                170
-            );
-            pixbuf.fill(uint32.MAX);
-            qr_pixbuf.copy_area(0, 0, 150, 150, pixbuf, 10, 10);
-
-            qrcode_image.set_from_pixbuf(pixbuf);
+
+            const int QUIET_ZONE_MODULES = 4;  // MUST be at least 4
+            const int MODULE_SIZE_PX = 4;  // arbitrary
+            Pixbuf qr_pixbuf = new QRcode(@"xmpp:$(account.bare_jid)?omemo-sid-$(sid)=$(fingerprint)", 2).to_pixbuf(MODULE_SIZE_PX);
+            qrcode_image.set_from_pixbuf(qr_pixbuf);
+            qrcode_image.margin = QUIET_ZONE_MODULES*MODULE_SIZE_PX;
+            qrcode_popover.get_style_context().add_class("qrcode-container");
+
             show_qrcode_button.clicked.connect(qrcode_popover.popup);
         }
 
diff --git a/plugins/omemo/vapi/libqrencode.vapi b/plugins/omemo/vapi/libqrencode.vapi
index fc77c855..253e239a 100644
--- a/plugins/omemo/vapi/libqrencode.vapi
+++ b/plugins/omemo/vapi/libqrencode.vapi
@@ -36,15 +36,28 @@ namespace Qrencode {
         [CCode (cname = "QRcode_encodeString")]
         public QRcode (string str, int version = 0, ECLevel level = ECLevel.L, EncodeMode hint = EncodeMode.EIGHT_BIT, bool casesensitive = true);
 
-        public Pixbuf to_pixbuf() {
-            uint8[] bitmap = new uint8[3*width*width];
-            for (int i = 0; i < width*width; i++) {
-                uint8 color = (data[i] & 1) == 1 ? 0 : 255;
-                bitmap[i*3] = color;
-                bitmap[i*3+1] = color;
-                bitmap[i*3+2] = color;
+        public Pixbuf to_pixbuf(int module_size) {
+            GLib.assert(module_size > 0);
+            var src_w = width;
+            var src   = data[0:width*width];
+            var dst_w = src_w*module_size;
+            var dst   = new uint8[dst_w*dst_w*3];
+            for (int src_y = 0; src_y < src_w; src_y++) {
+                for (int repeat_y = 0; repeat_y < module_size; repeat_y++) {
+                    var dst_y = src_y*module_size + repeat_y;
+                    for (int src_x = 0; src_x < src_w; src_x++) {
+                        uint8 color = (src[src_y*src_w + src_x] & 1) == 1 ? 0 : 255;
+                        for (int repeat_x = 0; repeat_x < module_size; repeat_x++) {
+                            var dst_x = src_x*module_size + repeat_x;
+                            var px_idx = dst_y*dst_w + dst_x;
+                            dst[px_idx*3+0] = color;
+                            dst[px_idx*3+1] = color;
+                            dst[px_idx*3+2] = color;
+                        }
+                    }
+                }
             }
-            return new Pixbuf.from_data(bitmap, Colorspace.RGB, false, 8, width, width, width*3);
+            return new Pixbuf.from_data(dst, Colorspace.RGB, false, 8, dst_w, dst_w, dst_w*3);
         }
     }
 }