Fix aspect ratio bugs

- ICCCM says: > If a base size is not provided, the minimum size is to
be used in its place and vice versa.
i3 didn't obey the "vice versa" part. Min size and base size are both
saved without replacements in window_update_normal_hints,
floating_check_size makes the needed replacements if either was not
provided.
- Aspect ratio is now saved correctly in manage_window because
window_update_normal_hints is called.
- i3 didn't save the aspect ratio if the window conformed the given
aspect ratio range when handle_normal_hints was called. If the window
was resized to a size outside of the given bounds, i3 didn't correct it.
- Aspect ratio now affects only tiling windows, like the rest of the
normal size hints
- The aspect ratio calculation is now done without a loop

A real life example of how these changes affect the workflow:
An mpv window, when playing a video, sets its min == max aspect ratio
during mapping. i3 ignored these hints. When resized, the window's
aspect ratio was not preserved. With this commit, resizing floating mpv
windows will always preserve the aspect ratio.

testcases/t/133-size-hints.t

@@ -16,31 +16,97 @@
 #
 # Checks if size hints are interpreted correctly.
 #
-use i3test;
+use i3test i3_config => <<EOT;
+# i3 config file (v4)
+font -misc-fixed-medium-r-normal--13-120-75-75-C-70-iso10646-1
 
-my $tmp = fresh_workspace;
+default_floating_border none
+floating_minimum_size -1 x -1
+floating_maximum_size -1 x -1
+EOT
 
-ok(@{get_ws_content($tmp)} == 0, 'no containers yet');
+sub open_with_aspect {
+    my ($min_num, $min_den, $max_num, $max_den) = @_;
+    open_floating_window(
+        rect => [0, 0, 100, 100],
+        before_map => sub {
+            my ($window) = @_;
+            my $aspect = X11::XCB::Sizehints::Aspect->new;
+            $aspect->min_num($min_num);
+            $aspect->min_den($min_den);
+            $aspect->max_num($max_num);
+            $aspect->max_den($max_den);
+            $window->hints->aspect($aspect);
+        });
+}
 
-my $win = open_window({ dont_map => 1 });
-# XXX: we should check screen size. in screens with an AR of 2.0,
-# this is not a good idea.
-my $aspect = X11::XCB::Sizehints::Aspect->new;
-$aspect->min_num(600);
-$aspect->min_den(300);
-$aspect->max_num(600);
-$aspect->max_den(300);
-$win->_create;
-$win->map;
-wait_for_map $win;
-$win->hints->aspect($aspect);
-$x->flush;
+################################################################################
+# Test aspect ratio set exactly to 2.0
+################################################################################
 
-sync_with_i3;
+fresh_workspace;
+my $win = open_with_aspect(600, 300, 600, 300);
 
 my $rect = $win->rect;
 my $ar = $rect->width / $rect->height;
-diag("Aspect ratio = $ar");
-ok(($ar > 1.90) && ($ar < 2.10), 'Aspect ratio about 2.0');
+cmp_float($ar, 2, 'Window set to floating with aspect ratio 2.0');
+
+cmd 'resize set 100';
+$rect = $win->rect;
+$ar = $rect->width / $rect->height;
+cmp_float($ar, 2, 'Window resized with aspect ratio kept to 2.0');
+
+cmd 'resize set 400 100';
+$rect = $win->rect;
+$ar = $rect->width / $rect->height;
+cmp_float($ar, 2, 'Window resized with aspect ratio kept to 2.0');
+
+# Also check that it is possible to resize by height only
+cmd 'resize set height 400';
+$rect = $win->rect;
+$ar = $rect->width / $rect->height;
+is($rect->height, 400, 'Window height is 400px');
+cmp_float($ar, 2, 'Window resized with aspect ratio kept to 2.0');
+
+cmd 'resize grow height 10';
+$rect = $win->rect;
+$ar = $rect->width / $rect->height;
+is($rect->height, 410, 'Window grew by 10px');
+cmp_float($ar, 2, 'Window resized with aspect ratio kept to 2.0');
+
+################################################################################
+# Test aspect ratio between 0.5 and 2.0
+################################################################################
+
+fresh_workspace;
+$win = open_with_aspect(1, 2, 2, 1);
+
+$rect = $win->rect;
+$ar = $rect->width / $rect->height;
+cmp_float($ar, 1, 'Window set to floating with aspect ratio 1.0');
+
+cmd 'resize set 200';
+$rect = $win->rect;
+$ar = $rect->width / $rect->height;
+is($rect->width, 200, 'Window width is 200px');
+is($rect->height, 100, 'Window height stayed 100px');
+cmp_float($ar, 2, 'Window resized, aspect ratio changed to 2.0');
+
+cmd 'resize set 100 200';
+$rect = $win->rect;
+$ar = $rect->width / $rect->height;
+is($rect->width, 100, 'Window width is 100px');
+is($rect->height, 200, 'Window height is 200px');
+cmp_float($ar, 0.5, 'Window resized, aspect ratio changed to 0.5');
+
+cmd 'resize set 500';
+$rect = $win->rect;
+$ar = $rect->width / $rect->height;
+cmp_float($ar, 2, 'Window resized, aspect ratio changed to maximum 2.0');
+
+cmd 'resize set 100 400';
+$rect = $win->rect;
+$ar = $rect->width / $rect->height;
+cmp_float($ar, 0.5, 'Window resized, aspect ratio changed to minimum 0.5');
 
 done_testing;