Adwaita: use a transition to animate checks and radios

see https://bugzilla.gnome.org/show_bug.cgi?id=762260

gtk/theme/Adwaita/_common.scss

@@ -2626,7 +2626,6 @@ radio {
       -gtk-icon-shadow: none;
       color: inherit;
       border-color: currentColor;
-      animation: none;
     }
   }
 }
@@ -2653,34 +2652,28 @@ radio {
                                             -gtk-recolor(url("assets/dash-symbolic.symbolic.png"))); }
 }
 
-// let's animate things
+// ANIMATION:
-@keyframes check_check {
+// this is made with those pretty convoluted transitions, since checks and radios have to animate only on state changes,
-  from { -gtk-icon-transform: translate(6px, -3px) rotate(-45deg) scaleY(0.2) rotate(45deg) scaleX(0); }
+// the transformation is set on the active state and it get reset on the checked state.
-  to { -gtk-icon-transform: unset; }
+radio:not(:indeterminate):not(:checked):active:not(:backdrop) { -gtk-icon-transform: scale(0); }
+
+check:not(:indeterminate):not(:checked):active:not(:backdrop) { -gtk-icon-transform: translate(6px, -3px) rotate(-45deg) scaleY(0.2) rotate(45deg) scaleX(0); }
+
+radio,
+check {
+  &:active { -gtk-icon-transform: scale(0, 1); } // should tackle the indeterminate state, untested
+
+  &:checked:not(:backdrop), &:indeterminate:not(:backdrop) {
+    -gtk-icon-transform: unset;
+    transition: 400ms;
+  }
 }
 
-@keyframes check_radio {
-  from { -gtk-icon-transform: scale(0); }
-  to { -gtk-icon-transform: unset; }
-}
-
-@keyframes check_indeterminate {
-  from { -gtk-icon-transform: scale(0, 1); }
-  to { -gtk-icon-transform: unset; }
-}
-
-check:not(:indeterminate):checked { animation: check_check 400ms; }
-
-radio:not(:indeterminate):checked { animation: check_radio 400ms; }
-
-check:indeterminate:checked, radio:indeterminate:checked { animation: check_indeterminate 400ms; }
-
-// no animations in menus
 menu menuitem {
-  check:not(:indeterminate):checked,
+  radio,
-  radio:not(:indeterminate):checked,
+  check {
-  check:indeterminate:checked:active,
+     &:checked:not(:backdrop), &:indeterminate:not(:backdrop) { transition: none; }
-  radio:indeterminate:checked { animation: none; }
+  }
 }
 
 treeview.view check,

gtk/theme/Adwaita/gtk-contained-dark.css

@@ -2970,8 +2970,7 @@ radio {
       box-shadow: none;
       -gtk-icon-shadow: none;
       color: inherit;
-      border-color: currentColor;
+      border-color: currentColor; }
-      animation: none; }
 
 check {
   border-radius: 3px; }
@@ -2990,35 +2989,25 @@ radio {
   radio:indeterminate {
     -gtk-icon-source: image(-gtk-recolor(url("assets/dash-symbolic.svg")), -gtk-recolor(url("assets/dash-symbolic.symbolic.png"))); }
 
-@keyframes check_check {
+radio:not(:indeterminate):not(:checked):active:not(:backdrop) {
-  from {
-    -gtk-icon-transform: translate(6px, -3px) rotate(-45deg) scaleY(0.2) rotate(45deg) scaleX(0); }
-  to {
-    -gtk-icon-transform: unset; } }
-@keyframes check_radio {
-  from {
   -gtk-icon-transform: scale(0); }
-  to {
+
-    -gtk-icon-transform: unset; } }
+check:not(:indeterminate):not(:checked):active:not(:backdrop) {
-@keyframes check_indeterminate {
+  -gtk-icon-transform: translate(6px, -3px) rotate(-45deg) scaleY(0.2) rotate(45deg) scaleX(0); }
-  from {
+
+radio:active,
+check:active {
   -gtk-icon-transform: scale(0, 1); }
-  to {
+radio:checked:not(:backdrop), radio:indeterminate:not(:backdrop),
-    -gtk-icon-transform: unset; } }
+check:checked:not(:backdrop),
-check:not(:indeterminate):checked {
+check:indeterminate:not(:backdrop) {
-  animation: check_check 400ms; }
+  -gtk-icon-transform: unset;
+  transition: 400ms; }
 
-radio:not(:indeterminate):checked {
+menu menuitem radio:checked:not(:backdrop), menu menuitem radio:indeterminate:not(:backdrop),
-  animation: check_radio 400ms; }
+menu menuitem check:checked:not(:backdrop),
-
+menu menuitem check:indeterminate:not(:backdrop) {
-check:indeterminate:checked, radio:indeterminate:checked {
+  transition: none; }
-  animation: check_indeterminate 400ms; }
-
-menu menuitem check:not(:indeterminate):checked,
-menu menuitem radio:not(:indeterminate):checked,
-menu menuitem check:indeterminate:checked:active,
-menu menuitem radio:indeterminate:checked {
-  animation: none; }
 
 treeview.view check:selected:focus, treeview.view check:selected,
 treeview.view radio:selected:focus,

gtk/theme/Adwaita/gtk-contained.css

@@ -3000,8 +3000,7 @@ radio {
       box-shadow: none;
       -gtk-icon-shadow: none;
       color: inherit;
-      border-color: currentColor;
+      border-color: currentColor; }
-      animation: none; }
 
 check {
   border-radius: 3px; }
@@ -3020,35 +3019,25 @@ radio {
   radio:indeterminate {
     -gtk-icon-source: image(-gtk-recolor(url("assets/dash-symbolic.svg")), -gtk-recolor(url("assets/dash-symbolic.symbolic.png"))); }
 
-@keyframes check_check {
+radio:not(:indeterminate):not(:checked):active:not(:backdrop) {
-  from {
-    -gtk-icon-transform: translate(6px, -3px) rotate(-45deg) scaleY(0.2) rotate(45deg) scaleX(0); }
-  to {
-    -gtk-icon-transform: unset; } }
-@keyframes check_radio {
-  from {
   -gtk-icon-transform: scale(0); }
-  to {
+
-    -gtk-icon-transform: unset; } }
+check:not(:indeterminate):not(:checked):active:not(:backdrop) {
-@keyframes check_indeterminate {
+  -gtk-icon-transform: translate(6px, -3px) rotate(-45deg) scaleY(0.2) rotate(45deg) scaleX(0); }
-  from {
+
+radio:active,
+check:active {
   -gtk-icon-transform: scale(0, 1); }
-  to {
+radio:checked:not(:backdrop), radio:indeterminate:not(:backdrop),
-    -gtk-icon-transform: unset; } }
+check:checked:not(:backdrop),
-check:not(:indeterminate):checked {
+check:indeterminate:not(:backdrop) {
-  animation: check_check 400ms; }
+  -gtk-icon-transform: unset;
+  transition: 400ms; }
 
-radio:not(:indeterminate):checked {
+menu menuitem radio:checked:not(:backdrop), menu menuitem radio:indeterminate:not(:backdrop),
-  animation: check_radio 400ms; }
+menu menuitem check:checked:not(:backdrop),
-
+menu menuitem check:indeterminate:not(:backdrop) {
-check:indeterminate:checked, radio:indeterminate:checked {
+  transition: none; }
-  animation: check_indeterminate 400ms; }
-
-menu menuitem check:not(:indeterminate):checked,
-menu menuitem radio:not(:indeterminate):checked,
-menu menuitem check:indeterminate:checked:active,
-menu menuitem radio:indeterminate:checked {
-  animation: none; }
 
 treeview.view check:selected:focus, treeview.view check:selected,
 treeview.view radio:selected:focus,