ui: render some wrapper components synchronously

This makes the wrappers (like Scrollpage and HoldToConfirmDialog) a bit weaker, as they won't support child components with custom event loop, but making the render/touch steps synchronous has other benefits. For example, io-heavy task of one child won't stall the other children.

src/apps/monero/layout/common.py

@@ -46,6 +46,9 @@ async def tx_dialog(
 
     await ctx.call(ButtonRequest(code=code), MessageType.ButtonAck)
 
+    if scroll_tuple and scroll_tuple[1] > 1:
+        content = Scrollpage(content, scroll_tuple[0], scroll_tuple[1])
+
     dialog = ConfirmDialog(
         content,
         cancel=cancel_btn,
@@ -53,9 +56,6 @@ async def tx_dialog(
         cancel_style=cancel_style,
         confirm_style=confirm_style,
     )
-    if scroll_tuple and scroll_tuple[1] > 1:
-        dialog = Scrollpage(dialog, scroll_tuple[0], scroll_tuple[1])
-
     return await ctx.wait(dialog)
 
 

src/trezor/ui/confirm.py

@@ -66,6 +66,11 @@ class HoldToConfirmDialog(Widget):
         self.button = Button(ui.grid(4, n_x=1), hold, style=button_style)
         self.loader = Loader(style=loader_style)
 
+        if content.__class__.__iter__ is not Widget.__iter__:
+            raise TypeError(
+                "HoldToConfirmDialog does not support widgets with custom event loop"
+            )
+
     def taint(self):
         super().taint()
         self.button.taint()
@@ -73,6 +78,8 @@ class HoldToConfirmDialog(Widget):
 
     def render(self):
         self.button.render()
+        if not self.loader.is_active():
+            self.content.render()
 
     def touch(self, event, pos):
         button = self.button
@@ -94,12 +101,15 @@ class HoldToConfirmDialog(Widget):
         result = None
         while result is None or result < 0:  # _STARTED or _STOPPED
             if self.loader.is_active():
-                content_loop = self.loader
-            else:
-                content_loop = self.content
-            confirm_loop = super().__iter__()  # default loop (render on touch)
                 if __debug__:
-                result = await loop.spawn(content_loop, confirm_loop, confirm_signal)
+                    result = await loop.spawn(
+                        self.loader, super().__iter__(), confirm_signal
+                    )
                 else:
-                result = await loop.spawn(content_loop, confirm_loop)
+                    result = await loop.spawn(self.loader, super().__iter__())
+            else:
+                if __debug__:
+                    result = await loop.spawn(super().__iter__(), confirm_signal)
+                else:
+                    result = await super().__iter__()
         return result

src/trezor/ui/scroll.py

@@ -75,6 +75,11 @@ class Scrollpage(ui.Widget):
         self.page = page
         self.page_count = page_count
 
+        if content.__class__.__iter__ is not ui.Widget.__iter__:
+            raise TypeError(
+                "Scrollpage does not support widgets with custom event loop"
+            )
+
     def taint(self):
         super().taint()
         self.content.taint()
@@ -83,5 +88,5 @@ class Scrollpage(ui.Widget):
         self.content.render()
         render_scrollbar(self.page, self.page_count)
 
-    async def __iter__(self):
-        return await loop.spawn(super().__iter__(), self.content)
+    def touch(self, event, pos):
+        return self.content.touch(event, pos)