feat(core): implement pagination for sign/verify

core/src/apps/common/layout.py

@@ -7,14 +7,14 @@ from trezor.ui.button import ButtonDefault
 from trezor.ui.container import Container
 from trezor.ui.qr import Qr
 from trezor.ui.scroll import Paginated
-from trezor.ui.text import Text
+from trezor.ui.text import TEXT_MAX_LINES, Span, Text
 from trezor.utils import chunks
 
 from apps.common import HARDENED
 from apps.common.confirm import confirm, require_confirm
 
 if False:
-    from typing import Iterable, Iterator, List
+    from typing import Iterable, Iterator, List, Union
     from trezor import wire
 
 
@@ -136,3 +136,48 @@ async def show_success(
     await require_confirm(
         ctx, text, ButtonRequestType.Success, confirm=button, cancel=None
     )
+
+
+def paginate_text(
+    text: str,
+    header: str,
+    font: int = ui.NORMAL,
+    header_icon: str = ui.ICON_DEFAULT,
+    icon_color: int = ui.ORANGE_ICON,
+    break_words: bool = False,
+) -> Union[Text, Paginated]:
+    span = Span(text, 0, font, break_words=break_words)
+    if span.count_lines() <= TEXT_MAX_LINES:
+        result = Text(
+            header,
+            header_icon=header_icon,
+            icon_color=icon_color,
+            new_lines=False,
+        )
+        result.content = [font, text]
+        return result
+
+    else:
+        pages: List[ui.Component] = []
+        span.reset(text, 0, font, break_words=break_words, line_width=204)
+        while span.has_more_content():
+            # advance to first line of the page
+            span.next_line()
+            page = Text(
+                header,
+                header_icon=header_icon,
+                icon_color=icon_color,
+                new_lines=False,
+                content_offset=0,
+                char_offset=span.start,
+                line_width=204,
+                render_page_overflow=False,
+            )
+            page.content = [font, text]
+            pages.append(page)
+
+            # roll over the remaining lines on the page
+            for _ in range(TEXT_MAX_LINES - 1):
+                span.next_line()
+
+        return Paginated(pages)

core/src/apps/common/signverify.py

@@ -1,15 +1,14 @@
 from ubinascii import hexlify
 
-from trezor import utils, wire
+from trezor import ui, utils, wire
 from trezor.crypto.hashlib import blake256, sha256
 from trezor.ui.text import Text
 
 from apps.common.confirm import require_confirm
-from apps.common.layout import split_address
+from apps.common.layout import paginate_text, split_address
 from apps.common.writers import write_bitcoin_varint
 
 if False:
-    from typing import List
     from apps.common.coininfo import CoinInfo
 
 
@@ -30,24 +29,18 @@ def message_digest(coin: CoinInfo, message: bytes) -> bytes:
     return ret
 
 
-def split_message(message: bytes) -> List[str]:
+def decode_message(message: bytes) -> str:
     try:
-        m = bytes(message).decode()
+        return bytes(message).decode()
-        words = m.split(" ")
     except UnicodeError:
-        m = "hex(%s)" % hexlify(message).decode()
+        return "hex(%s)" % hexlify(message).decode()
-        words = [m]
-    return words
 
 
 async def require_confirm_sign_message(
     ctx: wire.Context, coin: str, message: bytes
 ) -> None:
     header = "Sign {} message".format(coin)
-    message_lines = split_message(message)
+    await require_confirm(ctx, paginate_text(decode_message(message), header))
-    text = Text(header, new_lines=False)
-    text.normal(*message_lines)
-    await require_confirm(ctx, text)
 
 
 async def require_confirm_verify_message(
@@ -60,6 +53,7 @@ async def require_confirm_verify_message(
     text.mono(*split_address(address))
     await require_confirm(ctx, text)
 
-    text = Text(header, new_lines=False)
+    await require_confirm(
-    text.mono(*split_message(message))
+        ctx,
-    await require_confirm(ctx, text)
+        paginate_text(decode_message(message), header, font=ui.MONO),
+    )

tests/device_tests/test_msg_signmessage.py

@@ -206,3 +206,79 @@ def test_signmessage(client, coin_name, path, script_type, address, message, sig
     )
     assert sig.address == address
     assert sig.signature.hex() == signature
+
+
+MESSAGE_LENGTHS = (
+    pytest.param("This is a very long message. " * 16, id="normal_text"),
+    pytest.param("ThisIsAMessageWithoutSpaces" * 16, id="no_spaces"),
+    pytest.param("ThisIsAMessageWithLongWords " * 16, id="long_words"),
+    pytest.param("This\nmessage\nhas\nnewlines\nafter\nevery\nword", id="newlines"),
+    pytest.param("Příšerně žluťoučký kůň úpěl ďábelské ódy. " * 16, id="utf_text"),
+    pytest.param("PříšerněŽluťoučkýKůňÚpělĎábelskéÓdy" * 16, id="utf_nospace"),
+    pytest.param("1\n2\n3\n4\n5\n6", id="single_line_over"),
+)
+
+
+@pytest.mark.skip_t1
+@pytest.mark.parametrize("message", MESSAGE_LENGTHS)
+def test_signmessage_pagination(client, message):
+    message_read = ""
+    message += "End."
+
+    def input_flow():
+        # collect screen contents into `message_read`.
+        # Join lines that are separated by a single "-" string, space-separate lines otherwise.
+        nonlocal message_read
+
+        yield
+        # start assuming there was a word break; this avoids prepending space at start
+        word_break = True
+        max_attempts = 100
+        while max_attempts:
+            layout = client.debug.wait_layout()
+            for line in layout.lines[1:]:
+                if line == "-":
+                    # next line will be attached without space
+                    word_break = True
+                elif word_break:
+                    # attach without space, reset word_break
+                    message_read += line
+                    word_break = False
+                else:
+                    # attach with space
+                    message_read += " " + line
+
+            if not message_read.endswith("End."):
+                client.debug.swipe_up()
+            else:
+                client.debug.press_yes()
+                break
+
+            max_attempts -= 1
+
+        assert max_attempts > 0, "failed to scroll through message"
+
+    with client:
+        client.set_input_flow(input_flow)
+        client.debug.watch_layout(True)
+        btc.sign_message(
+            client,
+            coin_name="Bitcoin",
+            n=parse_path("m/44h/0h/0h/0/0"),
+            message=message,
+        )
+    assert message.replace("\n", " ") == message_read
+
+
+@pytest.mark.skip_t1
+def test_signmessage_pagination_trailing_newline(client):
+    # This can currently only be tested by a human via the UI test diff:
+    message = "THIS\nMUST\nNOT\nBE\nPAGINATED\n"
+    # The trailing newline must not cause a new paginated screen to appear.
+    # The UI must be a single dialog without pagination.
+    btc.sign_message(
+        client,
+        coin_name="Bitcoin",
+        n=parse_path("m/44h/0h/0h/0/0"),
+        message=message,
+    )