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[Win32, Keyboard] Store keyboard message session #31047

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dkwingsmt merged 4 commits into from
Jan 26, 2022
Merged

[Win32, Keyboard] Store keyboard message session #31047

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893cd3e
Impl
dkwingsmt Jan 25, 2022
ed405fe
Move session to pending event
dkwingsmt Jan 25, 2022
380ac2d
Format
dkwingsmt Jan 25, 2022
b4550a0
better type
dkwingsmt Jan 25, 2022
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203 changes: 103 additions & 100 deletions shell/platform/windows/keyboard_manager_win32.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -93,7 +93,7 @@ static bool IsKeyDownShiftRight(int virtual_key, bool was_down) {
}

// Returns if a character sent by Win32 is a dead key.
static bool _IsDeadKey(uint32_t ch) {
static bool IsDeadKey(uint32_t ch) {
return (ch & kDeadKeyCharMask) != 0;
}

Expand Down Expand Up @@ -181,49 +181,33 @@ bool KeyboardManagerWin32::RemoveRedispatchedEvent(
const PendingEvent& incoming) {
for (auto iter = pending_redispatches_.begin();
iter != pending_redispatches_.end(); ++iter) {
if ((*iter)->hash == incoming.hash) {
if ((*iter)->Hash() == incoming.Hash()) {
pending_redispatches_.erase(iter);
return true;
}
}
return false;
}

bool KeyboardManagerWin32::OnKey(int key,
int scancode,
int action,
char32_t character,
bool extended,
bool was_down,
bool KeyboardManagerWin32::OnKey(std::unique_ptr<PendingEvent> event,
OnKeyCallback callback) {
std::unique_ptr<PendingEvent> incoming =
std::make_unique<PendingEvent>(PendingEvent{
.key = static_cast<uint32_t>(key),
.scancode = static_cast<uint8_t>(scancode),
.action = static_cast<uint32_t>(action),
.character = character,
.extended = extended,
.was_down = was_down,
});
incoming->hash = ComputeEventHash(*incoming);

if (RemoveRedispatchedEvent(*incoming)) {
if (RemoveRedispatchedEvent(*event)) {
return false;
}

if (IsKeyDownAltRight(action, key, extended)) {
if (IsKeyDownAltRight(event->action, event->key, event->extended)) {
if (last_key_is_ctrl_left_down) {
should_synthesize_ctrl_left_up = true;
}
}
if (IsKeyDownCtrlLeft(action, key)) {
if (IsKeyDownCtrlLeft(event->action, event->key)) {
last_key_is_ctrl_left_down = true;
ctrl_left_scancode = scancode;
ctrl_left_scancode = event->scancode;
should_synthesize_ctrl_left_up = false;
} else {
last_key_is_ctrl_left_down = false;
}
if (IsKeyUpAltRight(action, key, extended)) {
if (IsKeyUpAltRight(event->action, event->key, event->extended)) {
if (should_synthesize_ctrl_left_up) {
should_synthesize_ctrl_left_up = false;
PendingEvent ctrl_left_up{
Expand All @@ -236,8 +220,10 @@ bool KeyboardManagerWin32::OnKey(int key,
}
}

window_delegate_->OnKey(key, scancode, action, character, extended, was_down,
[this, event = incoming.release(),
const PendingEvent clone = *event;
window_delegate_->OnKey(clone.key, clone.scancode, clone.action,
clone.character, clone.extended, clone.was_down,
[this, event = event.release(),
callback = std::move(callback)](bool handled) {
callback(std::unique_ptr<PendingEvent>(event),
handled);
Expand All @@ -261,7 +247,7 @@ void KeyboardManagerWin32::HandleOnKeyResult(
// |SendInput|.
const bool is_syskey =
event->action == WM_SYSKEYDOWN || event->action == WM_SYSKEYUP;
const bool real_handled = handled || _IsDeadKey(event->character) ||
const bool real_handled = handled || IsDeadKey(event->character) ||
is_syskey ||
IsKeyDownShiftRight(event->key, event->was_down);

Expand All @@ -284,93 +270,101 @@ void KeyboardManagerWin32::HandleOnKeyResult(
RedispatchEvent(std::move(event));
}

bool KeyboardManagerWin32::HandleMessage(UINT const message,
bool KeyboardManagerWin32::HandleMessage(UINT const action,
WPARAM const wparam,
LPARAM const lparam) {
switch (message) {
switch (action) {
case WM_DEADCHAR:
case WM_SYSDEADCHAR:
case WM_CHAR:
case WM_SYSCHAR: {
static wchar_t s_pending_high_surrogate = 0;
const Win32Message message =
Win32Message{.action = action, .wparam = wparam, .lparam = lparam};
current_session_.push_back(message);

wchar_t character = static_cast<wchar_t>(wparam);
std::u16string text;
char32_t code_point;
if (IS_HIGH_SURROGATE(character)) {
// Save to send later with the trailing surrogate.
s_pending_high_surrogate = character;
if (message.IsHighSurrogate()) {
// A high surrogate is always followed by a low surrogate. Process the
// session later and consider this message as handled.
return true;
} else if (IS_LOW_SURROGATE(character) && s_pending_high_surrogate != 0) {
text.push_back(s_pending_high_surrogate);
text.push_back(character);
// Merge the surrogate pairs for the key event.
} else if (message.IsLowSurrogate()) {
const Win32Message* last_message =
current_session_.size() <= 1
? nullptr
: &current_session_[current_session_.size() - 2];
if (last_message == nullptr || !last_message->IsHighSurrogate()) {
return false;
}
// A low surrogate always follows a high surrogate, marking the end of
// a char session. Process the session after the if clause.
text.push_back(static_cast<wchar_t>(last_message->wparam));
text.push_back(static_cast<wchar_t>(message.wparam));
code_point =
CodePointFromSurrogatePair(s_pending_high_surrogate, character);
s_pending_high_surrogate = 0;
CodePointFromSurrogatePair(last_message->wparam, message.wparam);
} else {
text.push_back(character);
code_point = character;
// A non-surrogate character always appears alone. Process the session
// after the if clause.
text.push_back(static_cast<wchar_t>(message.wparam));
code_point = static_cast<wchar_t>(message.wparam);
}

const unsigned int scancode = (lparam >> 16) & 0xff;

// All key presses that generate a character should be sent from
// WM_CHAR. In order to send the full key press information, the keycode
// is persisted in keycode_for_char_message_ obtained from WM_KEYDOWN.
//
// A high surrogate is always followed by a low surrogate, while a
// non-surrogate character always appears alone. Filter out high
// surrogates so that it's the low surrogate message that triggers
// the onKey, asks if the framework handles it (which can only be done
// once), and calls OnText during the redispatched messages.
if (keycode_for_char_message_ != 0 && !IS_HIGH_SURROGATE(character)) {
// If this char message is preceded by a key down message, then dispatch
// the key down message as a key down event first, and only dispatch the
// OnText if the key down event is not handled.
if (current_session_.front().IsGeneralKeyDown()) {
const Win32Message first_message = current_session_.front();
current_session_.clear();
const uint8_t scancode = (lparam >> 16) & 0xff;
const uint16_t key_code = first_message.wparam;
const bool extended = ((lparam >> 24) & 0x01) == 0x01;
const bool was_down = lparam & 0x40000000;
// Certain key combinations yield control characters as WM_CHAR's
// lParam. For example, 0x01 for Ctrl-A. Filter these characters. See
// https://docs.microsoft.com/en-us/windows/win32/learnwin32/accelerator-tables
char32_t event_character;
if (message == WM_DEADCHAR || message == WM_SYSDEADCHAR) {
char32_t character;
if (action == WM_DEADCHAR || action == WM_SYSDEADCHAR) {
// Mask the resulting char with kDeadKeyCharMask anyway, because in
// rare cases the bit is *not* set (US INTL Shift-6 circumflex, see
// https://github.com/flutter/flutter/issues/92654 .)
event_character =
window_delegate_->Win32MapVkToChar(keycode_for_char_message_) |
kDeadKeyCharMask;
character =
window_delegate_->Win32MapVkToChar(key_code) | kDeadKeyCharMask;
} else {
event_character = IsPrintable(code_point) ? code_point : 0;
}
bool is_new_event =
OnKey(keycode_for_char_message_, scancode,
message == WM_SYSCHAR ? WM_SYSKEYDOWN : WM_KEYDOWN,
event_character, extended, was_down,
[this, message, text](std::unique_ptr<PendingEvent> event,
bool handled) {
HandleOnKeyResult(std::move(event), handled, message, text);
});
if (!is_new_event) {
break;
character = IsPrintable(code_point) ? code_point : 0;
}
keycode_for_char_message_ = 0;

auto event = std::make_unique<PendingEvent>(PendingEvent{
.key = key_code,
.scancode = scancode,
.action = static_cast<uint32_t>(action == WM_SYSCHAR ? WM_SYSKEYDOWN
: WM_KEYDOWN),
.character = character,
.extended = extended,
.was_down = was_down,
.session = std::move(current_session_),
});
const bool is_unmet_event = OnKey(
std::move(event),
[this, char_action = action, text](
std::unique_ptr<PendingEvent> event, bool handled) {
HandleOnKeyResult(std::move(event), handled, char_action, text);
});
const bool is_syskey = action == WM_SYSCHAR;
// For system characters, always pass them to the default WndProc so
// that system keys like the ALT-TAB are processed correctly.
if (message == WM_SYSCHAR) {
break;
}
return true;
return is_unmet_event && !is_syskey;
}

// Of the messages handled here, only WM_CHAR should be treated as
// characters. WM_SYS*CHAR are not part of text input, and WM_DEADCHAR
// will be incorporated into a later WM_CHAR with the full character.
// Also filter out:
// - Lead surrogates, which like dead keys will be send once combined.
// - ASCII control characters, which are sent as WM_CHAR events for all
// control key shortcuts.
if (message == WM_CHAR && s_pending_high_surrogate == 0 &&
IsPrintable(character)) {
// If the charcter session is not preceded by a key down message, dispatch
// the OnText immediately.

// Only WM_CHAR should be treated as characters. WM_SYS*CHAR are not part
// of text input, and WM_DEADCHAR will be incorporated into a later
// WM_CHAR with the full character.
//
// Also filter out ASCII control characters, which are sent as WM_CHAR
// events for all control key shortcuts.
current_session_.clear();
if (action == WM_CHAR && IsPrintable(wparam)) {
window_delegate_->OnText(text);
}
return true;
Expand All @@ -380,8 +374,11 @@ bool KeyboardManagerWin32::HandleMessage(UINT const message,
case WM_SYSKEYDOWN:
case WM_KEYUP:
case WM_SYSKEYUP: {
current_session_.clear();
current_session_.push_back(
Win32Message{.action = action, .wparam = wparam, .lparam = lparam});
const bool is_keydown_message =
(message == WM_KEYDOWN || message == WM_SYSKEYDOWN);
(action == WM_KEYDOWN || action == WM_SYSKEYDOWN);
// Check if this key produces a character. If so, the key press should
// be sent with the character produced at WM_CHAR. Store the produced
// keycode (it's not accessible from WM_CHAR) to be used in WM_CHAR.
Expand All @@ -397,30 +394,36 @@ bool KeyboardManagerWin32::HandleMessage(UINT const message,
next_key_message == WM_SYSDEADCHAR || next_key_message == WM_CHAR ||
next_key_message == WM_SYSCHAR);
if (character > 0 && is_keydown_message && has_wm_char) {
keycode_for_char_message_ = wparam;
// This key down message has following char events. Process later,
// because the character for the OnKey should be decided by the char
// events. Consider this event as handled.
return true;
}
unsigned int keyCode(wparam);

// Resolve session: A non-char key event.
const uint8_t scancode = (lparam >> 16) & 0xff;
const bool extended = ((lparam >> 24) & 0x01) == 0x01;
// If the key is a modifier, get its side.
keyCode = ResolveKeyCode(keyCode, extended, scancode);
const uint16_t key_code = ResolveKeyCode(wparam, extended, scancode);
const bool was_down = lparam & 0x40000000;
bool is_syskey = message == WM_SYSKEYDOWN || message == WM_SYSKEYUP;
bool is_new_event = OnKey(
keyCode, scancode, message, 0, extended, was_down,
auto event = std::make_unique<PendingEvent>(PendingEvent{
.key = key_code,
.scancode = scancode,
.action = action,
.character = 0,
.extended = extended,
.was_down = was_down,
.session = std::move(current_session_),
});
const bool is_unmet_event = OnKey(
std::move(event),
[this](std::unique_ptr<PendingEvent> event, bool handled) {
HandleOnKeyResult(std::move(event), handled, 0, std::u16string());
});
if (!is_new_event) {
break;
}
const bool is_syskey = action == WM_SYSKEYDOWN || action == WM_SYSKEYUP;
// For system keys, always pass them to the default WndProc so that keys
// like the ALT-TAB or Kanji switches are processed correctly.
if (is_syskey) {
break;
}
return true;
return is_unmet_event && !is_syskey;
}
default:
assert(false);
Expand Down
45 changes: 33 additions & 12 deletions shell/platform/windows/keyboard_manager_win32.h
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Original file line number Diff line number Diff line change
Expand Up @@ -26,6 +26,18 @@ namespace flutter {
// implements the window delegate. The |OnKey| and |OnText| results are
// passed to those of |WindowWin32|'s, and consequently, those of
// |FlutterWindowsView|'s.
//
// ## Terminology
//
// The keyboard system follows the following terminology instead of the
// inconsistent/incomplete one used by Win32:
//
// * Message: An invocation of |WndProc|, which consists of an
// action, an lparam, and a wparam.
// * Action: The type of a message.
// * Session: One to three messages that should be processed together, such
// as a key down message followed by char messages.
// * Event: A FlutterKeyEvent/ui.KeyData sent to the framework.
class KeyboardManagerWin32 {
public:
// Define how the keyboard manager accesses Win32 system calls (to allow
Expand Down Expand Up @@ -92,30 +104,40 @@ class KeyboardManagerWin32 {
LPARAM const lparam);

private:
struct Win32Message {
UINT const action;
WPARAM const wparam;
LPARAM const lparam;

bool IsHighSurrogate() const { return IS_HIGH_SURROGATE(wparam); }

bool IsLowSurrogate() const { return IS_LOW_SURROGATE(wparam); }

bool IsGeneralKeyDown() const {
return action == WM_KEYDOWN || action == WM_SYSKEYDOWN;
}
};

struct PendingEvent {
uint32_t key;
uint16_t key;

@gspencergoog gspencergoog Jan 25, 2022

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Could you use the Windows type here (i.e. SHORT), and for the others that are derived from Windows struct values?

@dkwingsmt dkwingsmt Jan 25, 2022

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At some point we have to convert the Win32 types to fixed-width types. My idea here is that, the members of Win32Message preserve the original value, since they are to be redispatched, while the members of PendingEvent should be fixed-width values, since they are processed values and will be send to OnKey of the platform-independent FlutterWindowsView.

@dkwingsmt dkwingsmt Jan 25, 2022 •
edited
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I agree that the change here (or many of the numerical types) is debatable. WPARAM is technically uint64 nowadays in a 64-bit system, but the API dated back to the 32-bit era, and practically the virtual code never exceeds 16 bit.

@gspencergoog gspencergoog Jan 25, 2022

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Sure, and I'm sure that practically it makes no difference, but from a correctness standpoint it would be better to use the system defined types instead of making the (yes, perfectly valid) assumptions about the sizes of the types.

I'm OK with making the assumptions, though, if you think that the documentation value of showing the type sizes is important enough to trump the correctness.

@gspencergoog gspencergoog Jan 25, 2022

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It might be sufficient to have a compile-time static_assert that sizeof(SHORT) == sizeof(uint16_t).

@dkwingsmt dkwingsmt Jan 26, 2022 •
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I've replaced the types of key and action to win32 types since they directly come from win32 values. Others are extracted from lparam and have explicitly defined width, so I'm keeping their types.

uint8_t scancode;
uint32_t action;
char32_t character;
bool extended;
bool was_down;

std::vector<Win32Message> session;

// A value calculated out of critical event information that can be used
// to identify redispatched events.
uint64_t hash;
uint64_t Hash() const { return ComputeEventHash(*this); }
};

using OnKeyCallback =
std::function<void(std::unique_ptr<PendingEvent>, bool)>;

// Returns true if it's a new event, or false if it's a redispatched event.
bool OnKey(int key,
int scancode,
int action,
char32_t character,
bool extended,
bool was_down,
OnKeyCallback callback);
bool OnKey(std::unique_ptr<PendingEvent> event, OnKeyCallback callback);

void HandleOnKeyResult(std::unique_ptr<PendingEvent> event,
bool handled,
Expand All @@ -141,9 +163,8 @@ class KeyboardManagerWin32 {

WindowDelegate* window_delegate_;

// Keeps track of the last key code produced by a WM_KEYDOWN or WM_SYSKEYDOWN
// message.
int keycode_for_char_message_ = 0;
// Keeps track of all messages during the current session.
std::vector<Win32Message> current_session_;

std::map<uint16_t, std::u16string> text_for_scancode_on_redispatch_;

Expand Down