How can I catch a `shift`-`key` combination with Win32::Console::Input? - perl

Question

How can I catch a shift-some-key combination with this script?
When I press the Arrow-keys I get what I expect, but when I press shift-tab it doesn't return the KEY_BTAB value.
use warnings;
use 5.12.0;
use Win32::Console qw(STD_INPUT_HANDLE ENABLE_MOUSE_INPUT);
use constant {
RIGHT_ALT_PRESSED => 0x0001,
LEFT_ALT_PRESSED => 0x0002,
RIGHT_CTRL_PRESSED => 0x0004,
LEFT_CTRL_PRESSED => 0x0008,
SHIFT_PRESSED => 0x0010,
VK_LEFT => 0x25,
VK_UP => 0x26,
VK_RIGHT => 0x27,
VK_DOWN => 0x28,
VK_TAB => 0x09,
};
use constant SHIFTED_MASK =>
RIGHT_ALT_PRESSED |
LEFT_ALT_PRESSED |
RIGHT_CTRL_PRESSED |
LEFT_CTRL_PRESSED |
SHIFT_PRESSED;
my %d = (
KEY_DOWN => 258,
KEY_UP => 259,
KEY_LEFT => 260,
KEY_RIGHT => 261,
KEY_BTAB => 353,
);
my $con_in = Win32::Console->new(STD_INPUT_HANDLE);
$con_in->Mode(ENABLE_MOUSE_INPUT);
while ( 1 ) {
my $key = getch();
say "<$key>";
last if $key == 113;
}
sub getch {
my #event = $con_in->Input();
my $event_type = shift( #event );
if ( defined $event_type and $event_type == 1 ) {
my ( $key_down, $repeat_c, $vkcode, $vsccode, $char, $ctrl_ks ) = #event;
if ( $char ) {
return $char;
}
else {
if ( $vkcode == VK_UP and ( $ctrl_ks & SHIFTED_MASK ) == 0 ) {
return $d{KEY_UP};
}
elsif ( $vkcode == VK_DOWN and ( $ctrl_ks & SHIFTED_MASK ) == 0 ) {
return $d{KEY_DOWN};
}
elsif ( $vkcode == VK_RIGHT and ( $ctrl_ks & SHIFTED_MASK ) == 0 ) {
return $d{KEY_RIGHT};
}
elsif ( $vkcode == VK_LEFT and ( $ctrl_ks & SHIFTED_MASK ) == 0 ) {
return $d{KEY_LEFT};
}
elsif ( $vkcode == VK_TAB and $ctrl_ks == SHIFT_PRESSED ) {
return $d{KEY_BTAB}; # <--
}
else {
say "beep";
}
}
}
}
Output when I press shift and tab:
beep
<1>
<9>
<9>
beep
<1>
After editing the getch routine this way
sub getch {
my #event = $con_in->Input();
my $event_type = shift( #event );
if ( defined $event_type and $event_type == 1 ) {
my ( $key_down, $repeat_count, $virtual_keycode, $virtual_scancode, $char, $ctrl_key_state ) = #event;
if ( $char ) {
if ( $key_down ) {
return $char for $repeat_count;
}
}
else {
if ( $virtual_keycode == VK_UP and ( $ctrl_key_state & SHIFTED_MASK ) == 0 ) {
if ( $key_down ) {
return $d{KEY_UP} for $repeat_count;
}
}
elsif ( $virtual_keycode == VK_DOWN and ( $ctrl_key_state & SHIFTED_MASK ) == 0 ) {
if ( $key_down ) {
return $d{KEY_DOWN} for $repeat_count;
}
}
elsif ( $virtual_keycode == VK_RIGHT and ( $ctrl_key_state & SHIFTED_MASK ) == 0 ) {
if ( $key_down ) {
return $d{KEY_RIGHT} for $repeat_count;
}
}
elsif ( $virtual_keycode == VK_LEFT and ( $ctrl_key_state & SHIFTED_MASK ) == 0 ) {
if ( $key_down ) {
return $d{KEY_LEFT} for $repeat_count;
}
}
elsif ( $virtual_keycode == VK_TAB and ( $ctrl_key_state & SHIFTED_MASK ) == SHIFT_PRESSED ) {
if ( $key_down ) {
return $d{KEY_BTAB} for $repeat_count;
}
}
else {
say "beep";
}
}
}
}
I get this output:
beep
<1>
<9>
<0>
beep
<1>

Answer 1

When I run your code, $ctrl_ks has the value 48 (0x0030) when I hit Shift+Tab, and 32 (0x0020) when Shift is released. I think the check you want to make is
elsif ($vkcode==VK_TAB and ($ctrl_ks & SHIFT_PRESSED)==SHIFT_PRESSED) {
return $d{KEY_BTAB};

Answer 2

Firstly, $char is set to 9, so you never get to your check. Move the if ($char) check to somewhere more appropriate.
Secondly, your check is wrong. The following won't work if, say, Caps Lock is on.
elsif ( $vkcode == VK_TAB and $ctrl_ks == SHIFT_PRESSED )
You should only check the flags you are interested in.
elsif ($vkcode==VK_TAB and ( $ctrl_ks & SHIFTED_MASK ) == SHIFT_PRESSED)
Finally, sometimes you only get notified once for multiple presses. That is signaled by $repeat_count. You ignore this, so you potentially ignore keys.
You try to handle $repeat_count in the second snippet, but fail miserably. Part of the problem is you copied for $repeat_count from my other answer when it should be for 1..$repeat_count, and the other problem is that you only return one value even if $repeat_count is larger than one.
my #kbd_queue;
sub getch {
my #event;
if (#kbd_queue) {
#event = ( 1, #{ pop #kbd_queue } );
} else {
#event = $con_in->Input();
}
my $event_type = shift( #event );
if ( defined $event_type and $event_type == 1 ) {
my ( $key_down, $repeat_count, $virtual_keycode, $virtual_scancode, $char, $ctrl_key_state ) = #event;
return -1 if !$key_down;
if ( $virtual_keycode == VK_UP and ( $ctrl_key_state & SHIFTED_MASK ) == 0 ) {
push #kbd_queue, \#event for 2..$repeat_count;
return $d{KEY_UP};
}
...
elsif ( $virtual_keycode == VK_TAB and ( $ctrl_key_state & SHIFTED_MASK ) == SHIFT_PRESSED ) {
push #kbd_queue, \#event for 2..$repeat_count;
return $d{KEY_BTAB};
}
elsif ( $char ) {
push #kbd_queue, \#event for 2..$repeat_count;
return $char;
}
else {
say "beep";
}
}
}
You should convert this into something table-driven.