From da27e42316962be6f6b8ba2afb49760d9704d070 Mon Sep 17 00:00:00 2001

From: Hans de Goede <hdegoede@redhat.com>

Date: Sun, 21 Jan 2018 14:07:39 +0100

Subject: [PATCH 2/6] main: Do not update the display on backspace when there

 is no input to remove

On machines with a slow CPU (Atom) and a highres screen drawing the

diskcrypt dialog may take longer then the keyrepeat speed, this leads to

a long delay before showing keypresses when doing the following:

1) Type long password

2) Realize it is wrong, press + hold backspace

   the key-repeat will now generate backspace key presses faster then we

   process them as main.c does an update_display for each press

3) Users releases backspace when we've processed input-length backspace

   key-presses, but since we were drawing slower then key-presses were

   coming in many more backspace keypresses are in the keyboard buffer

4) User types first character of the right password, this shows up up to

   a couple of seconds later because first we are still processing all

   the queued up backspace presses and doing a redraw for each.

This commit fixes this by skipping the redraws in on_backspace when there

is no more input left in the input buffer.

https://bugs.freedesktop.org/show_bug.cgi?id=104714

---

 src/main.c | 2 ++

 1 file changed, 2 insertions(+)

diff --git a/src/main.c b/src/main.c

index 08c7fe1..f1e0fa7 100644

--- a/src/main.c

+++ b/src/main.c

@@ -1570,6 +1570,8 @@ on_backspace (state_t *state)

         bytes = ply_buffer_get_bytes (state->entry_buffer);

         size = ply_buffer_get_size (state->entry_buffer);

+        if (size == 0)

+                return;

         bytes_to_remove = MIN (size, PLY_UTF8_CHARACTER_SIZE_MAX);

         while ((previous_character_size = ply_utf8_character_get_size (bytes + size - bytes_to_remove, bytes_to_remove)) < bytes_to_remove) {

-- 

2.17.0