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Use RLE bitmap compression

This commit is contained in:
Přemysl Eric Janouch 2014-10-27 18:49:21 +01:00
parent 5cebe379c8
commit 606c5f43af
2 changed files with 36 additions and 24 deletions
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44
autistdraw.c
View File

@ -272,8 +272,26 @@ send_get_bitmap_response (client_t *client, app_context_t *app)
msg_writer_u64 (&writer, app->bitmap_w);
msg_writer_u64 (&writer, app->bitmap_h);
msg_writer_blob (&writer, app->bitmap,
app->bitmap_w * app->bitmap_h * sizeof *app->bitmap);
// Simple RLE compression
size_t size = app->bitmap_w * app->bitmap_h;
uint8_t last_value = 0, count = 0;
for (size_t i = 0; i < size; i++)
{
uint8_t value = app->bitmap[i];
if ((count && value != last_value) || count == 0xFF)
{
msg_writer_u8 (&writer, count);
msg_writer_u8 (&writer, last_value);
count = 0;
}
count++;
last_value = value;
}
if (count)
{
msg_writer_u8 (&writer, count);
msg_writer_u8 (&writer, last_value);
}
flush_writer_to_client (&writer, client);
}
@ -970,17 +988,27 @@ on_server_get_bitmap (app_context_t *app, struct msg_unpacker *unpacker)
|| !msg_unpacker_u64 (unpacker, &h))
return;
// TODO: employ at least some RLE encoding
size_t size = w * h * sizeof *app->bitmap;
size_t size = w * h;
if ((h && w > SIZE_MAX / h) || w > SIZE_MAX || h > SIZE_MAX)
return;
const void *data;
if (!msg_unpacker_blob (unpacker, &data, size))
return;
uint8_t *bitmap = xcalloc (size, sizeof *app->bitmap);
// RLE decompression
size_t i = 0;
uint8_t len, value;
while (msg_unpacker_u8 (unpacker, &len)
&& msg_unpacker_u8 (unpacker, &value))
{
// Don't allow overflow
if (i + len > size || i + len < i)
break;
for (size_t x = 0; x < len; x++)
bitmap[i++] = value;
}
free (app->bitmap);
app->bitmap = memcpy (xcalloc (1, size), data, size);
app->bitmap = bitmap;
app->bitmap_x = x;
app->bitmap_y = y;
app->bitmap_w = w;

16
utils.c
View File

@ -382,16 +382,6 @@ msg_unpacker_get_available (struct msg_unpacker *self)
return self->len - self->offset;
}
static bool
msg_unpacker_blob (struct msg_unpacker *self, const void **data, size_t len)
{
if (self->len - self->offset < len)
return false;
*data = self->data + self->offset;
self->offset += len;
return true;
}
#define UNPACKER_INT_BEGIN \
if (self->len - self->offset < sizeof *value) \
return false; \
@ -445,12 +435,6 @@ msg_writer_init (struct msg_writer *self)
str_append_data (&self->buf, "\x00\x00\x00\x00" "\x00\x00\x00\x00", 8);
}
static void
msg_writer_blob (struct msg_writer *self, const void *data, size_t len)
{
str_append_data (&self->buf, data, len);
}
static void
msg_writer_u8 (struct msg_writer *self, uint8_t x)
{