path: root/src/scan.c

/*
    Copyright (C) 2016  Jeremy White <jwhite@codeweavers.com>
    All rights reserved.

    This file is part of x11spice

    x11spice is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    x11spice is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with x11spice.  If not, see <http://www.gnu.org/licenses/>.
*/

/*----------------------------------------------------------------------------
**  scan.c
**      This code is meant to handle the logic around knowing which portions
**  of the display to push along to the spice server.  There are two key ways
**  we detect these changes - through periodic scans of the screen
**  (see scanner_periodic) and through XDAMAGE reports
**  (see display/handle_damage_notify)
**--------------------------------------------------------------------------*/

#include <stdlib.h>
#include <pthread.h>
#include <glib.h>
#include <pixman.h>

#include "x11spice.h"
#include "session.h"
#include "scan.h"

/*----------------------------------------------------------------------------
**  We will scan over the screen by breaking it into a grid of tiles, each
**   NUM_SCANLINES x NUM_HORIZONTAL_TILES.  We try to scan in a fashion designed
**   to catch changes with a fairly modest set of scans; this scan pattern is
**   taken from the x11vnc project.
**--------------------------------------------------------------------------*/
#define NUM_SCANLINES               32
#define NUM_HORIZONTAL_TILES        NUM_SCANLINES
#define MAX_SCAN_FPS                30
#define MIN_SCAN_FPS                 1

/* If we have more than this number of changes in any given row, we just
   copy the whole row */
#define SCAN_ROW_THRESHOLD          (NUM_HORIZONTAL_TILES / 2)

static int scanlines[NUM_SCANLINES] = {
    0, 16, 8, 24, 4, 20, 12, 28,
    10, 26, 18, 2, 22, 6, 30, 14,
    1, 17, 9, 25, 7, 23, 15, 31,
    19, 3, 27, 11, 29, 13, 5, 21
};


static QXLDrawable *shm_image_to_drawable(spice_t *s, shm_image_t *shmi, int x, int y)
{
    QXLDrawable *drawable;
    QXLImage *qxl_image;
    int i;

    drawable = calloc(1, sizeof(*drawable) + sizeof(*qxl_image));
    if (!drawable)
        return NULL;
    qxl_image = (QXLImage *) (drawable + 1);

    drawable->release_info.id = (uintptr_t) spice_create_release(s, RELEASE_SHMI, shmi);
    shmi->drawable_ptr = drawable;

    drawable->surface_id = 0;
    drawable->type = QXL_DRAW_COPY;
    drawable->effect = QXL_EFFECT_OPAQUE;
    drawable->clip.type = SPICE_CLIP_TYPE_NONE;
    drawable->bbox.left = x;
    drawable->bbox.top = y;
    drawable->bbox.right = x + shmi->w;
    drawable->bbox.bottom = y + shmi->h;

    for (i = 0; i < 3; ++i)
        drawable->surfaces_dest[i] = -1;

    drawable->u.copy.src_area.left = 0;
    drawable->u.copy.src_area.top = 0;
    drawable->u.copy.src_area.right = shmi->w;
    drawable->u.copy.src_area.bottom = shmi->h;
    drawable->u.copy.rop_descriptor = SPICE_ROPD_OP_PUT;

    drawable->u.copy.src_bitmap = (uintptr_t) qxl_image;

    qxl_image->descriptor.id = 0;
    qxl_image->descriptor.type = SPICE_IMAGE_TYPE_BITMAP;

    qxl_image->descriptor.flags = 0;
    qxl_image->descriptor.width = shmi->w;
    qxl_image->descriptor.height = shmi->h;

    qxl_image->bitmap.format = SPICE_BITMAP_FMT_RGBA;
    qxl_image->bitmap.flags = SPICE_BITMAP_FLAGS_TOP_DOWN | QXL_BITMAP_DIRECT;
    qxl_image->bitmap.x = shmi->w;
    qxl_image->bitmap.y = shmi->h;
    qxl_image->bitmap.stride = shmi->bytes_per_line;
    qxl_image->bitmap.palette = 0;
    qxl_image->bitmap.data = (uintptr_t) shmi->segment.shmaddr;

    return drawable;
}

static guint64 get_timeout(scanner_t *scanner)
{
    return G_USEC_PER_SEC / scanner->target_fps / NUM_SCANLINES;
}

static void scan_update_fps(scanner_t *scanner, int increment)
{
    scanner->target_fps += increment;
    if (scanner->target_fps > MAX_SCAN_FPS)
        scanner->target_fps = MAX_SCAN_FPS;

    if (scanner->target_fps < MIN_SCAN_FPS)
        scanner->target_fps = MIN_SCAN_FPS;
}

static void handle_scan_report(session_t *session, scan_report_t *r)
{
    shm_image_t *shmi;

    shmi = create_shm_image(&session->display, r->w, r->h);
    if (!shmi) {
        g_debug("Unexpected failure to create_shm_image of area %dx%d", r->w, r->h);
        return;
    }

    if (read_shm_image(&session->display, shmi, r->x, r->y) == 0) {
        //save_ximage_pnm(shmi);
        g_mutex_lock(session->lock);
        display_copy_image_into_fullscreen(&session->display, shmi, r->x, r->y);
        g_mutex_unlock(session->lock);

        QXLDrawable *drawable = shm_image_to_drawable(&session->spice, shmi, r->x, r->y);
        if (drawable) {
            g_async_queue_push(session->draw_queue, drawable);
            spice_qxl_wakeup(&session->spice.display_sin);
            /* NOTE: the shmi is intentionally not freed at this point.
               The call path will take care of that once it's been
               pushed to Spice. */
            return;
        } else
            g_debug("Unexpected failure to create drawable");
    } else
        g_debug("Unexpected failure to read shm of area %dx%d", r->w, r->h);

    if (shmi)
        destroy_shm_image(&session->display, shmi);
}


static void free_queue_item(gpointer data)
{
    free(data);
}

/* Note: session lock must be held by caller */
static void push_tiles_report(scanner_t *scanner, int start_row, int start_col, int end_row,
                              int end_col)
{
    /* Note: we do this as integer math, and so we multiply first to avoid discarding
       fractions in our calculations.  We also want to round down for our x, y, and
       round up for our width and height calculations, as doesn't hurt to send more */
    int x = (start_col * scanner->session->display.fullscreen->w) / NUM_HORIZONTAL_TILES;
    int w = ((end_col - start_col + 1) * scanner->session->display.fullscreen->w) /
        NUM_HORIZONTAL_TILES;
    if (((end_col - start_col + 1) * scanner->session->display.fullscreen->w) %
        NUM_HORIZONTAL_TILES)
        w++;

    int y = start_row * NUM_SCANLINES;
    int h = (end_row - start_row + 1) * NUM_SCANLINES;

    if (x + w > scanner->session->display.fullscreen->w)
        w = scanner->session->display.fullscreen->w - x;

    if (y + h > scanner->session->display.fullscreen->h)
        h = scanner->session->display.fullscreen->h - y;

    scanner_push(scanner, SCANLINE_SCAN_REPORT, x, y, w, h);
}

static void grow_changed_tiles(scanner_t *scanner G_GNUC_UNUSED,
                               int *tiles_changed_in_row,
                               int tiles_changed[][NUM_HORIZONTAL_TILES], int num_vertical_tiles)
{
    int i;
    int j;
    for (i = 0; i < num_vertical_tiles; i++) {
        if (!tiles_changed_in_row[i] || tiles_changed_in_row[i] == NUM_HORIZONTAL_TILES)
            continue;

        if (tiles_changed_in_row[i] > SCAN_ROW_THRESHOLD) {
            tiles_changed_in_row[i] = NUM_HORIZONTAL_TILES;
            continue;
        }

        for (j = 0; j < NUM_HORIZONTAL_TILES; j++) {
            if (!tiles_changed[i][j]) {
                int grow = 0;

                /* You get good optimzations from having multiple rows,
                   so be more aggressive in growing the first and last tile;
                   just require a neighbor be set */
                if (j == 0 && tiles_changed[i][1])
                    grow++;
                else if (j == NUM_HORIZONTAL_TILES - 1 && tiles_changed[i][j - 1])
                    grow++;

                /* Otherwise, require that growing 'fills' a gap */
                else if (j > 0 && j < (NUM_HORIZONTAL_TILES - 1) &&
                         tiles_changed[i][j - 1] && tiles_changed[i][j + 1])
                    grow++;

                if (grow) {
                    tiles_changed[i][j]++;
                    tiles_changed_in_row[i]++;
                }
            }
        }

        /* Recheck, in case our growth algorithm pushed this
           into the 'scan the whole row' category */
        if (tiles_changed_in_row[i] > SCAN_ROW_THRESHOLD)
            tiles_changed_in_row[i] = NUM_HORIZONTAL_TILES;
    }
}

static void push_changes_across_rows(scanner_t *scanner, int *tiles_changed_in_row,
                                     int num_vertical_tiles)
{
    int i = 0;
    int start_row = -1;
    int current_row = -1;

    for (i = 0; i < num_vertical_tiles; i++) {
        if (tiles_changed_in_row[i] == NUM_HORIZONTAL_TILES) {
            if (start_row == -1)
                start_row = i;
            current_row = i;
        } else {
            if (current_row != -1) {
                push_tiles_report(scanner, start_row, 0, current_row, NUM_HORIZONTAL_TILES - 1);
                start_row = current_row = -1;
            }
            continue;
        }
    }

    if (current_row != -1)
        push_tiles_report(scanner, start_row, 0, current_row, NUM_HORIZONTAL_TILES - 1);
}

static void push_changes_in_one_row(scanner_t *scanner, int row, int *tiles_changed)
{
    int i = 0;
    int start_tile = -1;
    int current_tile = -1;

    for (i = 0; i < NUM_HORIZONTAL_TILES; i++) {
        if (tiles_changed[i] == 0) {
            if (current_tile != -1) {
                push_tiles_report(scanner, row, start_tile, row, current_tile);
                start_tile = current_tile = -1;
            }
            continue;
        }
        if (start_tile == -1)
            start_tile = i;
        current_tile = i;
    }

    if (current_tile != -1)
        push_tiles_report(scanner, row, start_tile, row, current_tile);
}

static void push_changed_tiles(scanner_t *scanner, int *tiles_changed_in_row,
                               int tiles_changed[][NUM_HORIZONTAL_TILES], int num_vertical_tiles)
{
    int i = 0;

    push_changes_across_rows(scanner, tiles_changed_in_row, num_vertical_tiles);

    for (i = 0; i < num_vertical_tiles; i++)
        if (tiles_changed_in_row[i] > 0 && tiles_changed_in_row[i] < NUM_HORIZONTAL_TILES)
            push_changes_in_one_row(scanner, i, tiles_changed[i]);
}


static void scanner_remove_region(scanner_t *scanner, scan_report_t *r)
{
    pixman_region16_t remove;
    pixman_region_init_rect(&remove, r->x, r->y, r->w, r->h);

    g_mutex_lock(scanner->lock);
    pixman_region_subtract(&scanner->region, &scanner->region, &remove);
    g_mutex_unlock(scanner->lock);

    pixman_region_clear(&remove);
}

static void scanner_periodic(scanner_t *scanner)
{
    int i;
    int num_vertical_tiles;
    int y;
    int offset;
    int rc;

    g_mutex_lock(scanner->session->lock);
    num_vertical_tiles = scanner->session->display.fullscreen->h / NUM_SCANLINES;
    if (scanner->session->display.fullscreen->h % NUM_SCANLINES)
        num_vertical_tiles++;

    int tiles_changed_in_row[num_vertical_tiles];
    int tiles_changed[num_vertical_tiles][NUM_HORIZONTAL_TILES];

    offset = scanlines[scanner->current_scanline++];
    scanner->current_scanline %= NUM_SCANLINES;

    for (y = offset, i = 0; i < num_vertical_tiles; i++, y += NUM_SCANLINES) {
        if (y >= scanner->session->display.fullscreen->h)
            rc = 0;
        else
            rc = display_find_changed_tiles(&scanner->session->display,
                                            y, tiles_changed[i], NUM_HORIZONTAL_TILES);
        if (rc < 0) {
            g_mutex_unlock(scanner->session->lock);
            return;
        }

        tiles_changed_in_row[i] = rc;
    }
    grow_changed_tiles(scanner, tiles_changed_in_row, tiles_changed, num_vertical_tiles);
    push_changed_tiles(scanner, tiles_changed_in_row, tiles_changed, num_vertical_tiles);

    g_mutex_unlock(scanner->session->lock);
}

static void scan_full_screen(scanner_t *scanner)
{
    int num_vertical_tiles;
    int rc;

    g_mutex_lock(scanner->session->lock);
    num_vertical_tiles = scanner->session->display.fullscreen->h / NUM_SCANLINES;
    if (scanner->session->display.fullscreen->h % NUM_SCANLINES)
        num_vertical_tiles++;

    int tiles_changed_in_row[num_vertical_tiles];
    int tiles_changed[num_vertical_tiles][NUM_HORIZONTAL_TILES];

    rc = display_scan_whole_screen(&scanner->session->display,
                                   num_vertical_tiles, NUM_HORIZONTAL_TILES,
                                   tiles_changed, tiles_changed_in_row);
    if (rc < 0) {
        g_mutex_unlock(scanner->session->lock);
        return;
    }

    grow_changed_tiles(scanner, tiles_changed_in_row, tiles_changed, num_vertical_tiles);
    push_changed_tiles(scanner, tiles_changed_in_row, tiles_changed, num_vertical_tiles);
    g_mutex_unlock(scanner->session->lock);
}

#if ! GLIB_CHECK_VERSION(2, 31, 18)
static gpointer g_async_queue_timeout_pop(GAsyncQueue *queue, guint64 t)
{
    GTimeVal end;
    g_get_current_time(&end);
    g_time_val_add(&end, t);
    return g_async_queue_timed_pop(queue, &end);
}
#endif

static void *scanner_run(void *opaque)
{
    scanner_t *scanner = (scanner_t *) opaque;
    while (session_alive(scanner->session)) {
        scan_report_t *r;
        r = (scan_report_t *) g_async_queue_timeout_pop(scanner->queue, get_timeout(scanner));
        if (!r) {
            scan_update_fps(scanner, -1);
            scanner_periodic(scanner);
            continue;
        }

        if (r->type == FULLSCREEN_SCAN_REQUEST) {
            free_queue_item(r);
            scan_full_screen(scanner);
            continue;
        }

        if (r->type == EXIT_SCAN_REPORT) {
            free_queue_item(r);
            break;
        }

        /* Remaining scan types affect a region of the screen */
        scan_update_fps(scanner, 1);
        scanner_remove_region(scanner, r);

        handle_scan_report(scanner->session, r);
        free_queue_item(r);
    }

    return 0;
}


int scanner_create(scanner_t *scanner)
{
    scanner->queue = g_async_queue_new_full(free_queue_item);
    scanner->lock = g_mutex_new();
    scanner->current_scanline = 0;
    pixman_region_init(&scanner->region);
    scanner->target_fps = MIN_SCAN_FPS;
    return pthread_create(&scanner->thread, NULL, scanner_run, scanner);
}

int scanner_destroy(scanner_t *scanner)
{
    void *err;
    int rc;

    scanner_push(scanner, EXIT_SCAN_REPORT, 0, 0, 0, 0);
    rc = pthread_join(scanner->thread, &err);
    if (rc == 0)
        rc = (int) (long) err;

    g_mutex_lock(scanner->lock);
    if (scanner->queue) {
        g_async_queue_unref(scanner->queue);
        scanner->queue = NULL;
    }
    pixman_region_clear(&scanner->region);

    g_mutex_unlock(scanner->lock);
    g_mutex_free(scanner->lock);
    scanner->lock = NULL;

    return rc;
}

int scanner_push(scanner_t *scanner, scan_type_t type, int x, int y, int w, int h)
{
    scan_report_t *r;

#if defined(DEBUG_SCANLINES)
    fprintf(stderr, "scan: type %d, %dx%d @ %dx%d\n", type, w, h, x, y);
    fflush(stderr);
#endif

    g_mutex_lock(scanner->lock);

    if (!scanner->queue) {
        g_mutex_unlock(scanner->lock);
        return X11SPICE_ERR_SHUTTING_DOWN;
    }

    r = malloc(sizeof(*r));
    if (!r) {
        g_mutex_unlock(scanner->lock);
        return X11SPICE_ERR_MALLOC;
    }

    r->type = type;
    r->x = x;
    r->y = y;
    r->w = w;
    r->h = h;

    if (type == SCANLINE_SCAN_REPORT || type == DAMAGE_SCAN_REPORT) {
        pixman_box16_t rect;
        rect.x1 = x;
        rect.x2 = x + w;
        rect.y1 = y;
        rect.y2 = y + h;

        /* Optimization: if we're being notified of an area already to be
           rescanned, just discard this notice, otherwise update region and push */
        if (pixman_region_contains_rectangle(&scanner->region, &rect)) {
            free(r);
        } else {
            pixman_region_union_rect(&scanner->region, &scanner->region, x, y, w, h);
            g_async_queue_push(scanner->queue, r);
        }
    } else {
        g_async_queue_push(scanner->queue, r);
    }

    g_mutex_unlock(scanner->lock);

    return 0;
}