ev-pixbuf-cache.c

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#include <config.h>
#include "ev-pixbuf-cache.h"
#include "ev-job-scheduler.h"
#include "ev-view-private.h"

typedef enum {
        SCROLL_DIRECTION_DOWN,
        SCROLL_DIRECTION_UP
} ScrollDirection;

typedef struct _CacheJobInfo
{
    EvJob *job;
    gboolean page_ready;

    /* Region of the page that needs to be drawn */
    cairo_region_t  *region;

    /* Data we get from rendering */
    cairo_surface_t *surface;

    /* Device scale factor of target widget */
    int device_scale;

    /* Selection data. 
     * Selection_points are the coordinates encapsulated in selection.
     * target_points is the target selection size. */
    EvRectangle      target_points;
    EvSelectionStyle selection_style;
    gboolean         points_set;
    
    cairo_surface_t *selection;
    gdouble          selection_scale;
    EvRectangle      selection_points;

    cairo_region_t *selection_region;
    gdouble         selection_region_scale;
    EvRectangle     selection_region_points;
} CacheJobInfo;

struct _EvPixbufCache
{
    GObject parent;

    /* We keep a link to our containing view just for style information. */
    GtkWidget *view;
    EvDocument *document;
    EvDocumentModel *model;
    int start_page;
    int end_page;
        ScrollDirection scroll_direction;
    gboolean inverted_colors;

    gsize max_size;

    /* preload_cache_size is the number of pages prior to the current
     * visible area that we cache.  It's normally 1, but could be 2 in the
     * case of twin pages.
     */
    int preload_cache_size;
    guint job_list_len;

    CacheJobInfo *prev_job;
    CacheJobInfo *job_list;
    CacheJobInfo *next_job;
};

struct _EvPixbufCacheClass
{
    GObjectClass parent_class;

    void (* job_finished) (EvPixbufCache *pixbuf_cache);
};


enum
{
    JOB_FINISHED,
    N_SIGNALS,
};

static guint signals[N_SIGNALS] = {0, };

static void          ev_pixbuf_cache_init       (EvPixbufCache      *pixbuf_cache);
static void          ev_pixbuf_cache_class_init (EvPixbufCacheClass *pixbuf_cache);
static void          ev_pixbuf_cache_finalize   (GObject            *object);
static void          ev_pixbuf_cache_dispose    (GObject            *object);
static void          job_finished_cb            (EvJob              *job,
                         EvPixbufCache      *pixbuf_cache);
static CacheJobInfo *find_job_cache             (EvPixbufCache      *pixbuf_cache,
                         int                 page);
static gboolean      new_selection_surface_needed(EvPixbufCache      *pixbuf_cache,
                          CacheJobInfo       *job_info,
                          gint                page,
                          gfloat              scale);


/* These are used for iterating through the prev and next arrays */
#define FIRST_VISIBLE_PREV(pixbuf_cache) \
    (MAX (0, pixbuf_cache->preload_cache_size - pixbuf_cache->start_page))
#define VISIBLE_NEXT_LEN(pixbuf_cache) \
    (MIN(pixbuf_cache->preload_cache_size, ev_document_get_n_pages (pixbuf_cache->document) - (1 + pixbuf_cache->end_page)))
#define PAGE_CACHE_LEN(pixbuf_cache) \
    ((pixbuf_cache->end_page - pixbuf_cache->start_page) + 1)

#define MAX_PRELOADED_PAGES 3

G_DEFINE_TYPE (EvPixbufCache, ev_pixbuf_cache, G_TYPE_OBJECT)

static void
ev_pixbuf_cache_init (EvPixbufCache *pixbuf_cache)
{
    pixbuf_cache->start_page = -1;
    pixbuf_cache->end_page = -1;
}

static void
ev_pixbuf_cache_class_init (EvPixbufCacheClass *class)
{
    GObjectClass *object_class;

    object_class = G_OBJECT_CLASS (class);

    object_class->finalize = ev_pixbuf_cache_finalize;
    object_class->dispose = ev_pixbuf_cache_dispose;

    signals[JOB_FINISHED] =
        g_signal_new ("job-finished",
                  G_OBJECT_CLASS_TYPE (object_class),
                  G_SIGNAL_RUN_LAST | G_SIGNAL_ACTION,
                  G_STRUCT_OFFSET (EvPixbufCacheClass, job_finished),
                  NULL, NULL,
                  g_cclosure_marshal_VOID__POINTER,
                  G_TYPE_NONE, 1,
                  G_TYPE_POINTER);
}

static void
ev_pixbuf_cache_finalize (GObject *object)
{
    EvPixbufCache *pixbuf_cache;

    pixbuf_cache = EV_PIXBUF_CACHE (object);

    if (pixbuf_cache->job_list) {
        g_slice_free1 (sizeof (CacheJobInfo) * pixbuf_cache->job_list_len,
                   pixbuf_cache->job_list);
        pixbuf_cache->job_list = NULL;
    }
    if (pixbuf_cache->prev_job) {
        g_slice_free1 (sizeof (CacheJobInfo) * pixbuf_cache->preload_cache_size,
                   pixbuf_cache->prev_job);
        pixbuf_cache->prev_job = NULL;
    }
    if (pixbuf_cache->next_job) {
        g_slice_free1 (sizeof (CacheJobInfo) * pixbuf_cache->preload_cache_size,
                   pixbuf_cache->next_job);
        pixbuf_cache->next_job = NULL;
    }

    g_object_unref (pixbuf_cache->model);

    G_OBJECT_CLASS (ev_pixbuf_cache_parent_class)->finalize (object);
}

static void
end_job (CacheJobInfo *job_info,
     gpointer      data)
{
    g_signal_handlers_disconnect_by_func (job_info->job,
                          G_CALLBACK (job_finished_cb),
                          data);
    ev_job_cancel (job_info->job);
    g_object_unref (job_info->job);
    job_info->job = NULL;
}

static void
dispose_cache_job_info (CacheJobInfo *job_info,
            gpointer      data)
{
    if (job_info == NULL)
        return;

    if (job_info->job)
        end_job (job_info, data);

    if (job_info->surface) {
        cairo_surface_destroy (job_info->surface);
        job_info->surface = NULL;
    }
    if (job_info->region) {
        cairo_region_destroy (job_info->region);
        job_info->region = NULL;
    }
    if (job_info->selection) {
        cairo_surface_destroy (job_info->selection);
        job_info->selection = NULL;
    }
    if (job_info->selection_region) {
        cairo_region_destroy (job_info->selection_region);
        job_info->selection_region = NULL;
    }

    job_info->points_set = FALSE;
}

static void
ev_pixbuf_cache_dispose (GObject *object)
{
    EvPixbufCache *pixbuf_cache;
    int i;

    pixbuf_cache = EV_PIXBUF_CACHE (object);

    for (i = 0; i < pixbuf_cache->preload_cache_size; i++) {
        dispose_cache_job_info (pixbuf_cache->prev_job + i, pixbuf_cache);
        dispose_cache_job_info (pixbuf_cache->next_job + i, pixbuf_cache);
    }

    for (i = 0; i < PAGE_CACHE_LEN (pixbuf_cache); i++) {
        dispose_cache_job_info (pixbuf_cache->job_list + i, pixbuf_cache);
    }

    G_OBJECT_CLASS (ev_pixbuf_cache_parent_class)->dispose (object);
}


EvPixbufCache *
ev_pixbuf_cache_new (GtkWidget       *view,
             EvDocumentModel *model,
             gsize            max_size)
{
    EvPixbufCache *pixbuf_cache;

    pixbuf_cache = (EvPixbufCache *) g_object_new (EV_TYPE_PIXBUF_CACHE, NULL);
    /* This is a backlink, so we don't ref this */ 
    pixbuf_cache->view = view;
    pixbuf_cache->model = g_object_ref (model);
    pixbuf_cache->document = ev_document_model_get_document (model);
    pixbuf_cache->max_size = max_size;

    return pixbuf_cache;
}

void
ev_pixbuf_cache_set_max_size (EvPixbufCache *pixbuf_cache,
                  gsize          max_size)
{
    if (pixbuf_cache->max_size == max_size)
        return;

    if (pixbuf_cache->max_size > max_size)
        ev_pixbuf_cache_clear (pixbuf_cache);
    pixbuf_cache->max_size = max_size;
}

static int
get_device_scale (EvPixbufCache *pixbuf_cache)
{
#ifdef HAVE_HIDPI_SUPPORT
        return gtk_widget_get_scale_factor (pixbuf_cache->view);
#else
        return 1;
#endif
}

static void
set_device_scale_on_surface (cairo_surface_t *surface,
                             int              device_scale)
{
#ifdef HAVE_HIDPI_SUPPORT
        cairo_surface_set_device_scale (surface, device_scale, device_scale);
#else
        g_return_if_fail (device_scale == 1);
#endif
}

static void
copy_job_to_job_info (EvJobRender   *job_render,
              CacheJobInfo  *job_info,
              EvPixbufCache *pixbuf_cache)
{
    if (job_info->surface) {
        cairo_surface_destroy (job_info->surface);
    }
    job_info->surface = cairo_surface_reference (job_render->surface);
    set_device_scale_on_surface (job_info->surface, job_info->device_scale);
    if (pixbuf_cache->inverted_colors) {
        ev_document_misc_invert_surface (job_info->surface);
    }

    job_info->points_set = FALSE;
    if (job_render->include_selection) {
        if (job_info->selection) {
            cairo_surface_destroy (job_info->selection);
            job_info->selection = NULL;
        }
        if (job_info->selection_region) {
            cairo_region_destroy (job_info->selection_region);
            job_info->selection_region = NULL;
        }

        job_info->selection_points = job_render->selection_points;
        job_info->selection = cairo_surface_reference (job_render->selection);
                if (job_info->selection)
                        set_device_scale_on_surface (job_info->selection, job_info->device_scale);
        job_info->selection_scale = job_render->scale * job_info->device_scale;
        g_assert (job_info->selection_points.x1 >= 0);

        job_info->selection_region_points = job_render->selection_points;
        job_info->selection_region = cairo_region_reference (job_render->selection_region);
        job_info->selection_region_scale = job_render->scale;

        job_info->points_set = TRUE;
    }

    if (job_info->job)
        end_job (job_info, pixbuf_cache);

    job_info->page_ready = TRUE;
}

static void
job_finished_cb (EvJob         *job,
         EvPixbufCache *pixbuf_cache)
{
    CacheJobInfo *job_info;
    EvJobRender *job_render = EV_JOB_RENDER (job);

    /* If the job is outside of our interest, we silently discard it */
    if ((job_render->page < (pixbuf_cache->start_page - pixbuf_cache->preload_cache_size)) ||
        (job_render->page > (pixbuf_cache->end_page + pixbuf_cache->preload_cache_size))) {
        g_object_unref (job);
        return;
    }

    job_info = find_job_cache (pixbuf_cache, job_render->page);

    if (ev_job_is_failed (job)) {
        job_info->job = NULL;
        g_object_unref (job);
        return;
    }

    copy_job_to_job_info (job_render, job_info, pixbuf_cache);
    g_signal_emit (pixbuf_cache, signals[JOB_FINISHED], 0, job_info->region);
}

/* This checks a job to see if the job would generate the right sized pixbuf
 * given a scale.  If it won't, it removes the job and clears it to NULL.
 */
static void
check_job_size_and_unref (EvPixbufCache *pixbuf_cache,
              CacheJobInfo  *job_info,
              gfloat         scale)
{
    gint width, height;
    gint device_scale;

    g_assert (job_info);

    if (job_info->job == NULL)
        return;

        device_scale = get_device_scale (pixbuf_cache);
    if (job_info->device_scale == device_scale) {
        _get_page_size_for_scale_and_rotation (job_info->job->document,
                               EV_JOB_RENDER (job_info->job)->page,
                               scale,
                               EV_JOB_RENDER (job_info->job)->rotation,
                               &width, &height);
        if (width * device_scale == EV_JOB_RENDER (job_info->job)->target_width &&
            height * device_scale == EV_JOB_RENDER (job_info->job)->target_height)
            return;
    }

    end_job (job_info, pixbuf_cache);
}

/* Do all function that copies a job from an older cache to it's position in the
 * new cache.  It clears the old job if it doesn't have a place.
 */
static void
move_one_job (CacheJobInfo  *job_info,
          EvPixbufCache *pixbuf_cache,
          int            page,
          CacheJobInfo  *new_job_list,
          CacheJobInfo  *new_prev_job,
          CacheJobInfo  *new_next_job,
          int            new_preload_cache_size,
          int            start_page,
          int            end_page,
          gint           priority)
{
    CacheJobInfo *target_page = NULL;
    int page_offset;
    gint new_priority;

    if (page < (start_page - new_preload_cache_size) ||
        page > (end_page + new_preload_cache_size)) {
        dispose_cache_job_info (job_info, pixbuf_cache);
        return;
    }

    /* find the target page to copy it over to. */
    if (page < start_page) {
        page_offset = (page - (start_page - new_preload_cache_size));

        g_assert (page_offset >= 0 &&
              page_offset < new_preload_cache_size);
        target_page = new_prev_job + page_offset;
        new_priority = EV_JOB_PRIORITY_LOW;
    } else if (page > end_page) {
        page_offset = (page - (end_page + 1));

        g_assert (page_offset >= 0 &&
              page_offset < new_preload_cache_size);
        target_page = new_next_job + page_offset;
        new_priority = EV_JOB_PRIORITY_LOW;
    } else {
        page_offset = page - start_page;
        g_assert (page_offset >= 0 &&
              page_offset <= ((end_page - start_page) + 1));
        new_priority = EV_JOB_PRIORITY_URGENT;
        target_page = new_job_list + page_offset;
    }

    *target_page = *job_info;
    job_info->job = NULL;
    job_info->region = NULL;
    job_info->surface = NULL;

    if (new_priority != priority && target_page->job) {
        ev_job_scheduler_update_job (target_page->job, new_priority);
    }
}

static gsize
ev_pixbuf_cache_get_page_size (EvPixbufCache *pixbuf_cache,
                   gint           page_index,
                   gdouble        scale,
                   gint           rotation)
{
    gint width, height;

    _get_page_size_for_scale_and_rotation (pixbuf_cache->document,
                           page_index, scale, rotation,
                           &width, &height);
    return height * cairo_format_stride_for_width (CAIRO_FORMAT_RGB24, width);
}

static gint
ev_pixbuf_cache_get_preload_size (EvPixbufCache *pixbuf_cache,
                  gint           start_page,
                  gint           end_page,
                  gdouble        scale,
                  gint           rotation)
{
    gsize range_size = 0;
    gint  new_preload_cache_size = 0;
    gint  i;
    guint n_pages = ev_document_get_n_pages (pixbuf_cache->document);

    /* Get the size of the current range */
    for (i = start_page; i <= end_page; i++) {
        range_size += ev_pixbuf_cache_get_page_size (pixbuf_cache, i, scale, rotation);
    }

    if (range_size >= pixbuf_cache->max_size)
        return new_preload_cache_size;

    i = 1;
    while (((start_page - i > 0) || (end_page + i < n_pages)) &&
           new_preload_cache_size < MAX_PRELOADED_PAGES) {
        gsize    page_size;
        gboolean updated = FALSE;

        if (end_page + i < n_pages) {
            page_size = ev_pixbuf_cache_get_page_size (pixbuf_cache, end_page + i,
                                   scale, rotation);
            if (page_size + range_size <= pixbuf_cache->max_size) {
                range_size += page_size;
                new_preload_cache_size++;
                updated = TRUE;
            } else {
                break;
            }
        }

        if (start_page - i > 0) {
            page_size = ev_pixbuf_cache_get_page_size (pixbuf_cache, start_page - i,
                                   scale, rotation);
            if (page_size + range_size <= pixbuf_cache->max_size) {
                range_size += page_size;
                if (!updated)
                    new_preload_cache_size++;
            } else {
                break;
            }
        }
        i++;
    }

    return new_preload_cache_size;
}

static void
ev_pixbuf_cache_update_range (EvPixbufCache *pixbuf_cache,
                  gint           start_page,
                  gint           end_page,
                  guint          rotation,
                  gdouble        scale)
{
    CacheJobInfo *new_job_list;
    CacheJobInfo *new_prev_job = NULL;
    CacheJobInfo *new_next_job = NULL;
    gint          new_preload_cache_size;
    guint         new_job_list_len;
    int           i, page;

    new_preload_cache_size = ev_pixbuf_cache_get_preload_size (pixbuf_cache,
                                   start_page,
                                   end_page,
                                   scale,
                                   rotation);
    if (pixbuf_cache->start_page == start_page &&
        pixbuf_cache->end_page == end_page &&
        pixbuf_cache->preload_cache_size == new_preload_cache_size)
        return;

    new_job_list_len = (end_page - start_page) + 1;
    new_job_list = g_slice_alloc0 (sizeof (CacheJobInfo) * new_job_list_len);
    if (new_preload_cache_size > 0) {
        new_prev_job = g_slice_alloc0 (sizeof (CacheJobInfo) * new_preload_cache_size);
        new_next_job = g_slice_alloc0 (sizeof (CacheJobInfo) * new_preload_cache_size);
    }

    /* We go through each job in the old cache and either clear it or move
     * it to a new location. */

    /* Start with the prev cache. */
    page = pixbuf_cache->start_page - pixbuf_cache->preload_cache_size;
    for (i = 0; i < pixbuf_cache->preload_cache_size; i++) {
        if (page < 0) {
            dispose_cache_job_info (pixbuf_cache->prev_job + i, pixbuf_cache);
        } else {
            move_one_job (pixbuf_cache->prev_job + i,
                      pixbuf_cache, page,
                      new_job_list, new_prev_job, new_next_job,
                      new_preload_cache_size,
                      start_page, end_page, EV_JOB_PRIORITY_LOW);
        }
        page ++;
    }

    page = pixbuf_cache->start_page;
    for (i = 0; i < PAGE_CACHE_LEN (pixbuf_cache) && page >= 0; i++) {
        move_one_job (pixbuf_cache->job_list + i,
                  pixbuf_cache, page,
                  new_job_list, new_prev_job, new_next_job,
                  new_preload_cache_size,
                  start_page, end_page, EV_JOB_PRIORITY_URGENT);
        page ++;
    }

    for (i = 0; i < pixbuf_cache->preload_cache_size; i++) {
        if (page >= ev_document_get_n_pages (pixbuf_cache->document)) {
            dispose_cache_job_info (pixbuf_cache->next_job + i, pixbuf_cache);
        } else {
            move_one_job (pixbuf_cache->next_job + i,
                      pixbuf_cache, page,
                      new_job_list, new_prev_job, new_next_job,
                      new_preload_cache_size,
                      start_page, end_page, EV_JOB_PRIORITY_LOW);
        }
        page ++;
    }

    if (pixbuf_cache->job_list) {
        g_slice_free1 (sizeof (CacheJobInfo) * pixbuf_cache->job_list_len,
                   pixbuf_cache->job_list);
    }
    if (pixbuf_cache->prev_job) {
        g_slice_free1 (sizeof (CacheJobInfo) * pixbuf_cache->preload_cache_size,
                   pixbuf_cache->prev_job);
    }
    if (pixbuf_cache->next_job) {
        g_slice_free1 (sizeof (CacheJobInfo) * pixbuf_cache->preload_cache_size,
                   pixbuf_cache->next_job);
    }

    pixbuf_cache->preload_cache_size = new_preload_cache_size;
    pixbuf_cache->job_list_len = new_job_list_len;

    pixbuf_cache->job_list = new_job_list;
    pixbuf_cache->prev_job = new_prev_job;
    pixbuf_cache->next_job = new_next_job;

    pixbuf_cache->start_page = start_page;
    pixbuf_cache->end_page = end_page;
}

static CacheJobInfo *
find_job_cache (EvPixbufCache *pixbuf_cache,
        int            page)
{
    int page_offset;

    if (page < (pixbuf_cache->start_page - pixbuf_cache->preload_cache_size) ||
        page > (pixbuf_cache->end_page + pixbuf_cache->preload_cache_size))
        return NULL;

    if (page < pixbuf_cache->start_page) {
        page_offset = (page - (pixbuf_cache->start_page - pixbuf_cache->preload_cache_size));

        g_assert (page_offset >= 0 &&
              page_offset < pixbuf_cache->preload_cache_size);
        return pixbuf_cache->prev_job + page_offset;
    }

    if (page > pixbuf_cache->end_page) {
        page_offset = (page - (pixbuf_cache->end_page + 1));

        g_assert (page_offset >= 0 &&
              page_offset < pixbuf_cache->preload_cache_size);
        return pixbuf_cache->next_job + page_offset;
    }

    page_offset = page - pixbuf_cache->start_page;
    g_assert (page_offset >= 0 &&
          page_offset <= PAGE_CACHE_LEN(pixbuf_cache));
    return pixbuf_cache->job_list + page_offset;
}

static void
ev_pixbuf_cache_clear_job_sizes (EvPixbufCache *pixbuf_cache,
                 gfloat         scale)
{
    int i;

    for (i = 0; i < PAGE_CACHE_LEN (pixbuf_cache); i++) {
        check_job_size_and_unref (pixbuf_cache, pixbuf_cache->job_list + i, scale);
    }

    for (i = 0; i < pixbuf_cache->preload_cache_size; i++) {
        check_job_size_and_unref (pixbuf_cache, pixbuf_cache->prev_job + i, scale);
        check_job_size_and_unref (pixbuf_cache, pixbuf_cache->next_job + i, scale);
    }
}

static void
get_selection_colors (EvView *view, GdkColor *text, GdkColor *base)
{
        GdkRGBA fg, bg;

        _ev_view_get_selection_colors (view, &bg, &fg);

        text->pixel = 0;
        text->red = CLAMP ((guint) (fg.red * 65535), 0, 65535);
        text->green = CLAMP ((guint) (fg.green * 65535), 0, 65535);
        text->blue = CLAMP ((guint) (fg.blue * 65535), 0, 65535);

        base->pixel = 0;
        base->red = CLAMP ((guint) (bg.red * 65535), 0, 65535);
        base->green = CLAMP ((guint) (bg.green * 65535), 0, 65535);
        base->blue = CLAMP ((guint) (bg.blue * 65535), 0, 65535);
}

static void
add_job (EvPixbufCache  *pixbuf_cache,
     CacheJobInfo   *job_info,
     cairo_region_t *region,
     gint            width,
     gint            height,
     gint            page,
     gint            rotation,
     gfloat          scale,
     EvJobPriority   priority)
{
    job_info->device_scale = get_device_scale (pixbuf_cache);
    job_info->page_ready = FALSE;

    if (job_info->region)
        cairo_region_destroy (job_info->region);
    job_info->region = region ? cairo_region_reference (region) : NULL;

    if (job_info->job)
        end_job (job_info, pixbuf_cache);

    job_info->job = ev_job_render_new (pixbuf_cache->document,
                       page, rotation,
                                           scale * job_info->device_scale,
                       width * job_info->device_scale,
                                           height * job_info->device_scale);

    if (new_selection_surface_needed (pixbuf_cache, job_info, page, scale)) {
        GdkColor text, base;

        get_selection_colors (EV_VIEW (pixbuf_cache->view), &text, &base);
        ev_job_render_set_selection_info (EV_JOB_RENDER (job_info->job), 
                          &(job_info->target_points),
                          job_info->selection_style,
                          &text, &base);
    }

    g_signal_connect (job_info->job, "finished",
              G_CALLBACK (job_finished_cb),
              pixbuf_cache);
    ev_job_scheduler_push_job (job_info->job, priority);
}

static void
add_job_if_needed (EvPixbufCache *pixbuf_cache,
           CacheJobInfo  *job_info,
           gint           page,
           gint           rotation,
           gfloat         scale,
           EvJobPriority  priority)
{
    gint device_scale = get_device_scale (pixbuf_cache);
    gint width, height;

    if (job_info->job)
        return;

    _get_page_size_for_scale_and_rotation (pixbuf_cache->document,
                           page, scale, rotation,
                           &width, &height);

    if (job_info->surface &&
        job_info->device_scale == device_scale &&
        cairo_image_surface_get_width (job_info->surface) == width * device_scale &&
        cairo_image_surface_get_height (job_info->surface) == height * device_scale)
        return;

    /* Free old surfaces for non visible pages */
    if (priority == EV_JOB_PRIORITY_LOW) {
        if (job_info->surface) {
            cairo_surface_destroy (job_info->surface);
            job_info->surface = NULL;
        }

        if (job_info->selection) {
            cairo_surface_destroy (job_info->selection);
            job_info->selection = NULL;
        }
    }

    add_job (pixbuf_cache, job_info, NULL,
         width, height, page, rotation, scale,
         priority);
}

static void
add_prev_jobs_if_needed (EvPixbufCache *pixbuf_cache,
                         gint           rotation,
                         gfloat         scale)
{
        CacheJobInfo *job_info;
        int page;
        int i;

        for (i = pixbuf_cache->preload_cache_size - 1; i >= FIRST_VISIBLE_PREV(pixbuf_cache); i--) {
                job_info = (pixbuf_cache->prev_job + i);
                page = pixbuf_cache->start_page - pixbuf_cache->preload_cache_size + i;

                add_job_if_needed (pixbuf_cache, job_info,
                                   page, rotation, scale,
                                   EV_JOB_PRIORITY_LOW);
        }
}

static void
add_next_jobs_if_needed (EvPixbufCache *pixbuf_cache,
                         gint           rotation,
                         gfloat         scale)
{
        CacheJobInfo *job_info;
        int page;
        int i;

        for (i = 0; i < VISIBLE_NEXT_LEN(pixbuf_cache); i++) {
                job_info = (pixbuf_cache->next_job + i);
                page = pixbuf_cache->end_page + 1 + i;

                add_job_if_needed (pixbuf_cache, job_info,
                                   page, rotation, scale,
                                   EV_JOB_PRIORITY_LOW);
        }
}

static void
ev_pixbuf_cache_add_jobs_if_needed (EvPixbufCache *pixbuf_cache,
                    gint           rotation,
                    gfloat         scale)
{
    CacheJobInfo *job_info;
    int page;
    int i;

    for (i = 0; i < PAGE_CACHE_LEN (pixbuf_cache); i++) {
        job_info = (pixbuf_cache->job_list + i);
        page = pixbuf_cache->start_page + i;

        add_job_if_needed (pixbuf_cache, job_info,
                   page, rotation, scale,
                   EV_JOB_PRIORITY_URGENT);
    }

        if (pixbuf_cache->scroll_direction == SCROLL_DIRECTION_UP) {
                add_prev_jobs_if_needed (pixbuf_cache, rotation, scale);
                add_next_jobs_if_needed (pixbuf_cache, rotation, scale);
        } else {
                add_next_jobs_if_needed (pixbuf_cache, rotation, scale);
                add_prev_jobs_if_needed (pixbuf_cache, rotation, scale);
        }
}

static ScrollDirection
ev_pixbuf_cache_get_scroll_direction (EvPixbufCache *pixbuf_cache,
                                      gint           start_page,
                                      gint           end_page)
{
        if (start_page < pixbuf_cache->start_page)
                return SCROLL_DIRECTION_UP;

        if (end_page > pixbuf_cache->end_page)
                return SCROLL_DIRECTION_DOWN;

        if (start_page > pixbuf_cache->start_page)
                return SCROLL_DIRECTION_DOWN;

        if (end_page < pixbuf_cache->end_page)
                return SCROLL_DIRECTION_UP;

        return pixbuf_cache->scroll_direction;
}

void
ev_pixbuf_cache_set_page_range (EvPixbufCache  *pixbuf_cache,
                gint            start_page,
                gint            end_page,
                GList          *selection_list)
{
    gdouble scale = ev_document_model_get_scale (pixbuf_cache->model);
    gint    rotation = ev_document_model_get_rotation (pixbuf_cache->model);

    g_return_if_fail (EV_IS_PIXBUF_CACHE (pixbuf_cache));

    g_return_if_fail (start_page >= 0 && start_page < ev_document_get_n_pages (pixbuf_cache->document));
    g_return_if_fail (end_page >= 0 && end_page < ev_document_get_n_pages (pixbuf_cache->document));
    g_return_if_fail (end_page >= start_page);

        pixbuf_cache->scroll_direction = ev_pixbuf_cache_get_scroll_direction (pixbuf_cache, start_page, end_page);

    /* First, resize the page_range as needed.  We cull old pages
     * mercilessly. */
    ev_pixbuf_cache_update_range (pixbuf_cache, start_page, end_page, rotation, scale);

    /* Then, we update the current jobs to see if any of them are the wrong
     * size, we remove them if we need to. */
    ev_pixbuf_cache_clear_job_sizes (pixbuf_cache, scale);

    /* Next, we update the target selection for our pages */
    ev_pixbuf_cache_set_selection_list (pixbuf_cache, selection_list);

    /* Finally, we add the new jobs for all the sizes that don't have a
     * pixbuf */
    ev_pixbuf_cache_add_jobs_if_needed (pixbuf_cache, rotation, scale);
}

void
ev_pixbuf_cache_set_inverted_colors (EvPixbufCache *pixbuf_cache,
                     gboolean       inverted_colors)
{
    gint i;

    if (pixbuf_cache->inverted_colors == inverted_colors)
        return;

    pixbuf_cache->inverted_colors = inverted_colors;

    for (i = 0; i < pixbuf_cache->preload_cache_size; i++) {
        CacheJobInfo *job_info;

        job_info = pixbuf_cache->prev_job + i;
        if (job_info && job_info->surface)
            ev_document_misc_invert_surface (job_info->surface);

        job_info = pixbuf_cache->next_job + i;
        if (job_info && job_info->surface)
            ev_document_misc_invert_surface (job_info->surface);
    }

    for (i = 0; i < PAGE_CACHE_LEN (pixbuf_cache); i++) {
        CacheJobInfo *job_info;

        job_info = pixbuf_cache->job_list + i;
        if (job_info && job_info->surface)
            ev_document_misc_invert_surface (job_info->surface);
    }
}

cairo_surface_t *
ev_pixbuf_cache_get_surface (EvPixbufCache *pixbuf_cache,
                 gint           page)
{
    CacheJobInfo *job_info;

    job_info = find_job_cache (pixbuf_cache, page);
    if (job_info == NULL)
        return NULL;

    if (job_info->page_ready)
        return job_info->surface;

    /* We don't need to wait for the idle to handle the callback */
    if (job_info->job &&
        EV_JOB_RENDER (job_info->job)->page_ready) {
        copy_job_to_job_info (EV_JOB_RENDER (job_info->job), job_info, pixbuf_cache);
        g_signal_emit (pixbuf_cache, signals[JOB_FINISHED], 0, job_info->region);
    }

    return job_info->surface;
}

static gboolean
new_selection_surface_needed (EvPixbufCache *pixbuf_cache,
                  CacheJobInfo  *job_info,
                  gint           page,
                  gfloat         scale)
{
    if (job_info->selection)
        return job_info->selection_scale != scale;
    return job_info->points_set;
}

static gboolean
new_selection_region_needed (EvPixbufCache *pixbuf_cache,
                 CacheJobInfo  *job_info,
                 gint           page,
                 gfloat         scale)
{
    if (job_info->selection_region)
        return job_info->selection_region_scale != scale;
    return job_info->points_set;
}

static void
clear_selection_surface_if_needed (EvPixbufCache *pixbuf_cache,
                                   CacheJobInfo  *job_info,
                                   gint           page,
                                   gfloat         scale)
{
    if (new_selection_surface_needed (pixbuf_cache, job_info, page, scale)) {
        if (job_info->selection)
            cairo_surface_destroy (job_info->selection);
        job_info->selection = NULL;
        job_info->selection_points.x1 = -1;
    }
}

static void
clear_selection_region_if_needed (EvPixbufCache *pixbuf_cache,
                                  CacheJobInfo  *job_info,
                                  gint           page,
                                  gfloat         scale)
{
    if (new_selection_region_needed (pixbuf_cache, job_info, page, scale)) {
        if (job_info->selection_region)
            cairo_region_destroy (job_info->selection_region);
        job_info->selection_region = NULL;
        job_info->selection_region_points.x1 = -1;
    }
}

/* Clears the cache of jobs and pixbufs.
 */
void
ev_pixbuf_cache_clear (EvPixbufCache *pixbuf_cache)
{
    int i;

    if (!pixbuf_cache->job_list)
        return;

    for (i = 0; i < pixbuf_cache->preload_cache_size; i++) {
        dispose_cache_job_info (pixbuf_cache->prev_job + i, pixbuf_cache);
        dispose_cache_job_info (pixbuf_cache->next_job + i, pixbuf_cache);
    }

    for (i = 0; i < PAGE_CACHE_LEN (pixbuf_cache); i++) {
        dispose_cache_job_info (pixbuf_cache->job_list + i, pixbuf_cache);
    }
}


void
ev_pixbuf_cache_style_changed (EvPixbufCache *pixbuf_cache)
{
    gint i;

    if (!pixbuf_cache->job_list)
        return;

    /* FIXME: doesn't update running jobs. */
    for (i = 0; i < pixbuf_cache->preload_cache_size; i++) {
        CacheJobInfo *job_info;

        job_info = pixbuf_cache->prev_job + i;
        if (job_info->selection) {
            cairo_surface_destroy (job_info->selection);
            job_info->selection = NULL;
            job_info->selection_points.x1 = -1;
        }

        job_info = pixbuf_cache->next_job + i;
        if (job_info->selection) {
            cairo_surface_destroy (job_info->selection);
            job_info->selection = NULL;
            job_info->selection_points.x1 = -1;
        }
    }

    for (i = 0; i < PAGE_CACHE_LEN (pixbuf_cache); i++) {
        CacheJobInfo *job_info;

        job_info = pixbuf_cache->job_list + i;
        if (job_info->selection) {
            cairo_surface_destroy (job_info->selection);
            job_info->selection = NULL;
            job_info->selection_points.x1 = -1;
        }
    }
}

cairo_surface_t *
ev_pixbuf_cache_get_selection_surface (EvPixbufCache   *pixbuf_cache,
                       gint             page,
                       gfloat           scale)
{
    CacheJobInfo *job_info;

    /* the document does not implement the selection interface */
    if (!EV_IS_SELECTION (pixbuf_cache->document))
        return NULL;

    job_info = find_job_cache (pixbuf_cache, page);
    if (job_info == NULL)
        return NULL;

    /* No selection on this page */
    if (!job_info->points_set)
        return NULL;

    /* If we have a running job, we just return what we have under the
     * assumption that it'll be updated later and we can scale it as need
     * be */
    if (job_info->job && EV_JOB_RENDER (job_info->job)->include_selection)
        return job_info->selection;

    /* Now, lets see if we need to resize the image.  If we do, we clear the
     * old one. */
    clear_selection_surface_if_needed (pixbuf_cache, job_info, page, scale);

    /* Finally, we see if the two scales are the same, and get a new pixbuf
     * if needed.  We do this synchronously for now.  At some point, we
     * _should_ be able to get rid of the doc_mutex, so the synchronicity
     * doesn't kill us.  Rendering a few glyphs should really be fast.
     */
    if (ev_rect_cmp (&(job_info->target_points), &(job_info->selection_points))) {
        EvRectangle *old_points;
        GdkColor text, base;
        EvRenderContext *rc;
        EvPage *ev_page;
        gint width, height;

        /* we need to get a new selection pixbuf */
        ev_document_doc_mutex_lock ();
        if (job_info->selection_points.x1 < 0) {
            g_assert (job_info->selection == NULL);
            old_points = NULL;
        } else {
            old_points = &(job_info->selection_points);
        }

        ev_page = ev_document_get_page (pixbuf_cache->document, page);
                _get_page_size_for_scale_and_rotation (pixbuf_cache->document,
                                                       page,
                               scale * job_info->device_scale,
                               0, &width, &height);

        rc = ev_render_context_new (ev_page, 0, scale * job_info->device_scale);
                ev_render_context_set_target_size (rc, width, height);
        g_object_unref (ev_page);

        get_selection_colors (EV_VIEW (pixbuf_cache->view), &text, &base);
        ev_selection_render_selection (EV_SELECTION (pixbuf_cache->document),
                           rc, &(job_info->selection),
                           &(job_info->target_points),
                           old_points,
                           job_info->selection_style,
                           &text, &base);
                if (job_info->selection)
                        set_device_scale_on_surface (job_info->selection, job_info->device_scale);
        job_info->selection_points = job_info->target_points;
        job_info->selection_scale = scale * job_info->device_scale;
        g_object_unref (rc);
        ev_document_doc_mutex_unlock ();
    }
    return job_info->selection;
}

cairo_region_t *
ev_pixbuf_cache_get_selection_region (EvPixbufCache *pixbuf_cache,
                      gint           page,
                      gfloat         scale)
{
    CacheJobInfo *job_info;

    /* the document does not implement the selection interface */
    if (!EV_IS_SELECTION (pixbuf_cache->document))
        return NULL;

    job_info = find_job_cache (pixbuf_cache, page);
    if (job_info == NULL)
        return NULL;

    /* No selection on this page */
    if (!job_info->points_set)
        return NULL;

    /* If we have a running job, we just return what we have under the
     * assumption that it'll be updated later and we can scale it as need
     * be */
    if (job_info->job && EV_JOB_RENDER (job_info->job)->include_selection)
        return job_info->selection_region && !cairo_region_is_empty(job_info->selection_region) ?
                        job_info->selection_region : NULL;

    /* Now, lets see if we need to resize the region.  If we do, we clear the
     * old one. */
    clear_selection_region_if_needed (pixbuf_cache, job_info, page, scale);

    /* Finally, we see if the two scales are the same, and get a new region
     * if needed.
     */
    if (ev_rect_cmp (&(job_info->target_points), &(job_info->selection_region_points))) {
        EvRenderContext *rc;
        EvPage *ev_page;
        gint width, height;

        ev_document_doc_mutex_lock ();
        ev_page = ev_document_get_page (pixbuf_cache->document, page);

        _get_page_size_for_scale_and_rotation (pixbuf_cache->document,
                               page, scale, 0,
                               &width, &height);

        rc = ev_render_context_new (ev_page, 0, 0.);
        ev_render_context_set_target_size (rc, width, height);
        g_object_unref (ev_page);

        if (job_info->selection_region)
            cairo_region_destroy (job_info->selection_region);
        job_info->selection_region =
            ev_selection_get_selection_region (EV_SELECTION (pixbuf_cache->document),
                               rc, job_info->selection_style,
                               &(job_info->target_points));
        job_info->selection_region_points = job_info->target_points;
        job_info->selection_region_scale = scale;
        g_object_unref (rc);
        ev_document_doc_mutex_unlock ();
    }
    return job_info->selection_region && !cairo_region_is_empty(job_info->selection_region) ?
                job_info->selection_region : NULL;
}

static void
update_job_selection (CacheJobInfo    *job_info,
              EvViewSelection *selection)
{
    job_info->points_set = TRUE;        
    job_info->target_points = selection->rect;
    job_info->selection_style = selection->style;
}

static void
clear_job_selection (CacheJobInfo *job_info)
{
    job_info->points_set = FALSE;
    job_info->selection_points.x1 = -1;

    if (job_info->selection) {
        cairo_surface_destroy (job_info->selection);
        job_info->selection = NULL;
    }

        if (job_info->selection_region) {
                cairo_region_destroy (job_info->selection_region);
                job_info->selection_region = NULL;
        }
}

/* This function will reset the selection on pages that no longer have them, and
 * will update the target_selection on those that need it.  It will _not_ free
 * the previous selection_list -- that's up to caller to do.
 */
void
ev_pixbuf_cache_set_selection_list (EvPixbufCache *pixbuf_cache,
                    GList         *selection_list)
{
    EvViewSelection *selection;
    GList *list = selection_list;
    int page;
    int i;

    g_return_if_fail (EV_IS_PIXBUF_CACHE (pixbuf_cache));

    if (!EV_IS_SELECTION (pixbuf_cache->document))
        return;

        if (pixbuf_cache->start_page == -1 || pixbuf_cache->end_page == -1)
                return;

    /* We check each area to see what needs updating, and what needs freeing; */
    page = pixbuf_cache->start_page - pixbuf_cache->preload_cache_size;
    for (i = 0; i < pixbuf_cache->preload_cache_size; i++) {
        if (page < 0) {
            page ++;
            continue;
        }

        selection = NULL;
        while (list) {
            if (((EvViewSelection *)list->data)->page == page) {
                selection = list->data;
                break;
            } else if (((EvViewSelection *)list->data)->page > page) 
                break;
            list = list->next;
        }

        if (selection)
            update_job_selection (pixbuf_cache->prev_job + i, selection);
        else
            clear_job_selection (pixbuf_cache->prev_job + i);
        page ++;
    }

    page = pixbuf_cache->start_page;
    for (i = 0; i < PAGE_CACHE_LEN (pixbuf_cache); i++) {
        selection = NULL;
        while (list) {
            if (((EvViewSelection *)list->data)->page == page) {
                selection = list->data;
                break;
            } else if (((EvViewSelection *)list->data)->page > page) 
                break;
            list = list->next;
        }

        if (selection)
            update_job_selection (pixbuf_cache->job_list + i, selection);
        else
            clear_job_selection (pixbuf_cache->job_list + i);
        page ++;
    }

    for (i = 0; i < pixbuf_cache->preload_cache_size; i++) {
        if (page >= ev_document_get_n_pages (pixbuf_cache->document))
            break;

        selection = NULL;
        while (list) {
            if (((EvViewSelection *)list->data)->page == page) {
                selection = list->data;
                break;
            } else if (((EvViewSelection *)list->data)->page > page) 
                break;
            list = list->next;
        }

        if (selection)
            update_job_selection (pixbuf_cache->next_job + i, selection);
        else
            clear_job_selection (pixbuf_cache->next_job + i);
        page ++;
    }
}


/* Returns what the pixbuf cache thinks is */

GList *
ev_pixbuf_cache_get_selection_list (EvPixbufCache *pixbuf_cache)
{
    EvViewSelection *selection;
    GList *retval = NULL;
    int page;
    int i;

    g_return_val_if_fail (EV_IS_PIXBUF_CACHE (pixbuf_cache), NULL);

        if (pixbuf_cache->start_page == -1 || pixbuf_cache->end_page == -1)
                return NULL;

    /* We check each area to see what needs updating, and what needs freeing; */
    page = pixbuf_cache->start_page - pixbuf_cache->preload_cache_size;
    for (i = 0; i < pixbuf_cache->preload_cache_size; i++) {
        if (page < 0) {
            page ++;
            continue;
        }

        if (pixbuf_cache->prev_job[i].selection_points.x1 != -1) {
            selection = g_slice_new0 (EvViewSelection);
            selection->page = page;
            selection->rect = pixbuf_cache->prev_job[i].selection_points;
            if (pixbuf_cache->prev_job[i].selection_region)
                selection->covered_region = cairo_region_reference (pixbuf_cache->prev_job[i].selection_region);
            retval = g_list_prepend (retval, selection);
        }
        
        page ++;
    }

    page = pixbuf_cache->start_page;
    for (i = 0; i < PAGE_CACHE_LEN (pixbuf_cache); i++) {
        if (pixbuf_cache->job_list[i].selection_points.x1 != -1) {
            selection = g_slice_new0 (EvViewSelection);
            selection->page = page;
            selection->rect = pixbuf_cache->job_list[i].selection_points;
            if (pixbuf_cache->job_list[i].selection_region)
                selection->covered_region = cairo_region_reference (pixbuf_cache->job_list[i].selection_region);
            retval = g_list_prepend (retval, selection);
        }
        
        page ++;
    }

    for (i = 0; i < pixbuf_cache->preload_cache_size; i++) {
        if (page >= ev_document_get_n_pages (pixbuf_cache->document))
            break;

        if (pixbuf_cache->next_job[i].selection_points.x1 != -1) {
            selection = g_slice_new0 (EvViewSelection);
            selection->page = page;
            selection->rect = pixbuf_cache->next_job[i].selection_points;
            if (pixbuf_cache->next_job[i].selection_region)
                selection->covered_region = cairo_region_reference (pixbuf_cache->next_job[i].selection_region);
            retval = g_list_prepend (retval, selection);
        }
        
        page ++;
    }

    return g_list_reverse (retval);
}

void
ev_pixbuf_cache_reload_page (EvPixbufCache  *pixbuf_cache,
                 cairo_region_t *region,
                 gint            page,
                 gint            rotation,
                 gdouble         scale)
{
    CacheJobInfo *job_info;
        gint width, height;

    job_info = find_job_cache (pixbuf_cache, page);
    if (job_info == NULL)
        return;

    _get_page_size_for_scale_and_rotation (pixbuf_cache->document,
                           page, scale, rotation,
                           &width, &height);
        add_job (pixbuf_cache, job_info, region,
         width, height, page, rotation, scale,
         EV_JOB_PRIORITY_URGENT);
}