src/libaudcore/art.cc

/*
 * art.c
 * Copyright 2011-2012 John Lindgren
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice,
 *    this list of conditions, and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions, and the following disclaimer in the documentation
 *    provided with the distribution.
 *
 * This software is provided "as is" and without any warranty, express or
 * implied. In no event shall the authors be liable for any damages arising from
 * the use of this software.
 */

#include "internal.h"
#include "probe.h"

#include <assert.h>
#include <errno.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include <glib/gstdio.h>

#include "audstrings.h"
#include "hook.h"
#include "mainloop.h"
#include "multihash.h"
#include "runtime.h"
#include "scanner.h"
#include "threads.h"
#include "vfs.h"

#define FLAG_DONE 1
#define FLAG_SENT 2

struct AudArtItem
{
    String filename;
    int refcount;
    int flag;

    /* album art as JPEG or PNG data */
    Index<char> data;

    /* album art as (possibly a temporary) file */
    String art_file;
    bool is_temp;
};

static aud::mutex mutex;
static SimpleHash<String, AudArtItem> art_items;
static AudArtItem * current_item;
static QueuedFunc queued_requests;

static Index<AudArtItem *> get_queued()
{
    auto mh = mutex.take();
    Index<AudArtItem *> queued;

    art_items.iterate([&](const String &, AudArtItem & item) {
        if (item.flag == FLAG_DONE)
        {
            queued.append(&item);
            item.flag = FLAG_SENT;
        }
    });

    queued_requests.stop();

    return queued;
}

static void send_requests()
{
    auto queued = get_queued();
    for (AudArtItem * item : queued)
    {
        hook_call("art ready", (void *)(const char *)item->filename);
        aud_art_unref(item); /* release temporary reference */
    }
}

static void finish_item(aud::mutex::holder &, AudArtItem * item,
                        Index<char> && data, String && art_file)
{
    /* already finished? */
    if (item->flag)
        return;

    item->data = std::move(data);
    item->art_file = std::move(art_file);
    item->flag = FLAG_DONE;

    queued_requests.queue(send_requests);
}

static void request_callback(ScanRequest * request)
{
    auto mh = mutex.take();
    AudArtItem * item = art_items.lookup(request->filename);

    if (item)
        finish_item(mh, item, std::move(request->image_data),
                    std::move(request->image_file));
}

static AudArtItem * art_item_get(aud::mutex::holder &, const String & filename,
                                 bool * queued)
{
    if (queued)
        *queued = false;

    // blacklist stdin
    if (!strncmp(filename, "stdin://", 8))
        return nullptr;

    AudArtItem * item = art_items.lookup(filename);

    if (item && item->flag)
    {
        item->refcount++;
        return item;
    }

    if (!item)
    {
        item = art_items.add(filename, AudArtItem());
        item->filename = filename;
        item->refcount = 1; /* temporary reference */

        scanner_request(
            new ScanRequest(filename, SCAN_IMAGE, request_callback));
    }

    if (queued)
        *queued = true;

    return nullptr;
}

static void art_item_unref(aud::mutex::holder &, AudArtItem * item)
{
    if (!--item->refcount)
    {
        /* delete temporary file */
        if (item->art_file && item->is_temp)
        {
            StringBuf local = uri_to_filename(item->art_file);
            if (local)
                g_unlink(local);
        }

        art_items.remove(item->filename);
    }
}

static void clear_current(aud::mutex::holder & mh)
{
    if (current_item)
    {
        art_item_unref(mh, current_item);
        current_item = nullptr;
    }
}

void art_cache_current(const String & filename, Index<char> && data,
                       String && art_file)
{
    auto mh = mutex.take();
    clear_current(mh);

    AudArtItem * item = art_items.lookup(filename);

    if (!item)
    {
        item = art_items.add(filename, AudArtItem());
        item->filename = filename;
        item->refcount = 1; /* temporary reference */
    }

    finish_item(mh, item, std::move(data), std::move(art_file));

    item->refcount++;
    current_item = item;
}

void art_clear_current()
{
    auto mh = mutex.take();
    clear_current(mh);
}

void art_cleanup()
{
    auto queued = get_queued();
    for (AudArtItem * item : queued)
        aud_art_unref(item); /* release temporary reference */

    /* playback should already be stopped */
    assert(!current_item);

    if (art_items.n_items())
        AUDWARN("Album art reference count not zero at exit!\n");
}

EXPORT AudArtPtr aud_art_request(const char * file, int format, bool * queued)
{
    auto mh = mutex.take();
    AudArtItem * item = art_item_get(mh, String(file), queued);

    if (!item)
        return AudArtPtr();

    if (format & AUD_ART_DATA)
    {
        /* load data from external image file */
        if (!item->data.len() && item->art_file)
        {
            VFSFile file(item->art_file, "r");
            if (file)
                item->data = file.read_all();
        }

        if (!item->data.len())
        {
            art_item_unref(mh, item);
            return AudArtPtr();
        }
    }

    if (format & AUD_ART_FILE)
    {
        /* save data to temporary file */
        if (item->data.len() && !item->art_file)
        {
            String local =
                write_temp_file(item->data.begin(), item->data.len());
            if (local)
            {
                item->art_file = String(filename_to_uri(local));
                item->is_temp = true;
            }
        }

        if (!item->art_file)
        {
            art_item_unref(mh, item);
            return AudArtPtr();
        }
    }

    return AudArtPtr(item);
}

EXPORT const Index<char> * aud_art_data(const AudArtItem * item)
{
    return &item->data;
}
EXPORT const char * aud_art_file(const AudArtItem * item)
{
    return item->art_file;
}

EXPORT void aud_art_unref(AudArtItem * item)
{
    auto mh = mutex.take();
    art_item_unref(mh, item);
}