1

// A source of tile images of a specific width/height, zoom level range, and some other attributes

     2

     3

/**

     4

 * A source of image tiles.

     5

 *

     6

 * The image source is expected to serve fixed-size tiles (tile_width × tile_height) of image data based on the 

     7

 * x, y, zl URL query parameters. 

     8

 *

     9

 *  x, y        - the pixel coordinates of the top-left corner

    10

 *                XXX: these are scaled from the image coordinates by the zoom level

    11

 *

    12

 *  zl          - the zoom level used, out < zl < in.

    13

 *                The image pixels are scaled by powers-of-two, so a 256x256 tile at zl=-1 shows a 512x512 area of the

    14

 *                1:1 image.

    15

 */

    16

var Source = Class.create({

    17

    initialize: function (path, tile_width, tile_height, zoom_min, zoom_max, img_width, img_height) {

    18

        this.path = path;

    19

        this.tile_width = tile_width;

    20

        this.tile_height = tile_height;

    21

        this.zoom_min = zoom_min;

    22

        this.zoom_max = zoom_max;

    23

        this.img_width = img_width;

    24

        this.img_height = img_height;

    25

    26

        this.refresh = false;

    27

        this.opt_key = this.opt_value = null;

    28

    },

    29

    30

    /**

    31

     * Return an URL representing the tile at the given viewport (row, col) at the given zl.

    32

     *

    33

     * XXX: sw/sh = screen-width/height, used to choose an appropriate output size for dynamic image sources...

    34

     */

    35

    build_url: function (col, row, zl /*, sw, sh */) {

    36

        // XXX: distribute tile requests across tile*.foo.bar

    37

        if (0) {

    38

            // two-bit hash (0-4) based on the (col, row)

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            var hash = ( (col % 2) << 1 | (row % 2) ) + 1;

    40

    41

            // the subdomain to use

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            var subdomain = "";

    43

    44

            subdomain = "tile" + hash + ".";

    45

        }

    46

    47

        // the (x, y) co-ordinates

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        var x = col * this.tile_width;

    49

        var y = row * this.tile_height;

    50

    51

        var url = this.path + "?x=" + x + "&y=" + y + "&zl=" + zl; // + "&sw=" + sw + "&sh=" + sh;

    52

    53

        // refresh the tile each time it is loaded?

    54

        if (this.refresh)

    55

            url += "&ts=" + new Date().getTime();

    56

    57

        // XXX: additional parameters, not used

    58

        if (this.opt_key && this.opt_value)

    59

            url += "&" + this.opt_key + "=" + this.opt_value;

    60

    61

        return url;

    62

    },

    63

    64

    // build an URL for a full image

    65

    build_image_url: function (cx, cy, w, h, zl) {

    66

        return (this.path + "?cx=" + cx + "&cy=" + cy + "&w=" + w + "&h=" + h + "&zl=" + zl);

    67

    }

    68

});

    69

    70

/**

    71

 * Viewport implements the tiles-UI. It consists of a draggable substrate, which in turn consists of several

    72

 * ZoomLayers, which then contain the actual tile images.

    73

 *

    74

 * Vars:

    75

 *      scroll_x/y      - the visible pixel offset of the top-left corner

    76

 */

    77

var Viewport = Class.create({

    78

    initialize: function (source, viewport_id) {

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        this.source = source;

    80

    81

        // get a handle on the UI elements

    82

        this.id = viewport_id;

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        this.div = $(viewport_id);

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        this.substrate = this.div.down("div.substrate");

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        // make the substrate draggable

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        this.draggable = new Draggable(this.substrate, {

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            onStart: this.on_scroll_start.bind(this),

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            onDrag: this.on_scroll_move.bind(this),

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            onEnd: this.on_scroll_end.bind(this),

    91

    92

            zindex: false

    93

        });

    94

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        // register event handlers for other UI functions

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        Event.observe(this.substrate, "dblclick", this.on_dblclick.bindAsEventListener(this));

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        Event.observe(this.substrate, "mousewheel", this.on_mousewheel.bindAsEventListener(this));

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        Event.observe(this.substrate, "DOMMouseScroll", this.on_mousewheel.bindAsEventListener(this));     // mozilla

    99

        Event.observe(document, "resize", this.on_resize.bindAsEventListener(this));

   100

   101

        // init zoom UI buttons

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        this.btn_zoom_in = $("btn-zoom-in");

   103

        this.btn_zoom_out = $("btn-zoom-out");

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        if (this.btn_zoom_in)

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            Event.observe(this.btn_zoom_in, "click", this.zoom_in.bindAsEventListener(this));

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        if (this.btn_zoom_out)

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            Event.observe(this.btn_zoom_out, "click", this.zoom_out.bindAsEventListener(this));

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        // initial view location (centered)

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   116

        // from link?

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        if (document.location.hash) {

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            // parse x:y:z tuple

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            var pt = document.location.hash.substr(1).split(":");

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   121

            // unpack    

   125

        }

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        // initialize zoom state to given zl

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        this._init_zoom(zl);

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   130

        // initialize viewport size

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        this.update_size();

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        // initialize scroll offset

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        this._init_scroll(cx, cy);

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        // this comes after update_size, so that the initial update_size doesn't try and update the image_link,

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        // since this only works once we have the zoom layers set up...

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        this.image_link = $("lnk-image");

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        this.update_image_link();

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   141

        // display tiles!

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        this.update_tiles();

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    },

   144

   145

/*

   146

 * Initializers - only run once

   147

 */

   148

   149

    /** Initialize the zoom state to show the given zoom level */

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    _init_zoom: function (zl) {

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        // the stack of zoom levels

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        this.zoom_layers = [];

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        // populate the zoom-layers stack based on the number of zoom levels defined for the source

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        for (var zoom_level = this.source.zoom_min; zoom_level <= this.source.zoom_max; zoom_level++) {

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            var zoom_layer = new ZoomLayer(this.source, zoom_level);

   157

   158

            this.substrate.appendChild(zoom_layer.div);

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            this.zoom_layers[zoom_level] = zoom_layer;

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        }

   161

   162

        // is the new zoom level valid?

   163

        if (!this.zoom_layers[zl])

   164

            // XXX: nasty, revert to something else?

   165

            return false;

   166

   167

        // set the zoom layyer

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        this.zoom_layer = this.zoom_layers[zl];

   169

   170

        // enable it with initial z-index

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        this.zoom_layer.enable(11);

   172

   173

        // init the UI accordingly

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        this.update_zoom_ui();

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    },

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   177

    /** Initialize the scroll state to show the given (scaled) centered coordinates */

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    _init_scroll: function (cx, cy) {

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        // scroll center

   180

        this.scroll_center_to(cx, cy);

   181

    },

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   183

   184

/*

   185

 * Handle input events

   186

 */    

   187

   188

    /** Viewport resized */

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    on_resize: function (ev) {

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        this.update_size();

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        this.update_tiles();

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    },

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   194

    /** Double-click to zoom and center */

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    on_dblclick: function (ev) {

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        var offset = this.event_offset(ev);

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   198

        // center view and zoom in

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        this.center_and_zoom_in(

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            this.scroll_x + offset.x,

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            this.scroll_y + offset.y

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        );

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    },

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   205

    // mousewheel handler

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    on_mousewheel: function (ev) {

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        // this works in very weird ways, so it's based on code from http://adomas.org/javascript-mouse-wheel/

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        // (it didn't include any license, so this is written out manually)

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        var delta;

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        // this is browser-dependant...

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        if (ev.wheelDelta) {

   213

            // IE + Opera

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            delta = ev.wheelDelta;

   215

   216

            if (window.opera) {  

   217

                // Opera, but apparently not newer versions?

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                //delta = -delta;

   219

            }

   220

   221

        } else if (ev.detail) {

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            // Mozilla

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            delta = -ev.detail;

   224

   225

        } else {

   226

            // mousewheel not supported...

   227

            return;

   228

   229

        }

   230

   231

        // don't scroll the page

   232

        if (ev.preventDefault)

   233

            ev.preventDefault();

   234

   235

        // delta > 0 : scroll up, zoom in

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        // delta < 0 : scroll down, zoom out

   237

        delta = delta < 0 ? -1 : 1;

   238

   239

        // Firefox's DOMMouseEvent's pageX/Y attributes are broken. layerN is for mozilla, offsetN for IE, seems to work

   240

   241

        // absolute location of the cursor

   242

        var x = parseInt(ev.target.style.left) + (ev.layerX ? ev.layerX : ev.offsetX);

   243

        var y = parseInt(ev.target.style.top) + (ev.layerY ? ev.layerY : ev.offsetY);

   244

   245

        // zoom \o/

   246

        this.zoom_center_to(x, y, delta);

   247

    },

   248

   249

    /** Substrate scroll was started */

   250

    on_scroll_start: function (ev) {

   251

   252

    },

   253

   254

    /** Substrate was scrolled, update scroll_{x,y}, and then update tiles after 100ms */

   255

    on_scroll_move: function (ev) {

   256

        this.update_scroll();

   257

        this.update_after_timeout();

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    },

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   260

    /** Substrate scroll was ended, update tiles now */

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    on_scroll_end: function (ev) {

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        this.update_now();

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    },

   264

   265

    /** Calculate the absolute (x, y) coords of the given event inside the viewport */

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    event_offset: function (ev) {

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        var offset = this.div.cumulativeOffset();

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   269

        return {

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            x: ev.pointerX() - offset.left, 

   271

            y: ev.pointerY() - offset.top

   272

        };

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    },

   274

   275

/*

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 * Change view - scroll/zoom

   277

 */                  

   278

   279

    /** Scroll the view to place the given absolute (x, y) co-ordinate at the top left */

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    scroll_to: function (x, y) {

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        // update it via the style

   282

        this.substrate.style.top = "-" + y + "px";

   283

        this.substrate.style.left = "-" + x + "px";

   284

   285

        // update these as well

   286

        this.scroll_x = x;

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        this.scroll_y = y;

   288

    },

   289

   290

    /** Scroll the view to place the given absolute (x, y) co-ordinate at the center */

   291

    scroll_center_to: function (x, y) {

   292

        return this.scroll_to(

   293

            x - this.center_offset_x,

   294

            y - this.center_offset_y

   295

        );

   296

    },

   297

   298

    /** Zoom à la delta such that the given (zoomed) absolute (x, y) co-ordinates will be at the top left */

   299

    zoom_scaled: function (x, y, delta) {

   300

        if (!this.update_zoom(delta))

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            // couldn't zoom, scaled coords are wrong

   302

            return false;

   303

   304

        // scroll to the new position

   305

        this.scroll_to(x, y);

   306

   307

        // update view after 100ms - in case we zoom again?

   308

        this.update_after_timeout();

   309

   310

        return true;

   311

    },

   312

   313

    /** Zoom à la delta such that the given (current) absolute (x, y) co-ordinates will be at the top left */

   314

    zoom_to: function (x, y, delta) {

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        return this.zoom_scaled(

   316

            scaleByZoomDelta(x, delta),

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            scaleByZoomDelta(y, delta),

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            delta

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        );

   320

    },

   321

   322

    /** Zoom à la delta such that the given (current) absolute (x, y) co-ordinates will be at the center */

   323

    zoom_center_to: function (x, y, delta) {

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        return this.zoom_scaled(

   325

            scaleByZoomDelta(x, delta) - this.center_offset_x,

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            scaleByZoomDelta(y, delta) - this.center_offset_y,

   327

            delta

   328

        );

   329

    },

   330

   331

    /** Zoom à la delta, keeping the view centered */

   332

    zoom_centered: function (delta) {

   333

        return this.zoom_center_to(

   334

            this.scroll_x + this.center_offset_x,

   335

            this.scroll_y + this.center_offset_y,

   336

            delta

   337

        );

   338

    },

   339

   340

    /** Zoom in one level, keeping the view centered */

   341

    zoom_in: function () {

   342

        return this.zoom_centered(+1);

   343

    },

   344

   345

    /** Zoom out one level, keeping the view centered */

   346

    zoom_out: function () {

   347

        return this.zoom_centered(-1);

   348

    },

   349

   350

    /** Center the view on the given coords, and zoom in, if possible */

   351

    center_and_zoom_in: function (cx, cy) {

   352

        // try and zoom in

   353

        if (this.update_zoom(1)) {

   354

            // scaled coords

   355

            cx = scaleByZoomDelta(cx, 1);

   356

            cy = scaleByZoomDelta(cy, 1);

   357

        }

   358

   359

        // re-center

   360

        this.scroll_center_to(cx, cy);

   361

   362

        // update view after 100ms - in case we zoom again?

   363

        this.update_after_timeout();

   364

    },

   365

   366

/*

   367

 * Update view state

   368

 */              

   369

   370

    /** Update the view_* / center_offset_* vars, and any dependent items */

   371

    update_size: function () {

   372

        this.view_width = this.div.getWidth();

   373

        this.view_height = this.div.getHeight();

   374

   375

        this.center_offset_x = Math.floor(this.view_width / 2);

   376

        this.center_offset_y = Math.floor(this.view_height / 2);

   377

   378

        // the link-to-image uses the current view size

   379

        this.update_image_link();

   380

    },

   381

   382

    /**

   383

     * Update the scroll_x/y state

   384

     */    

   385

    update_scroll: function() {

   386

        this.scroll_x = -parseInt(this.substrate.style.left);

   387

        this.scroll_y = -parseInt(this.substrate.style.top);

   388

    },

   389

   390

    /**

   391

     * Switch zoom layers

   392

     */

   393

    update_zoom: function (delta) {

   394

        // is the new zoom level valid?

   395

        if (!this.zoom_layers[this.zoom_layer.level + delta])

   396

            return false;

   397

   398

        var zoom_old = this.zoom_layer;

   399

        var zoom_new = this.zoom_layers[this.zoom_layer.level + delta];

   400

   401

        // XXX: clear hide-zoom-after-timeout

   402

        if (this.zoom_timer) {

   403

            clearTimeout(this.zoom_timer);

   404

            this.zoom_timer = null;

   405

        }

   406

   407

        // get other zoom layers out of the way

   408

        // XXX: u

   409

        this.zoom_layers.each(function (zl) {

   410

            zl.disable();

   411

        });

   412

   413

        // update the current zoom layer

   414

        this.zoom_layer = zoom_new;

   415

   416

        // layer them such that the old on remains visible underneath the new one

   417

        zoom_new.enable(11);

   418

        zoom_old.enable(10);

   419

   420

        // resize the tiles in the two zoom layers

   421

        zoom_new.update_tiles(zoom_new.level);

   422

        zoom_old.update_tiles(zoom_new.level);

   423

   424

        // disable the old zoom layer after 1000ms - after the new zoom layer has loaded - not an optimal solution

   425

        this.zoom_timer = setTimeout(function () { zoom_old.disable()}, 1000);

   426

   427

        // update UI state

   428

        this.update_zoom_ui();

   429

   430

        return true;

   431

    },

   432

   433

    /** Schedule an update_tiles() after a 100ms interval */

   434

    update_after_timeout: function () {

   435

        // have not called update_tiles() yet

   436

        this._update_idle = false;

   437

   438

        // cancel old timeout

   439

        if (this._update_timeout)

   440

            clearTimeout(this._update_timeout);

   441

   442

        // trigger in 100ms

   443

        this._update_timeout = setTimeout(this._update_timeout_trigger.bind(this), 100);  

   444

    },

   445

   446

    _update_timeout_trigger: function () {

   447

        // have called update_tiles()

   448

        this._update_idle = true;

   449

   450

        this.update_tiles();

   451

    },

   452

   453

    /** 

   454

     * Unschedule the call to update_tiles() and call it now, unless it's already been triggered by the previous call to

   455

     * update_after_timeout

   456

     */

   457

    update_now: function () {

   458

        // abort trigger if active

   459

        if (this._update_timeout)

   460

            clearTimeout(this._update_timeout);

   461

   462

        // update now unless already done

   463

        if (!this._update_idle)

   464

            this.update_tiles();

   465

    },

   466

   467

    /**

   468

     * Determine the set of visible tiles, and ensure they are loaded

   469

     */

   470

    update_tiles: function () {

   471

        // short names for some vars...

   472

        var x = this.scroll_x;

   473

        var y = this.scroll_y;

   474

        var sw = this.view_width;

   475

        var sh = this.view_height;

   476

        var tw = this.source.tile_width;

   477

        var th = this.source.tile_height;

   478

        var zl = this.zoom_layer.level;

   479

   480

        // figure out which set of cols/rows are visible 

   481

        var start_col = Math.max(0, Math.floor(x / tw));

   482

        var start_row = Math.max(0, Math.floor(y / th));

   483

        var end_col = Math.floor((x + sw) / tw);

   484

        var end_row = Math.floor((y + sh) / th);

   485

   486

        // loop through all visible tiles

   487

        for (var col = start_col; col <= end_col; col++) {

   488

            for (var row = start_row; row <= end_row; row++) {

   489

                // the tile's id

   490

                var id = "tile_" + zl + "_" + col + "_" + row;

   491

   492

                // does the element exist already?

   493

                // XXX: use basic document.getElementById for perf?

   494

                var t = $(id);

   495

   496

                if (!t) {

   497

                    // build a new tile

   498

                    t = Builder.node("img", {

   499

                            src:    this.source.build_url(col, row, zl /* , sw, sh */),

   500

                            id:     id //,

   501

                            // title:  "(" + col + ", " + row + ")",

   502

                            // style set later