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Fix #23 - Image sizing/positioning issues #25

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Fix #23 - Image sizing/positioning issues #25

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37 changes: 32 additions & 5 deletions src/iiifsource.js
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Original file line number Diff line number Diff line change
Expand Up @@ -44,14 +44,41 @@ klokantech.IiifSource = function(options) {
quality = options.quality || 'default',
width = options.width,
height = options.height,
tileSize = options.tileSize || 256;
tileSize = options.tileSize || 256,
resolutions = options.resolutions;

var ceil_log2 = function(x) {
return Math.ceil(Math.log(x) / Math.LN2);
};

var maxZoom = Math.max(ceil_log2(width / tileSize),
ceil_log2(height / tileSize));
// sort resolutions because the spec does not specify any order
resolutions.sort(function(a, b) {
return a - b;
});

var ignoreScaleFactors = false,
maxZoom;
// check if provided resolutions are consecutive powers to 2
for (var i=0; i < resolutions.length; i++) {
if (Math.pow(2,i) != resolutions[i]) {
ignoreScaleFactors = true;
break;
}
}

// no resolutions are provided or they can't be continuously calculated with a zoomFactor of 2
if (resolutions.length == 0 || ignoreScaleFactors) {
maxZoom = Math.max(ceil_log2(width / tileSize),
ceil_log2(height / tileSize));
// provide resolutions from 2^0 to 2^maxZoom
resolutions = [];
for (var i = 0; i <= maxZoom; i++) {
resolutions.push(Math.pow(2,i));
}
} else {
var maxScaleFactor = Math.max.apply(null, resolutions);
maxZoom = Math.round(Math.log(maxScaleFactor) / Math.LN2);
}

var tierSizes = [];
for (var i = 0; i <= maxZoom; i++) {
Expand All @@ -66,8 +93,8 @@ klokantech.IiifSource = function(options) {
var tilePixelRatio = Math.min((window.devicePixelRatio || 1), 4);

var logicalTileSize = tileSize / tilePixelRatio;
var logicalResolutions = tilePixelRatio == 1 ? options.resolutions :
goog.array.map(options.resolutions, function(el, i, arr) {
var logicalResolutions = tilePixelRatio == 1 ? resolutions :
goog.array.map(resolutions, function(el, i, arr) {
return el * tilePixelRatio;
});

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