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Adding fractionalZoom property to the map. This allows zooming to an arbitrary level, making it possible to have non-discrete resolutions for layers that support it. This property should not be set to true for layers with fixed zoom levels (commercial layers or others with cached tiles). r=elemoine,crschmidt,ahocevar (closes #1243)

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git-svn-id: http://svn.openlayers.org/trunk/openlayers@5982 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf
This commit is contained in:
Tim Schaub
2008-02-04 06:23:54 +00:00
parent 1faf641806
commit 211a2834de
6 changed files with 225 additions and 20 deletions
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75
lib/OpenLayers/Layer.js
View File

@@ -758,7 +758,7 @@ OpenLayers.Layer = OpenLayers.Class({
*/
getResolution: function() {
var zoom = this.map.getZoom();
return this.resolutions[zoom];
return this.getResolutionForZoom(zoom);
},
/**
@@ -812,6 +812,29 @@ OpenLayers.Layer = OpenLayers.Class({
//to be implemented by subclasses
},
/**
* APIMethod: getResolutionForZoom
*
* Parameter:
* zoom - {Float}
*
* Returns:
* {Float} A suitable resolution for the specified zoom.
*/
getResolutionForZoom: function(zoom) {
zoom = Math.max(0, Math.min(zoom, this.resolutions.length - 1));
var resolution;
if(this.map.fractionalZoom) {
var low = Math.floor(zoom);
var high = Math.ceil(zoom);
resolution = this.resolutions[high] +
((zoom-low) * (this.resolutions[low]-this.resolutions[high]));
} else {
resolution = this.resolutions[Math.round(zoom)];
}
return resolution;
},
/**
* APIMethod: getZoomForResolution
*
@@ -831,22 +854,50 @@ OpenLayers.Layer = OpenLayers.Class({
* value and the 'closest' specification.
*/
getZoomForResolution: function(resolution, closest) {
var diff;
var minDiff = Number.POSITIVE_INFINITY;
for(var i=0; i < this.resolutions.length; i++) {
if (closest) {
diff = Math.abs(this.resolutions[i] - resolution);
if (diff > minDiff) {
break;
var zoom;
if(this.map.fractionalZoom) {
var lowZoom = 0;
var highZoom = this.resolutions.length - 1;
var highRes = this.resolutions[lowZoom];
var lowRes = this.resolutions[highZoom];
var res;
for(var i=0; i<this.resolutions.length; ++i) {
res = this.resolutions[i];
if(res >= resolution) {
highRes = res;
lowZoom = i;
}
minDiff = diff;
} else {
if (this.resolutions[i] < resolution) {
if(res <= resolution) {
lowRes = res;
highZoom = i;
break;
}
}
var dRes = highRes - lowRes;
if(dRes > 0) {
zoom = lowZoom + ((resolution - lowRes) / dRes);
} else {
zoom = lowZoom;
}
} else {
var diff;
var minDiff = Number.POSITIVE_INFINITY;
for(var i=0; i < this.resolutions.length; i++) {
if (closest) {
diff = Math.abs(this.resolutions[i] - resolution);
if (diff > minDiff) {
break;
}
minDiff = diff;
} else {
if (this.resolutions[i] < resolution) {
break;
}
}
}
zoom = Math.max(0, i-1);
}
return Math.max(0, i-1);
return zoom;
},
/**