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Additional simple examples for just CacheRead and CacheWrite.

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* Abort seeding immediately when cache is full.
* Abort seeding immediately when CORS image requests are not supported.
This commit is contained in:
ahocevar
2012-03-09 15:32:04 +01:00
parent e366722375
commit 51a11e053f
5 changed files with 215 additions and 31 deletions
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86
examples/offline-storage.js
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@@ -30,6 +30,9 @@ function init(){
imageFormat: "image/jpeg",
eventListeners: {
cachefull: function() {
if (seeding) {
stopSeeding();
}
status.innerHTML = "Cache full.";
cacheFull = true;
}
@@ -56,13 +59,16 @@ function init(){
var layerSwitcher = new OpenLayers.Control.LayerSwitcher();
map.addControls([cacheWrite, cacheRead1, cacheRead2, layerSwitcher]);
layerSwitcher.maximizeControl();
// add UI and behavior
var status = document.getElementById("status"),
hits = document.getElementById("hits"),
previousCount = -1,
cacheHits = 0,
cacheFull = false;
cacheFull = false,
seeding = false;
updateLayerInfo();
var read = document.getElementById("read");
read.checked = true;
@@ -75,7 +81,7 @@ function init(){
tileloadstart.checked = "checked";
tileloadstart.onclick = setType;
document.getElementById("tileerror").onclick = setType;
document.getElementById("seed").onclick = seedCache;
document.getElementById("seed").onclick = startSeeding;
// update the number of cached tiles and detect local storage support
function updateLayerInfo(evt) {
@@ -88,6 +94,7 @@ function init(){
status.innerHTML = "Local storage not supported. Try a different browser.";
}
}
// update the number of cache hits and detect missing CORS support
function updateTileInfo(evt) {
if (cacheWrite.active) {
@@ -100,6 +107,9 @@ function init(){
status.innerHTML = "Canvas not supported. Try a different browser.";
}
} catch(e) {
if (seeding) {
stopSeeding();
}
status.innerHTML = "CORS image requests not supported. Try a different layer.";
}
}
@@ -140,15 +150,18 @@ function init(){
}
}
// seed the cache
function seedCache() {
var zoom = map.getZoom();
var extent = map.getExtent();
var center = map.getCenter();
var active = cacheWrite.active;
var tileWidth = map.baseLayer.tileSize.w;
var layer = map.baseLayer;
var buffer = layer.buffer;
// start seeding the cache
function startSeeding() {
var layer = map.baseLayer,
zoom = map.getZoom();
seeding = {
zoom: zoom,
extent: map.getExtent(),
center: map.getCenter(),
cacheWriteActive: cacheWrite.active,
buffer: layer.buffer,
layer: layer
};
// make sure the next setCenter triggers a load
map.zoomTo(zoom === layer.numZoomLevels-1 ? zoom - 1 : zoom + 1);
// turn on cache writing
@@ -157,27 +170,38 @@ function init(){
cacheRead1.deactivate();
cacheRead2.deactivate();
layer.events.register("loadend", this, function next() {
var nextZoom = map.getZoom() + 1;
var extentWidth = extent.getWidth() / map.getResolutionForZoom(nextZoom);
// adjust the layer's buffer size so we don't have to pan
layer.buffer = Math.ceil((extentWidth / tileWidth - map.getSize().w / tileWidth) / 2);
map.zoomIn();
if (cacheFull || nextZoom === layer.numZoomLevels-1) {
// we're done - restore previous settings
layer.events.unregister("loadend", this, next);
layer.buffer = buffer;
map.setCenter(center, zoom);
if (!active) {
cacheWrite.deactivate();
}
if (read.checked) {
setType();
}
}
});
layer.events.register("loadend", null, seed);
// start seeding
map.setCenter(center, zoom);
map.setCenter(seeding.center, zoom);
}
// seed a zoom level based on the extent at the time startSeeding was called
function seed() {
var layer = seeding.layer;
var tileWidth = layer.tileSize.w;
var nextZoom = map.getZoom() + 1;
var extentWidth = seeding.extent.getWidth() / map.getResolutionForZoom(nextZoom);
// adjust the layer's buffer size so we don't have to pan
layer.buffer = Math.ceil((extentWidth / tileWidth - map.getSize().w / tileWidth) / 2);
map.zoomIn();
if (cacheFull || nextZoom === layer.numZoomLevels-1) {
stopSeeding();
}
}
// stop seeding (when done or when cache is full)
function stopSeeding() {
// we're done - restore previous settings
seeding.layer.events.unregister("loadend", null, seed);
seeding.layer.buffer = seeding.buffer;
map.setCenter(seeding.center, seeding.zoom);
if (!seeding.cacheWriteActive) {
cacheWrite.deactivate();
}
if (read.checked) {
setType();
}
seeding = false;
}
}