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Merge pull request #2937 from tschaub/clipped

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Clip layer rendering to limited extent.
This commit is contained in:
Tim Schaub
2014-11-29 14:01:43 -07:00
parent 56ad3ea9aa 3685626187
commit f57f0e17ab
4 changed files with 153 additions and 43 deletions
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68
examples/layer-extent.html Normal file
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@@ -0,0 +1,68 @@
<!doctype html>
<html lang="en">
<head>
<meta charset="utf-8">
<meta http-equiv="X-UA-Compatible" content="chrome=1">
<meta name="viewport" content="initial-scale=1.0, user-scalable=no, width=device-width">
<link rel="stylesheet" href="../css/ol.css" type="text/css">
<link rel="stylesheet" href="../resources/bootstrap/css/bootstrap.min.css" type="text/css">
<link rel="stylesheet" href="../resources/layout.css" type="text/css">
<link rel="stylesheet" href="../resources/bootstrap/css/bootstrap-responsive.min.css" type="text/css">
<title>Limited Layer Extent</title>
</head>
<body>
<div class="navbar navbar-inverse navbar-fixed-top">
<div class="navbar-inner">
<div class="container">
<a class="brand" href="./"><img src="../resources/logo.png"> OpenLayers 3 Examples</a>
</div>
</div>
</div>
<div class="container-fluid">
<div class="row-fluid">
<div class="span12">
<div id="map" class="map"></div>
</div>
</div>
<div class="row-fluid">
<div class="span12">
<h4 id="title">Limited layer extent</h4>
<p id="shortdesc">Restricting layer rendering to a limited extent.</p>
<div id="docs">
<p>
This example uses the <code>layer.setExtent()</code> method to
modify the extent of the overlay layer. Use the controls below
to limit rendering based on an extent.
</p>
<p>
<div class="btn-group">
<button type="button" class="btn btn-default" id="northwest">northwest</button>
<button type="button" class="btn btn-default" id="northeast">northeast</button>
<button type="button" class="btn btn-default" id="southeast">southeast</button>
<button type="button" class="btn btn-default" id="southwest">southwest</button>
<button type="button" class="btn btn-default" id="world">world</button>
</div>
</p>
<p>
See the <a href="layer-extent.js" target="_blank">layer-extent.js
source</a> for details on how this is done.
</p>
</div>
<div id="tags">extent, tilejson</div>
</div>
</div>
</div>
<script src="../resources/jquery.min.js" type="text/javascript"></script>
<script src="../resources/example-behaviour.js" type="text/javascript"></script>
<script src="loader.js?id=layer-extent" type="text/javascript"></script>
</body>
</html>

50
examples/layer-extent.js Normal file
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@@ -0,0 +1,50 @@
goog.require('ol.Map');
goog.require('ol.View');
goog.require('ol.layer.Tile');
goog.require('ol.proj');
goog.require('ol.source.TileJSON');
function transform(extent) {
return ol.proj.transformExtent(extent, 'EPSG:4326', 'EPSG:3857');
}
var extents = {
northwest: transform([-180, 0, 0, 85]),
northeast: transform([0, 0, 180, 85]),
southeast: transform([0, -85, 180, 0]),
southwest: transform([-180, -85, 0, 0]),
world: transform([-180, -85, 180, 85])
};
var base = new ol.layer.Tile({
source: new ol.source.TileJSON({
url: 'http://api.tiles.mapbox.com/v3/' +
'mapbox.world-black.jsonp',
crossOrigin: 'anonymous'
})
});
var overlay = new ol.layer.Tile({
extent: extents.northwest,
source: new ol.source.TileJSON({
url: 'http://api.tiles.mapbox.com/v3/' +
'mapbox.world-glass.jsonp',
crossOrigin: 'anonymous'
})
});
var map = new ol.Map({
layers: [base, overlay],
renderer: exampleNS.getRendererFromQueryString(),
target: 'map',
view: new ol.View({
center: [0, 0],
zoom: 1
})
});
for (var key in extents) {
document.getElementById(key).onclick = function(event) {
overlay.setExtent(extents[event.target.id]);
};
}

35
src/ol/renderer/canvas/canvaslayerrenderer.js
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@@ -1,8 +1,10 @@
goog.provide('ol.renderer.canvas.Layer');
goog.require('goog.array');
goog.require('goog.asserts');
goog.require('goog.vec.Mat4');
goog.require('ol.dom');
goog.require('ol.extent');
goog.require('ol.layer.Layer');
goog.require('ol.render.Event');
goog.require('ol.render.EventType');
@@ -44,6 +46,35 @@ ol.renderer.canvas.Layer.prototype.composeFrame =
var image = this.getImage();
if (!goog.isNull(image)) {
// clipped rendering if layer extent is set
var extent = layerState.extent;
var clipped = goog.isDef(extent);
if (clipped) {
goog.asserts.assert(goog.isDef(extent));
var topLeft = ol.extent.getTopLeft(extent);
var topRight = ol.extent.getTopRight(extent);
var bottomRight = ol.extent.getBottomRight(extent);
var bottomLeft = ol.extent.getBottomLeft(extent);
ol.vec.Mat4.multVec2(frameState.coordinateToPixelMatrix,
topLeft, topLeft);
ol.vec.Mat4.multVec2(frameState.coordinateToPixelMatrix,
topRight, topRight);
ol.vec.Mat4.multVec2(frameState.coordinateToPixelMatrix,
bottomRight, bottomRight);
ol.vec.Mat4.multVec2(frameState.coordinateToPixelMatrix,
bottomLeft, bottomLeft);
context.save();
context.beginPath();
context.moveTo(topLeft[0], topLeft[1]);
context.lineTo(topRight[0], topRight[1]);
context.lineTo(bottomRight[0], bottomRight[1]);
context.lineTo(bottomLeft[0], bottomLeft[1]);
context.clip();
}
var imageTransform = this.getImageTransform();
// for performance reasons, context.save / context.restore is not used
// to save and restore the transformation matrix and the opacity.
@@ -72,6 +103,10 @@ ol.renderer.canvas.Layer.prototype.composeFrame =
context.setTransform(1, 0, 0, 1, 0, 0);
}
context.globalAlpha = alpha;
if (clipped) {
context.restore();
}
}
this.dispatchPostComposeEvent(context, frameState);

43
src/ol/renderer/canvas/canvastilelayerrenderer.js
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@@ -5,16 +5,13 @@ goog.provide('ol.renderer.canvas.TileLayer');
goog.require('goog.array');
goog.require('goog.asserts');
goog.require('goog.events');
goog.require('goog.object');
goog.require('goog.vec.Mat4');
goog.require('ol.Object');
goog.require('ol.Size');
goog.require('ol.TileRange');
goog.require('ol.TileState');
goog.require('ol.dom');
goog.require('ol.extent');
goog.require('ol.layer.LayerProperty');
goog.require('ol.layer.Tile');
goog.require('ol.renderer.Map');
goog.require('ol.renderer.canvas.Layer');
@@ -81,32 +78,10 @@ ol.renderer.canvas.TileLayer = function(mapRenderer, tileLayer) {
*/
this.renderedTiles_ = null;
/**
* @private
* @type {Array.<goog.events.Key>}
*/
this.eventKeys_ = [
goog.events.listen(
tileLayer, ol.Object.getChangeEventType(ol.layer.LayerProperty.EXTENT),
this.handleLayerExtentChanged_, false, this)
];
};
goog.inherits(ol.renderer.canvas.TileLayer, ol.renderer.canvas.Layer);
/**
* @inheritDoc
*/
ol.renderer.canvas.TileLayer.prototype.disposeInternal = function() {
for (var i = 0, ii = this.eventKeys_.length; i < ii; ++i) {
goog.events.unlistenByKey(this.eventKeys_[i]);
}
this.eventKeys_.length = 0;
goog.base(this, 'disposeInternal');
};
/**
* @inheritDoc
*/
@@ -123,19 +98,6 @@ ol.renderer.canvas.TileLayer.prototype.getImageTransform = function() {
};
/**
* Handle layer extent changes. We clear the canvas any time the layer extent
* changes.
* @private
*/
ol.renderer.canvas.TileLayer.prototype.handleLayerExtentChanged_ = function() {
if (!goog.isNull(this.context_)) {
this.context_.clearRect(0, 0, this.canvasSize_[0], this.canvasSize_[1]);
this.renderedCanvasZ_ = NaN;
}
};
/**
* @inheritDoc
*/
@@ -278,11 +240,6 @@ ol.renderer.canvas.TileLayer.prototype.prepareFrame =
if (z != this.renderedCanvasZ_ ||
!this.renderedCanvasTileRange_.containsTileRange(tileRange)) {
this.renderedCanvasTileRange_ = null;
// Due to limited layer extent, we may be rendering tiles on a small
// portion of the canvas.
if (z < this.renderedCanvasZ_) {
this.context_.clearRect(0, 0, canvasWidth, canvasHeight);
}
}
}
}