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Avoid oversampling when view resolution lower than tile resolution

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This commit is contained in:
Andreas Hocevar
2017-02-02 22:13:25 +01:00
parent 9af1000874
commit 72af545a4a
1 changed files with 18 additions and 8 deletions
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26
src/ol/renderer/canvas/tilelayer.js
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@@ -28,6 +28,12 @@ ol.renderer.canvas.TileLayer = function(tileLayer) {
*/
this.context = ol.dom.createCanvasContext2D();
/**
* @private
* @type {number}
*/
this.oversampling_;
/**
* @private
* @type {ol.Extent}
@@ -105,6 +111,7 @@ ol.renderer.canvas.TileLayer.prototype.prepareFrame = function(frameState, layer
var tileGrid = tileSource.getTileGridForProjection(projection);
var z = tileGrid.getZForResolution(viewResolution, this.zDirection);
var tileResolution = tileGrid.getResolution(z);
var oversampling = Math.round(viewResolution / tileResolution) || 1;
var extent = frameState.extent;
if (layerState.extent !== undefined) {
@@ -168,19 +175,22 @@ ol.renderer.canvas.TileLayer.prototype.prepareFrame = function(frameState, layer
(hints[ol.ViewHint.ANIMATING] || hints[ol.ViewHint.INTERACTING])) &&
(newTiles || !(this.renderedExtent_ &&
ol.extent.equals(this.renderedExtent_, imageExtent)) ||
this.renderedRevision != sourceRevision)) {
this.renderedRevision != sourceRevision) ||
oversampling != this.oversampling_) {
var tilePixelSize = tileSource.getTilePixelSize(z, pixelRatio, projection);
var width = tileRange.getWidth() * tilePixelSize[0];
var height = tileRange.getHeight() * tilePixelSize[0];
var width = Math.round(tileRange.getWidth() * tilePixelSize[0] / oversampling);
var height = Math.round(tileRange.getHeight() * tilePixelSize[0] / oversampling);
var context = this.context;
var canvas = context.canvas;
var opaque = tileSource.getOpaque(projection);
if (canvas.width != width || canvas.height != height) {
this.oversampling_ = oversampling;
canvas.width = width;
canvas.height = height;
} else {
context.clearRect(0, 0, width, height);
oversampling = this.oversampling_;
}
this.renderedTiles.length = 0;
@@ -199,10 +209,10 @@ ol.renderer.canvas.TileLayer.prototype.prepareFrame = function(frameState, layer
for (var tileCoordKey in tilesToDraw) {
tile = tilesToDraw[tileCoordKey];
tileExtent = tileGrid.getTileCoordExtent(tile.getTileCoord(), tmpExtent);
x = (tileExtent[0] - imageExtent[0]) / tileResolution * tilePixelRatio;
y = (imageExtent[3] - tileExtent[3]) / tileResolution * tilePixelRatio;
w = currentTilePixelSize[0] * currentScale;
h = currentTilePixelSize[1] * currentScale;
x = (tileExtent[0] - imageExtent[0]) / tileResolution * tilePixelRatio / oversampling;
y = (imageExtent[3] - tileExtent[3]) / tileResolution * tilePixelRatio / oversampling;
w = currentTilePixelSize[0] * currentScale / oversampling;
h = currentTilePixelSize[1] * currentScale / oversampling;
if (!opaque) {
context.clearRect(x, y, w, h);
}
@@ -212,7 +222,7 @@ ol.renderer.canvas.TileLayer.prototype.prepareFrame = function(frameState, layer
}
this.renderedRevision = sourceRevision;
this.renderedResolution = tileResolution * pixelRatio / tilePixelRatio;
this.renderedResolution = tileResolution * pixelRatio / tilePixelRatio * oversampling;
this.renderedExtent_ = imageExtent;
}