ImgGridRenderer class
A renderer which renders map tiles with a grid of ImgElementss.
class ImgGridRenderer extends Renderer {
ImgGridRenderer(layer) : super(layer);
void beforeRender(){
_layer.container.children.clear();
}
void renderTile(Point2D tile) {
var url = _layer.bindTileToUrl(tile.x, tile.y, _layer.map.zoom);
var img = _layer._cache.lookup(url);
var tileOnZoomPlane = tile.scale(
sx: _layer.tileSize.width,
sy: _layer.tileSize.height
);
var tileOnViewport = _layer._map.zoomPlaneToViewport(tileOnZoomPlane);
img.style
..position = "absolute"
..left = "${tileOnViewport.x.toString()}px"
..top = "${tileOnViewport.y.toString()}px"
..opacity = "${_layer.opacity}";
_layer._container.children.add(img);
}
}
Extends
Renderer > ImgGridRenderer
Constructors
new ImgGridRenderer(layer) #
ImgGridRenderer(layer) : super(layer);
Methods
void afterRender() #
inherited from Renderer
Invoked after the tile grid is rendered using renderTileGrid.
Default implementation is empty. Override in subclasses if
necessary.
void afterRender(){}
void beforeRender() #
Invoked before the tile grid is rendered using renderTileGrid.
Default implementation is empty. Override in subclasses if
necessary.
docs inherited from Renderer
void beforeRender(){
_layer.container.children.clear();
}
void render() #
inherited from Renderer
Invoked by a TileLayer to render itself
void render() {
beforeRender();
renderTileGrid();
afterRender();
}
void renderTile(Point2D tile) #
Renders the tile at position tileCoord in the current
tile plane.
docs inherited from Renderer
void renderTile(Point2D tile) {
var url = _layer.bindTileToUrl(tile.x, tile.y, _layer.map.zoom);
var img = _layer._cache.lookup(url);
var tileOnZoomPlane = tile.scale(
sx: _layer.tileSize.width,
sy: _layer.tileSize.height
);
var tileOnViewport = _layer._map.zoomPlaneToViewport(tileOnZoomPlane);
img.style
..position = "absolute"
..left = "${tileOnViewport.x.toString()}px"
..top = "${tileOnViewport.y.toString()}px"
..opacity = "${_layer.opacity}";
_layer._container.children.add(img);
}
void renderTileGrid() #
inherited from Renderer
Renders the tile grid
void renderTileGrid() {
var map = _layer._map;
var tileSize = _layer.tileSize;
var centerOnZoomPlane = map.mapToZoomPlane(map.earthToMap(map.center));
var vshalf = (map.viewportSize / 2).toInt();
var topLeftOnZoomPlane = new Point2D(
centerOnZoomPlane.x - vshalf.width,
centerOnZoomPlane.y - vshalf.height
);
var viewportOnZoomPlaneBounds = new Bounds(
topLeftOnZoomPlane,
topLeftOnZoomPlane + map.viewportSize
);
tileIntersectsWithViewport(Point2D t) {
var tl = t.scale(sx:tileSize.width, sy:tileSize.height);
var tileBounds = new Bounds(
tl,
tl + tileSize
);
return viewportOnZoomPlaneBounds.intersects(tileBounds);
}
// the tile covering the map center
var tile = new Point2D(
centerOnZoomPlane.x ~/ tileSize.width,
centerOnZoomPlane.y ~/ tileSize.height
);
// find the first tile to be rendered
while(true) {
var candidate = tile.translate(dx:-1);
if (candidate.x < 0) break;
if (! tileIntersectsWithViewport(candidate)) break;
tile = candidate;
}
while(true) {
var candidate = tile.translate(dy:-1);
if (candidate.y < 0) break;
if (! tileIntersectsWithViewport(candidate)) break;
tile = candidate;
}
// render the tile grid intersecting with the viewport
var maxTileX = (1 << map.zoom);
var maxTileY = (1 << map.zoom);
var cur = new Point2D.from(tile);
while(cur.x < maxTileX && tileIntersectsWithViewport(cur)) {
while(cur.y < maxTileY && tileIntersectsWithViewport(cur)) {
renderTile(cur);
cur = cur.translate(dy:1);
}
cur = new Point2D(cur.x + 1, tile.y);
}
}