OpenLayers features in pixels

Question

I have a problem and I don't know very well to solve.

var deletedFeatures = [];
var nuevaRegionId = -1;
var featureID = -1;
var extent = [0, 0, 650, 366];
var projection = new ol.proj.Projection({
  code: 'xkcd-image',
  units: 'pixels',
  extent: extent
});

var map = new ol.Map({
  layers: [
    new ol.layer.Image({
      source: new ol.source.ImageStatic({
        attributions: [
          new ol.Attribution({
            html: '<a href="http://www.somepage.com/">More</a>'
          })
        ],
        url: "<?php echo $img ?>",
        projection: projection,
        imageExtent: extent
      })
    })
  ],
  target: 'map',
  view: new ol.View({
    projection: projection,
    center: ol.extent.getCenter(extent),
    zoom: 2,
    minZoom: 1,
    maxZoom: 4
  })
});

The problem is that I have the features saved from an image of 700px x 500px

When I add this feature it isn't drawn at the corresponding pixel of the image.

[[[432.275390625,268.188476562],[407.51953125,56.8115234375],[469.091796875,53.0029296875],[484.9609375,262.475585938],[432.275390625,268.188476562]]]

If i draw manually has different values.

Is there any way to draw features in pixels and not in openlayers metrics?

To save the features:

var features = featureOverlay.getSource().getFeatures();
var format = new ol.format["GeoJSON"]();
data = format.writeFeatures(features);

I solved my problem with var extent = [0, 0, 650, 366]; this has to be the same as the image width and height and the other problem was te axis, for me was X,Y from botton-left to up, and for them from top-left to bottom

Answer 1

var extent = [0, 0, 650, 366]; --> this needs to be same as the image, get the height and width and enter there.

Then in my case, the x,y coord I recieved where from top-left(0,0) and in OpenLayers the (0,0) was bottom-left

for example: If the image was 500x500, and the rectangle coord I recieved was: [0,0][0,100],[100,100],[100,0] for me the correct coords in OpenLayers where: [[0,0],[0,400],[0,400],[100,400],[0,0]] for me the Y was = 500-y = 400.