How to control relays using Raspberry PI and Nodejs? - node.js

I am using the watch method from the onoff module to watch to status of the input, the callback function will be called for any change in the input (from 0 to 1 or from 1 to 0) which is what I want.
The problem is when I first run the application if the main is on (inputMain is 1 ) or the main is off (inputMain is 0 ) the callback function is not executed because there is no change in the value of the input.
So if the main is on I can't call the main() function until it becomes off then on, this problem only happens when I first run the application.
How do I get around this ? Is there a better approach to handle relays ?
var GPIO = require('onoff').Gpio,
inputMain = new GPIO(17,'in','both'),
inputGen1 = new GPIO(4,'in','both'),
inputGen2 = new GPIO(27,'in','both'),
inputGen3 = new GPIO(22,'in','both'),
outMain = new GPIO(11,'high'),
outGen1 = new GPIO(15,'high'),
outGen2P = new GPIO(18,'high'), // Generator 2 power
outGen2SM = new GPIO(23,'high'), //Generator 2 starting motor
outGen2 = new GPIO(24,'high'), // Generator 2 contactor
outGen3P = new GPIO(25,'high'),
outGen3SM = new GPIO(8,'high'),
outGen3 = new GPIO(7,'high'),
objects =[outMain,outGen1,outGen2P,outGen2SM,outGen2,outGen3P,outGen3SM,outGen3];
// Checking if there is main or not which is the refrence for all other power sources
inputMain.watch(function(err,state){
if (state)
main(1);
});
// Switch to Main contactor
function main (arg) {
console.log('test');
if (arg == 1) {
value = [0,1,1,1,1,1,1,1];}
else {
value = [0,0,0,0,0,0,0,0];
}
out(value);
}
// Turn on all the relays depending on values of the array ...
function out(value) {
for ( var i = 0; i< value.length; i++) {
if (value[i] == 0 ) {
var a = objects[i];
} else {
objects[i].writeSync(value[i]);
}
}
setTimeout(function() {
a.writeSync(0);
},5000);
}

I'm afraid you will need to call read or readSync for that.
...
outGen3SM = new GPIO(8,'high'),
outGen3 = new GPIO(7,'high'),
objects =[outMain,outGen1,outGen2P,outGen2SM,outGen2,outGen3P,outGen3SM,outGen3];
//Forces the first output update
main(inputMain.readSync());

Related

Reusing a function for buttons that work independently of each other?

I'm trying to create something with P5.js that resembles an audio looper—that is, you record a snippet of audio, it plays back to you as a loop, and then you can record other snippets of audio to play together to create a song.
I figured out how to record audio, play it back as a loop, and stop the loop, but I'm not sure the best way to repeat that function so that it can be used for buttons that function independently of each other and record separate audio files, as I would like to record multiple loops.
I'm still pretty new to P5.js, so there's probably a simple way to do this—any ideas help! In general, if you have any ideas on how to achieve this project as a whole (the audio looper) I'd love to hear them.
This is my code:
let mic, recorder, soundFile, button;
let state = 0;
function setup() {
createCanvas(windowWidth, windowHeight);
background(200);
mic = new p5.AudioIn();
mic.start();
recorder = new p5.SoundRecorder();
recorder.setInput(mic);
soundFile = new p5.SoundFile();
button = createButton("record");
button.size(200, 100);
button.style("font-family", "Bodoni");
button.style("font-size", "48px");
button.position(10, 10, 10);
button.mouseClicked(loopRecord);
}
// this is the looper
function loopRecord() {
if (state === 0 && mic.enabled) {
recorder.record(soundFile);
background(255, 0, 0);
state++;
} else if (state === 1) {
recorder.stop();
background(0, 255, 0);
state++;
} else if (state === 2) {
soundFile.loop();
state++;
} else if (state === 3) {
soundFile.stop();
state++;
} else if (state === 4) {
state === 0;
}
}
You should somehow structure your data so that each button has its own state (and other parameters that should not be global, but instead unique to each loop).
Here an example using an array of track objects:
https://editor.p5js.org/RemyDekor/sketches/gM75vBYmk
I'll copy the code here as well
let mic
// this array will be filled afterwards
let tracksArray = [];
function setup() {
createCanvas(400, 400);
background(200);
// we need only one mic (it is still global)
mic = new p5.AudioIn();
mic.start();
// we call a function that creates a custom "track" object and puts it in the tracksArray (which you could use for some other things, but is currently un-used)
createTrack();
// we create a button that call the same function when we click on it
const addTrackButton = createButton("add track");
addTrackButton.mouseClicked(createTrack)
addTrackButton.position(10, 10)
}
// We now use names (strings) instead of abstract numbers to set the state of the track
function handleTrackButtonClick(trackObject) {
if (trackObject.state === "idle" && mic.enabled) {
trackObject.recorder.record(trackObject.soundFile);
background(255, 0, 0);
trackObject.state = "recording";
console.dir(trackObject.button.elt.innerText = "[recording..]");
} else if (trackObject.state === "recording") {
trackObject.recorder.stop();
background(0, 255, 0);
trackObject.state = "stopped";
console.dir(trackObject.button.elt.innerText = "play");
} else if (trackObject.state === "stopped") {
trackObject.soundFile.loop();
trackObject.state = "playing";
console.dir(trackObject.button.elt.innerText = "[playing..] stop")
} else if (trackObject.state === "playing") {
trackObject.soundFile.stop();
trackObject.state = "stopped";
console.dir(trackObject.button.elt.innerText = "[stopped..] play")
}
}
function createTrack() {
const newButton = createButton("record");
newButton.style("font-family", "Bodoni");
newButton.style("font-size", "48px");
// we do not position this button anymore, and use the "flow" of the html document
newButton.style("display", "block");
// this is the "track" object we create, and we attach the previously global parameters/states on it
const newTrackObject = {
button: newButton,
state: "idle",
recorder: new p5.SoundRecorder(),
soundFile: new p5.SoundFile()
};
newButton.mouseClicked(function() {
handleTrackButtonClick(newTrackObject)
});
newTrackObject.recorder.setInput(mic);
tracksArray.push(newTrackObject);
}

Prevent nested lists in text-editor (froala)

I need to prevent/disable nested lists in text editor implemented in Angular. So far i wrote a hack that undos a nested list when created by the user. But if the user creates a normal list and presses the tab-key the list is shown as nested for a few milliseconds until my hack sets in back to a normal list. I need something like event.preventDefault() or stopPropagation() on tab-event keydown but unfortunately that event is not tracked for some reason. Also the froala settings with tabSpaces: falseis not showing any difference when it comes to nested list...in summary i want is: if the user creates a list and presses the tab-key that nothing happens, not even for a millisecond. Has anyone an idea about that?
Froala’s support told us, there’s no built-in way to suppress nested list creation. They result from TAB key getting hit with the caret on a list item. However we found a way to get around this using MutationObserver
Basically we move the now nested list item to his former sibling and remove the newly created list. Finally we take care of the caret position.
var observer = new MutationObserver(mutationObserverCallback);
observer.observe(editorNode, {
childList: true,
subtree: true
});
var mutationObserverCallback = function (mutationList) {
var setCaret = function (ele) {
if (ele.nextSibling) {
ele = ele.nextSibling;
}
var range = document.createRange();
var sel = window.getSelection();
range.setStart(ele, 0);
range.collapse(true);
sel.removeAllRanges();
sel.addRange(range);
};
var handleAddedListNode = function (listNode) {
if (! listNode.parentNode) {
return;
}
var parentListItem = listNode.parentNode.closest('li');
if (!parentListItem) {
return;
}
var idx = listNode.children.length - 1;
while (idx >= 0) {
var childNode = listNode.children[idx];
if (parentListItem.nextSibling) {
parentListItem.parentNode.insertBefore(childNode, parentListItem.nextSibling);
} else {
parentListItem.parentNode.appendChild(childNode);
}
--idx;
}
setCaret(parentListItem);
listNode.parentNode.removeChild(listNode);
};
mutationList.forEach(function (mutation) {
var addedNodes = mutation.addedNodes;
if (!addedNodes.length) {
return;
}
for (var i = 0; i < addedNodes.length; i++) {
var currentNode = addedNodes[i];
switch (currentNode.nodeName.toLowerCase()) {
case 'ol':
case 'ul':
handleAddedListNode(currentNode);
break;
// more optimizations
}
}
})
};

Need to execute function when forEach functions ends

I have this code in node js / firebase :
ref.child("recipts").once("value", function(usersSnap) {
usersSnap.forEach(function(reciptsSnap) {
reciptsSnap.forEach(function(reciptSnap) {
reciptSnap.ref.child("last_recipt").once("value", function(b) {
b.forEach(function(c) { //Here I fill some "product" object
});
});
reciptSnap.forEach(function(b) { //Here I fill some "product" object
});
});
});
});
I need to execute a function just when "reciptSnap" forEachs finished. How can I accomplish this, I try using a variable i++ and i-- but only work for one forEach iteration.
The function I call is for manipulating the product object I created with the filled data from the forEachs loops.
If I have understood correctly, you want to call a function when reciptsSnap.forEach is complete and all async tasks inside it are also complete.
For achieving this, you can use the index parameter and the original array that is passed to the callback function of forEach. (See Documentation)
The code will be like this:
(Note: The following code is without changing the current forEach loop structure used. However, re-writing the code with Promise or async would be a better & cleaner way to do it).
var loop1Done = false;
var loop2Done = false;
ref.child("recipts").once("value", function (usersSnap) {
usersSnap.forEach(function (reciptsSnap) {
reciptsSnap.forEach(function (reciptSnap, index, colA) {
const idx = index;
const col = colA;
reciptSnap.ref.child("last_recipt").once("value", function (b) {
const i = idx;
const c = col;
b.forEach(function (c, j, colB) { //Here I fill some "product" object
// Do what you want here
// Check if all done for this loop
if ((j >= colB.length) && (i >= c.length)) {
loop1Done = true;
// Check if all loops done
if (loop1Done && loop2Done) {
// Call final callback function
// e.g. myFinalCallback();
}
}
});
});
reciptSnap.forEach(function (b, k, colC) { //Here I fill some "product" object
const i = idx;
const c = col;
// Do what you want here
// Check if all done for this loop
if ((k >= colC.length) && (i >= c.length)) {
loop2Done = true;
// Check if all loops done
if (loop1Done && loop2Done) {
// Call final callback function
// e.g. myFinalCallback();
}
}
});
});
});
});
Try:
reciptSnap.child("last_recipt").forEach(function(b) {
b.forEach(function(c) {
//Here I fill some "product" object
});
});
This should work since all of your data should already have been fetched when you did "value" on the receipts node.
If this works, your code is no longer asynchronous and right after the last forEach, you can execute the function you wanted to.
reciptSnap.forEach(function(b) {
//Here I fill some "product" object
});
//Execute your function here
});

How to properly delete a box2d body in version: Box2dWeb-2.1.a.3, Box2D_v2.3.1r3? Box2D bug?

Update
Since the problem has been found I've also find out that Box2D for web is leaking on every side :/
To show this I made a simple circle moving in a static polygon and here is the result after some time.
Notice how the following items are leaking as I'm not creating any body or changing the world in any way:
b2Vec2
Features
b2ManifoldPoint
b2ContactID
b2Manifold
b2ContactEdge
b2PolyAndCircleContact
Array
...
Original post
I have a problem because I'm profiling my game and the garbage collector doesnt' delete my bodies, contacts and other stuff. Then I've looked at what are they keeping from the GC and was the Box2D itself. This might lead to 2 options: I'm doing it bad or Box2D is leaking. I consider is my cause.
What exactly is keeping it?
contact.m_nodeA.other was appearing to be the most used to keep it from GC.
other times: m_fixtureB in a contact... see image
You can see that the body has a __destroyed property. That is set manually before deleting it with world.DestroyBody(body)
When I destroy a body I call it after I call the step method on the world.
As you can see from the box2d method it doesn't get rid of the other variable nor it changes it to another body and my body is not GC.
Any idea of what I'm missing here?
Now I can fix the problem only if the world.Step is not ran:
var gravity = new Box2D.Vec2(0, 0);
var doSleep = true;
var world = new Box2D.World(gravity, doSleep);
var step = false;
var fixtureDef = new Box2D.FixtureDef();
fixtureDef.density = 1.0;
fixtureDef.friction = 0.5;
fixtureDef.restitution = 0.2;
fixtureDef.shape = new Box2D.PolygonShape();
fixtureDef.shape.SetAsBox(1, 1);
var bodyDef = new Box2D.BodyDef;
bodyDef.type = Box2D.Body.b2_dynamicBody;
bodyDef.position.x = 0.4;
bodyDef.position.y = 0.4;
var bodies = []
var fix = [];
window.c = function(){
for(var i = 0; i < 100; i++){
var body = world.CreateBody(bodyDef);
body._id = i;
fix.push(body.CreateFixture(fixtureDef));
bodies.push(body);
}
if(step){world.Step(1/60, 3, 3); world.ClearForces();}
console.log('Created', bodies)
fixtureDef = null;
bodyDef = null;
}
window.d = function(){
_.each(bodies, function(body, i){
body.DestroyFixture(fix[i]);
world.DestroyBody(body);
fix[i] = null;
bodies[i] = null;
})
if(step){world.Step(1/60, 3, 3); world.ClearForces();}
bodies = null;
fix = null;
}
Change the step to true and the memory leak problem appears again.
Reproduce the memory leak problem:
Code in your file:
var gravity = new Box2D.Vec2(0, 0);
var doSleep = true;
var world = new Box2D.World(gravity, doSleep);
var bodies = []
window.c = function(){
for(var i = 0; i < 100; i++){
var bodyDef = new Box2D.BodyDef();
bodyDef.type = 2;
var shape = new Box2D.PolygonShape();
shape.SetAsBox(1, 1);
var fixtureDef = new Box2D.FixtureDef();
fixtureDef.shape = shape;
var body = world.CreateBody(bodyDef);
body._id = i;
body.CreateFixture(fixtureDef);
bodies.push(body);
}
world.Step(0.3, 3, 3);
console.log('Created', bodies)
}
window.d = function(){
_.each(bodies, function(body, i){
world.DestroyBody(body);
bodies[i] = null;
})
world.Step(0.3, 3, 3);
bodies = null;
}
Open google chrome:
Then open your profile and make a snapshot.
Now run the c() method in your console to create 100 bodies
Now snapshot 2
Search in snapshot for b2Body and you'll find 100 Object count
Now run d() to delete all your bodies;
Force Garbage collection by clicking on the garbage can
Make a snapshot 3
Search for b2Body and you'll also find 100 Object count
At the last step should only be 0 objects as they have been destroyed. Instead of this you'll find this:
Now you can see there are a lot of references from b2ContactEdge. Now if you remove the world.Step part of the code you will only see 2 references to the body.
If you remove this line
body.CreateFixture(fixtureDef);
or making the body static is not leaking anymore.
My game loop
...gameLoop = function(o){
// used a lot here
var world = o.world;
// calculate the new positions
var worldStepSeconds = o.worldStepMs / 1000;
// step world
world.Step(worldStepSeconds, o.velocityIterations, o.positionIterations)
// render debug
if(o.renderDebug){
world.DrawDebugData();
}
// always to not accumulate forces, maybe some bug occurs
world.ClearForces();
// tick all ticking entities
_.each(o.getTickEntitiesFn(), function(actor){
if(!actor) return;
actor.tick(o.worldStepMs, o.lastFrameMs);
})
// update PIXI entities
var body = world.GetBodyList();
var worldScale = world.SCALE;
var destroyBody = world.DestroyBody.bind(world);
while(body){
var actor = null;
var visualEntity = null;
var box2DEntity = o.getBox2DEntityByIdFn(body.GetUserData());
if(box2DEntity){
visualEntity = o.getVisualEntityByIdFn(box2DEntity.getVisualEntityId());
if(box2DEntity.isDestroying()){
// optimization
body.__destroyed = true;
world.DestroyBody(body);
box2DEntity.completeDestroy();
}
}
if(visualEntity){
if(visualEntity.isDestroying()){
visualEntity.completeDestroy();
}else{
var inverseY = true;
var bodyDetails = Utils.getScreenPositionAndRotationOfBody(world, body, inverseY);
visualEntity.updateSprite(bodyDetails.x, bodyDetails.y, bodyDetails.rotation);
}
}
// this delegates out functionality for each body processed
if(o.triggersFn.eachBody) o.triggersFn.eachBody(world, body, visualEntity);
body = body.GetNext();
}
// when a joint is created is then also created it's visual counterpart and then set to userData.
var joint = world.GetJointList();
while(joint){
var pixiGraphics = joint.GetUserData();
if(pixiGraphics){
// In order to draw a distance joint we need to know the start and end positions.
// The joint saves the global (yes) anchor positions for each body.
// After that we need to scale to our screen and invert y axis.
var anchorA = joint.GetAnchorA();
var anchorB = joint.GetAnchorB();
var screenPositionA = anchorA.Copy();
var screenPositionB = anchorB.Copy();
// scale
screenPositionA.Multiply(world.SCALE);
screenPositionB.Multiply(world.SCALE);
// invert y
screenPositionA.y = world.CANVAS_HEIGHT - screenPositionA.y
screenPositionB.y = world.CANVAS_HEIGHT - screenPositionB.y
// draw a black line
pixiGraphics.clear();
pixiGraphics.lineStyle(1, 0x000000, 0.7);
pixiGraphics.moveTo(screenPositionA.x, screenPositionA.y);
pixiGraphics.lineTo(screenPositionB.x, screenPositionB.y);
}
joint = joint.GetNext();
}
// render the PIXI scene
if(o.renderPixi){
o.renderer.render(o.stage)
}
// render next frame
requestAnimFrame(o.requestAnimFrameFn);
}
Code from Box2d:
b2ContactManager.prototype.Destroy = function (c) {
var fixtureA = c.GetFixtureA();
var fixtureB = c.GetFixtureB();
var bodyA = fixtureA.GetBody();
var bodyB = fixtureB.GetBody();
if (c.IsTouching()) {
this.m_contactListener.EndContact(c);
}
if (c.m_prev) {
c.m_prev.m_next = c.m_next;
}
if (c.m_next) {
c.m_next.m_prev = c.m_prev;
}
if (c == this.m_world.m_contactList) {
this.m_world.m_contactList = c.m_next;
}
if (c.m_nodeA.prev) {
c.m_nodeA.prev.next = c.m_nodeA.next;
}
if (c.m_nodeA.next) {
c.m_nodeA.next.prev = c.m_nodeA.prev;
}
if (c.m_nodeA == bodyA.m_contactList) {
bodyA.m_contactList = c.m_nodeA.next;
}
if (c.m_nodeB.prev) {
c.m_nodeB.prev.next = c.m_nodeB.next;
}
if (c.m_nodeB.next) {
c.m_nodeB.next.prev = c.m_nodeB.prev;
}
if (c.m_nodeB == bodyB.m_contactList) {
bodyB.m_contactList = c.m_nodeB.next;
}
this.m_contactFactory.Destroy(c);
--this.m_contactCount;
}
b2ContactFactory.prototype.Destroy = function (contact) {
if (contact.m_manifold.m_pointCount > 0) {
contact.m_fixtureA.m_body.SetAwake(true);
contact.m_fixtureB.m_body.SetAwake(true);
}
var type1 = parseInt(contact.m_fixtureA.GetType());
var type2 = parseInt(contact.m_fixtureB.GetType());
var reg = this.m_registers[type1][type2];
if (true) {
reg.poolCount++;
contact.m_next = reg.pool;
reg.pool = contact;
}
var destroyFcn = reg.destroyFcn;
destroyFcn(contact, this.m_allocator);
}
I have the same problem, but I think I find out from where it comes.
Instead of m_* try functions, like GetFixtureA() instead of m_fixtureA.
Totti did you ever figure this out? It looks like box2dweb requires manual destruction and memory management.
I think I have found your leaks, un-implemented ( static class ) destruction functions:
b2Joint.Destroy = function (joint, allocator) {}
b2CircleContact.Destroy = function (contact, allocator) {}<
b2PolygonContact.Destroy = function (contact, allocator) {}
b2EdgeAndCircleContact.Destroy = function (contact, allocator) {}<
b2PolyAndCircleContact.Destroy = function (contact, allocator) {}
b2PolyAndEdgeContact.Destroy = function (contact, allocator) {}
[UPDATE...]
b2DestructionListener.b2DestructionListener = function () {};
b2DestructionListener.prototype.SayGoodbyeJoint = function (joint) {}
b2DestructionListener.prototype.SayGoodbyeFixture = function (fixture) {}
b2Contact.prototype.Reset(fixtureA, fixtureB)
called with with one/both fixture arguments resets passed in fixture/s BUT ALSO pass in NO arguments and it 'nulls' all the the b2Contact properties! (UNTESTED:) but I suggest set your YOURcontactListener class up to handle all contact callbacks EVERY call with Reset(??) dynamically configureable as logic requies EVERY call (there are more than you'd imagine each and every world step).
Also take Colt McAnlis clever advice and strategically pre allocate all the memory the life of your game will need (by creating game and box2d object pools now you know objects can be reset) so the garbage collector NEVER runs until, you destroy object pools at times of your own convenience.... i.e when you close the tab, or your device needs recharging! ;D [...UPDATE]
// you can define and assign your own contact listener ...via...
YOUR.b2world.b2ContactManager.m_world.m_contactList = new YOURcontactlistener();<br>[edit]...if you dont it actually does have Box2D.Dynamics.b2ContactListener.b2_defaultListener.
// box2d in the worldStep calls YOURcontactlistener.update() via:
this.b2world.b2ContactManager.m_world.m_contactList.Update(this.m_contactListener) // this.m_contactListener being YOURS || b2_defaultListener;
// which instantiates ALL your listed leaking object like so:
{b2Contact which instantiates {b2ContactEdge} and {b2Manifold which instantiates {b2ManifoldPoint{which instantiates m_id.key == ContactID{which instantiates Features}}}} along with {B2Vec2} are instantiated in b2ContactResult ...which I can not actually find but assume it must be instantiated in the Solver.
// There is a Contacts.destroyFcn callback is CREATED in....
b2ContactFactory.prototype.Destroy = function (contact) {...}
// then Contacts.destroyFcn callback(s) are privately REGISTERED in....
b2ContactFactory.prototype.InitializeRegisters() {...}
...via...
this.AddType = function (createFcn, destroyFcn, type1, type2) {...}
...BUT... THOSE privately registered ARE four of the un-implimented static class function from above...
b2PolygonContact.Destroy = function (contact, allocator) {}
b2EdgeAndCircleContact.Destroy = function (contact, allocator) {}
b2PolyAndCircleContact.Destroy = function (contact, allocator) {}
b2PolyAndEdgeContact.Destroy = function (contact, allocator) {}
So I havn't tested it yet but it looks like box2dweb just gives you the Destroy callback/handler functions and you have to read the source to find all the properties you need to null. [Edit] In combination with b2Contact.prototype.Reset(fixtureA, fixtureB)
But either way pretty confident the functions above(possibly incomplete) are callback/handlers, and can be used to null your way back to performance for anyone else who stumbles across this problem. Pretty sure Totti's moved on(dont forget to handle your 'this' scope in callbacks).

Drag/Move Multiple Selected Features - OpenLayers

I know that I can easily allow a user to select multiple Features/Geometries in OpenLayers but I then want enable the user to easily drag/move all of the selected features at the same time.
With the ModifyFeature control it only moves one feature at a time ... is there a way to easily extend this control (or whatever works) to move all of the selected features on that layer?
Okay, skip the ModifyFeature control and just hook into the SelectFeature control to keep track of the selected features and then use the DragControl to manipulate the selected points at the same time.
Example of the control instantiation:
var drag = new OpenLayers.Control.DragFeature(vectors, {
onStart: startDrag,
onDrag: doDrag,
onComplete: endDrag
});
var select = new OpenLayers.Control.SelectFeature(vectors, {
box: true,
multiple: true,
onSelect: addSelected,
onUnselect: clearSelected
});
Example of the event handling functions:
/* Keep track of the selected features */
function addSelected(feature) {
selectedFeatures.push(feature);
}
/* Clear the list of selected features */
function clearSelected(feature) {
selectedFeatures = [];
}
/* Feature starting to move */
function startDrag(feature, pixel) {
lastPixel = pixel;
}
/* Feature moving */
function doDrag(feature, pixel) {
for (f in selectedFeatures) {
if (feature != selectedFeatures[f]) {
var res = map.getResolution();
selectedFeatures[f].geometry.move(res * (pixel.x - lastPixel.x), res * (lastPixel.y - pixel.y));
vectors.drawFeature(selectedFeatures[f]);
}
}
lastPixel = pixel;
}
/* Featrue stopped moving */
function endDrag(feature, pixel) {
for (f in selectedFeatures) {
f.state = OpenLayers.State.UPDATE;
}
}
Hmm...
I tried the code above, and couldn't make it work. Two issues:
1) To move each feature, you need to use the original position of that feature, and add the "drag vector" from whatever feature the DragControl is moving around by itself (i.e. the feature-parameter to doDrag).
2) Since DragFeatures own code sets lastPixel=pixel before calling onDrag, the line calling move() will move the feature to (0,0).
My code looks something like this:
var lastPixels;
function startDrag(feature, pixel) {
// save hash with selected features start position
lastPixels = [];
for( var f=0; f<wfs.selectedFeatures.length; f++){
lastPixels.push({ fid: layer.selectedFeatures[f].fid,
lastPixel: map.getPixelFromLonLat( layer.selectedFeatures[f].geometry.getBounds().getCenterLonLat() )
});
}
}
function doDrag(feature, pixel) {
/* because DragFeatures own handler overwrites dragSelected.lastPixel with pixel before this is called, calculate drag vector from movement of "feature" */
var g = 0;
while( lastPixels[g].fid != feature.fid ){ g++; }
var lastPixel = lastPixels[g].lastPixel;
var currentCenter = map.getPixelFromLonLat( feature.geometry.getBounds().getCenterLonLat() );
var dragVector = { dx: currentCenter.x - lastPixel.x, dy: lastPixel.y - currentCenter.y };
for( var f=0; f<layer.selectedFeatures.length; f++){
if (feature != layer.selectedFeatures[f]) {
// get lastpixel of this feature
lastPixel = null;
var h = 0;
while( lastPixels[h].fid != layer.selectedFeatures[f].fid ){ h++; }
lastPixel = lastPixels[h].lastPixel;
var newPixel = new OpenLayers.Pixel( lastPixel.x + dragVector.dx, lastPixel.y - dragVector.dy );
// move() moves polygon feature so that centre is at location given as parameter
layer.selectedFeatures[f].move(newPixel);
}
}
}
I had a similar problem and solved it by overriding DragFeature's moveFeature function and putting this.lastPixel = pixel inside the for loop that applies the move to all features within my layer vector. Until I moved this.lastPixel = pixel inside the loop, all features except the one being dragged got crazily distorted.
`OpenLayers.Control.DragFeature.prototype.moveFeature = function (pixel) {
var res = this.map.getResolution();
for (var i = 0; i < vector.features.length; i++) {
var feature = vector.features[i];
feature .geometry.move(res * (pixel.x - this.lastPixel.x),
res * (this.lastPixel.y - pixel.y));
this.layer.drawFeature(feature );
this.lastPixel = pixel;
}
this.onDrag(this.feature, pixel);
};
`

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