Lets say I have an arrays of pixels. Basically an array of this data {x,y,r,g,b,a} for each pixel.
How would I go about converting all this data into an actual image file (png preferably)?
Could not find a solution. Any help would be very appreciated.
I had some time to code up a little example. You should be able to see and note that:
the red component increases towards the bottom of the image
the green component increases towards the right of the image
the blue component is absent
the alpha channel is random and between 0 (opaque) and 127 (fully transparent)
// Define width and height
$w=800;
$h=600;
// Create truecolour image so we can have infinitely many colours rather than a limited palette
$img=imagecreatetruecolor($w,$h);
imagesavealpha($img,true);
imagealphablending($img,false);
// Iterate over all pixels
for($y=0;$y<$h;$y++){
for($x=0;$x<$w;$x++){
$r = round(255*$y/$h);
$g = round(255*$x/$w);
$b = 0;
$alpha = rand(0,127);
$color = imagecolorallocatealpha($img,$r,$g,$b,$alpha);
imagesetpixel($img,$x,$y,$color);
}
}
// Save result
imagepng($img,"result.png");
I'll admit I haven't actually used this API, but looks like PHP has what you're looking for.
You create an image identifier with imagecreate or one of the related functions, then color in each pixel with imagesetpixel, using a color identifier created with imagecolorallocatealpha. From there you should be able to output as a PNG with imagepng.
It's worth noting that this image library seems to support drawing lines and shapes and other structures higher than the per-pixel level, so I'd also look into whether your code necessarily needs to build a big pixel array, rather than drawing the image some other way.
I'm trying to modify SVG files via a PHP script and at one point I need to calculate the length of some path elements.
In JavaScript, there's the handy function .getTotalLength(), but I wasn't able to find a PHP parser for SVG that offers something similiar, so I guess I'll have to manually parse the d-attribute and calculate the paths.
Loading the XML, getting the attribute etc. is not the problem, but I'm not very good at mathematics and especially not in the field of vectors. Let's take this example:
<path d="m 268.87448,476.05362 c -25.0135,11.49888 -35.53725,21.39636 -29.14819,47.61221 -0.79153,89.53821 7.5531,195.5936 -11.71546,284.63588 -24.02796,67.23588 -51.61983,89.1027 -112.32477,124.52935 0,0 -38.977804,16.40902 -54.19931,20.52688" />
What I would do first is explode the path by spaces and iterate through the result, then check whether it's a letter or a number and act accordingly. And that's where I'm stuck and don't even know how to begin.
I have read the SVG path specs at https://www.w3.org/TR/SVG/paths.html - but still can't get my mind around the number crunching.
i need some help, google makes me sad
I got polygon http://geojson.io/#id=gist:anonymous/069b8a955897723ca256&map=4/58.75/48.03
And it covering a lot.
And i got geoPHP library https://github.com/phayes/geoPHP
Which got methods contains, covers, coveredBy...
And everything is normal, except that point like 74.224074, 96.428248 is always false for methods contains,coveredBy,covers, etc for this polygon. But it must be true.
Please, tell me why. I got a headache.
OR
Tell me please, how check that the lat lng is inside polygon. I tested about 3 libraries in perl and php, making my own code, etc... But the right results i got only from google containsLocation in javascript. But i have to use it on server side, not in browser. If there any chance to use containsLocation in nodejs it would be very nice.
Thank you
A little code for geoPHP:
$a='JSON FROM LINK';
$b=geoPHP::load("POINT(74.224074 96.428248)","wkt");
$a=geoPHP::load($a, 'json');
$result=$a->contains($b);
var_dump($result);
And it will be false
EDIT:
I think i got it.
GeoJson making coordinates in wrong way, longtitude, latitude. But it must be latitude, longtitude.
Will try and then write here if it works
ANSWER:
Use this www.birdtheme.org/useful/v3tool.html to make polygon on maps. It making it in right way(latitude,longtitude)
Working code for geoPHP:
include_once('geoPHP.inc');
$addr=file_get_contents('https://maps.googleapis.com/maps/api/geocode/json?address='.urlencode($_GET['address']).'&sensor=false');
foreach($addr->{results} as $addr1)
{
if(array_key_exists("geometry",$addr1)){
$lat=$addr1->{geometry}->{location}->{lat};
$lng=$addr1->{geometry}->{location}->{lng};
break;
}
}
$point1 = geoPHP::load("POINT($lat $lng)","wkt");
$ya200=geoPHP::load("POLYGON((41.51 12.3, 38.27 28.83, 32.55 41.84, 27.6 55.55, 29.54 71.37, 33.43 83.32, 36.6 94.92, 36.6 99.49, 35.17 111.45, 32.55 124.8, 35.17 130.78, 39.64 142.73, 43.58 152.58, 45.83 166.29, 56.17 163.83, 63.07 159.26, 68.66 154.69, 72.18 148.71, 75.93 140.63, 78.49 129.02, 80.3 114.26, 80.98 100.2, 81.2 87.54, 80.87 73.83, 79.62 59.41, 76.27 40.43, 71.07 28.13, 67.2 23.2, 63.55 20.04, 59.01 17.23, 54.16 15.12, 48.46 13.36,41.51 12.3))","wkt");
var_dump($ya200->contains($point1));
I am the maintainer of the geoPHP library (https://geophp.net). You have your latitude and longitude mixed up. WKT specifies that x comes first, then y, and then (optionally) z. This makes sense, as we usually do things in XYZ order.
It's conventional in mathematics for the horizontal axis to be X, and the vertical axis to be Y. If we think of a globe overlaid on a piece of graphing paper with X and Y axes specified, we can see that longitude is the horizontal axis, which corresponds to X, and the latitude is the vertical axis, which corresponds to Y. Therefore reading it as "longitude, latitude" makes perfect sense.
Regrettably, this sensical approach is backwards from the way mariners and other cartographers have described coordinates on the globe it throughout history. Historically it has often been described as "latitude, longitude".
This clash of history vs mathematical-convention is why you see different conventions in different systems. In Google Maps API its "latitude, longitude", while in OpenLayers it's "longitude, latitude".
In this particular case, you are using WKT, which is specified in "longitude, latitude" order.
WKT format expects POINT(lon, lat), with lon being first. You mixed up the order. Corrected:
geoPHP::load("POINT($lon $lat)","wkt");
I have answered almost the same question but don't know how to make a repost of it, so I just repeat it here (sorry)
If you use this PHP library (https://github.com/xopbatgh/sb-polygon-pointer), it may do all you need
(but first you need to convert GEOjson coordinates to lat/lng)
Plan to do:
Insert the coordinates of your polygon into array
Ask the library is the any point with lat/lng inside this polygon
$polygonBox = [
[55.761515, 37.600375],
[55.759428, 37.651156],
[55.737112, 37.649566],
[55.737649, 37.597301],
];
$sbPolygonEngine = new sbPolygonEngine($polygonBox);
$isCrosses = $sbPolygonEngine->isCrossesWith(55.746768, 37.625605);
// $isCrosses is boolean
After hours of struggle, I could not get the contains method to work with geoPHP. It turns out, as pointed out from this SO response that the geos library needs to be installed manually (no composer), which I could not get working after sifting through documentation on archive.org.
As an alternative, I found the mjaschen/phpgeo to be simple to use to do polygon contains point calculations. Simply load in your lat lons to objects and call the contains method as outlined in the documentation:
$polygon = new Polygon();
$polygon->addPoint(new Coordinate(12.3, 41.51));
$polygon->addPoint(new Coordinate(28.83, 38.27));
$polygon->addPoint(new Coordinate(41.84, 32.55));
$point = new Coordinate(74.224074, 96.428248)
var_dump($polygon->contains($point))
All advanced methods in geoPHP requires that GEOS is installed. If You are not able to install it but still want to use intersects test for point and polygon, then I have forked geoPHP and added Polygon->pointInPolygon and MultiPolygon->pointInPolygon methods for that purpose. Take a look:
https://github.com/sookoll/geoPHP
$point = \geoPHP::load('POINT (x y)','wkt');
$polygon = \geoPHP::load('POLYGON ((x y...))','wkt');
$point_is_in_polygon = $polygon->pointInPolygon($point);
I would like to rotate an image (with a user-defined angle of rotation), but without making the image smaller.
is what happens already, saving the shaded area as a smaller image
is what I would like, the dashed line being the new image size.
The server has PHP 5.3+. Links, code and explanations all very welcome.
This is not complete answer but I would take the four corners as coordinates rotate them by your angle and then calculate the new bounding box based on the extent of the new coordinates.
(assuming coordinates with origin on the bottom left).
corners = rotate_each ( [(left,top) (left,bottom), (right,top), (right,bottom)], angle)
new_bb_left = min([corners[0].x, corners[1].x, corners[2].x, corners[3].x])
new_bb_right = max([corners[0].x, corners[1].x, corners[2].x, corners[3].x])
new_bb_bottom = min([corners[0].y, corners[1].y, corners[2].y, corners[3].y])
new_bb_top = max([corners[0].y, corners[1].y, corners[2].y, corners[3].y])
This could be a way to do it. Calculate the diagonal width.
PHP has a Square root function: http://se2.php.net/manual/en/function.sqrt.php
In that way you should have the diagonal width which you could apply on the transformed image.
There are many solutions including the trigonometric formulas but this library seems to be the shortcut.
http://wideimage.sourceforge.net/
Example: http://wideimage.sourceforge.net/wp-content/current/demo/index.php?demo=rotate&output=preset%20for%20demo&colors=255&dither=1&match_palette=1
Is there any good function to calculate the pixel width and height? Can imagettfbbox be used to do that? I mean which ttf file is needed for the different fonts used by different browsers?
Thx
As PHP run's on the server there is no way to do that with PHP alone. The size of the text depends on the operating system, the browser (and the browser settings like zoom) of the client. You could however use javascript to get the size of an element once its rendered.
height = document.getElementById("elementId").style.height; // Will return 176px for example
width = document.getElementById("elementId").style.width; // Will return 176px for example
Hope this helps
There is a function (imagefontwidth and imagefontheight), but they only return the size of one character using the built-in fonts (which are all fixed-width). You'll get the width/height of the entire string by multiplying the number returned by the number of characters.
I don't know of any way that lets you get the width or height of a string using a custom font, but I'm interested in this too.
Hope this helps.