Should I use SVG or PNG for Xamarin Forms for iOS and Android?

If we use PNG – for iOS we use @ x1 @ x2 @ x3 size per image (which in Zeplin / Sketch is just a click). Android – about 5 image sizes, so we need to manage 8 PNG images per graphic element.

while SVG – will work for iOS and Android, but there are technical limitations. For example, the SVGs are distorted during rendering. We may be able to fix the problem by sketching the individual SVG elements / layers.

I hope someone can help us find the best format for our app.

Many Thanks!

Changes from svg to png do not apply

I had an SVG, I changed it and created a gradient.

Then I converted it to a PNG, but the gradient is not in the new PNG.

I tried to convert the SVG to PNG with an internet converter, but the gradient is still not forwarded.

When I open SVG with Illustrator, I can not see the gradient. In the preview of the SVG I can see the color gradient.

I get the following error: org.apache.batik.bridge.BridgeException The attribute & # 39; d & # 39; of the element is invalid.

My question is:

If someone has found this or similar error or has an idea how to fix it, can you give me some advice on how to fix it?

My converter:

public void svgToPng () throws MalformedURLException {

String svg = "/ Users / userName / svg /";
File Folder = New File (svg);

for (file fileEntry: folder.listFiles ()) {

string[] codeAux = fileEntry.getName (). split ("\.");

if (codeAux[0].isEmpty ()) {

LOGGER.debug ("name of file is empty");

} else {
tries {

PNG Transcoder Transcoder = new PNG Transcoder ();

String svgURI = fileEntry.toURI (). ToURL (). ToString ();
Transcoder input input = new transcoder input (svgURI);

String outputPath = "/ Users / userName / png /";

OutputStream ostream = new FileOutputStream (outputPath + codigoAux[0] + ".png");
TranscoderOutput output = new TranscoderOutput (ostream);

transcoder.transcode (input, output);

ostream.flush ();
ostream.close ();

} catch (TranscoderException ex) {

LOGGER.error (ex);

} catch (IOException ex) {

LOGGER.error (ex);





And here is my path element:

The expected result is a PNG with the gradient.

Running the script from & # 39; * .js & # 39; was rejected because the MIME type (& # 39; image / png & # 39;) is not executable.


The website worked fine. It often does not work properly in the last month.
However, the script loads properly into the Hawkhost support team. They sent me a picture of the script as a screenshot.

But for me it is displayed as a picture. A green shield with a check mark.

The website will not load because it was created with "reacts".

How do I solve the problem? What is the reason for that?
Why is the mime type image / png?

1. No problem with Hawkhost
2. I have not changed anything in the script

What is the cause of the problem then?

Please tell me how to track down the problem.

About the PNG vulnerability in Android – Information Security Stack Exchange

The file may be specially designed to trigger the malicious code when the user opens it (viewed locally) on its device (locally or through a received link).

The vulnerability associated with the PNG bug can be traced as CVE-2019-1986, CVE-2019-1987, CVE-2019-1988.

CVE-2019-1986 – Uninitialized errors in SkPngCodec

CVE-2019-1987 – heap buffer overflow

CVE-2019-1988 – Error decoding JCS_RGB JPEG files

WPF Path Markup Syntax vs. Png XAML benefits?

I have made some WPF Xaml designs. The current workflow is that our designer sends a design file containing all PNG assets and embeds the PNGs into the application.

But I found a XAML with the tool I use to display the design <Path ... is also generated, which I can copy and paste directly into the XAML.

I could not find any articles about these types of best practices, but is there a compelling reason to do that Path markup syntax instead of embedding PNGs directly (is this a better practice than using PNGs)?

Nginx proxy cache 404 did not find any static files (css, js, jpg, png vb)

My nginx proxy server:
My backend server:

My proxy server does not load static files (css, js, woff, png vb.)

My conf

Proxy_Cache_Path / etc / nginx / Proxy_Cache Layers = 1: 2 keys_zone = ferditest: 10m inactive = 60m;
proxy_cache_key "$ scheme $ request_method $ host $ request_uri";

Server {

listen 80;
you hear 443 ssl;
Server name;

ssl_certificate /etc/letsencrypt/live/;
ssl_certificate_key /etc/letsencrypt/live/;

location ~ * . (jpg | jpeg | png | gif | ico | css | js | pdf | woff | woff2 | pdf) $ {
expires 30d;

#include /etc/nginx/bots.d/ddos.conf;
#include /etc/nginx/bots.d/blockbots.conf;
#include /etc/nginx/bots.d/blacklist-ips.conf;

ssl_ciphers HIGH :! aNULL :! MD5;
ssl_prefer_server_ciphers on;
ssl_session_cache shared: SSL: 1m;
ssl_session_timeout 5m;
ssl_protocols TLSv1 TLSv1.1 TLSv1.2; # Do not use SSLv3 for killer glands

Page number on;
pagespeed FileCachePath "/ etc / nginx / ngx_pagespeed /";
pagespeed EnableFilters collapse_whitespace;
pagespeed EnableFilters extend_cache;
pagespeed EnableFilters make_google_analytics_async;
pagespeed EnableFilters lazyload_images;
pagespeed EnableFilters rewrite_images;

location ~ " .pagespeed . ([a-z].)?[a-z]{2} .[^.]{10} .[^.]+ "{
add_header "" "";
location ~ "^ / pagespeed_static /" {}
location ~ "^ / ngx_pagespeed_beacon $" {}

Location / {

add_header Strict-Transport-Security "max-age = 31536000";
add_header X-Content-Type-Options nosniff;
add_header X-Cache $ upstream_cache_status;

proxy_cache ferditest;
add_header X proxy cache $ upstream_cache_status;
proxy_ignore_headers X-Accel-Expires Expires Cache-Control-Set-Cookie;
proxy_set_header Accept-Encoding "gzip";

proxy_buffering on;
proxy_cache_valid 200 302 1m;
proxy_cache_valid 404 1m;
proxy_cache_methods GET HEAD;

proxy_cache_use_stale Error Timeout invalid_header Updated from http_500 http_502 http_503 http_504;
proxy_cache_use_stale update;


proxy_set_header Host $ http_host;
proxy_set_header X-Forwarded host $ http_host;
proxy_set_header X-Real-IP $ remote_addr;
proxy_set_header X-Forwarded-For $ proxy_add_x_forwarded_for;
proxy_set_header X-Forwarded-Proto https;
proxy_set_header HTTPS "on";
proxy_set_header X-NginX proxy true;
proxy_set_header X-Accel Internal / Internal Nginx Static Location;


error log

[error]    23151 # 23151: * 6 open () "/etc/nginx/html/test1/wp-includes/js/wp-embed.min.js" failed (2: No such file or directory), client:

Many Thanks

Add tEXt blocks to PNG frames exported from ffmpeg

I currently use ffmpeg and make a video as input and a complex filter:

  • Split into multiple streams
  • Apply a set of filters for each stream (each filter performs a different transformation).

Then I assign each of the streams to output a sequence of PNG images.

Currently I am writing everything Pipe: 1 (stdout) so that the program that starts ffmpeg can process the output.

Each of the streams must be processed separately in the calling program.

So I want to tag the PNGs to identify how they should be processed. The text Chunk type in PNGs would be perfect for that.

The question is, how can I have ffmpeg encode this piece (or another piece of metadata) into the PNG?

Right now I'm trying the following:

Split = 2[in1][in2];[in1][out1];[in2][out2]    
-Map [out1] -metadata title = -codec png -f image2pipe pipe: 1 
-Map [out2] -metadata title = -codec png -f image2pipe pipe: 1

However, there are no extra chunks in the PNGs being streamed to the pipe.

I tried that too metadata filter like this:

Split = 2[in1][in2];[in1], metadata = add: key = mykey: value = mytag1[out1];[in2], metadata = add: key = mykey: value = mytag2[out2] 
-Map [out1] -metadata title = -codec png -f image2pipe pipe: 1 
-Map [out2] -metadata title = -codec png -f image2pipe pipe: 1

However, this does not generate additional metadata in the PNG stream.

Is this possible or do I have to find another way to somehow separate and process the streams?

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html – jpg / png Problems with Huzzah ESP2866 + Arduino IDE

I am using a Huzzah ESP2866 with Arduino IDE. I'm trying to upload images with html + spiffy, but the broken image logo still appears. The text works well. Also, the HTML file will open with a working image in a browser, so I'm pretty sure the location of jpeg / png is not the problem.
I also tried different jpegs / pngs, but the same result.

I use code from here:

The text works well. The HTML file is also opened with a working image in a browser. So I'm pretty sure the JPEG position is not the problem. I also tried different jpegs / pngs, but the same result.

I use code from here:


This example shows how to load images from the ESP8266 Web server "Image" and HTML web page files are uploaded to ESP Flash with the SPIFFS tool:

Picture of ESP8266


* ESP8266 SPIFF HTML web page with JPEG, PNG image
* /

#include    // Include file system headers

const char * imagefile = "";
const char * htmlfile = "index.html";

// Configuration of the ESP-AP mode
const char * ssid = "";
const char * password = "password";

ESP8266 Web server server (80);

void handleRoot () {
server.sendHeader ("Location", "/index.html",true); // Forward to
our HTML website
server.send (302, "text / plane", "");

void handleWebRequests () {
if (loadFromSpiffs (server.uri ())) return;
String message = "File not found  n  n";
message + = "URI:";
message + = server.uri ();
message + = " nMethod:";
message + = (server.method () == HTTP_GET)? "GET": "POST";
message + = " nArguments:";
message + = server.args ();
Message + = " n";
for (uint8_t i = 0; i <server.args (); i ++) {
message + = "NAME:" + server.argName (i) + " n VALUE:" + server.arg (i)
+ " n";
server.send (404, "text / plain", message);
Serial.println (message);

void setup () {
Delay (1000);
Series start (115200);
Serial.println ();

// initialize file system
SPIFFS.begin ();
Serial.println ("file system initialized");

// Initialize AP mode
WiFi.softAP (ssid); // password not used
IP address myIP = WiFi.softAPIP ();
Serial.print ("Web Server IP:");
Serial.println (myIP);

// Initialize web server
server.on ("/", handleRoot);
server.onNotFound (handleWebRequests); // set all paths
not found, so we can handle via URI
server.begin ();

Empty loop () {
server.handleClient ();

bool loadFromSpiffs (String Path) {
String dataType = "text / plain";
if (path.endsWith ("/")) path + = "index.htm";

if (path.endsWith (".src")) path = path.substring (0,
path.lastIndexOf ("."));
else if (path.endsWith (".html")) dataType = "text / html";
else if (path.endsWith (".htm")) dataType = "text / html";
else if (path.endsWith (".css")) dataType = "text / css";
else if (path.endsWith (".js")) dataType = "application / javascript";
else if (path.endsWith (".png")) dataType = "image / png";
else if (path.endsWith (".gif")) dataType = "image / gif";
else if (path.endsWith (".jpg")) dataType = "image / jpeg";
else if (path.endsWith (".ico")) dataType = "image / x-icon";
else if (path.endsWith (".xml")) dataType = "text / xml";
else if (path.endsWith (".pdf")) dataType = "application / pdf";
else if (path.endsWith (".zip")) dataType = "application / zip";
File dataFile = (path.c_str (), "r");
if (server.hasArg ("download")) dataType = "application / octet-
if (server.streamFile (dataFile, dataType)! = dataFile.size ()) {

dataFile.close ();
return true;

Javascript – How to Download Images Using the Base64 URL (Data: image / png)

I have the following code to use to transform an element of my site into png using the html2canvas library:

Function saveStory () {
html2canvas (document.querySelector ("# story")). then (canvas => {
$ (& # 39; # appCanvas & # 39;). append (artboard)
var canvaUrl = canvas.toDataURL ("image / png");
$ (# Test #). attr (& # 39; href & # 39; canvaUrl);
$ (# Test #). attr (& # 39; download & # 39 ;, test file.png & # 39;);
$ (# Test #)[0]click ();

However, I have a problem and the download does not start because Chrome at least does not allow the pictures base64, I've tried to change the following code, but will then download without the .png extension, so it's an unknown file until the extension is added manually.

Instead of var canvaUrl = canvas.toDataURL ("image / png"); :

var canvaUrl = canvas.toDataURL ("image / png"). replace (/ ^ data: image  /[^;]+ /, # Data: application / octet-stream & # 39;);

Note: #test is an empty link, which then takes the link of the image, but pressing does not matter.