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Martin Hope
simon
Asked: 2020-01-08 17:07:18 +0800 CST
  • 18

I don't see any functionality in an anonymous class.

Could someone explain to me what it can help me with?

Unfortunately, I don't get it. Of course I read its documentation in Oracle, but I don't see a use in production that works, I see it as if it were a method.

java
Martin Hope
Otto
Asked: 2020-12-22 13:22:26 +0800 CST
  • 18

It seems to be extensive but it is necessary to get to the idea.

I am developing a captcha image one of my ideas was to model a captcha image similar to google text captcha.

enter image description here

I have not been able to create the same style but I have generated a somewhat similar captcha image and I think it is more original for my own system.

enter image description here

I generate the text of the image in this way:

imagettftext($image,25,mt_rand(-40,30),10,30,$black,"resources/fonts/font.ttf",$first); //tamaño de la fuente se realiza en la primera numeración(25)
imagettftext($image,25,mt_rand(-40,30),30,30,$black,"resources/fonts/font1.ttf",$second); //giro de la fuente se realiza en la segunda y tercera numeración (-40,30)
imagettftext($image,25,mt_rand(-40,30),50,30,$black,"resources/fonts/font2.ttf",$third); // Espacio la cuarta, alto la quinta (50,30)
imagettftext($image,25,mt_rand(-40,30),70,30,$black,"resources/fonts/font3.ttf",$fourth); // se puede cambiar varios modelo de fuente

For a more ordered and optimized code try to implement an array but the image did not load.

$fonts = array(
    'font'  => array('spacing' => -3, 'minSize' => 27, 'maxSize' => 30, 'font' => 'resources/fonts/font.ttf'),
    'font1'  => array('spacing' =>-1.5,'minSize' => 28, 'maxSize' => 31, 'font' => 'resources/fonts/font1.ttf'),
    'font2' => array('spacing' => -2, 'minSize' => 24, 'maxSize' => 30, 'font' => 'resources/fonts/font2.ttf'),
    'font3'  => array('spacing' => -2, 'minSize' => 30, 'maxSize' => 38, 'font' => 'resources/fonts/font3.ttf'),
    'font4' => array('spacing' => -2, 'minSize' => 24, 'maxSize' => 34, 'font' => 'resources/fonts/font4.ttf'),
    'font5'     => array('spacing' => -2, 'minSize' => 28, 'maxSize' => 32, 'font' => 'resources/fonts/font5.ttf'),
    'font6' => array('spacing' =>-1.5,'minSize' => 28, 'maxSize' => 32, 'font' => 'resources/fonts/font6.ttf'),
    'font7'    => array('spacing' => -2, 'minSize' => 28, 'maxSize' => 34, 'font' => 'resources/fonts/font7.ttf'),
    'font8' => array('spacing' => -1, 'minSize' => 20, 'maxSize' => 28, 'font' => 'resources/fonts/font8.ttf'),
  );

The font color, a different color for each page update:

$black = imagecolorallocate($image,rand(78,181),rand(163,35),rand(36,7));

The problem with this parameter is that getting the color to my liking with an array would be much better, but I had the same problem as before.

$black = array(
  array(17,70,121),
  array(12,133,25),
  array(114,26,7),
  array(38,44,10),
  array(16,113,52),
  array(123,29,26)
);

The background color of the image is white.

$white = imagecolorallocate($image,255,255,255);

I don't know if it's possible to create a transparent background color by adding a variation of a rgba.

rgba(82, 56, 76, 0.15);

Thus:

imagecolorallocate($image,82, 56, 76, 0.15);

does not print the image.

Analyzing the different types of captcha on the web I have observed in some captcha where the text of the image is personalized, this is due to .txtpersonalized libraries where the file .txthas different personalized text used as text of the captcha image.

Unlike a random image:

$source = "abcdefghijklmnopqrstuvwxyz0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";

It would be useful to be able to replace a random text to a custom text using libraries.txt

My captcha code in the current layout captcha.php .

<?php
session_start();
$image = imagecreatetruecolor(120,50); //Ancho y alto de la imagen
$white = imagecolorallocate($image,255,255,255); // Color de fondo de la imagen
$black = imagecolorallocate($image,rand(78,181),rand(163,35),rand(36,7)); //Cambio de color de la fuente al refrescar

imagefill($image,0,0,$white);


imagerectangle($image,1,1,99,39 ,$white); // Configura el color del marco

$source = "abcdefghijklmnopqrstuvwxyz0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";
$first = $source[mt_rand(0,61)];
$second = $source[mt_rand(0,61)];
$third = $source[mt_rand(0,61)];
$fourth = $source[mt_rand(0,61)];
$_SESSION['captcha_secure'] = $first.$second.$third.$fourth;
imagettftext($image,25,mt_rand(-40,30),10,30,$black,"resources/fonts/Quixley.ttf",$first); //tamaño de la fuente se realiza en la primera numeracion -> (25)
imagettftext($image,25,mt_rand(-40,30),30,30,$black,"resources/fonts/AntykwaBold.ttf",$second); //giro de la fuente se realiza en la segunda y tercera numeración -> (-40,30)
imagettftext($image,25,mt_rand(-40,30),50,30,$black,"resources/fonts/Ding-DongDaddyO.ttf",$third); // Espacio la cuarta, alto la quinta -> (50,30)
imagettftext($image,25,mt_rand(-40,30),70,30,$black,"resources/fonts/Duality.ttf",$fourth); // se puede cambiar varios modelo de fuente

// Para añadir más caracters a la imagen se debe multiplicar estos parametros al caracters deseado
/*
imagettftext($image,25,mt_rand(-40,30),70,30,$black,"resources/fonts/Duality.ttf",$fourth);
*/

header("content-type:image/png");
imagepng($image);
?>
php
Martin Hope
Black Sheep
Asked: 2020-11-07 04:51:01 +0800 CST
  • 18

I have seen on many occasions when receiving data from a form the following check:

if (isset($_POST['campo1'])) {
   // Resto de código
}

What if the value $_POST['campo1']is empty?

Or on many other occasions I have seen the following check:

if (isset($_POST['campo1']) && !empty($_POST['campo1'])) {
   // Resto de código
}

It is completely redundant to check the value $_POST['campo1']at the same time with isset()and !empty()?

So my question is: how and when are they used isset()and empty()correctly?

php
Martin Hope
Edwin V
Asked: 2020-10-12 12:59:32 +0800 CST
  • 18

I want to know if there is any way to make a button that allows to download images that are saved in another server from a URL. That is, like right click - save image as but with a button. I searched for solutions with PHP or JavaScript but haven't found anything yet.

The HTML5 attribute downloaddoes not work in all browsers. Is there an alternative with JavaScript?

javascript
Martin Hope
Alvaro Montoro
Asked: 2020-02-03 14:53:15 +0800 CST
  • 18

Nested AJAX calls are referenced in another Spanish StackOverflow question and the answer suggests using promisesinstead of nesting AJAX calls. And from there I have had some doubts.

Note: I'm going to use jQuery notation by removing quite a few parameters and renaming the functions to make it easier to read. It doesn't mean that this question is about jQuery or AJAX in jQuery.

Basically what the question asks is this:

Structure A

$.ajax({
    url: URL1,
    success: function() {
        a1();
        $.ajax({
            url: URL2,
            success: function() {
                a2();
            },
            error: function() {
                b2();
            }
        });
    },
    error: function() {
        b1();
    }
});

And what is suggested in the answer is something like this:

Structure B

var promise = $.ajax({
    url: URL1,
    success: function() {
        a1();
    },
    error: function() {
        b1();
    }
});

promise.then(function() { 
    $.ajax({
        url: URL2,
        success: function() {
            a2();
        },
        error: function() {
            b2();
        }
    });
});

And now my questions:

  • Are structure A and B equivalent? What is the difference between them?
  • Is there an advantage to using one over the other?
  • Is one of the methods recommended over the other?
javascript
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