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WIP: Support Alpha Channels for Colors #41

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WIP: Support Alpha Channels for Colors #41

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896800f
Remove the color class in favor of our own hex2rgba function
kingkool68 Aug 16, 2023
caf12aa
Allow setting the transparency on colors
kingkool68 Aug 16, 2023
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88 changes: 73 additions & 15 deletions code.php
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Original file line number Diff line number Diff line change
Expand Up @@ -79,6 +79,64 @@ function imagettfbbox_t( $size, $text_angle, $fontfile, $text ) {
return $ret;
}

/**
* Convert a hex string to red, green, blue, and alpha values between 0 - 255.
*
* Accepts a 1, 2, 3, 4, 6, and 8 digit hex code.
*
* The alpha transparency can be set with :50 at the end of the hex string.
*
* #ccc:50 would be R = 204, G = 204, B = 204, Alpha = 128 (or 50%)
* Same thing for #cccccc80
*
* @param string $hex The hex string to convert
*/
function hex2rgba( $hex = '' ) {
$hex = strtolower( $hex );
$hex = str_replace( '#', '', $hex );
$hex_parts = explode( ':', $hex );
$hex = $hex_parts[0];
$hex_length = strlen( $hex );
$input = $hex;
switch ($hex_length) {
case 1:
$hex = $input . $input . $input . $input . $input . $input;
break;
case 2:
$hex = $input[0] . $input[1] . $input[0] . $input[1] . $input[0] . $input[1];
break;
case 3:
$hex = $input[0] . $input[0] . $input[1] . $input[1] . $input[2] . $input[2];
break;
case 4:
$hex = $input[0] . $input[0] . $input[1] . $input[1] . $input[2] . $input[2] . $input[3] . $input[3];
break;
}
// Set the alpha level to 100% for 6 character hex codes
if ( strlen( $hex ) === 6 ) {
$hex .= 'ff';
}
$parts = str_split( $hex, 2 );
$alpha = $parts[3];
$alpha = hexdec( $alpha );
$alpha_percent = round( $alpha / 255, 2 );
if ( isset( $hex_parts[1] ) ) {
$user_supplied_alpha = $hex_parts[1];
$user_supplied_alpha = abs( (int) $user_supplied_alpha );
$user_supplied_alpha = min( $user_supplied_alpha, 100 );
$alpha_percent = $user_supplied_alpha / 100;
$alpha = round( $alpha_percent * 255 );
}

return (object) array(
'r' => hexdec( $parts[0] ),
'g' => hexdec( $parts[1] ),
'b' => hexdec( $parts[2] ),
'alpha' => (int) $alpha,
'alpha_percent' => $alpha_percent,
);
}

// Get the query string from the URL. x would = 600x400 if the url was https://dummyimage.com/600x400
$x = strtolower( $_GET['x'] );
// Strip / if it's the first character
Expand Down Expand Up @@ -242,9 +300,6 @@ function imagettfbbox_t( $size, $text_angle, $fontfile, $text ) {
$width = round( $width, 3 );
$height = round( $height, 3 );

// To easily manipulate colors between different formats
require 'color.class.php';

// Find the background color which is always after the 2nd slash in the url
$bg_color = 'ccc';
if ( ! empty( $x_pieces[1] ) ) {
Expand All @@ -253,8 +308,7 @@ function imagettfbbox_t( $size, $text_angle, $fontfile, $text ) {
$bg_color = $bg_color_parts[0];
}
}
$background = new color();
$background->set_hex( $bg_color );
$background = hex2rgba( $bg_color );

// Find the foreground color which is always after the 3rd slash in the url
$fg_color = '000';
Expand All @@ -264,8 +318,7 @@ function imagettfbbox_t( $size, $text_angle, $fontfile, $text ) {
$fg_color = $fg_color_parts[0];
}
}
$foreground = new color();
$foreground->set_hex( $fg_color );
$foreground = hex2rgba( $fg_color );

// This is the default text string that will go right in the middle of the rectangle
// × is the multiplication sign, it is not an 'x'
Expand All @@ -292,17 +345,22 @@ function imagettfbbox_t( $size, $text_angle, $fontfile, $text ) {

// Create an image
$img = imageCreate( $width, $height );
$bg_color = imageColorAllocate(
$bg_alpha = 127 - ( $background->alpha >> 1);
$bg_color = imagecolorallocatealpha(
$img,
$background->get_rgb( 'r' ),
$background->get_rgb( 'g' ),
$background->get_rgb( 'b' )
$background->r,
$background->g,
$background->b,
$bg_alpha
);
$fg_color = imageColorAllocate(

$fg_alpha = 127 - ( $foreground->alpha >> 1);
$fg_color = imagecolorallocatealpha(
$img,
$foreground->get_rgb( 'r' ),
$foreground->get_rgb( 'g' ),
$foreground->get_rgb( 'b' )
$foreground->r,
$foreground->g,
$foreground->b,
$fg_alpha
);

// Ric Ewing: I modified this to behave better with long or narrow images and condensed the resize code to a single line
Expand Down
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