Can someone help me to draw single pixel using php GD library?
I have such code:
$img = imagecreatetruecolor(100, 100);
$c = imagecolorallocate($img, 255, 0, 0);
$white = imagecolorallocate($img, 255, 255, 255);
imagefill($img, 0, 0, $white);
imagesetpixel($img, 0, 0, $c);
imagejpeg($img, 'created.jpg');die();
But the output is really weird (it is approximate image in top-left corner):
Is it possible to draw just one red pixel at x-0 y-0 position?
Related
So I have a 3x3 pixel image using imagecreate. I want to scale up the image with imagescale while maintaining the look of a 3x3 grid of "pixels". However, the pixels on the right and bottom edge are not the same size.
Here is my code and output image:
<?php
$image = imagecreate(3, 3);
imagecolorallocate($image, 0, 0, 255);
$red = imagecolorallocate($image, 255, 0, 0);
imagesetpixel($image, 0, 0, $red);
imagesetpixel($image, 1, 1, $red);
imagesetpixel($image, 2, 2, $red);
imagepng(imagescale($image, 200, 200, IMG_NEAREST_NEIGHBOUR));
header("Content-Type: image/png");
This is my output:
Notice how the bottom-right pixel is cut off. I kept playing with the numbers for the new dimensions and arrived at 256x256 at which point the pixels are all the same size.
This is the output after using 256x256:
My question is: How can I derive the dimensions to use for the resized image with the effect I described?
Bonus question: Is an alternative method which will allow me to resize to an arbitrary size and keep the pixels approximately the same size?
I would use imagecopyresampled to achieve this.
http://php.net/manual/en/function.imagecopyresampled.php
<?php
$width = 3;
$height = 3;
$image = imagecreate($width, $height);
imagecolorallocate($image, 0, 0, 255);
$red = imagecolorallocate($image, 255, 0, 0);
imagesetpixel($image, 0, 0, $red);
imagesetpixel($image, 1, 1, $red);
imagesetpixel($image, 2, 2, $red);
$new_width = 200;
$new_height = 200;
$dst = imagecreatetruecolor($new_width, $new_height);
imagecopyresampled($dst, $image, 0, 0, 0, 0, $new_width, $new_height, $width, $height);
imagepng($dst);
header("Content-Type: image/png");
My problem is this, I want to create image thats combination of 3 image, first is yellow background, then I use PHP and GD to write some text on it, text is black, so I made it transparent in next step, then I want to put that picture over background picture, so text has texture on it. It works fine, if I upload PNG from my computer created in Gimp, but picture created with gd has transparency on it but result is again yellow background with black letters.
how it should be
good result
what I get now from code:
enter link description here
how it gets now with image created from gd
<?php
header('Content-Type: image/png');
$title = "PULEŽANI";
$im = imagecreatetruecolor(1200, 320);
//$im = imagecreatetruecolor(1200, 320);
$white = imagecolorallocate($im, 255, 255, 255);
$crna = imagecolorallocate($im, 0, 0, 0);
$black = imagecolorallocatealpha($im, 255, 255, 255, 127);
$yellow = imagecolorallocate($im, 251, 189, 8);
// kreiram kvadrat sa žutom pozadinom
imagefill($im, 0, 0, $yellow);
$font = "/AlrightSans-Ultra-v3.ttf";
//dodajem text na žutu pozadinu
imagettftext($im, 122, 0, 40, 160, $crna, $font, $title);
//kreiram sliku crni tekst na žutoj pozadini
imagepng($im, 'sl.png');
imagedestroy($im);
//ovaj dio bi trebao napraviti da crna slova postanu prozirna
$image = imagecreatefrompng('sl.png');
$odabirprozirne = imagecolorallocatealpha($image, 0, 0, 0,127);
imagealphablending($image, true);
imagecolortransparent($image,$odabirprozirne);
imagepng($image, 'sl114.png');
imagedestroy($image);
/* dodaj zvijezde odispod */
$image_1 = imagecreatefrompng('TexturaZvijezde.png');
$image_2 = imagecreatefrompng('sl114.png');
imagesavealpha($image_1, true);
imagecopy($image_1, $image_2, 0, 0, 0, 0, 1200, 120);
imagepng($image_1);
imagedestroy($image_1);
I haven't tested this, but according to the manual for imagesavealpha function,
You have to unset alphablending (imagealphablending($im, false)), to use it.
Example:
// Turn off alpha blending and set alpha flag
imagealphablending($png, false);
imagesavealpha($png, true);
I'm struggling with PHP's GDLib just a little bit here. I'm trying to overlay two .PNG images on top of eachother, which so far works fine.
The one problem I run into is that sometimes, the overlay image comes with a white background. I can make this transparent (using the imagecolortransparent function), but this transparency isn't saved when I copy this image onto a new one.
// Load the background image first
$background = imagecreatefrompng($this->background);
// Load the overlaying image next, and set white as a transparent color
$overlay = imagecreatefrompng($this->image);
imagecolortransparent($overlay, imagecolorallocate($overlay, 255, 255, 255));
// So far, this all works. But when I create a new image,
// and paste both $background and $overlay into it,
// $overlay loses transparency and reverts to a white fill.
$image = imagecreatetruecolor(16, 16);
imagesavealpha($image, true);
$trans_colour = imagecolorallocatealpha($image, 255, 255, 255, 127);
imagefill($image, 0, 0, $trans_colour);
imagecopyresampled($image, $background, 0, 0, 0, 0, 16, 16, 16, 16);
imagecopyresampled($image, $overlay, 0, 0, 0, 0, 16, 16, 16, 16);
#mkdir(dirname($file), 0777, true);
imagepng($image, $file);
// The new $image is now mostly white. The transparency on $overlay
// was lost, meaning that the $background image is completely invisible.
How can I keep the transparency when copying $overlay into a new image?
$photo_to_paste = "photo_to_paste.png";
$white_image = "white_image.png";
$im = imagecreatefrompng($white_image);
$im2 = imagecreatefrompng($photo_to_paste);
imagecopy($im, $im2, (imagesx($im) / 2) - (imagesx($im2) / 2), (imagesy($im) / 2) - (imagesy($im2) / 2), 0, 0, imagesx($im2), imagesy($im2));
// Save alpha for the destination image.
imagesavealpha($im, true);
$trans_colour = imagecolorallocatealpha($im, 0, 0, 0, 127);
imagefill($im, 0, 0, $trans_colour);
// Save final image after placing one on another image
imagepng($im, "output.png", 0);
imagedestroy($im);
imagedestroy($im2);
I am calling imagecopymerge($dst_r, $logo, 0, 0, 0, 0, $LogoX, $LogoY, 100); where $logo is a png file with transparent background. From some reason the background comes out white instead.
What am I doing wrong?
Thanks.
You need to use imagealphablending($dst_r, TRUE); to allow copying with retaining the transparent colors. Many more comments (...) in the manual suggest using imagecopy instead, because imagecopymerge was never intended to be used with transparency. If you use pct=100 anyway, then the normal imagecopy might be an option.
This is for text, but you can get the point. It would be more helpful if you post entire code.
$font = 25;
$string = "Hello";
$im = #imagecreatetruecolor(strlen($string) * $font / 1.5, $font);
imagesavealpha($im, true);
imagealphablending($im, false);
$white = imagecolorallocatealpha($im, 255, 255, 255, 127);
imagefill($im, 0, 0, $white);
$lime = imagecolorallocate($im, 204, 255, 51);
imagettftext($im, $font, 0, 0, $font - 3, $lime, "font.ttf", $string);
header("Content-type: image/png");
imagepng($im);
imagedestroy($im);
When I perform and image overlay in php using the GD library, I always get a black background, however, all the images overlay correctly. Can someone help?
<?php
$images = array( $_GET['color'], $_GET['face'], $_GET['hat'] );
$img = imagecreatetruecolor(58, 75);
imagealphablending($img, true);
imagesavealpha($img, true);
imagecolorallocate($img, 255, 205, 255);
imagecolorallocate($img, 255, 255, 255);
imagecolortransparent($img, $white);
imagefilledrectangle($img, 0, 0, $imgWidth, $imgHeight, $white);
foreach($images as $fn) {
$cur = imagecreatefrompng($fn);
imagealphablending($cur, true);
imagesavealpha($cur, true);
imagecopy($img, $cur, 0, 0, 0, 0, 58, 75);
imagedestroy($cur);
}
header('Content-Type: image/png');
imagepng($img);
?>
// Create an image
$img = imagecreatetruecolor($imgWidth, $imgHeight);
$white = imagecolorallocate($img, 255, 255, 255);
// Make the background white
imagefilledrectangle($img, 0, 0, $imgWidth, $imgHeight, $white);
...could help.
This is a common problem, and the answer is already available on stack overflow; the answer there fixes the problem perfectly. You may want to try searching harder :)
I would suggest that you can make your life easier by using the vastly more powerful (but unfortunately poorly documented) imagick library if you're going to try to do anything more than the most basic image manipulation; it's faster, easier (again, once you get past the documentation) and more powerful.