问题
I recently received an emailer from Onnit Labs that included a Countdown Module Timer inside the emailer using a gif image. The emailer can be viewed here: https://www.onnit.com/emails/lastchance-historic/
The Image can be seen here:
I looked into it, and it seems you can keep sending new frames to an animated GIF using gifsockets, as a GIF doesn't specify how many frames it has when loaded in the browser. Here it is on github: http://github.com/videlalvaro/gifsockets
I thought this was pretty interesting and a cool effect indeed. Does anyone have any other insights on how this could be accomplished? It seems as though the one they're using at Onnit seems to change the countdown according to date appended at the end of URL or image.
onnit.com/emails/_modules/timer/?end=2012-12-27+00:00:00&dark=1
I'm trying to accomplish the same thing to send in an email, but I am a little stumped.
回答1:
While maybe gifsockets would work (I haven't tried that before...), there is no network traffic while I am looking at the image other than the initial image load. I am also seeing it it jump from 41 to 42 again. A Reload took it down to 39.
It appears to be just a script that generates 60 frames of animation and sends them to the user. This could probably be done in any language.
Here is how it is done in php:
http://seanja.com/secret/countdown/
回答2:
I found http://sendtric.com/ which is free and very easy to integrate.
回答3:
I really appreciated Sean Ja's answer. (He deserves more upvotes.) And then I wanted to make the code more readable and configurable (and support text on a transparent gif and automatically center the text):
use Carbon\Carbon;
class CountdownGifHelper {
const DELAY = 100; /* Why was this labeled as 'milliseconds' when it seems like a value of 100 here causes 1 frame to be shown per second? */
const MAX_FRAMES = 120;
/**
*
* @param string $bgImg
* @param \DateInterval $interval
* @param array $fontArr
* @param array $frames
* @param array $delays
* @param string $format
*/
public function addFrame($bgImg, $interval, $fontArr, &$frames, &$delays, $format) {
$image = imagecreatefrompng($bgImg); //Each frame needs to start by creating a new image because otherwise the new numbers would draw on top of old ones. Here, it doesn't really matter what the PNG is (other than for size) because it's about to get filled with a new color.
$text = $interval->format($format);
ob_start();
imageSaveAlpha($image, true);
$backgroundColor = $fontArr['backgroundColor'];
imagefill($image, 0, 0, $backgroundColor); //https://stackoverflow.com/a/17016252/470749 was a helpful hint
imagecolortransparent($image, $backgroundColor);
$this->insertCenteredText($image, $fontArr, $text);
//imagettftext($image, $font['size'], $font['angle'], $font['x-offset'], $font['y-offset'], $font['color'], $font['file'], $text);//this was the old way
imagegif($image); //The image format will be GIF87a unless the image has been made transparent with imagecolortransparent(), in which case the image format will be GIF89a.
$frames[] = ob_get_contents();
ob_end_clean();
$delays[] = self::DELAY;
}
/**
*
* @param resource $image
* @param array $fontArray
* @param string $text
*/
public function insertCenteredText(&$image, $fontArray, $text) {
$image_width = imagesx($image);
$image_height = imagesy($image);
$text_box = imagettfbbox($fontArray['size'], $fontArray['angle'], $fontArray['file'], $text); // Get Bounding Box Size
$text_width = $text_box[2] - $text_box[0];
$text_height = $text_box[7] - $text_box[1];
// Calculate coordinates of the text https://stackoverflow.com/a/14517450/470749
$x = ($image_width / 2) - ($text_width / 2);
$y = ($image_height / 2) - ($text_height / 2);
imagettftext($image, $fontArray['size'], $fontArray['angle'], $x, $y, $fontArray['color'], $fontArray['file'], $text);
}
/**
*
* @param int $timestamp
* @param string $bgImg
* @param array $fontArray
* @return string [can be used by Laravel response()->make($gifString, 200, $headers)]
*/
public function getAnimatedGif($timestamp, $bgImg, $fontArray) {
$future_date = Carbon::createFromTimestamp($timestamp);
$time_now = time();
$moment = new \DateTime(date('r', $time_now));
$frames = [];
$delays = [];
for ($i = 0; $i <= self::MAX_FRAMES; $i++) {
$interval = date_diff($future_date, $moment);
if ($future_date < $moment) {
$this->addFrame($bgImg, $interval, $fontArray, $frames, $delays, '00 : 00 : 00');
$loops = 1; //stay stuck on this frame
break;
} else {
$this->addFrame($bgImg, $interval, $fontArray, $frames, $delays, '%H : %I : %S');
$loops = 0; //infinite loop
}
$moment->modify('+1 second');
}
$animatedGif = new \App\Helpers\AnimatedGif($frames, $delays, $loops, 0, 0, 0);
return $animatedGif->getAnimation();
}
/**
* ONEDAY allow config via params
* @param resource $image
* @return array
*/
public function getFontArray($image) {
$fontArr = [
'file' => resource_path('assets/fonts/Kanit-Regular.ttf'),
'size' => 30,
//'x-offset' => 5,
//'y-offset' => 30,
'color' => imagecolorallocate($image, 90, 90, 90), //gray
'backgroundColor' => imagecolorallocate($image, 0, 0, 0), //white. Must match the arguments provided to AnimatedGif (such as 0,0,0).
'angle' => 0,
];
return $fontArr;
}
}
回答4:
You could try http://makedreamprofits.com/pt/. Instead of supplying additional content to a gif, this countdown is broken into separate images and can count for up to 20 mins without increasing much traffic.
P.S. Gmail is precaching images, so, supplying it endlessly with new frames is not possible.
来源：https://stackoverflow.com/questions/13593420/countdown-timer-image-gif-in-email