du6029076877
2010-08-15 04:36 阅读 35
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PHP GD修剪透明像素来自创建的PNG

I am currently working on a website and lately have been using GD with PHP to automatically create transparent images that consist of text for use with navigation, headers, etc on the website. It saves me a lot of time in Photoshop plus I can change the text on the buttons instantly when needed.

Well I have hit a dead end here. I found the method of sizing the "textbox", created as my image, to what the size of the text is. But the problem I am facing is the fact that I am using a TTF font which is different then what GD expects the size to be. Basically, the last letter would be chopped off the outputted image. So I was wondering if there was a way to fix this while keeping a tight edge to the text or make the original textbox a much larger size and then "trim" the transparent pixels off the image.

This is the code I'm working with now...

<?
$text = strip_tags($_GET['btn']);
if(file_exists('nav_'.$text.'.png')) {
    header("Content-type: image/png");

    $image = imagecreatefrompng('nav_'.$text.'.png');
    imagesavealpha($image, true);
    imagealphablending($image, false);
    imagepng($image);
    imagedestroy($image);
} else {
    header("Content-type: image/png");

    $fontSize = 10;
    $angle = 0;
    $font = "RonniaBold.ttf";

    $size = imagettfbbox($fontSize, $angle, $font, $text);
    $image = imagecreatetruecolor(abs($size[2]) + abs($size[0]) + 5, abs($size[7]) + abs($size[1]) + 5);
    imagesavealpha($image, true);
    imagealphablending($image, false);

    $transparentColor = imagecolorallocatealpha($image, 200, 200, 200, 127);
    imagefill($image, 0, 0, $transparentColor);

    $textColor = imagecolorallocate($image, 125, 184, 222);
    imagettftext($image, $fontSize, 0, 1, abs($size[5])+1, $textColor, $font, str_replace('_',' ',strtoupper($text)));
    imagepng($image, 'nav_'.$text.'.png', 0);
    imagedestroy($image);
}
?>

Hopefully you guys have some insight to this, I could really use it!

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2条回答 默认 最新

  • 已采纳
    drze7794 drze7794 2010-08-15 07:00

    Wherever possible, I use the Imagick class, as I prefer the ImageMagick library. The following example is taken almost verbatim from the example given here. It creates an image based on the size of the text supplied:

    $text = 'Hello World!';
    
    // Create a new ImageMagick objects.
    $im = new Imagick();
    $draw = new ImagickDraw();
    $colour = new ImagickPixel('#000000');
    $background = new ImagickPixel('none');
    
    // Set font properties.
    $draw->setFont('Fertigo_PRO.otf');
    $draw->setFontSize(72);
    $draw->setFillColor($colour);
    $draw->setStrokeAntialias(true);
    $draw->setTextAntialias(true);
    
    // Get font metrics.
    $fm = $im->queryFontMetrics($draw, $text);
    
    // Create text.
    $draw->annotation(0, $fm['ascender'], $text);
    
    // Create a new empty canvas, using the text size.
    $im->newImage($fm['textWidth'], $fm['textHeight'], $background);
    
    // Create the image.
    $im->setImageFormat('png');
    $im->drawImage($draw);
    
    // Save the image.
    $im->writeImage('test.png');
    

    If you want more information on the Imagick class, I recommend the excellent Imagick articles from Mikko's Blog.

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  • dony39517 dony39517 2011-08-26 08:25

    You have a problem with your code which prevents you from determining the correct size of your text - when asking for the size of the text box with imagettfbox you use $text:

    $size = imagettfbbox($fontSize, $angle, $font, $text);
    

    But when you write the text to the image you use strtoupper($text) - which makes your text bigger (unless you're using a monospaced font).

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