许多图像/ GD问题：裁剪，设置颜色和透明度

Question

I wrote some PHP code that uses GD on a Ubuntu machine (PHP 5.5.9) and just moved it over to a amazon EC2 with Amazon Linux (PHP 5.5.31) and I'm getting quite different results from the code from the same input data file (I'm only using imagecreatefromstring() ; $data contains the contents of a JPEG file.)

1. Before I changed machines it would change the white to transparent. It no longer makes that change.
2. It used to crop the graphic perfectly. Now it leaves a little white on the left and cuts off the image by a little bit on the right.
3. There is a thin black line on the left side.
4. I can't even seem to make the image change a color with imagecolorset() .

Here's the code:

if ($isFileString) {
    $src2 = imagecreatefromstring($data);
} else {
    $src2 = imagecreatefromjpeg($data);
}

// This was an attempt to get it to recognize transparent.
if (!unlink ("../drive/sigs/tmp.png"))
    die("Failed to delete tmp.png");

imagepng($src2, "../drive/sigs/tmp.png");
imagedestroy($src2);
$src = imagecreatefrompng("../drive/sigs/tmp.png");

imagealphablending($src, false);
imagesavealpha($src, true);

for ($i=0; $i< 1024; $i++) {
    echo $i;
    echo print_r(imagecolorsforindex($src, $i));
    imagecolorset($src, $i, 255, 255, 255,255);
    echo print_r(imagecolorsforindex($src, $i));
    echo "<BR>";
}

$src = imagecropauto($src, IMG_CROP_WHITE);
$white = imagecolorallocate($src, 255, 255, 255);
imagecolortransparent($src, $white);
$src = imagerotate($src, -90, 0);

EDIT As an example of my not being able to get imagecolorset() to make a change in the file, below is the output from the loop on $i :

1Array ( [red] => 0 [green] => 0 [blue] => 1 [alpha] => 0 ) 1Array ( [red] => 0 [green] => 0 [blue] => 1 [alpha] => 0 ) 1
2Array ( [red] => 0 [green] => 0 [blue] => 2 [alpha] => 0 ) 1Array ( [red] => 0 [green] => 0 [blue] => 2 [alpha] => 0 ) 1
3Array ( [red] => 0 [green] => 0 [blue] => 3 [alpha] => 0 ) 1Array ( [red] => 0 [green] => 0 [blue] => 3 [alpha] => 0 ) 1

EDIT2

A little more information: I checked the gd versions ( php -i | grep -i gd ). I am surprised to see the Ubuntu box with GD version 2.1.1-dev and the EC2 box with "bundled (2.1.0 compatible)". I'm new to GD so I'm more inclined to believe this is my fault, rather than Amazon providing a bad version of GD.

EDIT3

• It doesn't appear to be a memory issue. The memory_get_peak_usage() reports about 35MB.

• The only difference that gd_info() reports is the version number.

Answer 1

That version of GD seems to have some issues. It's not perfect, but here's the final code we settled on:

    if ($isFileString) {
        $im1 = imagecreatefromstring($data);
    } else {
        $im1 = imagecreatefromjpeg($data);
    }
    $tmp_file = $this->tmp_dir . md5(time() . mt_rand());
    imagepng($im1, $tmp_file);
    imagedestroy($im1);

    // rotate, pre-resize and resample the source image
    $im2 = imagecreatefrompng($tmp_file);
    unlink($tmp_file);
    if (imagesy($im2) > imagesx($im2))
        $im2 = imagerotate($im2, $this->rotate, 0);
    $width = imagesx($im2);
    $height = imagesy($im2);
    $percent = ($this->standard_width * 2) / $width;
    $newWidth = $width * $percent;
    $newHeight = $height * $percent;
    $im = imagecreatetruecolor($newWidth, $newHeight);
    imagecopyresampled($im, $im2, 0, 0, 0, 0, $newWidth, $newHeight, $width, $height);

    // create a transparent image with a size like $im image
    $im3 = imagecreatetruecolor($newWidth, $newHeight);
    imagesavealpha($im3, TRUE);
    imagefill($im3, 0, 0, imagecolorallocatealpha($im3, 0, 0, 0, 127));

    // find non-white-ish pixels on $im and copy them to $dst
    $sizeX = $newWidth;
    $sizeY = $newHeight;
    $startX = $startY = 100000;
    $finishX = $finishY = 0;
    for ($x = 1; $x < $sizeX - 1; $x++) {
        for ($y = 1; $y < $sizeY - 1; $y++) {
            $rgb = imagecolorat($im, $x, $y);
            $colors = imagecolorsforindex($im, $rgb);
            $r = $colors['red'];
            $g = $colors['green'];
            $b = $colors['blue'];
            if ($r < $this->redLimit && $g < $this->greenLimit && $b < $this->blueLimit) {
                imagesetpixel($im3, $x, $y, $rgb);
                if ($startX > $x) {
                    $startX = $x;
                }
                if ($startY > $y) {
                    $startY = $y;
                }
                if ($finishX < $x)
                    $finishX = $x;
                if ($finishY < $y)
                    $finishY = $y;
            }
        }
    }

    // final resize
    $width = $finishX - $startX + 1;
    $height = $finishY - $startY + 1;
    $percent = $this->standard_width / $width;
    $newWidth = $width * $percent;
    $newHeight = $height * $percent;
    $im4 = imagecreatetruecolor($newWidth, $newHeight);
    imagesavealpha($im4, TRUE);
    imagefill($im4, 0, 0, imagecolorallocatealpha($im4, 0, 0, 0, 127));
    imagecopyresampled($im4, $im3, 0, 0, $startX, $startY, $newWidth, $newHeight, $width, $height);

    // returning image
    ob_start();
    imagepng($im4);
    $image_data = ob_get_contents();
    ob_end_clean();
    return $image_data;