php从图像流调整图像大小

Question

基本上，在canvas html5元素上创建一个Image，并使用以下代码将其另存为服务器上的图像

<?php
$upload_dir = "uploads/";
$img = $_POST['hidden_data'];
$imageID = $_POST['imageID'];
$img = str_replace('data:image/png;base64,', '', $img);
$img = str_replace(' ', '+', $img);
$data = base64_decode($img);
$file = $upload_dir . "gillette_" . $imageID . ".png";
$success = file_put_contents($file, $data);
print $success ? $file : 'Unable to save the file.';
?>

我想保存缩略图版本100X100像素，但更喜欢直接从流中完成。任何帮助将不胜感激

以下用于调整大小和保存图像的代码无法尝试使用imagecreatefromstring

<?php
############ Configuration ##############
$thumb_square_size      = 100; //Thumbnails will be cropped to 200x200 pixels
$max_image_size = 520; //Maximum image size (height and width)
$thumb_prefix = "small_"; //Normal thumb Prefix
$destination_folder = 'uploads/'; //upload directory ends with / (slash)
$jpeg_quality           = 90; //jpeg quality
##########################################


$upload_dir = "uploads/";
$img = $_POST['hidden_data'];
$imageID = $_POST['imageID'];
$img = str_replace('data:image/png;base64,', '', $img);
$img = str_replace(' ', '+', $img);
$data = base64_decode($img);
$file = $upload_dir . "gillette_" . $imageID . ".png";
$success = file_put_contents($file, $data);
print $success ? $file : 'Unable to save the file.';

$im = imagecreatefromstring($data);

    if($im){


        $new_file_name =  $imageID . ".png";
        $thumb_save_folder  = $destination_folder . $thumb_prefix . $new_file_name; 

            //call crop_image_square() function to create square thumbnails
            if(!crop_image_square($im, $thumb_save_folder, "png", $thumb_square_size, 520, 382, $jpeg_quality))
            {
                die('Error Creating thumbnail');
            }

        imagedestroy($im); //freeup memory
    }



##### This function corps image to create exact square, no matter what its original size! ######
function crop_image_square($source, $destination, $image_type, $square_size, $image_width, $image_height, $quality){
    if($image_width <= 0 || $image_height <= 0){return false;} //return false if nothing to resize

    if( $image_width > $image_height )
    {
        $y_offset = 0;
        $x_offset = ($image_width - $image_height) / 2;
        $s_size     = $image_width - ($x_offset * 2);
    }else{
        $x_offset = 0;
        $y_offset = ($image_height - $image_width) / 2;
        $s_size = $image_height - ($y_offset * 2);
    }
    $new_canvas = imagecreatetruecolor( $square_size, $square_size); //Create a new true color image

    //Copy and resize part of an image with resampling
    if(imagecopyresampled($new_canvas, $source, 0, 0, $x_offset, $y_offset, $square_size, $square_size, $s_size, $s_size)){
        save_image($new_canvas, $destination, $image_type, $quality);
    }

    return true;
}

##### Saves image resource to file ##### 
function save_image($source, $destination, $image_type, $quality){
    switch(strtolower($image_type)){//determine mime type
        case 'image/png': 
            imagepng($source, $destination); return true; //save png file
            break;
        case 'image/gif': 
            imagegif($source, $destination); return true; //save gif file
            break;          
        case 'image/jpeg': case 'image/pjpeg': 
            imagejpeg($source, $destination, $quality); return true; //save jpeg file
            break;
        default: return false;
    }
}

?>

Answer 1

问题解决了：

代码现在可以使用了。图像类型应该是整个mime类型 - image / png而不仅仅是png

这是固定代码，希望它可以帮助某人：

<?php
############ Configuration ##############
$thumb_square_size      = 100; //Thumbnails will be cropped to 200x200 pixels
$max_image_size = 520; //Maximum image size (height and width)
$thumb_prefix = "small_"; //Normal thumb Prefix
$destination_folder = 'uploads/'; //upload directory ends with / (slash)
$jpeg_quality           = 90; //jpeg quality
##########################################


$upload_dir = "uploads/";
$img = $_POST['hidden_data'];
$imageID = $_POST['imageID'];
$img = str_replace('data:image/png;base64,', '', $img);
$img = str_replace(' ', '+', $img);
$data = base64_decode($img);
$file = $upload_dir . "gillette_" . $imageID . ".png";
$success = file_put_contents($file, $data);
print $success ? $file : 'Unable to save the file.';

$im = imagecreatefromstring($data);

    if($im){


        $new_file_name =  $imageID . ".png";
        $thumb_save_folder  = $destination_folder . $thumb_prefix . $new_file_name; 

            //call crop_image_square() function to create square thumbnails
            if(!crop_image_square($im, $thumb_save_folder, "image/png", $thumb_square_size, 520, 382, $jpeg_quality))
            {
                die('Error Creating thumbnail');
            }

        imagedestroy($im); //freeup memory
    }



##### This function corps image to create exact square, no matter what its original size! ######
function crop_image_square($source, $destination, $image_type, $square_size, $image_width, $image_height, $quality){
    if($image_width <= 0 || $image_height <= 0){return false;} //return false if nothing to resize

    if( $image_width > $image_height )
    {
        $y_offset = 0;
        $x_offset = ($image_width - $image_height) / 2;
        $s_size     = $image_width - ($x_offset * 2);
    }else{
        $x_offset = 0;
        $y_offset = ($image_height - $image_width) / 2;
        $s_size = $image_height - ($y_offset * 2);
    }
    $new_canvas = imagecreatetruecolor( $square_size, $square_size); //Create a new true color image

    //Copy and resize part of an image with resampling
    if(imagecopyresampled($new_canvas, $source, 0, 0, $x_offset, $y_offset, $square_size, $square_size, $s_size, $s_size)){
        save_image($new_canvas, $destination, $image_type, $quality);
    }

    return true;
}

##### Saves image resource to file ##### 
function save_image($source, $destination, $image_type, $quality){
    switch(strtolower($image_type)){//determine mime type
        case 'image/png': 
            imagepng($source, $destination); return true; //save png file
            break;
        case 'image/gif': 
            imagegif($source, $destination); return true; //save gif file
            break;          
        case 'image/jpeg': case 'image/pjpeg': 
            imagejpeg($source, $destination, $quality); return true; //save jpeg file
            break;
        default: return false;
    }
}

?>