Phonegap / Cordova camera plugin - how to get phot

问题:

I have a Phonegap app that needs to let the user both take photos using the phone's camera and let the user select from photo's already on the device.

I need to capture the date/time the photo was taken as part of the metadata, but I'm having a hard time figuring out how to do this with Phonegap / Cordova.

Initially I thought I could use the File API's FileEntry.getMetadata() call but this doesn't return a valid date for the modificationTime attribute. I think that phonegap also transforms the file on the device so that the you recieve back from the camera plugin is not the original file on the device, so even if the getMetadata() call worked, the date wouldn't be the correct one.

Is there any other way around this, short of writing my own version of the camera plugin for each platform I need?

Seems crazy that this would be the only way around it.

回答1:

So, I've managed to figure this out.

The date/time stamp along with a bunch of other information can be retrieved from the EXIF data tags inside the JPEG file. This can be done using this helpful JS library - https://github.com/jseidelin/exif-js

Unfortunately the Cordova camera plugin for Android doesn't copy EXIF tags when transforming an image selected from the gallery, only when taking an image using the camera, so this is a problem, but I will fix this by forking the plugin. The iOS version of the plugin seems to do this right thing.

Code for anyone interested -

var source = fromCamera 
       ? Camera.PictureSourceType.CAMERA 
       : Camera.PictureSourceType.PHOTOLIBRARY;

var opts = {
    encodingType: Camera.EncodingType.JPEG,
    sourceType: source,
    destinationType: Camera.DestinationType.NATIVE_URI
};

navigator.camera.getPicture(
        function(imageURI) {
            window.resolveLocalFileSystemURL(imageURI,
                    function(entry) {
                        entry.file(function(file) {
                            EXIF.getData(file, function() {
                                var datetime = EXIF.getTag(this, "DateTimeOriginal");
                                alert(datetime);
                            });                                                

                            // do something useful....

                        }, standardErrorHandler);
                    },
                    function(e) {
                        alert('Unexpected error obtaining image file.');
                        standardErrorHandler(e);
                    });
        },
        function() {
            // nada - cancelled
        },
        opts);

回答2:

Like everyone else I dislike answers that start with "do this a completely different way" but I had the same problems as the original poster and using the alternate camera plugin cordova-plugin-camera-with-exif was the best solution I found.