如何将GPS坐标写入Android上的EXIF数据 [英] How to write GPS coordinates to EXIF data on Android

问题描述

我试图编写地理标记应用程序，用户从照片库中选择图像，然后该图像通过其EXIF文件获取当前GPS坐标。

到目前为止，我可以拉起画廊，选择图像，并找到我当前的GPS坐标，但我无法将这些坐标写入EXIF文件。每当我选择一个图像，我都可以查看它，但没有数据写入EXIF文件。

我查阅了几个如何写入EXIF的例子，并且我的代码看起来是正确的（至少对我来说）。任何人都可以帮我弄清楚为什么我不写任何数据？

这是我的代码：

  //将GPS线插入exif文件
 try {
 ExifInterface exif = new ExifInterface（/ sdcard / dcim / 100MEDIA / IMAG0020.jpg）; 
 
 exif.setAttribute（ExifInterface.TAG_GPS_LATITUDE，DMSconv（lat））; 
 exif.setAttribute（ExifInterface.TAG_GPS_LONGITUDE，DMSconv（lon））; 
 if（lat> 0）
 exif.setAttribute（ExifInterface.TAG_GPS_LATITUDE_REF，N）; 
 else 
 exif.setAttribute（ExifInterface.TAG_GPS_LATITUDE_REF，S）; 
 if（lon> 0）
 exif.setAttribute（ExifInterface.TAG_GPS_LONGITUDE_REF，E）; 
 else 
 exif.setAttribute（ExifInterface.TAG_GPS_LONGITUDE_REF，W）; 
 exif.saveAttributes（）; 
 
} catch（IOException e）{
 e.printStackTrace（）; 
} 
 
 //将十进制度数转换为DMS 
 String DMSconv（double coord）{
 coord =（coord> 0）？ coord：（-1）* coord; // -105.9876543  - > 105.9876543 
 String sOut = Integer.toString（（int）coord）+/ 1，; // 105/1，
 coord =（coord％1）* 60; // .987654321 * 60 = 59.259258 
 sOut = sOut + Integer.toString（（int）coord）+/ 1，; // 105 / 1,59 / 1，
 coord =（coord％1）* 6000; // .259258 * 6000 = 1555 
 sOut = sOut + Integer.toString（（int）coord）+/ 1000; // 105 / 1,59 / 1,15555 / 1000 
 return sOut; 
 
  

感谢您的帮助！

编辑：此时我试图将文件路径和名称硬编码到ExifInterface中，所以这就是为什么它说/ sdcard / dcim / 100MEDIA / IMAG0020.jpg而不是文件名。这可能与我的问题有关吗？

解决方案

解决方案。对文件路径进行硬编码是个问题。我使用了代码

  int columnIndex = cursor.getColumnIndex（filePathColumn [0]）; 
 String picturePath = cursor.getString（columnIndex）; 
  

获得 picturePath 然后用于

  ExifInterface exif = new ExifInterface（picturePath）; 
  

I'm trying to write a geotagging app where the user selects an image form the photo gallery, and then that image gets the current GPS coordinates written to it through its EXIF file.

So far I am able to pull up the gallery, select an image, and find my current GPS coordinates, but I cannot write those coordinates to the EXIF file. Whenever I do select an image, I can view it, but no data is written to the EXIF file.

I have looked up several examples for how to write to EXIF, and my code looks correct (to me at least). Can anyone help me figure out why I am not writing any data?

Here's my code:

//place GPS cords into exif file
        try {
            ExifInterface exif = new ExifInterface("/sdcard/dcim/100MEDIA/IMAG0020.jpg");

            exif.setAttribute(ExifInterface.TAG_GPS_LATITUDE, DMSconv(lat));
            exif.setAttribute(ExifInterface.TAG_GPS_LONGITUDE,DMSconv(lon));
            if (lat > 0) 
              exif.setAttribute(ExifInterface.TAG_GPS_LATITUDE_REF, "N"); 
            else              
              exif.setAttribute(ExifInterface.TAG_GPS_LATITUDE_REF, "S");
            if (lon > 0) 
              exif.setAttribute(ExifInterface.TAG_GPS_LONGITUDE_REF, "E");    
             else             
               exif.setAttribute(ExifInterface.TAG_GPS_LONGITUDE_REF, "W");
            exif.saveAttributes();

        } catch (IOException e) {
            e.printStackTrace();
        }

 //convert from decimal degrees to DMS
String DMSconv(double coord) {  
      coord = (coord > 0) ? coord : (-1)*coord;  // -105.9876543 -> 105.9876543
      String sOut = Integer.toString((int)coord) + "/1,";   // 105/1,
      coord = (coord % 1) * 60;         // .987654321 * 60 = 59.259258
      sOut = sOut + Integer.toString((int)coord) + "/1,";   // 105/1,59/1,
      coord = (coord % 1) * 6000;             // .259258 * 6000 = 1555
      sOut = sOut + Integer.toString((int)coord) + "/1000";   // 105/1,59/1,15555/1000
      return sOut;
    }

Thanks for the help!

Edit: At this time I was trying to hardcode the file path and name into ExifInterface, so that's why it says "/sdcard/dcim/100MEDIA/IMAG0020.jpg"instead of filename. Could that have anything to do with my problem?

解决方案

Solved it. Hardcoding the file path was the problem. I used the code

        int columnIndex = cursor.getColumnIndex(filePathColumn[0]);
        String picturePath = cursor.getString(columnIndex);

to obtain picturePath which was then used in

ExifInterface exif = new ExifInterface(picturePath);

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