Saved image is empty

antiplastik

Hi,

I am drawing on a PGraphics and want to save the rendered image to the relevant pictures directory on the external storage. I have set the proper WRITE_EXTERNAL_STORAGE permission. I am using createGraphics() and later save() and everything seems to work fine, but the resulting image is an empty file (0.00 byte).

import android.os.Environment;

try {
  if (!Environment.MEDIA_MOUNTED.equals(Environment.getExternalStorageState())) {
    throw new Exception("External storage is not writable.");
  }

  File directory = new File(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES), "draw");
  if (!directory.exists() && !directory.mkdirs()) {
    throw new Exception("Directory could not be created.");
  }

  String filename = directory.getAbsolutePath() + File.separator + System.currentTimeMillis() + ".jpg";
  canvas.save(filename);

  println("Picture has been saved to: " + filename);
} catch (Exception e) {
  this.showDialog("Error", e.getMessage());
}

This code would print Picture has been saved to: /storage/emulated/0/Pictures/draw/1483309392341.jpg but the resulting image is an empty file.

Did I miss something?

akenaton

@antiplastik=== ia am quite sure that your code runs as for the path but it creates an empty file (yet you can "find" it if you try listing your directory folder); so in my mind the problem is with your canvas.save(): but i cannot see in your code when this canvas was created ...

antiplastik

@akenaton actually this is a simple PGraphics object:

void setup() {
    fullScreen();
    canvas = createGraphics(width, height);
    canvas.background(255);
    // some more drawing on "canvas" in draw()
}

I've found this issue that could be related: https://github.com/processing/processing-android/issues/250

Will dig into the source code...

antiplastik

OK, I managed to save the picture by setting the DISABLE_ASYNC_SAVEFRAME hint with:

canvas.hint(DISABLE_ASYNC_SAVEFRAME);
canvas.save(filename);

which bypasses the AsyncImageSaver: https://github.com/processing/processing-android/blob/android-255/core/src/processing/core/PGraphics.java#L5709-L5711

so I guess there is something wrong with the AsyncImageSaver here.

kfrajer

Thanks for sharing your solution.

Kf

akenaton

@antiplastik=== ok:that means that there is a problem with save ()+android mode,which seemed to me probable; and your solution works... but for PGraphics object ( though i dont understand why!!!, because it s only (according with .docs) a question of Asynctask or not))

Now try to save some frame (not pGraphics) and see what happens...

I have done that and tried a lot of solutions (even native android code):: in the best case i get some Image which has a width, an height, a name... that i can load() and i am happy but it is black!!! can you explain???

PS: of course, anyway, i can get an image using your workaround but that is ugly PS2 : anywise save() (Without path, only filename) save nothing,, against what .docs are saying...

akenaton

@antiplastik===

ok, i finally got it (i mean not using Graphics, but perhaps it works also with it); it was more simple than i thought: main problem is that the save() method in android does not work as in java. Try the code below, which btw, is a solution for a screen shot.

PS= a lot of imports are useless, only for testing!

    import android.net.Uri;
    import android.content.Intent;
    import android.graphics.Bitmap;
    import android.widget.FrameLayout;
    import java.io.FileNotFoundException;
    import java.io.FileOutputStream;
    import java.io.ByteArrayOutputStream;
    import android.view.View;
    import android.graphics.Bitmap;
    import android.graphics.Canvas;
    import android.os.Environment;
    import android.app.Activity;

    PGraphics pg;
    PImage[] imag;
    File[] listOfFiles;
    String files;
    String [] Resultat;

    Canvas canvas;
    FrameLayout fl;
    PApplet pAp;
    boolean charge = false;

    public void onStart(){
      super.onStart();
      fl = (FrameLayout)this.getActivity().findViewById(0x1000);
    }

    void settings(){
      size(displayWidth, displayHeight);
    }
    void setup(){
      //place une image dans la dsCard; ne pas oublier les permissions dans le manifeste
      orientation(PORTRAIT);

    background(255,0,0);
    //pg = createGraphics(400, 800);

    }
     void draw(){
       background(255,0,0);
        //pg.beginDraw();
      //pg//.background(102);
      //pg//.stroke(255);
      //pg//.fill(0,255,0);
      //pg//.ellipse(50,50, 100,100);
      ///pg//.endDraw();

      if(!charge){
      ///image(pg, 50, 50);
      fill(0,255,0);
      ellipse(100,100,100,100);

      }else{
       background(0);
       PImage img = loadImage("essaiencre.jpg");
       image (img, 400,400);
       fill(0,0,255);
       rect(0,0,100,100);
      }


     }



    void saveImageInit(){
       try
        {

            PImage temp= this.get();
             String nom = "essaiencre.jpg" ;
           temp.save(nom);

            verifie();
        } 

        catch (Exception e) 
        {
            println("Error while saving file: " + e.getMessage());      
        }


    }
    public void verifie(){
      String directory = new String(Environment.getExternalStorageDirectory().getAbsolutePath() );
    File folder = new File(directory);
      listOfFiles = folder.listFiles(); 
      Resultat = new String[listOfFiles.length];

    imag=new PImage[listOfFiles.length];

      for (int i = 0; i < listOfFiles.length; i++) 
      {

      if (listOfFiles[i].isFile()) 
      {
      files = listOfFiles[i].getName();
      Resultat[i] = files;
      System.out.println("i=====" + i + "    " + files);
     }
     }


      charge= true;

    }

    void mouseReleased(){
      saveImageInit();
      verifie();


    }

akenaton

@antiplastik=== tested:: it also works with pGraphics

antiplastik

Indeed converting to PImage with get() does the trick, thanks!

PGraphics graphics = createGraphics(width, height);
PImage image = graphics.get();
image.save(someAbsolutePath);

akenaton

@antiplastik=== yes, it works fine; what is strange is that it does not use any path and yet create the file in the external storage (that s why i have added the verifie() method in my code); when i get some more time i shall se what happens if you add some absolute path in save()... Anyway i think that this could be added to the doc for android save() which seems to do nothing (as it s said on the github link you have given)