selectInput() and image import

gius

Hello everyone,

In my small program, the user selects an image file and then the file can be seen in full screen, I have made some mistakes in my code:

 import  java.io.File;
 import processing.opengl.*;
 PImage img;

 int mX, mY;



void setup() {
       size(640, 200);
       background(0);
       selectInput("Select a file to process:", "fileSelected");
}

void draw() {
      stroke(255);
      if(mousePressed) {
      line(mouseX, mouseY, pmouseX, pmouseY);
}
}

void fileSelected(File selection) {
      image(img, 0, 0);
      img = loadImage(selection.getAbsolutePath());
}

but it does not work, where I'm wrong? Another question: how can I directly open the browser in the folder where is the code?

thanks!

GoToLoop

https://Processing.org/reference/selectInput_.html
https://forum.Processing.org/two/discussions/tagged?Tag=selectinput()

gius

thanks for the link GoToLoop, but I do not find the solution to my problems. If you have time, or someone helps me to understand how to solve, Thank you in advance.

GoToLoop

https://forum.Processing.org/two/discussion/16705/null-pointer-exception-when-loading-image-in-settings-p3-1-1#Item_1

Chrisir

in simple terms, the program doesn't wait for the user to select a file.

you should also catch the situation when user hit cancel in the dialogue :

 if (selection == null) {
    println("Window was closed or the user hit cancel.");
  } else {
    println("User selected " + selection.getAbsolutePath());
    // load image here 
  }

Obviously you can't also display an image before loading it. Without loading it, img is still empty!!!

so this

  image(img, 0, 0);
  img = loadImage(selection.getAbsolutePath());

must be

  img = loadImage(selection.getAbsolutePath());
  image(img, 0, 0);

this might even work surprisingly, since you don't use background in draw(). If you would, you would use image(img, 0, 0); in draw

gius

GoToLoop, I understand that the problem is "null pointer exception"

your code GoToLoop:

/**
* SelectInput() for loadImage() in settings() (v1.0)
* GoToLoop (2016-May-19)
*
* forum.Processing.org/two/discussion/16705/
* null-pointer-exception-when-loading-image-in-settings-p3-1-1
*/

PImage canvas;

void settings() {
selectInput("Please select canvas picture:", "selectImage");
while (canvas == null)  delay(100);

size(canvas.width, canvas.height);
noSmooth();
noLoop();
}

void draw() {
background(canvas);
 }

void selectImage(final File f) {
if (f == null || f.isDirectory()) {
println("Window was closed or you've hit cancel.\n");
System.exit(0);
}

final String canvasPath = f.getPath();
println(canvasPath);

if ((canvas = loadImage(canvasPath)) == null) {
println("is an invalid image file. Try again...\n");
selectInput("Please select canvas picture:", "selectImage");
}
}

does not work with Processing 3.3 you can fix it?

Thanks Chrisir for having me explain an important aspect of my mistake. I have done the changes that you've recommended, but it does not work, I have error: "Null pointer exception", you can solve it?

thank you all.

GoToLoop

... does not work with Processing 3.3 you can fix it?

Have you even tried it out? Just copied & pasted it in my PDE 3.3 and it's simply worked here! 8->

BtW, the code you've posted is mal-indented. L-)

gius

GoToLoop, I'm sorry for how I've posted the code.

You're right, your example works well. For a few minutes my PC would not open the execution of the file in the window, and I thought of a problem with the file, sorry again.

I've added to your code the option to draw lines with the mouse, but I see nothing,

/**
 * SelectInput() for loadImage() in settings() (v1.0)
 * GoToLoop (2016-May-19)
 *
 * forum.Processing.org/two/discussion/16705/
 * null-pointer-exception-when-loading-image-in-settings-p3-1-1
 */
 import  java.io.File;
 import processing.opengl.*;

 PImage canvas;
 int mX, mY;



 void settings() {
 selectInput("Please select canvas picture:", "selectImage");
 while (canvas == null)  delay(100);

size(canvas.width, canvas.height);
noSmooth();
noLoop();
}

void draw() {
background(canvas);
stroke(255);
if(mousePressed) {
line(mouseX, mouseY, pmouseX, pmouseY);
}
}

void selectImage(final File f) {
if (f == null || f.isDirectory()) {
println("Window was closed or you've hit cancel.\n");
System.exit(0);
}

final String canvasPath = f.getPath();
println(canvasPath);

if ((canvas = loadImage(canvasPath)) == null) {
println("is an invalid image file. Try again...\n");
selectInput("Please select canvas picture:", "selectImage");
}
}

I doing something wrong?

What is the directory to be added to open the "Browser" in the folder where the file is currently running?

thanks

Chrisir

hit ctrl-t in processing to auto-format the code (indents!!!!) prior to posting it here

to tell the load dialogue the folder use selectInput with 3 parameters:

      File start1 = new File(sketchPath("")+"/myPrograms/*.*"); 
      selectInput("Select a file to write to:", "fileSelectedForLoad", start1);

why do you use noLoop()? Don't.

not sure we can use size after the whole thing but I think gotoloop is in the lead.