saveCanvas() is being called over and over, crashes fiefox.

RobotProcess

Hello,

I am attempting to utilize the saveCanvas() function to save the canvas as an image (duh).

function mouseClicked(){ saveCanvas(myCanvas, 'someImage', 'png'); }

However, when I click the mouse, the function seems to be called over and over again, flooding the window with dialogue boxes.

Please let me know if I am using this function wrong.

Thanks

GoToLoop

I believe it's more stable to do that inside draw().
Just set apart some boolean variable in order to flag it's time to saveCanvas():

// forum.processing.org/two/discussion/13376/
// savecanvas-is-being-called-over-and-over-crashes-fiefox

// GoToLoop (2015-Nov-03)

var saveRequest;

function draw() {
  if (saveRequest) {
    saveCanvas('img-' + nf(frameCount, 4), 'png');
    saveRequest = false;
  }

  background(0350);
}

function mouseClicked() {
  saveRequest = true;
}

blindfish

@GoToLoop's workaround works - and suggests there's some kind of event handling conflict in saveCanvas(). You should report a bug

GoToLoop

I don't think it's a bug but rather an annoying glitch. :-\"
AFAIK, saveCanvas() is modal. That is, it pops up a blocking window save dialog in the browser.
However, we end up clicking the mouse while dealing w/ that. Thus more MouseEvents occur! #-o

RobotProcess

Thanks guys,

I'm an experienced C programmer, but still figuring out how the processing functions interact with each other.

GoToLoop

• I know some times it's not as intuitive as we all would like to.
• If we have saveCanvas() inside any Event, it's gonna request a new save modal window for as many times that it had triggered. Even if we're already busy w/ 1 or more!
• However, just flagging the Event as true, and postponing it to draw() to deal w/ it, we assure ourselves that only 1 happens for each draw() callback and the rest is discarded. *-:)

GoToLoop

• On 2nd thought after further experiments, perhaps @blindfish was correct there's some bug there.
• It seems to trigger "infinite" saveCanvas() even though I had made sure I've just clicked once! ~:>

blindfish

@RobotProcess: Try it with mousePressed

That appears to work fine; though I'm slightly surprised there's such a big difference in behaviour...

@GoToLoop: the bug appears to be in mouseClicked. The documentation is a little too vague but at first glance the behaviour suggests that mouseClicked is firing events for as long as the mouse button is down; rather than waiting till the mouseDown/Up cycle is complete and then firing a single event :/

blindfish

No - that's not it:

var count1 = 0,
      count2 = 0;

function setup() {
    createCanvas(600, 400); 
}

function draw() {

}

function mouseClicked() {
    count1++;
    console.log("count1: " + count1);  
}

function mousePressed() {
    count2++;
    console.log("count2: " + count2);  
}

There must be some problematic interaction between saveCanvas and mouseClicked. Don't have time to dig any deeper right now..