Copy PGraphics by value

cameyo

Which is the best(fast) way to copy two PGraphics (P1 over P2) by value ?
P2 = P1 seems to copy by reference :(
Thanks.
cameyo

Lord_of_the_Galaxy

P1 = P2.copy() I guess?

cameyo

Sorry, but i get an error:
cannot convert from PImage to PGraphics

Lord_of_the_Galaxy

Then use this workaround - it's not perfect in that the transformation matrix, the styles etc will not be copied, but the pixel values will be :

PGraphics createGraphics(PImage img, String render){
  PGraphics pg = createGraphics(img.width, img.height, render);
  pg.beginDraw();
  pg.copy(img, 0, 0, img.width, img.height, 0, 0, img.width, img.height);
  pg.endDraw();
  return pg;
}

Lord_of_the_Galaxy

Use it like this - P2 = createGraphics(P1);

cameyo

I have already PGraphics P2 :(
i'm trying to use a "for" with "pixels" property.

Lord_of_the_Galaxy

That's it? Simple - p2.copy(p1, 0, 0, p1.width, p1.height, 0, 0, p2.width, p2.height);
Capitalise the p's yourself.

Also note that if the two PGraphics are different sized, it will end up stretching/shrinking accordingly.

cameyo

PGraphics p1;
PGraphics p2;
void setup()
{
  p1 = createGraphics(100, 100);
  p2 = createGraphics(100, 100);
  p1.beginDraw();
  p1.ellipse(50, 50, 10, 10);
  p1.endDraw();
  p2.beginDraw();
  p2.ellipse(10, 10, 5, 5);
  p2.endDraw();
  p2.copy(p1, 0, 0, p1.width, p1.height, 0, 0, p2.width, p2.height);
  p1.save("p1.png");
  p2.save("p2.png");
  exit();
}
void draw () {
}
//copia.pde:13:0:13:0: ClassCastException: sun.java2d.SunGraphics2D cannot be cast to java.awt.Image  

cameyo

This is a bit slow :-S

void copyPGraphics(PGraphics a, PGraphics b)
{
  // b = a;
  a.loadPixels();
  b.loadPixels();
  b.beginDraw();
  for (int i = 0; i < b.pixels.length; i++) 
  {
    b.pixels[i] = a.pixels[i];
  }
  //a.updatePixels();
  b.updatePixels();
  b.endDraw();
}

GoToLoop

/**
 * PImage/PGraphics pixels[] copyTo() (v1.1.1)
 * GoToLoop (2017-Feb-08)
 * forum.Processing.org/two/discussion/20716/copy-pgraphics-by-value#Item_9
 */

PGraphics pg;

void setup() {
  size(500, 400);
  noLoop();

  pg = createGraphics(width, height); // same dimensions as canvas.
  pg.beginDraw();
  pg.background(#0000FF); // blue PGraphics.
  pg.endDraw();

  background(#FF0000); // red canvas
  copyImg(getGraphics(), pg); // make target PGraphics red too.
}

void draw() {
  background(pg); // PGraphics is indeed red.
}

static final void copyImg(final PImage src, final PImage tgt) {
  src.loadPixels();
  tgt.loadPixels();

  arrayCopy(src.pixels, tgt.pixels);
  tgt.updatePixels();
}

static final void copyPixels(final color[] src, final color[] tgt) {
  arrayCopy(src, tgt);
}

cameyo

@GoToLoop and @Lord_of_the_Galaxy: thank you so much ;)

Lord_of_the_Galaxy

@cameyo Why not stick to the PImage class's copy function? It's clearly easier, even if it is a bit slower. And when working with PGraphics, speed is generally not much of a concern.

cameyo

arrayCopy(src.pixels, tgt.pixels); works well and is fast :)

GoToLoop

New version 1.1.1 -> deleted src.updatePixels();. Completely unnecessary! =P~

cameyo

@GoToLoop

static final void copyPixels(final color[] src, final color[] tgt) {
  arrayCopy(src, tgt);
}

never used ;)

GoToLoop

That was just an extra option when we just wanna re-using the pixels[] directly w/o loadPixels() & updatePixels() each time.

quark

The solution assumes that both

1) P2 and P1 exist
2) P2 has the same number of pixels as P1

I would prefer a more flexible solution that would handle these cases like this

PGraphics p2, p1;

void setup() {
  size(400, 200);
  textSize(18);
  textAlign(CENTER, CENTER);
  p1 = makeRandomGraphic(width/2, height);
}

/**
 Duplicate and return a graphic that is an exact replica of the 
 source graphic.
 If the dest graphic does not exist or does not match the source then 
 a new graphic is instantiated and returned else this method overwrites
 the image in the dest graphic.
 Expected usage would be
 dest = copyGraphics(src, dest);

 @param src the graphic to copy
 @param dest the pgraphic to overwrite (if possible)
 @return the duplicated graphic
 */
PGraphics copyGraphics(PGraphics src, PGraphics dest) {
  if (dest == null || dest.width != src.width || dest.height != src.height) {
    dest = createGraphics(src.width, src.height);
    dest.beginDraw();
    dest.endDraw();
  }
  src.loadPixels();
  dest.loadPixels();
  arrayCopy(src.pixels, 0, dest.pixels, 0, src.pixels.length);
  dest.updatePixels();
  return dest;
}

PGraphics makeRandomGraphic(int w, int h) {
  PGraphics pg = createGraphics(w, h);
  noiseSeed(millis());
  float ns = 0.02;
  pg.beginDraw();
  pg.background(0);
  for (int i = 0; i < w; i++) {
    for (int j = 0; j < h; j++) {
      int cc = int(noise(i * ns, j * ns) * 200 + 55);
      pg.set(i, j, color(cc, 0, cc));
    }
  }
  pg.endDraw();
  return pg;
}

void draw() {
  background(0);
  if (p2 == null) {
    fill(255);
    String info = "Hit 'n' to get a new graphic on the left and 'c' to create a copy and display it on the right";
    text(info, width/2, 0, width/2, height);
  } else {
    image(p2, width/2, 0);
  }
  image(p1, 0, 0);
}

void keyTyped() {
  if (key == 'n')
    p1 = makeRandomGraphic(width/2, height);
  else if (key == 'c')
    p2 = copyGraphics(p1, p2);
}

kfrajer

Great effort! if you can make PImage work in your application, then get() is all what you need to create a copy. With PGraphics you have to do it differently as shown here in this post. However PImage is not a substitute for PGraphics... Otherwise life would be easier I-)

Kf

GoToLoop

However PImage is not a substitute for PGraphics...

My solution needs PImage only, b/c it is the parent class for PGraphics and even other types like Movie & Capture. \m/

If the only thing we demand is a transfer of pixels[], there's no need to go beyond what PImage already offers. O:-)

GoToLoop

then get() is all what you need to create a copy.

@cameyo was asking for the fastest way to copy. 8-|
get() clones a PImage rather than simply copying it to another existing 1. :-@

Lord_of_the_Galaxy

@GoToLoop Then why exactly is copy() slower?

Lord_of_the_Galaxy

(Than ArrayCopy)

quark

The copy() method does a lot of calculation/work under the hood.

On the other hand arrayCopy() uses a JVM native method to copy of a single block of memory to another location - can't copy an array faster than that. :)

Lord_of_the_Galaxy

@quark thanks for the info, was half expecting something like that.

Lord_of_the_Galaxy

Related - https://forum.processing.org/two/discussion/20761/set-part-of-pgraphics-transparent#latest