Making a new PGraphics and displaying causes NullPointer

[processing-bugs]

Issue by GKFX
Saturday May 31, 2014 at 12:19 GMT
Originally opened as processing/processing-android-archive#68

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The simplest form of this is:

PGraphics pg = createGraphics(100, 100);
pg.background(100); //optional
image(pg, 0, 0);

To rectify it, you need to type:

PGraphics pg = createGraphics(100, 100);
pg.background(#ff0000); //optional
pg.loadPixels();
image(pg, 0, 0);

[processing-bugs]

Comment by GKFX
Saturday May 31, 2014 at 12:22 GMT

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Oddly, the second example didn't look right when background was 0;

[Techy4198]

Why did this get left in the dust? The issue is most certainly still present. Additionally the loadPixels workaround now seems to produce the same error itself.

[codeanticode]

Note that, in order to be able to use a PGraphics correctly, you need to call beginDraw()/enDraw(), as detailed in the tutorials and reference.

I'm able to run the following code without any errors:

PGraphics pg = createGraphics(100, 100);
pg.beginDraw();
pg.background(100);
pg.endDraw();
image(pg, 0, 0);

Please indicate in what specific situations you see the NPE error (also adding what version of the Android mode are you using, and device).

[Techy4198]

Looking back, I think my issue was actually more centered around trying to render a global PGraphics before it's been drawn to at all. I think I solved it by just drawing a background right after creating it. I guess I can see the reasoning behind an uninitialized canvas being partly treated as null.

[codeanticode]

That's right, before calling beginDraw()/endDraw() at least once, then the PGraphics is not properly initialized for rendering. I think this clarifies the issue, so it can be closed now.