processing / processing/processing4

NullPointerException on Dynamic Window Resize in Processing

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#1,146 6 comentarios 0 reacciones 1 asignado Ver en GitHub

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Desde el 10/7/2025.

bug
Lenguaje dominante
Java
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494
Forks
183
Merge medio
4 h 39 min
PR fusionados (30 d)
3

Descripción

Most appropriate sub-area of Processing 4?

Core/Environment/Rendering

Processing version

4.4.4

Operating system

Windows 10

Steps to reproduce this

1. Description :
When dynamically resizing a Processing sketch window (via surface.setSize(w, h) or by enabling surface.setResizable(true)), a NullPointerException may occur in Component$BltBufferStrategy.revalidate(...), due to an internal backBuffers[] array being null.

This happens during the rendering phase, likely due to an invalidated or uninitialized BufferStrategy after the resize.

2. Example Stack Trace :

java.lang.NullPointerException: Cannot invoke "java.awt.image.VolatileImage.validate(java.awt.GraphicsConfiguration)" because "this.backBuffers[...]" is null
    at java.desktop/java.awt.Component$BltBufferStrategy.revalidate(Component.java:4552)
    at java.desktop/java.awt.Component$BltBufferStrategy.getDrawGraphics(Component.java:4449)
    at processing.awt.PSurfaceAWT.render(PSurfaceAWT.java:242)
    at processing.awt.PSurfaceAWT$9.callDraw(PSurfaceAWT.java:1389)
    at processing.core.PSurfaceNone$AnimationThread.run(PSurfaceNone.java:356)

3. Expected Behavior :
When resizing the window, either manually (with setResizable(true)) or programmatically (via surface.setSize(w, h)), the sketch should continue rendering smoothly without crashing or throwing an exception.

snippet

// Paste your code below :)

void setup() {
  size(600, 400);
  surface.setResizable(true);
}

void draw() {
  background(200);
}
Additional context

Discovered Workaround :

Calling surface.setVisible(true) immediately after resizing prevents the crash :

surface.setSize(w, h);
surface.setVisible(true);               // Prevents the NPE
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