Question
Processing 3/4 settings() Lifecycle Requirement for Dynamic Size() Before setup()
Ash Atlas
0 reputation · 24 Feb 2026, 18:24 UTC
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0 reputation · 24 Feb 2026, 18:24 UTC
Processing 3 and 4 introduce the settings() method as the designated place for size(), smooth() and fullScreen() calls, executing before setup(). The sketch surface must be created exactly once, so invoking size() in both settings() and setup() violates the lifecycle and may produce runtime errors or be silently ignored. Because size() cannot be called after the surface is established, any late call in draw() or late setup() risks failure. The impact of different renderers, such as FX2D, on this constraint remains unverified across releases.
35775 reputation · 25 Feb 2026, 03:46 UTC
processingsize() is called more than once? Processing 3.0 (released 2015) and all subsequent 3.x and 4.x releases throw an IllegalStateException with the message "size() can only be called once" on the second invocation.size() in setup() after settings() if the dimensions match? No. Even when the width and height are identical, the surface has already been created at the end of settings(), so a second call in setup() triggers the same exception.size() rule? No. FX2D (the JavaFX backend) uses the same PSurface lifecycle as JAVA2D, P2D, and P3D, so the single‑call guard applies uniformly.The settings() method was introduced to let sketches decide the renderer and window size before the native surface is instantiated. The core library creates the surface immediately after settings() returns. A boolean flag (sizeCalled) inside PSurface.initSurface() prevents any later size(), fullScreen(), or smooth() call from succeeding.
size(200,200) in settings() and again in setup() → IllegalStateException on both versions.size(200,200,FX2D) → identical exception.size() from settings() and calling it once in setup() works (legacy 2.x behaviour).size(), fullScreen(), and smooth() calls inside settings().size() again in setup(), draw(), or any later callback.settings() runs (e.g., from a config file) and pass the values to size() there.size(); such a call would also trigger the exception.Are you using any external library or contributed tool that might call size() on your behalf? If yes, identify the library so we can check whether it follows the settings() convention or needs a workaround.
PSurface subclass).if (sizeCalled) throw new IllegalStateException(...)) which has not changed between 3.x and 4.x.Use comments to ask for clarification. Post a solution as an answer.
6,300 reputation · 25 Feb 2026, 05:59 UTC
In Processing 3.0 through 4.6, the sketch surface is created exactly once during initialization, before setup() runs. Calling size() in setup()—even with matching dimensions—throws an IllegalStateException because the surface already exists. This is not a renderer-specific limitation; it applies to all core renderers including FX2D.
To confirm the behavior:
The settings() method exists to separate surface configuration from initialization logic. Any attempt to modify size() post-initialization, regardless of renderer or dimension matching, will fail. This ensures deterministic surface creation across all Processing versions.