prevent attempts to do 2x on non-2x hardware

core/src/processing/core/PApplet.java

@@ -1050,7 +1050,12 @@ public class PApplet implements PConstants {
         if (density != 1 && density != 2) {
           throw new RuntimeException("pixelDensity() can only be 1 or 2");
         }
-        this.pixelDensity = density;
+        if (density == 2 && displayDensity() == 1) {
+          // Don't throw exception because the sketch should still work
+          System.err.println("pixelDensity(2) is not available for this display, using pixelDensity(1) instead");
+        } else {
+          this.pixelDensity = density;
+        }
       }
     }
   }

core/todo.txt

@@ -83,6 +83,10 @@ X   just do pixelFactor() (and pull it during compilation)?
 X   add sketchPixelFactor() to handle the scenario?
 X   or is it just a boolean, because pixelFactor(2) is the only option?
 X remove retina hint
+X move checkRetina()/highResDisplay() to PApplet
+X   and out of Toolkit and PSurfaceAWT
+X prevent running _2X renderers on non-2x hardware
+X   pixelDensity() needs to be called after size() or fullScreen()
 
 andres/opengl
 X set(0, 0, image) does not set alpha channel to opaque in P2D/P3D
@@ -134,7 +138,6 @@ _ sketch sometimes doesn't show with noLoop() on Linux
 _   https://github.com/processing/processing/issues/3316
 _ sketch not always showing with empty draw()
 _   https://github.com/processing/processing/issues/3363
-_ prevent running _2X renderers on non-2x hardware
 _ PGraphic ignores PNG transparency (regression from 3.0a5)
 _   https://github.com/processing/processing/issues/3317
 _ strokeWeight() in setup() not working for default renderer
@@ -442,8 +445,6 @@ _ add requestFocus() method to PApplet (or surface?)
 o destroy() removed, but bring back? is that better than dispose()?
 _   destroy() only called dispose(), so no difference
 _   Python Mode has a hook for when it's called
-_ move checkRetina()/highResDisplay() to PApplet
-_   and out of Toolkit and PSurfaceAWT
 _ probably should also check to make sure PApplet running JVM 8
 _   or compile against 1.8 and force it?
 

todo.txt

@@ -27,7 +27,6 @@ o Update Windows icons for multiple sizes, implement them in the PDE
 o   http://code.google.com/p/processing/issues/detail?id=632
 X   closed during the 2.x cycle
 
-
 contribs
 X several Greek translation updates
 X   https://github.com/processing/processing/issues/3329
@@ -56,6 +55,8 @@ _   a checkbox for "show this welcome each time" (default to checked)
 _   a button to dismiss the welcome screen (e.g., "get started")
 _ 2.x vs 3.x sketchbook battle (part of the welcome screen item)
 _   if a v2 sketchbook already exists, show a prompt to choose either creating a new Processing 3 sketch folder or use the existing v2 one, plus a link to GitHub wiki page with details
+_ send list of installed Libraries, Modes, Tools, and Examples on update
+_   https://github.com/processing/processing/issues/3365
 
 
 gui