warn the user if drawing unavailable chars with default font

core/src/processing/awt/PGraphicsJava2D.java

@@ -2055,8 +2055,20 @@ public class PGraphicsJava2D extends PGraphics {
   protected void textLineImpl(char[] buffer, int start, int stop,
                               float x, float y) {
     Font font = (Font) textFont.getNative();
-//    if (font != null && (textFont.isStream() || hints[ENABLE_NATIVE_FONTS])) {
     if (font != null) {
+      // If using the default font, warn the user when their code calls
+      // text() called with unavailable characters. Not done with all
+      // fonts because it would be too slow, but useful/acceptable for
+      // the default case because it will hit beginners/casual use.
+      if (textFont.getName().equals(defaultFontName)) {
+        if (font.canDisplayUpTo(buffer, start, stop) != -1) {
+          final String msg =
+            "Some characters not available in the current font, " +
+            "use createFont() to specify a typeface the includes them.";
+          showWarning(msg);
+        }
+      }
+
       /*
       // save the current setting for text smoothing. note that this is
       // different from the smooth() function, because the font smoothing
@@ -2109,7 +2121,7 @@ public class PGraphicsJava2D extends PGraphics {
       //g2.setRenderingHint(RenderingHints.KEY_TEXT_ANTIALIASING, textAntialias);
       g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, antialias);
 
-    } else {  // otherwise just do the default
+    } else {  // otherwise, just do the default
       super.textLineImpl(buffer, start, stop, x, y);
     }
   }

core/src/processing/core/PGraphics.java

@@ -460,6 +460,9 @@ public class PGraphics extends PImage implements PConstants {
   /** The current text leading (read-only) */
   public float textLeading;
 
+  /** Used internally to check whether still using the default font */
+  protected String defaultFontName;
+
   static final protected String ERROR_TEXTFONT_NULL_PFONT =
     "A null PFont was passed to textFont()";
 
@@ -4243,6 +4246,7 @@ public class PGraphics extends PImage implements PConstants {
       InputStream input = getClass().getResourceAsStream("/font/ProcessingSansPro-Regular.ttf");
       if (input != null) {
         baseFont = Font.createFont(Font.TRUETYPE_FONT, input);
+        defaultFontName = baseFont.getName();
       }
     } catch (Exception e) {
       e.printStackTrace(); // dammit