Added GraphicsObject.renderToBuffer()

src/edu/macalester/graphics/GraphicsObject.java

@@ -1,9 +1,11 @@
 package edu.macalester.graphics;
 
 import java.awt.Graphics2D;
+import java.awt.RenderingHints;
 import java.awt.geom.AffineTransform;
 import java.awt.geom.Point2D;
 import java.awt.geom.Rectangle2D;
+import java.awt.image.BufferedImage;
 import java.util.ArrayList;
 import java.util.List;
 import java.util.function.BiConsumer;
@@ -39,6 +41,18 @@ final void draw(Graphics2D gc) {
      */
     protected abstract void drawInLocalCoordinates(Graphics2D gc);
 
+    /**
+     * Renders this graphics object to an offscreen pixel buffer.
+     * @param image The destination buffer.
+     */
+    public void renderToBuffer(BufferedImage image) {
+        var gc = image.createGraphics();
+        gc.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
+        gc.setRenderingHint(RenderingHints.KEY_RENDERING, RenderingHints.VALUE_RENDER_QUALITY);
+        gc.setRenderingHint(RenderingHints.KEY_STROKE_CONTROL, RenderingHints.VALUE_STROKE_PURE);
+        draw(gc);
+    }
+
     /**
      * Gets the position of the object on the canvas. The “position” is typically the upper left,
      * but this can vary. With text, for example, the y component of the position is the baseline,

test/edu/macalester/graphics/testsupport/RenderingTestMode.java

@@ -137,27 +137,12 @@ public void render(BufferedImage image, GraphicsObject gobj) {
     public abstract void render(BufferedImage image, GraphicsObject gobj);
 
     private static void renderWithBounds(BufferedImage image, GraphicsObject gobj) {
-        var gc = image.createGraphics();
-        gc.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
-        gc.setRenderingHint(RenderingHints.KEY_RENDERING, RenderingHints.VALUE_RENDER_QUALITY);
-        gc.setRenderingHint(RenderingHints.KEY_STROKE_CONTROL, RenderingHints.VALUE_STROKE_PURE);
-
-        // This messy reflection code is secretly just `gobj.draw(gc)`. We could make
-        // GraphicsObject.draw() a public method, but it would confuse students by showing up in
-        // autocomplete. We could move this class into the same package as GraphicsObject, but
-        // that makes the tests harder to navigate. The mess thus lives here.
-        try {
-            var drawMethod = GraphicsObject.class.getDeclaredMethod("draw", new Class[] { Graphics2D.class });
-            drawMethod.setAccessible(true);
-            drawMethod.invoke(gobj, gc);
-        } catch (Exception e) {
-            throw new RuntimeException("Unable to draw " + gobj, e);
-        }
-        visualizeBounds(gc, gobj);
+        gobj.renderToBuffer(image);
+        visualizeBounds(image, gobj);
     }
 
     /// Draws printer-style crop marks around the bounding box of the graphics object.
-    private static void visualizeBounds(Graphics2D g, GraphicsObject gobj) {
+    private static void visualizeBounds(BufferedImage image, GraphicsObject gobj) {
         var bounds = gobj.getBoundsInParent();
         var cropMarks = new Path2D.Double(GeneralPath.WIND_EVEN_ODD);
         for(int side = 0; side < 2; side++) {
@@ -172,6 +157,9 @@ private static void visualizeBounds(Graphics2D g, GraphicsObject gobj) {
                 cropMarks.lineTo(x, y + (side * 2 - 1) * 4);
             }
         }
+
+        var g = image.createGraphics();
+        g.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
         g.setStroke(new BasicStroke(0.5f));
         g.setPaint(new Color(0, 0, 0, 128));
         g.draw(cropMarks);