Adding a few random AOSP 9 patch images to more test suite more robust.

brut.apktool/apktool-lib/src/main/java/brut/androlib/res/decoder/Res9patchStreamDecoder.java

@@ -176,16 +176,16 @@ public class Res9patchStreamDecoder implements ResStreamDecoder {
         }
 
         public static NinePatch decode(ExtDataInput di) throws IOException {
-            di.skipBytes(1);
+            di.skipBytes(1); // wasDeserialized
             byte numXDivs = di.readByte();
             byte numYDivs = di.readByte();
-            di.skipBytes(1);
+            di.skipBytes(1); // numColors
-            di.skipBytes(8);
+            di.skipBytes(8); // xDivs/yDivs offset
             int padLeft = di.readInt();
             int padRight = di.readInt();
             int padTop = di.readInt();
             int padBottom = di.readInt();
-            di.skipBytes(4);
+            di.skipBytes(4); // colorsOffset
             int[] xDivs = di.readIntArray(numXDivs);
             int[] yDivs = di.readIntArray(numYDivs);
 

brut.apktool/apktool-lib/src/test/java/brut/androlib/BuildAndDecodeTest.java

@@ -389,12 +389,50 @@ public class BuildAndDecodeTest {
         final int[] controlImageGrid = controlImage.getRGB(0, 0, w, h, null, 0, w);
         final int[] testImageGrid = testImage.getRGB(0, 0, w, h, null, 0, w);
 
-
         for (int i = 0; i < controlImageGrid.length; i++) {
             assertEquals("Image lost Optical Bounds at i = " + i, controlImageGrid[i], testImageGrid[i]);
         }
     }
 
+    @Test
+    public void robust9patchTest() throws BrutException, IOException {
+        String[] ninePatches = {"ic_notification_overlay.9.png", "status_background.9.png",
+                "search_bg_transparent.9.png", "screenshot_panel.9.png", "recents_lower_gradient.9.png"};
+
+        char slash = File.separatorChar;
+        String location = slash + "res" + slash + "drawable-xxhdpi" + slash;
+
+        for (String ninePatch : ninePatches) {
+            File control = new File((sTestOrigDir + location), ninePatch);
+            File test = new File((sTestNewDir + location), ninePatch);
+
+            BufferedImage controlImage = ImageIO.read(control);
+            BufferedImage testImage = ImageIO.read(test);
+
+            int w = controlImage.getWidth(), h = controlImage.getHeight();
+
+            // Check the entire horizontal line
+            for (int i = 1; i < w; i++) {
+                if (isTransparent(controlImage.getRGB(i, 0))) {
+                    assertTrue(isTransparent(testImage.getRGB(i, 0)));
+                } else {
+                    assertEquals("Image lost npTc chunk on image " + ninePatch + " at (x, y) (" + i + "," + 0 + ")",
+                            controlImage.getRGB(i, 0), testImage.getRGB(i, 0));
+                }
+            }
+
+            // Check the entire vertical line
+            for (int i = 1; i < h; i++) {
+                if (isTransparent(controlImage.getRGB(0, i))) {
+                    assertTrue(isTransparent(testImage.getRGB(0, i)));
+                } else {
+                    assertEquals("Image lost npTc chunk on image " + ninePatch + " at (x, y) (" + 0 + "," + i + ")",
+                            controlImage.getRGB(0, i), testImage.getRGB(0, i));
+                }
+            }
+        }
+    }
+
     @Test
     public void drawableXxhdpiTest() throws BrutException, IOException {
         compareResFolder("drawable-xxhdpi");
@@ -515,6 +553,10 @@ public class BuildAndDecodeTest {
         assertTrue(f.isDirectory());
     }
 
+    private boolean isTransparent(int pixel) {
+        return pixel >> 24 == 0x00;
+    }
+
     private void compareXmlFiles(String path, ElementQualifier qualifier) throws BrutException {
         DetailedDiff diff;
         try {