check (thread-tricky) colortable after we've copied the bitmap into a per-thread context

src/core/SkBitmapProcState.cpp

 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkBitmapCache.h"
 #include "SkBitmapProcState.h"
 #include "SkColorPriv.h"
@@ skipping 306 matching lines @@
         }
     }
     fBitmap = &fScaledBitmap;
     return true;
 }
 
 SkBitmapProcState::~SkBitmapProcState() {
     SkDELETE(fBitmapFilter);
 }
 
+static bool valid_for_drawing(const SkBitmap& bm) {
+    if (0 == bm.width() || 0 == bm.height()) {
+        return false;   // nothing to draw
+    }
+    if (NULL == bm.pixelRef()) {
+        return false;   // no pixels to read
+    }
+    if (bm.getTexture()) {
+        // we can handle texture (ugh) since lockPixels will perform a read-back
+        return true;
+    }
+    if (kIndex_8_SkColorType == bm.colorType()) {
+        SkAutoLockPixels alp(bm); // but we need to call it before getColorTable() is safe.
+        if (!bm.getColorTable()) {
+            return false;
+        }
+    }
+    return true;
+}
+
 bool SkBitmapProcState::chooseProcs(const SkMatrix& inv, const SkPaint& paint) {
-    SkASSERT(fOrigBitmap.width() && fOrigBitmap.height());
+    if (!valid_for_drawing(fOrigBitmap)) {
+        return false;
+    }
 
     fBitmap = NULL;
     fInvMatrix = inv;
     fFilterLevel = paint.getFilterLevel();
 
     // possiblyScaleImage will look to see if it can rescale the image as a
     // preprocess; either by scaling up to the target size, or by selecting
     // a nearby mipmap level.  If it does, it will adjust the working
     // matrix as well as the working bitmap.  It may also adjust the filter
     // quality to avoid re-filtering an already perfectly scaled image.
@@ skipping 723 matching lines @@
             fx += dx;
         }
     } else {
         for (int i = 0; i < count; ++i) {
             dst[i] = src[SkClampMax(SkFractionalIntToInt(fx), maxX)];
             fx += dx;
         }
     }
 }