Add modulo flag to lua_pictures.

tools/lua/lua_pictures.cpp

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkLua.h"
 #include "SkLuaCanvas.h"
 #include "SkPicture.h"
@@ skipping 15 matching lines @@
 }
 
 static const char gStartCanvasFunc[] = "sk_scrape_startcanvas";
 static const char gEndCanvasFunc[] = "sk_scrape_endcanvas";
 static const char gAccumulateFunc[] = "sk_scrape_accumulate";
 static const char gSummarizeFunc[] = "sk_scrape_summarize";
 
 // PictureRenderingFlags.cpp
 extern bool lazy_decode_bitmap(const void* buffer, size_t size, SkBitmap*);
 
+// Example usage for the modulo flag:
+// for i in {0..5}; do lua_pictures --skpPath SKP_PATH -l YOUR_SCRIPT --modulo $i 6 &; done
+DEFINE_string(modulo, "", "[--modulo <remainder> <divisor>]: only run tests for which "
+              "testIndex %% divisor == remainder.");
 DEFINE_string2(skpPath, r, "", "Read this .skp file or .skp files from this dir");
 DEFINE_string2(luaFile, l, "", "File containing lua script to run");
 DEFINE_string2(headCode, s, "", "Optional lua code to call at beginning");
 DEFINE_string2(tailFunc, s, "", "Optional lua function to call at end");
 
 static SkPicture* load_picture(const char path[]) {
     SkAutoTUnref<SkStream> stream(SkStream::NewFromFile(path));
     SkPicture* pic = NULL;
     if (stream.get()) {
         bool success;
@@ skipping 62 matching lines @@
         if (!L.runCode(data->data(), data->size())) {
             SkDebugf("failed to load luaFile %s\n", FLAGS_luaFile[i]);
             exit(-1);
         }
     }
 
     if (!FLAGS_headCode.isEmpty()) {
         L.runCode(FLAGS_headCode[0]);
     }
 
+    int moduloRemainder = -1;
+    int moduloDivisor = -1;
+    SkString moduloStr;
+
+    if (FLAGS_modulo.count() == 2) {
+        moduloRemainder = atoi(FLAGS_modulo[0]);
+        moduloDivisor = atoi(FLAGS_modulo[1]);
+        if (moduloRemainder < 0 || moduloDivisor <= 0 || moduloRemainder >= moduloDivisor) {
+            SkDebugf("invalid modulo values.\n");
+            return -1;
+        }
+    }
+
     for (int i = 0; i < FLAGS_skpPath.count(); i ++) {
         SkTArray<SkString> paths;
         if (sk_isdir(FLAGS_skpPath[i])) {
             // Add all .skp in this directory.
             const SkString directory(FLAGS_skpPath[i]);
             SkString filename;
             SkOSFile::Iter iter(FLAGS_skpPath[i], "skp");
             while(iter.next(&filename)) {
                 sk_tools::make_filepath(&paths.push_back(), directory, filename);
             }
         } else {
             // Add this as an .skp itself.
             paths.push_back() = FLAGS_skpPath[i];
         }
 
         for (int i = 0; i < paths.count(); i++) {
+            if (moduloRemainder >= 0) {
+                if ((i % moduloDivisor) != moduloRemainder) {
+                    continue;
+                }
+                moduloStr.printf("[%d.%d] ", i, moduloDivisor);
+            }
             const char* path = paths[i].c_str();
-            SkDebugf("scraping %s\n", path);
+            SkDebugf("scraping %s %s\n", path, moduloStr.c_str());
 
             SkAutoTUnref<SkPicture> pic(load_picture(path));
             if (pic.get()) {
                 SkAutoTUnref<SkLuaCanvas> canvas(
                                     new SkLuaCanvas(pic->width(), pic->height(),
                                                     L.get(), gAccumulateFunc));
 
                 call_canvas(L.get(), canvas.get(), path, gStartCanvasFunc);
                 canvas->drawPicture(*pic);
                 call_canvas(L.get(), canvas.get(), path, gEndCanvasFunc);
 
             } else {
                 SkDebugf("failed to load\n");
             }
         }
     }
     return 0;
 }
 
 #if !defined SK_BUILD_FOR_IOS
 int main(int argc, char * const argv[]) {
     return tool_main(argc, (char**) argv);
 }
 #endif