add SetFlags for command line control

http://codereview.appspot.com/5416047/

M    include/core/SkGraphics.h
M    src/core/SkGraphics.cpp



git-svn-id: http://skia.googlecode.com/svn/trunk@2727 2bbb7eff-a529-9590-31e7-b0007b416f81

include/core/SkGraphics.h

@@ -45,6 +45,16 @@ public:
      *  draws to be recreated, since they will no longer be in the cache.
      */
     static void PurgeFontCache();
+    
+    /**
+     *  Applications with command line options may pass optional state, such
+     *  as cache sizes, here, for instance:
+     *  font-cache-limit=12345678
+     *
+     *  The flags format is name=value[;name=value...] with no spaces.
+     *  This format is subject to change.
+     */
+    static void SetFlags(const char* flags);
 
 private:
     /** This is automatically called by SkGraphics::Init(), and must be

src/core/SkGraphics.cpp

@@ -157,3 +157,50 @@ void SkGraphics::PurgeFontCache() {
     SkGlyphCache::SetCacheUsed(0);
 }
 
+///////////////////////////////////////////////////////////////////////////////
+
+static const char kFontCacheLimitStr[] = "font-cache-limit";
+static const size_t kFontCacheLimitLen = sizeof(kFontCacheLimitStr) - 1; 
+
+static const struct {
+    const char* fStr;
+    size_t fLen;
+    size_t (*fFunc)(size_t);
+} gFlags[] = {
+    {kFontCacheLimitStr, kFontCacheLimitLen, SkGraphics::SetFontCacheLimit}
+};
+
+/* flags are of the form param; or param=value; */
+void SkGraphics::SetFlags(const char* flags) {
+    if (!flags) {
+        return;
+    }
+    const char* nextSemi;
+    do {
+        size_t len = strlen(flags);
+        const char* paramEnd = flags + len;
+        const char* nextEqual = strchr(flags, '=');
+        if (nextEqual && paramEnd > nextEqual) {
+            paramEnd = nextEqual;
+        }
+        nextSemi = strchr(flags, ';');
+        if (nextSemi && paramEnd > nextSemi) {
+            paramEnd = nextSemi;
+        }
+        size_t paramLen = paramEnd - flags;
+        for (int i = 0; i < (int)SK_ARRAY_COUNT(gFlags); ++i) {
+            if (paramLen != gFlags[i].fLen) {
+                continue;
+            }
+            if (strncmp(flags, gFlags[i].fStr, paramLen) == 0) {
+                size_t val = 0;
+                if (nextEqual) {
+                    val = (size_t) atoi(nextEqual + 1);
+                }
+                (gFlags[i].fFunc)(val);
+                break;
+            }
+        }
+        flags = nextSemi + 1;
+    } while (nextSemi);
+}