Runtime configuration system for skia. This will allow developers to control settings at launch time without relying on compile-time flags or recompilation. It can be used to turn features on and off, as well as to control numeric quantities to 'tune' algorithms. Once I make sure it's working across all platforms I'll send out a quick tutorial on its use.

Review URL: https://codereview.appspot.com/7098051

git-svn-id: http://skia.googlecode.com/svn/trunk@7158 2bbb7eff-a529-9590-31e7-b0007b416f81

1 files changed, 135 insertions, 0 deletions

diff --git a/include/utils/SkRTConf.h b/include/utils/SkRTConf.h
new file mode 100644
index 0000000000..22d7e606ee
--- /dev/null
+++ b/include/utils/SkRTConf.h
@@ -0,0 +1,135 @@
+/*
+ * Copyright 2013 Google, Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+
+#ifndef SkRTConf_DEFINED
+#define SkRTConf_DEFINED
+
+#include "SkString.h"
+#include "SkStream.h"
+
+#include "SkTDict.h"
+#include "SkTArray.h"
+
+/** \class SkRTConfBase
+    Non-templated base class for the runtime configs
+*/
+
+class SkRTConfBase {
+public:
+    SkRTConfBase(const char *name) : fName(name) {}
+    virtual ~SkRTConfBase() {}
+    virtual const char *getName() const { return fName.c_str(); }
+    virtual bool isDefault() const = 0;
+    virtual void print(SkWStream *o) const = 0;
+    virtual bool equals(const SkRTConfBase *conf) const = 0;
+protected:
+    SkString fName;
+};
+
+/** \class SkRTConf
+    A class to provide runtime configurability.
+*/
+template<typename T> class SkRTConf: public SkRTConfBase {
+public:
+    SkRTConf(const char *name, const T &defaultValue, const char *description);
+    operator const T&() const { return fValue; }
+    void print(SkWStream *o) const;
+    bool equals(const SkRTConfBase *conf) const;
+    bool isDefault() const { return fDefault == fValue; }
+    void set(const T& value) { fValue = value; }
+protected:
+    void doPrint(char *s) const;
+    
+    SkString fDescription;
+    T           fDefault;
+    T           fValue; 
+};
+
+#ifdef SK_DEVELOPER
+#define SK_CONF_DECLARE(confType, varName, confName, defaultValue, description) static SkRTConf<confType> varName(confName, defaultValue, description)
+#define SK_CONF_SET(confname, value) skRTConfRegistry().set(confname, value)
+#else
+#define SK_CONF_DECLARE(confType, varName, confName, defaultValue, description) static const confType varName = defaultValue
+#define SK_CONF_SET(confname, value) (void) confname, (void) value
+#endif
+
+/** \class SkRTConfRegistry
+    A class that maintains a systemwide registry of all runtime configuration
+    parameters.  Mainly used for printing them out and handling multiply-defined
+    knobs.
+*/
+
+class SkRTConfRegistry {
+public:
+    SkRTConfRegistry();
+    void printAll(const char *fname = NULL) const;
+    void printNonDefault(const char *fname = NULL) const;
+    const char *configFileLocation() const;
+    void possiblyDumpFile() const;
+    void validate() const;
+    template <typename T> void set(const char *confname, T value);
+private:
+    template<typename T> friend class SkRTConf;
+    
+    void registerConf(SkRTConfBase *conf);
+    template <typename T> bool parse(const char *name, T* value);
+        
+    SkTDArray<SkString *> fConfigFileKeys, fConfigFileValues;
+    typedef SkTDict< SkTDArray<SkRTConfBase *> * > ConfMap;
+    ConfMap fConfs;
+};
+
+// our singleton registry
+
+SkRTConfRegistry &skRTConfRegistry();
+
+template<typename T>
+SkRTConf<T>::SkRTConf(const char *name, const T &defaultValue, const char *description)
+    : SkRTConfBase(name)
+    , fValue(defaultValue)
+    , fDefault(defaultValue)
+    , fDescription(description) {
+    
+    T value;
+    if (skRTConfRegistry().parse(fName.c_str(), &value)) {
+        fValue = value;
+    }
+    skRTConfRegistry().registerConf(this);
+}
+
+template<typename T>
+void SkRTConf<T>::print(SkWStream *o) const {
+    char outline[200]; // should be ok because we specify a max. width for everything here.
+
+    sprintf(outline, "%-30.30s", getName());
+    doPrint(&(outline[30]));
+    sprintf(&(outline[60]), " %.128s", fDescription.c_str());
+    if (' ' == outline[strlen(outline)-1]) {
+        for (int i = strlen(outline)-1 ; ' ' == outline[i] ; i--) {
+            outline[i] = '\0';
+        }
+    }
+    o->writeText(outline);
+}
+
+template<typename T>
+void SkRTConf<T>::doPrint(char *s) const {
+    sprintf(s, "%-30.30s", "How do I print myself??");
+}
+
+template<typename T>
+bool SkRTConf<T>::equals(const SkRTConfBase *conf) const {
+    const SkRTConf<T> *child_pointer = dynamic_cast<const SkRTConf<T> *>(conf);
+    return child_pointer && 
+           fName == child_pointer->fName &&
+           fDescription == child_pointer->fDescription &&
+           fValue == child_pointer->fValue &&
+           fDefault == child_pointer->fDefault;
+}
+
+#endif