expand SkLua to handle creation of its own State

samplecode/SampleLua.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 "SampleCode.h"
+#include "SkView.h"
+#include "SkLua.h"
+#include "SkCanvas.h"
+
+extern "C" {
+#include "lua.h"
+#include "lualib.h"
+#include "lauxlib.h"
+}
+
+static const char gDrawName[] = "onDrawContent";
+
+static const char gCode[] = ""
+    "local r = { left = 10, top = 10, right = 100, bottom = 80 } "
+    "local x = 0;"
+    ""
+    "local paint = Sk.newPaint();"
+    "paint:setAntiAlias(true);"
+    ""
+    "local color = {a = 1, r = 1, g = 0, b = 0};"
+    ""
+    "function onDrawContent(canvas) "
+    "   color.g = x / 100;"
+    "   paint:setColor(color) "
+    "   canvas:translate(x, 0);"
+    "   canvas:drawOval(r, paint) "
+    "   x = x + 1;"
+    "   if x > 100 then x = 0 end;"
+    "end";
+
+class LuaView : public SampleView {
+public:
+    LuaView() : fLua(NULL) {}
+    
+    virtual ~LuaView() {
+        SkDELETE(fLua);
+    }
+
+    lua_State* ensureLua() {
+        if (NULL == fLua) {
+            fLua = SkNEW(SkLua);
+            fLua->runCode(gCode);
+        }
+        return fLua->get();
+    }
+
+protected:
+    virtual bool onQuery(SkEvent* evt) SK_OVERRIDE {
+        if (SampleCode::TitleQ(*evt)) {
+            SampleCode::TitleR(evt, "Lua");
+            return true;
+        }
+        SkUnichar uni;
+        if (SampleCode::CharQ(*evt, &uni)) {
+            switch (uni) {
+                default:
+                    break;
+            }
+        }
+        return this->INHERITED::onQuery(evt);
+    }
+
+    virtual void onDrawContent(SkCanvas* canvas) SK_OVERRIDE {
+        lua_State* L = this->ensureLua();
+
+        lua_getglobal(L, gDrawName);
+        if (!lua_isfunction(L, -1)) {
+            int t = lua_type(L, -1);
+            SkDebugf("--- expected %s function %d, ignoring.\n", gDrawName, t);
+            lua_pop(L, 1);
+        } else {
+            // does it make sense to try to "cache" the lua version of this
+            // canvas between draws?
+            fLua->pushCanvas(canvas);
+            if (lua_pcall(L, 1, 0, 0) != LUA_OK) {
+                SkDebugf("lua err: %s\n", lua_tostring(L, -1));
+            }
+        }
+        // need a way for the lua-sample to tell us if they want animations...
+        // hard-code it ON for now.
+        this->inval(NULL);
+    }
+
+    virtual SkView::Click* onFindClickHandler(SkScalar x, SkScalar y,
+                                              unsigned modi) SK_OVERRIDE {
+        return this->INHERITED::onFindClickHandler(x, y, modi);
+    }
+
+    virtual bool onClick(Click* click) SK_OVERRIDE {
+        return this->INHERITED::onClick(click);
+    }
+
+private:
+    SkLua* fLua;
+
+    typedef SampleView INHERITED;
+};
+
+//////////////////////////////////////////////////////////////////////////////
+
+static SkView* MyFactory() { return new LuaView; }
+static SkViewRegister reg(MyFactory);