Add method to sk_gpu_test::TestContext to automatically restore the previous context.

The motivation for this is to allow a GM to create a GL context, do some some work in it, and then return to the context that was set when it was invoked.

Change-Id: Ie8496072a10f8f3ff36a08889e593a6ca961b61a
Reviewed-on: https://skia-review.googlesource.com/70720
Commit-Queue: Brian Salomon <bsalomon@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>

1 files changed, 53 insertions, 0 deletions

diff --git a/src/core/SkScopeExit.h b/src/core/SkScopeExit.h
new file mode 100644
index 0000000000..95804e637a
--- /dev/null
+++ b/src/core/SkScopeExit.h
@@ -0,0 +1,53 @@
+/*
+ * Copyright 2016 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef SkScopeExit_DEFINED
+#define SkScopeExit_DEFINED
+
+#include "SkTypes.h"
+
+/** SkScopeExit calls a std:::function<void()> in its destructor. */
+class SkScopeExit {
+public:
+    SkScopeExit(std::function<void()> f) : fFn(std::move(f)) {}
+    SkScopeExit(SkScopeExit&& that) : fFn(std::move(that.fFn)) {}
+
+    ~SkScopeExit() {
+        if (fFn) {
+            fFn();
+        }
+    }
+
+    SkScopeExit& operator=(SkScopeExit&& that) {
+        fFn = std::move(that.fFn);
+        return *this;
+    }
+
+private:
+    std::function<void()> fFn;
+
+    SkScopeExit(           const SkScopeExit& ) = delete;
+    SkScopeExit& operator=(const SkScopeExit& ) = delete;
+};
+
+/**
+ * SK_AT_SCOPE_EXIT(stmt) evaluates stmt when the current scope ends.
+ *
+ * E.g.
+ *    {
+ *        int x = 5;
+ *        {
+ *           SK_AT_SCOPE_EXIT(x--);
+ *           SkASSERT(x == 5);
+ *        }
+ *        SkASSERT(x == 4);
+ *    }
+ */
+#define SK_AT_SCOPE_EXIT(stmt)                              \
+    SkScopeExit SK_MACRO_APPEND_LINE(at_scope_exit_)([&]() { stmt; })
+
+#endif  // SkScopeExit_DEFINED