Add sw support to viewer on Linux.

tools/viewer/Viewer.cpp

 /*
 * Copyright 2016 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */
 
 #include "Viewer.h"
 
 #include "GMSlide.h"
@@ skipping 40 matching lines @@
 DEFINE_string(key, "", "Space-separated key/value pairs to add to JSON identifying this builder.");
 DEFINE_string2(match, m, nullptr,
                "[~][^]substring[$] [...] of bench name to run.\n"
                "Multiple matches may be separated by spaces.\n"
                "~ causes a matching bench to always be skipped\n"
                "^ requires the start of the bench to match\n"
                "$ requires the end of the bench to match\n"
                "^ and $ requires an exact match\n"
                "If a bench does not match any list entry,\n"
                "it is skipped unless some list entry starts with ~");
+
+#ifdef SK_VULKAN
+#    define BACKENDS_STR "\"sw\", \"gl\", and \"vulkan\""
+#else
+#    define BACKENDS_STR "\"sw\" and \"gl\""
+#endif
+
 #ifdef SK_BUILD_FOR_ANDROID
 DEFINE_string(skps, "/data/local/tmp/skia", "Directory to read skps from.");
 DEFINE_string(jpgs, "/data/local/tmp/skia", "Directory to read jpgs from.");
-DEFINE_bool(vulkan, false, "Run with Vulkan.");
 #else
 DEFINE_string(skps, "skps", "Directory to read skps from.");
 DEFINE_string(jpgs, "jpgs", "Directory to read jpgs from.");
-DEFINE_bool(vulkan, true, "Run with Vulkan.");
 #endif
 
+DEFINE_string2(backend, b, "sw", "Backend to use. Allowed values are " BACKENDS_STR ".");
+
 const char *kBackendTypeStrings[sk_app::Window::kBackendTypeCount] = {
     " [OpenGL]",
 #ifdef SK_VULKAN
     " [Vulkan]",
 #endif
     " [Raster]"
 };
 
+static sk_app::Window::BackendType get_backend_type(const char* str) {
+#ifdef SK_VULKAN
+    if (0 == strcmp(str, "vk")) {
+        return sk_app::Window::kVulkan_BackendType;
+    } else
+#endif
+    if (0 == strcmp(str, "gl")) {
+        return sk_app::Window::kNativeGL_BackendType;
+    } else if (0 == strcmp(str, "sw")) {
+        return sk_app::Window::kRaster_BackendType;
+    } else {
+        SkDebugf("Unknown backend type, %s, defaulting to sw.", str);
+        return sk_app::Window::kRaster_BackendType;
+    }
+}
+
 const char* kName = "name";
 const char* kValue = "value";
 const char* kOptions = "options";
 const char* kSlideStateName = "Slide";
 const char* kBackendStateName = "Backend";
 const char* kSoftkeyStateName = "Softkey";
 const char* kSoftkeyHint = "Please select a softkey";
 const char* kFpsStateName = "FPS";
 const char* kSplitScreenStateName = "Split screen";
 const char* kON = "ON";
@@ skipping 14 matching lines @@
     memset(fMeasurements, 0, sizeof(fMeasurements));
 
     SkDebugf("Command line arguments: ");
     for (int i = 1; i < argc; ++i) {
         SkDebugf("%s ", argv[i]);
     }
     SkDebugf("\n");
 
     SkCommandLineFlags::Parse(argc, argv);
 
-#ifdef SK_VULKAN
-    fBackendType = FLAGS_vulkan ? sk_app::Window::kVulkan_BackendType
-                                : sk_app::Window::kNativeGL_BackendType;
-#endif
+    fBackendType = get_backend_type(FLAGS_backend[0]);
     fWindow = Window::CreateNativeWindow(platformData);
     fWindow->attach(fBackendType, DisplayParams());
 
     // register callbacks
     fCommands.attach(fWindow);
     fWindow->registerPaintFunc(on_paint_handler, this);
     fWindow->registerTouchFunc(on_touch_handler, this);
     fWindow->registerUIStateChangedFunc(on_ui_state_changed_handler, this);
 
     // add key-bindings
@@ skipping 481 matching lines @@
             updateUIState();
         }
     } else if (stateName.equals(kRefreshStateName)) {
         // This state is actually NOT in the UI state.
         // We use this to allow Android to quickly set bool fRefresh.
         fRefresh = stateValue.equals(kON);
     } else {
         SkDebugf("Unknown stateName: %s", stateName.c_str());
     }
 }