Add Xlib support to viewer

tools/viewer/sk_app/unix/VulkanWindowContext_unix.cpp

Index: tools/viewer/sk_app/unix/VulkanWindowContext_unix.cpp
diff --git a/tools/viewer/sk_app/unix/VulkanWindowContext_unix.cpp b/tools/viewer/sk_app/unix/VulkanWindowContext_unix.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..ddfc8e3068d39583c86ea76dc39e1c57c3662fa4
--- /dev/null
+++ b/tools/viewer/sk_app/unix/VulkanWindowContext_unix.cpp
@@ -0,0 +1,74 @@
+
+/*
+ * 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 "../VulkanWindowContext.h"
+#include "Window_unix.h"
+
+#include "vk/GrVkInterface.h"
+#include "vk/GrVkUtil.h"
+
+#include <X11/Xlib-xcb.h>
+
+namespace sk_app {
+
+// Platform dependant call
+VkSurfaceKHR VulkanWindowContext::createVkSurface(VkInstance instance, void* platformData) {
+    static PFN_vkCreateXcbSurfaceKHR createXcbSurfaceKHR = nullptr;
+    if (!createXcbSurfaceKHR) {
+        createXcbSurfaceKHR = (PFN_vkCreateXcbSurfaceKHR) vkGetInstanceProcAddr(instance,
+                                                                        "vkCreateXcbSurfaceKHR");
+    }
+
+    if (!platformData) {
+        return VK_NULL_HANDLE;
+    }
+    ContextPlatformData_unix* unixPlatformData =
+                                          reinterpret_cast<ContextPlatformData_unix*>(platformData);
+
+
+    VkSurfaceKHR surface;
+
+    VkXcbSurfaceCreateInfoKHR surfaceCreateInfo;
+    memset(&surfaceCreateInfo, 0, sizeof(VkXcbSurfaceCreateInfoKHR));
+    surfaceCreateInfo.sType = VK_STRUCTURE_TYPE_XCB_SURFACE_CREATE_INFO_KHR;
+    surfaceCreateInfo.pNext = nullptr;
+    surfaceCreateInfo.flags = 0;
+    surfaceCreateInfo.connection = XGetXCBConnection(unixPlatformData->fDisplay);
+    surfaceCreateInfo.window = unixPlatformData->fHWnd;
+
+    VkResult res = createXcbSurfaceKHR(instance, &surfaceCreateInfo, nullptr, &surface);
+    if (VK_SUCCESS != res) {
+        return VK_NULL_HANDLE;
+    }
+
+    return surface;
+}
+
+// Platform dependant call
+bool VulkanWindowContext::canPresent(VkInstance instance, VkPhysicalDevice physDev,
+                                     uint32_t queueFamilyIndex, void* platformData) {
+    static PFN_vkGetPhysicalDeviceXcbPresentationSupportKHR
+                                            getPhysicalDeviceXcbPresentationSupportKHR = nullptr;
+    if (!getPhysicalDeviceXcbPresentationSupportKHR) {
+        getPhysicalDeviceXcbPresentationSupportKHR =
+            (PFN_vkGetPhysicalDeviceXcbPresentationSupportKHR) vkGetInstanceProcAddr(instance,
+                                                 "vkGetPhysicalDeviceXcbPresentationSupportKHR");
+    }
+
+    ContextPlatformData_unix* unixPlatformData =
+                                          reinterpret_cast<ContextPlatformData_unix*>(platformData);
+
+    Display* display = unixPlatformData->fDisplay;
+    VkBool32 check = getPhysicalDeviceXcbPresentationSupportKHR(physDev, 
+                                                                queueFamilyIndex, 
+                                                                XGetXCBConnection(display),
+                                                                unixPlatformData->fVisualID);
+    return (VK_FALSE != check);
+}
+
+}   // namespace sk_app