Add Xlib support to viewer

tools/viewer/sk_app/VulkanWindowContext.cpp

 
 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "GrContext.h"
 #include "GrRenderTarget.h"
@@ skipping 23 matching lines @@
     , fSurfaces(nullptr)
     , fCommandPool(VK_NULL_HANDLE)
     , fBackbuffers(nullptr) {
 
     // any config code here (particularly for msaa)?
 
     this->initializeContext(platformData, params);
 }
 
 void VulkanWindowContext::initializeContext(void* platformData, const DisplayParams& params) {
+    fBackendContext.reset(GrVkBackendContext::Create(&fPresentQueueIndex, canPresent, 
+                                                     platformData));
 
-    fBackendContext.reset(GrVkBackendContext::Create(&fPresentQueueIndex, canPresent));
     if (!(fBackendContext->fExtensions & kKHR_surface_GrVkExtensionFlag) ||
         !(fBackendContext->fExtensions & kKHR_swapchain_GrVkExtensionFlag)) {
         fBackendContext.reset(nullptr);
         return;
     }
 
     VkInstance instance = fBackendContext->fInstance;
     VkDevice device = fBackendContext->fDevice;
     GET_PROC(DestroySurfaceKHR);
     GET_PROC(GetPhysicalDeviceSurfaceSupportKHR);
@@ skipping 84 matching lines @@
         extent.width = caps.minImageExtent.width;
     } else if (extent.width > caps.maxImageExtent.width) {
         extent.width = caps.maxImageExtent.width;
     }
     // clamp height
     if (extent.height < caps.minImageExtent.height) {
         extent.height = caps.minImageExtent.height;
     } else if (extent.height > caps.maxImageExtent.height) {
         extent.height = caps.maxImageExtent.height;
     }
+
     fWidth = (int)extent.width;
     fHeight = (int)extent.height;
 
     uint32_t imageCount = caps.minImageCount + 2;
     if (caps.maxImageCount > 0 && imageCount > caps.maxImageCount) {
         // Application must settle for fewer images than desired:
         imageCount = caps.maxImageCount;
     }
 
     VkImageUsageFlags usageFlags = VK_IMAGE_USAGE_COLOR_ATTACHMENT_BIT |
@@ skipping 432 matching lines @@
         &fSwapchain, // pSwapchains
         &backbuffer->fImageIndex, // pImageIndices
         NULL // pResults
     };
 
     fQueuePresentKHR(fPresentQueue, &presentInfo);
 
 }
 
 }   //namespace sk_app