Add option to disable vsync on viewer unix.

This also fixes an issue where vulkan would crash any time we change a
display param on unix.

Bug: skia:
Change-Id: Ic6c3843e04bc77c2e9c5301ee38fcc58a409495d
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/203380
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Greg Daniel <egdaniel@google.com>

tools/sk_app/DisplayParams.h

@@ -19,6 +19,7 @@ struct DisplayParams {
         , fColorSpace(nullptr)
         , fMSAASampleCount(1)
         , fSurfaceProps(SkSurfaceProps::kLegacyFontHost_InitType)
+        , fDisableVsync(false)
     {}
 
     SkColorType         fColorType;
@@ -26,6 +27,7 @@ struct DisplayParams {
     int                 fMSAASampleCount;
     GrContextOptions    fGrContextOptions;
     SkSurfaceProps      fSurfaceProps;
+    bool                fDisableVsync;
 };
 
 }   // namespace sk_app

tools/sk_app/VulkanWindowContext.cpp

@@ -262,12 +262,18 @@ bool VulkanWindowContext::createSwapchain(int width, int height,
     // If mailbox mode is available, use it, as it is the lowest-latency non-
     // tearing mode. If not, fall back to FIFO which is always available.
     VkPresentModeKHR mode = VK_PRESENT_MODE_FIFO_KHR;
+    bool hasImmediate = false;
     for (uint32_t i = 0; i < presentModeCount; ++i) {
         // use mailbox
         if (VK_PRESENT_MODE_MAILBOX_KHR == presentModes[i]) {
-            mode = presentModes[i];
-            break;
+            mode = VK_PRESENT_MODE_MAILBOX_KHR;
         }
+        if (VK_PRESENT_MODE_IMMEDIATE_KHR == presentModes[i]) {
+            hasImmediate = true;
+        }
+    }
+    if (params.fDisableVsync && hasImmediate) {
+        mode = VK_PRESENT_MODE_IMMEDIATE_KHR;
     }
 
     VkSwapchainCreateInfoKHR swapchainCreateInfo;

tools/sk_app/unix/GLWindowContext_unix.cpp

@@ -67,6 +67,7 @@ sk_sp<const GrGLInterface> GLWindowContext_xlib::onInitializeContext() {
     SkASSERT(!fGLContext);
     sk_sp<const GrGLInterface> interface;
     bool current = false;
+
     // We attempt to use glXCreateContextAttribsARB as RenderDoc requires that the context be
     // created with this rather than glXCreateContext.
     CreateContextAttribsFn* createContextAttribs = (CreateContextAttribsFn*)glXGetProcAddressARB(
@@ -126,6 +127,17 @@ sk_sp<const GrGLInterface> GLWindowContext_xlib::onInitializeContext() {
     if (!current && !glXMakeCurrent(fDisplay, fWindow, fGLContext)) {
         return nullptr;
     }
+
+    const char* glxExtensions = glXQueryExtensionsString(fDisplay, DefaultScreen(fDisplay));
+    if (glxExtensions) {
+        if (strstr(glxExtensions, "GLX_EXT_swap_control")) {
+            PFNGLXSWAPINTERVALEXTPROC glXSwapIntervalEXT =
+                    (PFNGLXSWAPINTERVALEXTPROC)glXGetProcAddressARB(
+                            (const GLubyte*)"glXSwapIntervalEXT");
+            glXSwapIntervalEXT(fDisplay, fWindow, fDisplayParams.fDisableVsync ? 0 : 1);
+        }
+    }
+
     glClearStencil(0);
     glClearColor(0, 0, 0, 0);
     glStencilMask(0xffffffff);

tools/sk_app/unix/Window_unix.cpp

@@ -333,6 +333,8 @@ void Window_unix::show() {
 }
 
 bool Window_unix::attach(BackendType attachType) {
+    fBackend = attachType;
+
     this->initWindow(fDisplay);
 
     window_context_factory::XlibWindowInfo winInfo;
@@ -384,4 +386,21 @@ void Window_unix::onInval() {
     XSendEvent(fDisplay, fWindow, False, 0, &event);
 }
 
+void Window_unix::setRequestedDisplayParams(const DisplayParams& params, bool allowReattach) {
+#if defined(SK_VULKAN)
+    // Vulkan on unix crashes if we try to reinitialize the vulkan context without remaking the
+    // window.
+    if (fBackend == kVulkan_BackendType && allowReattach) {
+        // Need to change these early, so attach() creates the window context correctly
+        fRequestedDisplayParams = params;
+
+        this->detach();
+        this->attach(fBackend);
+        return;
+    }
+#endif
+
+    INHERITED::setRequestedDisplayParams(params, allowReattach);
+}
+
 }   // namespace sk_app

tools/sk_app/unix/Window_unix.h

@@ -74,6 +74,8 @@ public:
         }
     }
 
+    void setRequestedDisplayParams(const DisplayParams&, bool allowReattach) override;
+
 private:
     void closeWindow();
 
@@ -90,6 +92,10 @@ private:
     int      fPendingWidth;
     int      fPendingHeight;
     bool     fPendingResize;
+
+    BackendType fBackend;
+
+    typedef Window INHERITED;
 };
 
 }   // namespace sk_app

tools/viewer/Viewer.cpp

@@ -406,6 +406,13 @@ Viewer::Viewer(int argc, char** argv, void* platformData)
         this->updateTitle();
         fWindow->inval();
     });
+    fCommands.addCommand('v', "VSync", "Toggle vsync on/off", [this]() {
+        DisplayParams params = fWindow->getRequestedDisplayParams();
+        params.fDisableVsync = !params.fDisableVsync;
+        fWindow->setRequestedDisplayParams(params);
+        this->updateTitle();
+        fWindow->inval();
+    });
     fCommands.addCommand('H', "Font", "Hinting mode", [this]() {
         if (!fFontOverrides.fHinting) {
             fFontOverrides.fHinting = true;