[gtk+] vulkan: Only render minimal region

[Benjamin Otte <otte src gnome org>]

commit a5f8a74ec1d7390c81f4cbae9b84ca942b879233
Author: Benjamin Otte <otte redhat com>
Date:   Tue Dec 27 00:18:52 2016 +0100

    vulkan: Only render minimal region
    
    It's faster to render once for every rectangle in the clip region than
    rendering the outline of the clip region.
    Especially because this reduces the time necessary to build up the frame
    data.
    
    In widget-factory (where we have 3 rectangles), this leads to a 5x
    speedup in the rendering time rendering alone.
    Snapshotting time goes from 10ms to ~1ms, which is another huge
    improvement.

 gsk/gskvulkanrender.c   |   88 +++++++++++++++++++++++++----------------------
 gsk/gskvulkanrenderer.c |   16 +-------
 2 files changed, 49 insertions(+), 55 deletions(-)
---
diff --git a/gsk/gskvulkanrender.c b/gsk/gskvulkanrender.c
index a2968cc..12dac4d 100644
--- a/gsk/gskvulkanrender.c
+++ b/gsk/gskvulkanrender.c
@@ -26,7 +26,7 @@ struct _GskVulkanRender
   graphene_matrix_t mvp;
   int scale_factor;
   VkRect2D viewport;
-  VkRect2D scissor;
+  cairo_region_t *clip;
 
   GHashTable *framebuffers;
   GskVulkanCommandPool *command_pool;
@@ -49,32 +49,31 @@ struct _GskVulkanRender
 };
 
 static void
-gsk_vulkan_render_compute_mvp (GskVulkanRender       *self,
-                               const graphene_rect_t *rect)
+gsk_vulkan_render_setup (GskVulkanRender       *self,
+                         GskVulkanImage        *target,
+                         const graphene_rect_t *rect)
 {
   GdkWindow *window = gsk_renderer_get_window (self->renderer);
   graphene_matrix_t modelview, projection;
-  cairo_rectangle_int_t extents;
+
+  self->target = g_object_ref (target);
 
   if (rect)
     {
-      self->scissor = (VkRect2D) { { 0, 0 }, { rect->size.width, rect->size.height } };
       self->viewport = (VkRect2D) { { rect->origin.x, rect->origin.y }, { rect->size.width, 
rect->size.height } };
       self->scale_factor = 1;
+      self->clip = cairo_region_create_rectangle (&(cairo_rectangle_int_t) {
+                                                      0, 0,
+                                                      gsk_vulkan_image_get_width (target), 
gsk_vulkan_image_get_height (target)
+                                                  });
     }
   else
     {
-      cairo_region_get_extents (gdk_drawing_context_get_clip (gsk_renderer_get_drawing_context 
(self->renderer)),
-                                &extents);
-
       self->scale_factor = gsk_renderer_get_scale_factor (self->renderer);
       self->viewport.offset = (VkOffset2D) { 0, 0 };
       self->viewport.extent.width = gdk_window_get_width (window) * self->scale_factor;
       self->viewport.extent.height = gdk_window_get_height (window) * self->scale_factor;
-      self->scissor.offset.x = extents.x * self->scale_factor;
-      self->scissor.offset.y = extents.y * self->scale_factor;
-      self->scissor.extent.width = extents.width * self->scale_factor;
-      self->scissor.extent.height = extents.height * self->scale_factor;
+      self->clip = gdk_drawing_context_get_clip (gsk_renderer_get_drawing_context (self->renderer));
     }
 
   graphene_matrix_init_scale (&modelview, self->scale_factor, self->scale_factor, 1.0);
@@ -464,6 +463,7 @@ gsk_vulkan_render_draw (GskVulkanRender   *self,
   GskVulkanBuffer *buffer;
   VkCommandBuffer command_buffer;
   GSList *l;
+  guint i;
 
   gsk_vulkan_render_prepare_descriptor_sets (self, sampler);
 
@@ -483,36 +483,43 @@ gsk_vulkan_render_draw (GskVulkanRender   *self,
                       .maxDepth = 1
                     });
 
-  vkCmdSetScissor (command_buffer,
-                   0,
-                   1,
-                   &self->scissor);
-
-  vkCmdBeginRenderPass (command_buffer,
-                        &(VkRenderPassBeginInfo) {
-                            .sType = VK_STRUCTURE_TYPE_RENDER_PASS_BEGIN_INFO,
-                            .renderPass = self->render_pass,
-                            .framebuffer = gsk_vulkan_render_get_framebuffer (self, self->target),
-                            .renderArea = { 
-                                { 0, 0 },
-                                {
-                                    gsk_vulkan_image_get_width (self->target),
-                                    gsk_vulkan_image_get_height (self->target)
+  for (i = 0; i < cairo_region_num_rectangles (self->clip); i++)
+    {
+      cairo_rectangle_int_t rect;
+
+      cairo_region_get_rectangle (self->clip, i, &rect);
+
+      vkCmdSetScissor (command_buffer,
+                       0,
+                       1,
+                       &(VkRect2D) {
+                           { rect.x * self->scale_factor, rect.y * self->scale_factor },
+                           { rect.width * self->scale_factor, rect.height * self->scale_factor }
+                       });
+
+      vkCmdBeginRenderPass (command_buffer,
+                            &(VkRenderPassBeginInfo) {
+                                .sType = VK_STRUCTURE_TYPE_RENDER_PASS_BEGIN_INFO,
+                                .renderPass = self->render_pass,
+                                .framebuffer = gsk_vulkan_render_get_framebuffer (self, self->target),
+                                .renderArea = { 
+                                    { rect.x * self->scale_factor, rect.y * self->scale_factor },
+                                    { rect.width * self->scale_factor, rect.height * self->scale_factor }
+                                },
+                                .clearValueCount = 1,
+                                .pClearValues = (VkClearValue [1]) {
+                                    { .color = { .float32 = { 0.f, 0.f, 0.f, 0.f } } }
                                 }
                             },
-                            .clearValueCount = 1,
-                            .pClearValues = (VkClearValue [1]) {
-                                { .color = { .float32 = { 0.f, 0.f, 0.f, 0.f } } }
-                            }
-                        },
-                        VK_SUBPASS_CONTENTS_INLINE);
+                            VK_SUBPASS_CONTENTS_INLINE);
 
-  for (l = self->render_passes; l; l = l->next)
-    {
-      gsk_vulkan_render_pass_draw (l->data, self, buffer, self->layout, command_buffer);
-    }
+      for (l = self->render_passes; l; l = l->next)
+        {
+          gsk_vulkan_render_pass_draw (l->data, self, buffer, self->layout, command_buffer);
+        }
 
-  vkCmdEndRenderPass (command_buffer);
+      vkCmdEndRenderPass (command_buffer);
+    }
 
   gsk_vulkan_command_pool_submit_buffer (self->command_pool, command_buffer, self->fence);
 
@@ -563,6 +570,7 @@ gsk_vulkan_render_cleanup (GskVulkanRender *self)
   g_slist_free_full (self->cleanup_images, g_object_unref);
   self->cleanup_images = NULL;
 
+  g_clear_pointer (&self->clip, cairo_region_destroy);
   g_clear_object (&self->target);
 }
 
@@ -631,9 +639,7 @@ gsk_vulkan_render_reset (GskVulkanRender       *self,
 {
   gsk_vulkan_render_cleanup (self);
 
-  self->target = g_object_ref (target);
-
-  gsk_vulkan_render_compute_mvp (self, rect);
+  gsk_vulkan_render_setup (self, target, rect);
 }
 
 GskRenderer *
diff --git a/gsk/gskvulkanrenderer.c b/gsk/gskvulkanrenderer.c
index 747ed09..4ae0f4d 100644
--- a/gsk/gskvulkanrenderer.c
+++ b/gsk/gskvulkanrenderer.c
@@ -257,23 +257,11 @@ gsk_vulkan_renderer_begin_draw_frame (GskRenderer          *renderer,
                                       const cairo_region_t *region)
 {
   GskVulkanRenderer *self = GSK_VULKAN_RENDERER (renderer);
-  cairo_region_t *whole_window;
   GdkDrawingContext *result;
-  GdkWindow *window;
-
-  window = gsk_renderer_get_window (renderer);
-  
-  whole_window = cairo_region_create_rectangle (&(GdkRectangle) {
-                                                    0, 0,
-                                                    gdk_window_get_width (window),
-                                                    gdk_window_get_height (window)
-                                                });
 
-  result = gdk_window_begin_draw_frame (window,
+  result = gdk_window_begin_draw_frame (gsk_renderer_get_window (renderer),
                                         GDK_DRAW_CONTEXT (self->vulkan),
-                                        whole_window);
-
-  cairo_region_destroy (whole_window);
+                                        region);
 
   return result;
 }