gpu: Add support for mask patterns

gsk/gpu/gskgpunodeprocessor.c

@@ -1047,6 +1047,67 @@ gsk_gpu_node_processor_create_cross_fade_pattern (GskGpuPatternWriter *self,
   return TRUE;
 }
 
+static gboolean
+gsk_gpu_node_processor_create_mask_pattern (GskGpuPatternWriter *self,
+                                            GskRenderNode       *node)
+{
+  GskRenderNode *source_child, *mask_child;
+
+  source_child = gsk_mask_node_get_source (node);
+  mask_child = gsk_mask_node_get_mask (node);
+
+  if (!gsk_gpu_node_processor_create_node_pattern (self, source_child))
+    return FALSE;
+  if (!gsk_rect_contains_rect (&source_child->bounds, &node->bounds))
+    {
+      gsk_gpu_buffer_writer_append_uint (&self->writer, GSK_GPU_PATTERN_CLIP);
+      gsk_gpu_buffer_writer_append_rect (&self->writer, &source_child->bounds, &self->offset);
+    }
+
+  gsk_gpu_buffer_writer_append_uint (&self->writer, GSK_GPU_PATTERN_PUSH_COLOR);
+
+  if (!gsk_gpu_pattern_writer_push_stack (self))
+    return FALSE;
+
+  if (!gsk_gpu_node_processor_create_node_pattern (self, mask_child))
+    {
+      gsk_gpu_pattern_writer_pop_stack (self);
+      return FALSE;
+    }
+  if (!gsk_rect_contains_rect (&mask_child->bounds, &node->bounds))
+    {
+      gsk_gpu_buffer_writer_append_uint (&self->writer, GSK_GPU_PATTERN_CLIP);
+      gsk_gpu_buffer_writer_append_rect (&self->writer, &mask_child->bounds, &self->offset);
+    }
+
+  switch (gsk_mask_node_get_mask_mode (node))
+  {
+    case GSK_MASK_MODE_ALPHA:
+      gsk_gpu_buffer_writer_append_uint (&self->writer, GSK_GPU_PATTERN_POP_MASK_ALPHA);
+      break;
+
+    case GSK_MASK_MODE_INVERTED_ALPHA:
+      gsk_gpu_buffer_writer_append_uint (&self->writer, GSK_GPU_PATTERN_POP_MASK_INVERTED_ALPHA);
+      break;
+
+    case GSK_MASK_MODE_LUMINANCE:
+      gsk_gpu_buffer_writer_append_uint (&self->writer, GSK_GPU_PATTERN_POP_MASK_LUMINANCE);
+      break;
+
+    case GSK_MASK_MODE_INVERTED_LUMINANCE:
+      gsk_gpu_buffer_writer_append_uint (&self->writer, GSK_GPU_PATTERN_POP_MASK_INVERTED_LUMINANCE);
+      break;
+
+    default:
+      g_return_val_if_reached (FALSE);
+  }
+
+
+  gsk_gpu_pattern_writer_pop_stack (self);
+
+  return TRUE;
+}
+
 static void
 gsk_gpu_node_processor_add_glyph_node (GskGpuNodeProcessor *self,
                                        GskRenderNode       *node)
@@ -1448,8 +1509,8 @@ static const struct
   },
   [GSK_MASK_NODE] = {
     0,
-    NULL,
-    NULL,
+    gsk_gpu_node_processor_add_node_as_pattern,
+    gsk_gpu_node_processor_create_mask_pattern,
   },
   [GSK_FILL_NODE] = {
     0,

gsk/gpu/gskgputypesprivate.h

@@ -47,5 +47,9 @@ typedef enum {
   GSK_GPU_PATTERN_POSITION_POP,
   GSK_GPU_PATTERN_PUSH_COLOR,
   GSK_GPU_PATTERN_POP_CROSS_FADE,
+  GSK_GPU_PATTERN_POP_MASK_ALPHA,
+  GSK_GPU_PATTERN_POP_MASK_INVERTED_ALPHA,
+  GSK_GPU_PATTERN_POP_MASK_LUMINANCE,
+  GSK_GPU_PATTERN_POP_MASK_INVERTED_LUMINANCE,
 } GskGpuPatternType;
 

gsk/gpu/shaders/color.glsl

@@ -13,4 +13,10 @@ color_unpremultiply (vec4 color)
   return color.a > 0.0 ? color / vec4 (color.aaa, 1.0) : color;
 }
 
+float
+luminance (vec3 color)
+{
+  return dot (vec3 (0.2126, 0.7152, 0.0722), color);
+}
+
 #endif /* _COLOR_ */

gsk/gpu/shaders/enums.glsl

@@ -24,6 +24,10 @@
 #define GSK_GPU_PATTERN_POSITION_POP 14u
 #define GSK_GPU_PATTERN_PUSH_COLOR 15u
 #define GSK_GPU_PATTERN_POP_CROSS_FADE 16u
+#define GSK_GPU_PATTERN_POP_MASK_ALPHA 17u
+#define GSK_GPU_PATTERN_POP_MASK_INVERTED_ALPHA 18u
+#define GSK_GPU_PATTERN_POP_MASK_LUMINANCE 19u
+#define GSK_GPU_PATTERN_POP_MASK_INVERTED_LUMINANCE 20u
 
 #define TOP 0u
 #define RIGHT 1u

gsk/gpu/shaders/pattern.glsl

@@ -150,6 +150,42 @@ cross_fade_pattern (inout uint reader,
   color = mix (start, color, progress);
 }
 
+void
+mask_alpha_pattern (inout uint reader,
+                    inout vec4 color)
+{
+  vec4 source = stack_pop ();
+
+  color = source * color.a;
+}
+
+void
+mask_inverted_alpha_pattern (inout uint reader,
+                             inout vec4 color)
+{
+  vec4 source = stack_pop ();
+
+  color = source * (1.0 - color.a);
+}
+
+void
+mask_luminance_pattern (inout uint reader,
+                        inout vec4 color)
+{
+  vec4 source = stack_pop ();
+
+  color = source * luminance (color.rgb);
+}
+
+void
+mask_inverted_luminance_pattern (inout uint reader,
+                                 inout vec4 color)
+{
+  vec4 source = stack_pop ();
+
+  color = source * (color.a - luminance (color.rgb));
+}
+
 vec4
 glyphs_pattern (inout uint reader,
                 vec2       pos)
@@ -311,6 +347,18 @@ pattern (uint reader,
         case GSK_GPU_PATTERN_POP_CROSS_FADE:
           cross_fade_pattern (reader, color);
           break;
+        case GSK_GPU_PATTERN_POP_MASK_ALPHA:
+          mask_alpha_pattern (reader, color);
+          break;
+        case GSK_GPU_PATTERN_POP_MASK_INVERTED_ALPHA:
+          mask_inverted_alpha_pattern (reader, color);
+          break;
+        case GSK_GPU_PATTERN_POP_MASK_LUMINANCE:
+          mask_luminance_pattern (reader, color);
+          break;
+        case GSK_GPU_PATTERN_POP_MASK_INVERTED_LUMINANCE:
+          mask_inverted_luminance_pattern (reader, color);
+          break;
       }
     }
 }