ector: Fix precomp layer rendering issue when it has alpha value

Summary:
When the precomp layer(parent layer) has alpha transparency and has more than 1 child layer
and they overlap each other if vg object just propagate the alpha to child layer
it will be applied twice in overlapped area.
Even if the child layer does not have alpha transparency, parent alpha is applied to each child.

Test Plan: N/A

Reviewers: Hermet, smohanty

Reviewed By: Hermet

Subscribers: cedric, #reviewers, kimcinoo, #committers

Tags: #efl

Differential Revision: https://phab.enlightenment.org/D9072

src/lib/ector/ector_surface.eo

@@ -21,5 +21,15 @@ mixin @beta Ector.Surface extends Ector.Buffer
             @in type: const(Efl.Class); [[Efl class]] /* FIXME: Should probably be a more restricted type */
          }
       }
+      draw_image @pure_virtual {
+         [[ Draw image's buffer to surface buffer. ]]
+         params {
+            @in image: Ector.Buffer; [[Image buffer]]
+            @in x: int; [[Buffer position x]]
+            @in y: int; [[Buffer position y]]
+            @in alpha: int; [[Buffer alpha value]]
+         }
+         return: bool; [[True if drawing was successful]]
+      }
    }
 }

src/lib/ector/software/ector_software_private.h

@@ -5,6 +5,7 @@
 #include "sw_ft_raster.h"
 #include "sw_ft_stroker.h"
 #include "../ector_private.h"
+#include "draw.h"
 
 typedef struct _Ector_Software_Surface_Data Ector_Software_Surface_Data;
 typedef struct _Ector_Software_Thread Ector_Software_Thread;

src/lib/ector/software/ector_software_surface.c

@@ -245,5 +245,31 @@ _ector_software_surface_ector_surface_reference_point_set(Eo *obj EINA_UNUSED,
    pd->y = y;
 }
 
+static Eina_Bool
+_ector_software_surface_ector_surface_draw_image(Eo *obj EINA_UNUSED,
+                                                 Ector_Software_Surface_Data *pd,
+                                                 Ector_Buffer *buffer, int x, int y, int alpha)
+{
+   if (!buffer || !pd->rasterizer || !pd->rasterizer->fill_data.raster_buffer->pixels.u32)
+     return EINA_FALSE;
+
+   Ector_Software_Buffer_Base_Data *bd = efl_data_scope_get(buffer, ECTOR_SOFTWARE_BUFFER_BASE_MIXIN);
+   const int pix_stride = pd->rasterizer->fill_data.raster_buffer->stride / 4;
+
+   uint32_t *src = bd->pixels.u32;
+   for (unsigned int local_y = 0; local_y <  bd->generic->h; local_y++)
+     {
+        uint32_t *dst = pd->rasterizer->fill_data.raster_buffer->pixels.u32 + (x + ((local_y + y) * pix_stride));
+        for (unsigned int local_x = 0; local_x <  bd->generic->w; local_x++)
+          {
+             *src = draw_mul_256(alpha, *src);
+             int inv_alpha = 255 - ((*src) >> 24);
+             *dst = *src + draw_mul_256(inv_alpha, *dst);
+             dst++;
+             src++;
+          }
+     }
+   return EINA_TRUE;
+}
 #include "ector_software_surface.eo.c"
 #include "ector_renderer_software.eo.c"

src/lib/ector/software/ector_software_surface.eo

@@ -6,6 +6,7 @@ class @beta Ector.Software.Surface extends Ector.Software.Buffer implements Ecto
    implements {
       Ector.Surface.renderer_factory_new;
       Ector.Surface.reference_point { set; }
+      Ector.Surface.draw_image;
       Efl.Object.destructor;
       Efl.Object.constructor;
    }

src/lib/evas/canvas/efl_canvas_vg_container.c

@@ -236,6 +236,9 @@ static void
 _efl_canvas_vg_container_efl_object_destructor(Eo *obj,
                                                Efl_Canvas_Vg_Container_Data *pd)
 {
+   if (pd->blend_pixels) free(pd->blend_pixels);
+   if (pd->blend_buffer) efl_unref(pd->blend_buffer);
+
    //Destroy mask surface
    if (pd->mask.buffer) efl_unref(pd->mask.buffer);
    if (pd->mask.pixels) free(pd->mask.pixels);

src/lib/evas/canvas/efl_canvas_vg_object.c

@@ -386,22 +386,66 @@ _efl_canvas_vg_object_efl_object_finalize(Eo *obj, Efl_Canvas_Vg_Object_Data *pd
 static void
 _evas_vg_render(Evas_Object_Protected_Data *obj, Efl_Canvas_Vg_Object_Data *pd,
                 void *engine, void *output, void *context, Efl_VG *node,
-                Eina_Array *clips, Eina_Bool do_async)
+                Eina_Array *clips, int w, int h, Ector_Surface *ector, Eina_Bool do_async)
 {
    if (!efl_gfx_entity_visible_get(node)) return;
 
    if (efl_isa(node, EFL_CANVAS_VG_CONTAINER_CLASS))
      {
-        Efl_Canvas_Vg_Container_Data *cd =
-           efl_data_scope_get(node, EFL_CANVAS_VG_CONTAINER_CLASS);
+        Efl_VG *child;
+        Eina_List *l;
+        Efl_Canvas_Vg_Container_Data *cd = efl_data_scope_get(node, EFL_CANVAS_VG_CONTAINER_CLASS);
 
         if (cd->mask.target) return;   //Don't draw mask itself.
 
-        Efl_VG *child;
-        Eina_List *l;
+        int alpha = 255;
+        efl_gfx_color_get(node, NULL, NULL, NULL, &alpha);
 
-        EINA_LIST_FOREACH(cd->children, l, child)
-          _evas_vg_render(obj, pd, engine, output, context, child, clips, do_async);
+        if (alpha < 255)
+          {
+             // Reuse buffer
+             if (!cd->blend_pixels)
+               cd->blend_pixels = calloc(w * h, sizeof(uint32_t*));
+             else
+               memset(cd->blend_pixels, 0, sizeof(uint32_t) * (w * h));
+
+             if (!cd->blend_buffer)
+               {
+                  cd->blend_buffer = ENFN->ector_buffer_new(ENC, obj->layer->evas->evas,
+                                                                    w, h,
+                                                                    EFL_GFX_COLORSPACE_ARGB8888,
+                                                                    ECTOR_BUFFER_FLAG_DRAWABLE |
+                                                                    ECTOR_BUFFER_FLAG_CPU_READABLE |
+                                                                    ECTOR_BUFFER_FLAG_CPU_WRITABLE);
+                  ector_buffer_pixels_set(cd->blend_buffer, cd->blend_pixels,
+                                          w, h, 0,
+                                          EFL_GFX_COLORSPACE_ARGB8888, EINA_TRUE);
+               }
+
+             // Buffer change
+             ector_buffer_pixels_set(ector, cd->blend_pixels,
+                                     w, h, 0,
+                                     EFL_GFX_COLORSPACE_ARGB8888, EINA_TRUE);
+             ector_surface_reference_point_set(ector, 0,0);
+
+             // Draw child node to changed buffer
+             EINA_LIST_FOREACH(cd->children, l, child)
+                _evas_vg_render(obj, pd, engine, output, context, child, clips, w, h, ector, do_async);
+
+             // Re-set original surface
+             ENFN->ector_begin(engine, output, context, ector, 0, 0, EINA_FALSE, do_async);
+
+             // Draw buffer to original surface.(Ector_Surface)
+             ector_surface_draw_image(ector, cd->blend_buffer, 0, 0, alpha);
+
+          }
+        else
+          {
+             if (cd->blend_pixels) free(cd->blend_pixels);
+             if (cd->blend_buffer) efl_unref(cd->blend_buffer);
+             EINA_LIST_FOREACH(cd->children, l, child)
+                _evas_vg_render(obj, pd, engine, output, context, child, clips, w, h, ector, do_async);
+          }
      }
    else
      {
@@ -451,6 +495,7 @@ _render_to_buffer(Evas_Object_Protected_Data *obj, Efl_Canvas_Vg_Object_Data *pd
                    engine, buffer,
                    context, root,
                    NULL,
+                   w, h, ector,
                    do_async);
 
    ENFN->image_dirty_region(engine, buffer, 0, 0, w, h);

src/lib/evas/canvas/evas_vg_private.h

@@ -94,6 +94,10 @@ struct _Efl_Canvas_Vg_Container_Data
    //Masking feature.
    Efl_Canvas_Vg_Node *mask_src;         //Mask Source
    Vg_Mask mask;                         //Mask source data
+
+   //Layer transparency feature. This buffer is only valid when the layer has transparency.
+   Ector_Buffer *blend_buffer;
+   void *blend_pixels;
 };
 
 struct _Efl_Canvas_Vg_Gradient_Data