sw_engine: refactoring of the radial gradient rle rastering function

The translucent rastering function is split into 3 other (instead of if/else statement).
An additional function is introduced to decide which one of the 3 should be called.
This refactoring is done to preserve the convention used for all other rastering functs.

src/lib/sw_engine/tvgSwRaster.cpp

@@ -928,7 +928,7 @@ static bool _rasterOpaqueLinearGradientRle(SwSurface* surface, const SwRleData*
 
     auto span = rle->spans;
 
-    for (uint32_t i = 0; i < rle->size; ++i) {
+    for (uint32_t i = 0; i < rle->size; ++i, ++span) {
         if (span->coverage == 255) {
             fillFetchLinear(fill, surface->buffer + span->y * surface->stride + span->x, span->y, span->x, span->len);
         } else {
@@ -939,7 +939,96 @@ static bool _rasterOpaqueLinearGradientRle(SwSurface* surface, const SwRleData*
                 dst[i] = ALPHA_BLEND(buf[i], span->coverage) + ALPHA_BLEND(dst[i], ialpha);
             }
         }
-        ++span;
+    }
+    return true;
+}
+
+
+static bool _translucentRadialGradientRle(SwSurface* surface, const SwRleData* rle, const SwFill* fill)
+{
+    if (fill->radial.a < FLT_EPSILON) return false;
+
+    auto span = rle->spans;
+    auto buffer = static_cast<uint32_t*>(alloca(surface->w * sizeof(uint32_t)));
+    if (!buffer) return false;
+
+    for (uint32_t i = 0; i < rle->size; ++i, ++span) {
+        auto dst = &surface->buffer[span->y * surface->stride + span->x];
+        fillFetchRadial(fill, buffer, span->y, span->x, span->len);
+        if (span->coverage == 255) {
+            for (uint32_t i = 0; i < span->len; ++i) {
+                dst[i] = buffer[i] + ALPHA_BLEND(dst[i], 255 - surface->blender.alpha(buffer[i]));
+            }
+        } else {
+           for (uint32_t i = 0; i < span->len; ++i) {
+                auto tmp = ALPHA_BLEND(buffer[i], span->coverage);
+                dst[i] = tmp + ALPHA_BLEND(dst[i], 255 - surface->blender.alpha(tmp));
+            }
+        }
+    }
+    return true;
+}
+
+
+static bool _translucentRadialGradientRleAlphaMask(SwSurface* surface, const SwRleData* rle, const SwFill* fill)
+{
+    if (fill->radial.a < FLT_EPSILON) return false;
+
+    auto span = rle->spans;
+    auto cbuffer = surface->compositor->image.data;
+    auto buffer = static_cast<uint32_t*>(alloca(surface->w * sizeof(uint32_t)));
+    if (!buffer) return false;
+
+    for (uint32_t i = 0; i < rle->size; ++i, ++span) {
+        fillFetchRadial(fill, buffer, span->y, span->x, span->len);
+        auto dst = &surface->buffer[span->y * surface->stride + span->x];
+        auto cmp = &cbuffer[span->y * surface->stride + span->x];
+        auto src = buffer;
+        if (span->coverage == 255) {
+            for (uint32_t x = 0; x < span->len; ++x, ++dst, ++cmp, ++src) {
+                auto tmp = ALPHA_BLEND(*src, surface->blender.alpha(*cmp));
+                *dst = tmp + ALPHA_BLEND(*dst, 255 - surface->blender.alpha(tmp));
+            }
+        } else {
+            auto ialpha = 255 - span->coverage;
+            for (uint32_t x = 0; x < span->len; ++x, ++dst, ++cmp, ++src) {
+                auto tmp = ALPHA_BLEND(*src, surface->blender.alpha(*cmp));
+                tmp = ALPHA_BLEND(tmp, span->coverage) + ALPHA_BLEND(*dst, ialpha);
+                *dst = tmp + ALPHA_BLEND(*dst, 255 - surface->blender.alpha(tmp));
+            }
+        }
+    }
+    return true;
+}
+
+
+static bool _translucentRadialGradientRleInvAlphaMask(SwSurface* surface, const SwRleData* rle, const SwFill* fill)
+{
+    if (fill->radial.a < FLT_EPSILON) return false;
+
+    auto span = rle->spans;
+    auto cbuffer = surface->compositor->image.data;
+    auto buffer = static_cast<uint32_t*>(alloca(surface->w * sizeof(uint32_t)));
+    if (!buffer) return false;
+
+    for (uint32_t i = 0; i < rle->size; ++i, ++span) {
+        fillFetchRadial(fill, buffer, span->y, span->x, span->len);
+        auto dst = &surface->buffer[span->y * surface->stride + span->x];
+        auto cmp = &cbuffer[span->y * surface->stride + span->x];
+        auto src = buffer;
+        if (span->coverage == 255) {
+            for (uint32_t x = 0; x < span->len; ++x, ++dst, ++cmp, ++src) {
+                auto tmp = ALPHA_BLEND(*src, 255 - surface->blender.alpha(*cmp));
+                *dst = tmp + ALPHA_BLEND(*dst, 255 - surface->blender.alpha(tmp));
+            }
+        } else {
+            auto ialpha = 255 - span->coverage;
+            for (uint32_t x = 0; x < span->len; ++x, ++dst, ++cmp, ++src) {
+                auto tmp = ALPHA_BLEND(*src, 255 - surface->blender.alpha(*cmp));
+                tmp = ALPHA_BLEND(tmp, span->coverage) + ALPHA_BLEND(*dst, ialpha);
+                *dst = tmp + ALPHA_BLEND(*dst, 255 - surface->blender.alpha(tmp));
+            }
+        }
     }
     return true;
 }
@@ -947,78 +1036,17 @@ static bool _rasterOpaqueLinearGradientRle(SwSurface* surface, const SwRleData*
 
 static bool _rasterTranslucentRadialGradientRle(SwSurface* surface, const SwRleData* rle, const SwFill* fill)
 {
-    if (fill->radial.a < FLT_EPSILON) return false;
+    if (!rle) return false;
-
-    auto buf = static_cast<uint32_t*>(alloca(surface->w * sizeof(uint32_t)));
-    if (!buf) return false;
-
-    auto span = rle->spans;
 
     if (surface->compositor) {
-        auto method = surface->compositor->method;
+        if (surface->compositor->method == CompositeMethod::AlphaMask) {
-        auto cbuffer = surface->compositor->image.data;
+            return _translucentRadialGradientRleAlphaMask(surface, rle, fill);
-
-        if (method == CompositeMethod::AlphaMask) {
-            for (uint32_t i = 0; i < rle->size; ++i, ++span) {
-                fillFetchRadial(fill, buf, span->y, span->x, span->len);
-                auto dst = &surface->buffer[span->y * surface->stride + span->x];
-                auto cmp = &cbuffer[span->y * surface->stride + span->x];
-                auto src = buf;
-                if (span->coverage == 255) {
-                    for (uint32_t x = 0; x < span->len; ++x, ++dst, ++cmp, ++src) {
-                        auto tmp = ALPHA_BLEND(*src, surface->blender.alpha(*cmp));
-                        *dst = tmp + ALPHA_BLEND(*dst, 255 - surface->blender.alpha(tmp));
         }
-                } else {
+        if (surface->compositor->method == CompositeMethod::InvAlphaMask) {
-                    auto ialpha = 255 - span->coverage;
+            return _translucentRadialGradientRleInvAlphaMask(surface, rle, fill);
-                    for (uint32_t x = 0; x < span->len; ++x, ++dst, ++cmp, ++src) {
-                        auto tmp = ALPHA_BLEND(*src, surface->blender.alpha(*cmp));
-                        tmp = ALPHA_BLEND(tmp, span->coverage) + ALPHA_BLEND(*dst, ialpha);
-                        *dst = tmp + ALPHA_BLEND(*dst, 255 - surface->blender.alpha(tmp));
         }
     }
-            }
+    return _translucentRadialGradientRle(surface, rle, fill);
-            return true;
-        } else if (method == CompositeMethod::InvAlphaMask) {
-            for (uint32_t i = 0; i < rle->size; ++i, ++span) {
-                fillFetchRadial(fill, buf, span->y, span->x, span->len);
-                auto dst = &surface->buffer[span->y * surface->stride + span->x];
-                auto cmp = &cbuffer[span->y * surface->stride + span->x];
-                auto src = buf;
-                if (span->coverage == 255) {
-                   for (uint32_t x = 0; x < span->len; ++x, ++dst, ++cmp, ++src) {
-                        auto tmp = ALPHA_BLEND(*src, 255 - surface->blender.alpha(*cmp));
-                        *dst = tmp + ALPHA_BLEND(*dst, 255 - surface->blender.alpha(tmp));
-                    }
-                } else {
-                    auto ialpha = 255 - span->coverage;
-                    for (uint32_t x = 0; x < span->len; ++x, ++dst, ++cmp, ++src) {
-                        auto tmp = ALPHA_BLEND(*src, 255 - surface->blender.alpha(*cmp));
-                        tmp = ALPHA_BLEND(tmp, span->coverage) + ALPHA_BLEND(*dst, ialpha);
-                        *dst = tmp + ALPHA_BLEND(*dst, 255 - surface->blender.alpha(tmp));
-                    }
-                }
-            }
-            return true;
-        }
-    }
-
-    for (uint32_t i = 0; i < rle->size; ++i) {
-        auto dst = &surface->buffer[span->y * surface->stride + span->x];
-        fillFetchRadial(fill, buf, span->y, span->x, span->len);
-        if (span->coverage == 255) {
-            for (uint32_t i = 0; i < span->len; ++i) {
-                dst[i] = buf[i] + ALPHA_BLEND(dst[i], 255 - surface->blender.alpha(buf[i]));
-            }
-        } else {
-            for (uint32_t i = 0; i < span->len; ++i) {
-                auto tmp = ALPHA_BLEND(buf[i], span->coverage);
-                dst[i] = tmp + ALPHA_BLEND(dst[i], 255 - surface->blender.alpha(tmp));
-            }
-        }
-        ++span;
-    }
-    return true;
 }
 
 
@@ -1031,7 +1059,7 @@ static bool _rasterOpaqueRadialGradientRle(SwSurface* surface, const SwRleData*
 
     auto span = rle->spans;
 
-    for (uint32_t i = 0; i < rle->size; ++i) {
+    for (uint32_t i = 0; i < rle->size; ++i, ++span) {
         auto dst = &surface->buffer[span->y * surface->stride + span->x];
         if (span->coverage == 255) {
             fillFetchRadial(fill, dst, span->y, span->x, span->len);
@@ -1042,7 +1070,6 @@ static bool _rasterOpaqueRadialGradientRle(SwSurface* surface, const SwRleData*
                 dst[i] = ALPHA_BLEND(buf[i], span->coverage) + ALPHA_BLEND(dst[i], ialpha);
             }
         }
-        ++span;
     }
     return true;
 }