Core: Wrap low-level alpha-blending routines in C++.

Author: kaixiong

libvisual/libvisual/CMakeLists.txt

@@ -63,10 +63,10 @@ SET(libvisual_SOURCES
   lv_cpu.c
   lv_error.c
   lv_gl.c
-  lv_alpha_blend.c
   lv_util.c
 
   lv_actor.cpp
+  lv_alpha_blend.cpp
   lv_audio.cpp
   lv_bin.cpp
   lv_buffer.cpp

libvisual/libvisual/lv_alpha_blend.c

@@ -0,0 +1,98 @@
+#include "config.h"
+#include "lv_alpha_blend.h"
+#include "lv_common.h"
+#include "lv_cpu.h"
+#include "lv_alpha_blend_orc.h"
+#include <cassert>
+
+namespace {
+
+  #pragma pack(1)
+
+  struct rgb16_t {
+  #if VISUAL_LITTLE_ENDIAN == 1
+      std::uint16_t b:5, g:6, r:5;
+  #else
+      std::uint16_t r:5, g:6, b:5;
+  #endif
+  };
+
+  #pragma pack()
+
+  static_assert (sizeof (rgb16_t) == 2);
+
+} // anonymous namespace
+
+namespace LV {
+
+  void alpha_blend_8 (std::span<std::uint8_t> dst, std::span<std::uint8_t const> src1, std::span<std::uint8_t const> src2, std::uint8_t alpha)
+  {
+      assert (dst.data () != src1.data ());
+      assert (dst.data () != src2.data ());
+      assert (src1.size () == src2.size ());
+
+      auto size {static_cast<int> (std::min (dst.size (), src1.size ()))};
+      ::simd_interpolate_8 (dst.data (), src1.data (), src2.data (), alpha, size);
+  }
+
+  void alpha_blend_16 (std::span<std::uint8_t> dst, std::span<std::uint8_t const> src1, std::span<std::uint8_t const> src2, std::uint8_t alpha)
+  {
+      assert (dst.data () != src1.data ());
+      assert (dst.data () != src2.data ());
+      assert (src1.size () == src2.size ());
+
+      auto dst_ptr  = reinterpret_cast<rgb16_t*> (dst.data ());
+      auto src1_ptr = reinterpret_cast<rgb16_t const*> (src1.data ());
+      auto src2_ptr = reinterpret_cast<rgb16_t const*> (src2.data ());
+
+      auto size {static_cast<int> (std::min (dst.size (), src1.size ()))};
+
+      for (auto i = 0; i < size / sizeof (rgb16_t); i++) {
+          dst_ptr[i].r = (alpha * (src2_ptr[i].r - src1_ptr[i].r)) / 255 + src1_ptr[i].r;
+          dst_ptr[i].g = (alpha * (src2_ptr[i].g - src1_ptr[i].g)) / 255 + src1_ptr[i].g;
+          dst_ptr[i].b = (alpha * (src2_ptr[i].b - src1_ptr[i].b)) / 255 + src1_ptr[i].b;
+      }
+  }
+
+  void alpha_blend_24 (std::span<std::uint8_t> dst, std::span<std::uint8_t const> src1, std::span<std::uint8_t const> src2, std::uint8_t alpha)
+  {
+      assert (dst.data () != src1.data ());
+      assert (dst.data () != src2.data ());
+      assert (src1.size () == src2.size ());
+
+      auto size {static_cast<int> (std::min (dst.size (), src1.size ()))};
+      ::simd_interpolate_8 (dst.data (), src1.data (), src2.data (), alpha, size * 3);
+  }
+
+  void alpha_blend_32 (std::span<std::uint8_t> dst, std::span<std::uint8_t const> src1, std::span<std::uint8_t const> src2, std::uint8_t alpha)
+  {
+      assert (dst.data () != src1.data ());
+      assert (dst.data () != src2.data ());
+      assert (src1.size () == src2.size ());
+
+      auto size {static_cast<int> (std::min (dst.size (), src1.size ()))};
+      ::simd_interpolate_8 (dst.data (), src1.data (), src2.data (), alpha, size * 4);
+  }
+
+} // LV namespace
+
+
+void visual_alpha_blend_8 (uint8_t *LV_RESTRICT dest, const uint8_t *LV_RESTRICT src1, const uint8_t *LV_RESTRICT src2, visual_size_t size, uint8_t alpha)
+{
+    simd_interpolate_8 (dest, src1, src2, alpha, (int) size);
+}
+
+void visual_alpha_blend_16 (uint8_t *LV_RESTRICT dest, const uint8_t *LV_RESTRICT src1, const uint8_t *LV_RESTRICT src2, visual_size_t size, uint8_t alpha)
+{
+    LV::alpha_blend_16 ({dest, size}, {src1, size}, {src2, size}, alpha);
+}
+
+void visual_alpha_blend_24 (uint8_t *LV_RESTRICT dest, const uint8_t *LV_RESTRICT src1, const uint8_t *LV_RESTRICT src2, visual_size_t size, uint8_t alpha)
+{
+    simd_interpolate_8 (dest, src1, src2, alpha, (int) size * 3);
+}
+
+void visual_alpha_blend_32 (uint8_t *LV_RESTRICT dest, const uint8_t *LV_RESTRICT src1, const uint8_t *LV_RESTRICT src2, visual_size_t size, uint8_t alpha)
+{
+    simd_interpolate_8 (dest, src1, src2, alpha, (int) size * 4);
+}

libvisual/libvisual/lv_alpha_blend.cpp

@@ -5,6 +5,22 @@
 #include <libvisual/lv_defines.h>
 #include <libvisual/lv_types.h>
 
+#ifdef __cplusplus
+
+#include <cstdint>
+#include <span>
+
+namespace LV {
+
+  LV_API void alpha_blend_8  (std::span<std::uint8_t> dst, std::span<std::uint8_t const> src1, std::span<std::uint8_t const> src2, std::uint8_t alpha);
+  LV_API void alpha_blend_16 (std::span<std::uint8_t> dst, std::span<std::uint8_t const> src1, std::span<std::uint8_t const> src2, std::uint8_t alpha);
+  LV_API void alpha_blend_24 (std::span<std::uint8_t> dst, std::span<std::uint8_t const> src1, std::span<std::uint8_t const> src2, std::uint8_t alpha);
+  LV_API void alpha_blend_32 (std::span<std::uint8_t> dst, std::span<std::uint8_t const> src1, std::span<std::uint8_t const> src2, std::uint8_t alpha);
+
+} // LV namespace
+
+#endif /* __cplusplus */
+
 LV_BEGIN_DECLS
 
 LV_API void visual_alpha_blend_8  (uint8_t *LV_RESTRICT dest, const uint8_t *LV_RESTRICT src1, const uint8_t *LV_RESTRICT src2, visual_size_t size, uint8_t alpha);

libvisual/libvisual/lv_alpha_blend.h

@@ -1,7 +1,7 @@
 libvisual/lv_libvisual.cpp
 libvisual/lv_libvisual_c.cpp
 libvisual/lv_actor.cpp
-libvisual/lv_alpha_blend.c
+libvisual/lv_alpha_blend.cpp
 libvisual/lv_audio.cpp
 libvisual/lv_audio_c.cpp
 libvisual/lv_buffer.cpp