Evas DDS: Implement decoding of DXT2 and DXT3

src/modules/evas/loaders/dds/evas_image_load_dds.c

@@ -34,8 +34,6 @@ struct _Evas_Loader_Internal
       unsigned int g_mask;
       unsigned int b_mask;
       unsigned int a_mask;
-
-      Eina_Bool has_alpha : 1;
       // TODO: check mipmaps to load faster a small image :)
    } pf; // pixel format
 };
@@ -159,7 +157,7 @@ _dword_read(const char **m)
    return val;
 }
 
-#define FAIL() do { fprintf(stderr, "DDS: ERROR at %s:%d", \
+#define FAIL() do { fprintf(stderr, "DDS: ERROR at %s:%d\n", \
    __FUNCTION__, __LINE__); goto on_error; } while (0)
 
 static Eina_Bool
@@ -228,7 +226,6 @@ evas_image_load_file_head_dds(void *loader_data,
    if (!(loader->pf.flags & DDPF_FOURCC))
      FAIL(); // Unsupported (uncompressed formats may not have a FOURCC)
    loader->pf.fourcc = _dword_read(&m);
-   loader->pf.has_alpha = EINA_TRUE;
    loader->block_size = 16;
    switch (loader->pf.fourcc)
      {
@@ -238,7 +235,6 @@ evas_image_load_file_head_dds(void *loader_data,
           {
              prop->alpha = EINA_FALSE;
              prop->cspaces = cspaces_s3tc_dxt1_rgb;
-             loader->pf.has_alpha = EINA_FALSE;
              loader->format = EVAS_COLORSPACE_RGB_S3TC_DXT1;
           }
         else
@@ -248,7 +244,6 @@ evas_image_load_file_head_dds(void *loader_data,
              loader->format = EVAS_COLORSPACE_RGBA_S3TC_DXT1;
           }
         break;
-#if 0
       case FOURCC('D', 'X', 'T', '2'):
         loader->format = EVAS_COLORSPACE_RGBA_S3TC_DXT2;
         prop->alpha = EINA_TRUE;
@@ -259,6 +254,7 @@ evas_image_load_file_head_dds(void *loader_data,
         prop->alpha = EINA_TRUE;
         prop->cspaces = cspaces_s3tc_dxt5;
         break;
+#if 0
       case FOURCC('D', 'X', 'T', '4'):
         loader->format = EVAS_COLORSPACE_RGBA_S3TC_DXT4;
         prop->alpha = EINA_TRUE;
@@ -353,9 +349,19 @@ evas_image_load_file_data_dds(void *loader_data,
      {
       case EVAS_COLORSPACE_RGB_S3TC_DXT1:
         func = s3tc_decode_dxt1_rgb;
+        prop->premul = EINA_FALSE;
         break;
       case EVAS_COLORSPACE_RGBA_S3TC_DXT1:
         func = s3tc_decode_dxt1_rgba;
+        prop->premul = EINA_FALSE;
+        break;
+      case EVAS_COLORSPACE_RGBA_S3TC_DXT2:
+        func = s3tc_decode_dxt2_rgba;
+        prop->premul = EINA_FALSE;
+        break;
+      case EVAS_COLORSPACE_RGBA_S3TC_DXT3:
+        func = s3tc_decode_dxt3_rgba;
+        prop->premul = EINA_TRUE;
         break;
       default:
         FAIL();

src/modules/evas/loaders/dds/s3tc.h

@@ -3,5 +3,7 @@
 
 void s3tc_decode_dxt1_rgb(unsigned int *bgra, const unsigned char *s3tc);
 void s3tc_decode_dxt1_rgba(unsigned int *bgra, const unsigned char *s3tc);
+void s3tc_decode_dxt2_rgba(unsigned int *bgra, const unsigned char *s3tc);
+void s3tc_decode_dxt3_rgba(unsigned int *bgra, const unsigned char *s3tc);
 
 #endif // EFL_S3TC_H

src/modules/evas/loaders/dds/s3tc_decoder.c

@@ -10,15 +10,11 @@
          ((((s) << 5) & 0xfc00) | (((s) >> 1) & 0x300)) | \
          ((((s) << 8) & 0xf80000) | (((s) << 3) & 0x70000)))
 
-static inline unsigned int
+#define ALPHA4(a) (((a) << 4) | (a))
-_rgb565_to_rgba8888(unsigned short s)
-{
-   return 0xFF000000 | CONVERT_RGB_565_TO_RGB_888(s);
-}
 
 static void
 _decode_dxt1_rgb(unsigned int *bgra, const unsigned char *s3tc,
-                 Eina_Bool alpha)
+                 unsigned int amask, Eina_Bool dxt1, Eina_Bool alpha)
 {
    unsigned short color0, color1;
    unsigned int colors[4];
@@ -27,18 +23,18 @@ _decode_dxt1_rgb(unsigned int *bgra, const unsigned char *s3tc,
    color0 = s3tc[0] | (s3tc[1] << 8);
    color1 = s3tc[2] | (s3tc[3] << 8);
 
-   colors[0] = _rgb565_to_rgba8888(color0);
+   colors[0] = amask | CONVERT_RGB_565_TO_RGB_888(color0);
-   colors[1] = _rgb565_to_rgba8888(color1);
+   colors[1] = amask | CONVERT_RGB_565_TO_RGB_888(color1);
-   if (color0 > color1)
+   if (!dxt1 || (color0 > color1))
      {
         // This is what's not supported by S2TC.
-        colors[2] = 0xFF000000 | INTERP_RGB_256((2*256)/3, colors[0], colors[1]);
+        colors[2] = amask | INTERP_RGB_256((2*256)/3, colors[0], colors[1]);
-        colors[3] = 0xFF000000 | INTERP_RGB_256((1*256)/3, colors[0], colors[1]);
+        colors[3] = amask | INTERP_RGB_256((1*256)/3, colors[0], colors[1]);
      }
    else
      {
-        colors[2] = 0xFF000000 | INTERP_RGB_256(128, colors[0], colors[1]);
+        colors[2] = amask | INTERP_RGB_256(128, colors[0], colors[1]);
-        colors[3] = (alpha ? 0x00000000 : 0xFF000000);
+        colors[3] = (alpha ? 0x00000000 : amask);
      }
 
    bits = s3tc[4] + ((s3tc[5] + ((s3tc[6] + (s3tc[7] << 8)) << 8)) << 8);
@@ -46,18 +42,42 @@ _decode_dxt1_rgb(unsigned int *bgra, const unsigned char *s3tc,
      for (int i = 0; i < 4; i++)
        {
           int idx = bits & 0x3;
-          bits >>= 2;
-
           bgra[(j * 4) + i] = colors[idx];
+          bits >>= 2;
        }
 }
 
+static void
+_decode_alpha4(unsigned int *bgra, const unsigned char *s3tc)
+{
+   for (int k = 0; k < 16; k += 2)
+     {
+        unsigned int a0 = ALPHA4((*s3tc) & 0x0F);
+        unsigned int a1 = ALPHA4(((*s3tc) & 0xF0) >> 4);
+        *bgra++ |= (a0 << 24);
+        *bgra++ |= (a1 << 24);
+        s3tc++;
+     }
+}
+
 void s3tc_decode_dxt1_rgb(unsigned int *bgra, const unsigned char *s3tc)
 {
-   _decode_dxt1_rgb(bgra, s3tc, EINA_FALSE);
+   _decode_dxt1_rgb(bgra, s3tc, 0xFF000000, EINA_TRUE, EINA_FALSE);
 }
 
 void s3tc_decode_dxt1_rgba(unsigned int *bgra, const unsigned char *s3tc)
 {
-   _decode_dxt1_rgb(bgra, s3tc, EINA_TRUE);
+   _decode_dxt1_rgb(bgra, s3tc, 0xFF000000, EINA_TRUE, EINA_TRUE);
+}
+
+void s3tc_decode_dxt2_rgba(unsigned int *bgra, const unsigned char *s3tc)
+{
+   _decode_dxt1_rgb(bgra, s3tc + 8, 0x0, EINA_FALSE, EINA_FALSE);
+   _decode_alpha4(bgra, s3tc);
+}
+
+void s3tc_decode_dxt3_rgba(unsigned int *bgra, const unsigned char *s3tc)
+{
+   _decode_dxt1_rgb(bgra, s3tc + 8, 0x0, EINA_FALSE, EINA_FALSE);
+   _decode_alpha4(bgra, s3tc);
 }