populate 'libwebpextras' with: import gray, rgb565 and rgb4444 functions

update makefile.unix to provide 'make extras' building instructions.

note: input ordering depends on WEBP_SWAP_16BIT_CSP for rgb565 and rgb4444

Change-Id: I6f22d32189d9ba2619146a9714cedabfe28e2ad0

makefile.unix

@@ -2,8 +2,8 @@
 # system, for simple local building of the libraries and tools.
 # It will not install the libraries system-wide, but just create the 'cwebp'
 # and 'dwebp' tools in the examples/ directory, along with the static
-# libraries 'src/libwebp.a', 'src/libwebpdecoder.a', 'src/mux/libwebpmux.a' and
-# 'src/demux/libwebpdemux.a'.
+# libraries 'src/libwebp.a', 'src/libwebpdecoder.a', 'src/mux/libwebpmux.a',
+# 'src/demux/libwebpdemux.a' and 'src/libwebpextras.a'.
 #
 # To build the library and examples, use:
 #    make -f makefile.unix
@@ -224,11 +224,15 @@ UTILS_ENC_OBJS = \
     src/utils/huffman_encode.o \
     src/utils/quant_levels.o \
 
+EXTRA_OBJS = \
+    src/extras/extras.o \
+
 LIBWEBPDECODER_OBJS = $(DEC_OBJS) $(DSP_DEC_OBJS) $(UTILS_DEC_OBJS)
 LIBWEBP_OBJS = $(LIBWEBPDECODER_OBJS) $(ENC_OBJS) $(DSP_ENC_OBJS) \
                $(UTILS_ENC_OBJS)
 LIBWEBPMUX_OBJS = $(MUX_OBJS)
 LIBWEBPDEMUX_OBJS = $(DEMUX_OBJS)
+LIBWEBPEXTRA_OBJS = $(EXTRA_OBJS)
 
 HDRS_INSTALLED = \
     src/webp/decode.h \
@@ -275,6 +279,7 @@ HDRS = \
     $(HDRS_INSTALLED) \
 
 OUT_LIBS = examples/libexample_util.a src/libwebpdecoder.a src/libwebp.a
+EXTRA_LIB = src/libwebpextras.a
 OUT_EXAMPLES = examples/cwebp examples/dwebp
 EXTRA_EXAMPLES = examples/gif2webp examples/vwebp examples/webpmux
 
@@ -287,6 +292,7 @@ endif
 
 ex: $(OUT_EXAMPLES)
 all: ex $(EXTRA_EXAMPLES)
+extras: $(EXTRA_LIB)
 
 $(EX_FORMAT_DEC_OBJS): %.o: %.h
 
@@ -307,6 +313,7 @@ src/libwebpdecoder.a: $(LIBWEBPDECODER_OBJS)
 src/libwebp.a: $(LIBWEBP_OBJS)
 src/mux/libwebpmux.a: $(LIBWEBPMUX_OBJS)
 src/demux/libwebpdemux.a: $(LIBWEBPDEMUX_OBJS)
+src/libwebpextras.a: $(LIBWEBPEXTRA_OBJS)
 
 %.a:
 	$(AR) $(ARFLAGS) $@ $^

src/extras/extras.c

@@ -12,6 +12,8 @@
 
 #include "../webp/extras.h"
 
+#include <string.h>
+
 #define XTRA_MAJ_VERSION 0
 #define XTRA_MIN_VERSION 0
 #define XTRA_REV_VERSION 0
@@ -21,3 +23,89 @@
 int WebPGetExtrasVersion(void) {
   return (XTRA_MAJ_VERSION << 16) | (XTRA_MIN_VERSION << 8) | XTRA_REV_VERSION;
 }
+
+//------------------------------------------------------------------------------
+
+int WebPImportGray(const uint8_t* gray_data, WebPPicture* pic) {
+  int y, width, uv_width;
+  if (pic == NULL || gray_data == NULL) return 0;
+  pic->colorspace = WEBP_YUV420;
+  if (!WebPPictureAlloc(pic)) return 0;
+  width = pic->width;
+  uv_width = (width + 1) >> 1;
+  for (y = 0; y < pic->height; ++y) {
+    memcpy(pic->y + y * pic->y_stride, gray_data, width);
+    gray_data += width;    // <- we could use some 'data_stride' here if needed
+    if ((y & 1) == 0) {
+      memset(pic->u + (y >> 1) * pic->uv_stride, 128, uv_width);
+      memset(pic->v + (y >> 1) * pic->uv_stride, 128, uv_width);
+    }
+  }
+  return 1;
+}
+
+int WebPImportRGB565(const uint8_t* rgb565, WebPPicture* pic) {
+  int x, y;
+  if (pic == NULL || rgb565 == NULL) return 0;
+  pic->colorspace = WEBP_YUV420;
+  pic->use_argb = 1;
+  if (!WebPPictureAlloc(pic)) return 0;
+  for (y = 0; y < pic->height; ++y) {
+    const int width = pic->width;
+    uint32_t* dst = pic->argb + y * pic->argb_stride;
+    for (x = 0; x < width; ++x) {
+#ifdef WEBP_SWAP_16BIT_CSP
+      const uint32_t rg = rgb565[2 * x + 1];
+      const uint32_t gb = rgb565[2 * x + 0];
+#else
+      const uint32_t rg = rgb565[2 * x + 0];
+      const uint32_t gb = rgb565[2 * x + 1];
+#endif
+      uint32_t r = rg & 0xf8;
+      uint32_t g = ((rg << 5) | (gb >> 3)) & 0xfc;
+      uint32_t b = (gb << 5);
+      // dithering
+      r = r | (r >> 5);
+      g = g | (g >> 6);
+      b = b | (b >> 5);
+      dst[x] = (r << 16) | (g << 8) | b;
+    }
+    rgb565 += 2 * width;
+  }
+  return 1;
+}
+
+int WebPImportRGB4444(const uint8_t* rgb4444, WebPPicture* pic) {
+  int x, y;
+  if (pic == NULL || rgb4444 == NULL) return 0;
+  pic->colorspace = WEBP_YUV420;
+  pic->use_argb = 1;
+  if (!WebPPictureAlloc(pic)) return 0;
+  for (y = 0; y < pic->height; ++y) {
+    const int width = pic->width;
+    uint32_t* dst = pic->argb + y * pic->argb_stride;
+    for (x = 0; x < width; ++x) {
+#ifdef WEBP_SWAP_16BIT_CSP
+      const uint32_t rg = rgb4444[2 * x + 1];
+      const uint32_t ba = rgb4444[2 * x + 0];
+#else
+      const uint32_t rg = rgb4444[2 * x + 0];
+      const uint32_t ba = rgb4444[2 * x + 1];
+#endif
+      uint32_t r = rg & 0xf0;
+      uint32_t g = (rg << 4);
+      uint32_t b = (ba & 0xf0);
+      uint32_t a = (ba << 4);
+      // dithering
+      r = r | (r >> 4);
+      g = g | (g >> 4);
+      b = b | (b >> 4);
+      a = a | (a >> 4);
+      dst[x] = (a << 24) | (r << 16) | (g << 8) | b;
+    }
+    rgb4444 += 2 * width;
+  }
+  return 1;
+}
+
+//------------------------------------------------------------------------------

src/webp/extras.h

@@ -17,6 +17,8 @@
 extern "C" {
 #endif
 
+#include "./encode.h"
+
 #define WEBP_EXTRAS_ABI_VERSION 0x0000    // MAJOR(8b) + MINOR(8b)
 
 //------------------------------------------------------------------------------
@@ -25,6 +27,21 @@ extern "C" {
 // 8bits for each of major/minor/revision. E.g: v2.5.7 is 0x020507.
 WEBP_EXTERN(int) WebPGetExtrasVersion(void);
 
+//------------------------------------------------------------------------------
+// Ad-hoc colorspace importers.
+
+// Import luma sample (gray scale image) into 'picture'. The 'picture'
+// width and height must be set prior to calling this function.
+WEBP_EXTERN(int) WebPImportGray(const uint8_t* gray, WebPPicture* picture);
+
+// Import rgb sample in RGB565 packed format into 'picture'. The 'picture'
+// width and height must be set prior to calling this function.
+WEBP_EXTERN(int) WebPImportRGB565(const uint8_t* rgb565, WebPPicture* pic);
+
+// Import rgb sample in RGB4444 packed format into 'picture'. The 'picture'
+// width and height must be set prior to calling this function.
+WEBP_EXTERN(int) WebPImportRGB4444(const uint8_t* rgb4444, WebPPicture* pic);
+
 //------------------------------------------------------------------------------
 
 #ifdef __cplusplus