restore decode API compatibility

protect flip/alpha_dither w/a WEBP_DECODER_ABI_VERSION check

Change-Id: I437a5d5f78800f71b7e7e323faa321f946bf9515

README

@@ -270,11 +270,9 @@ Use following options to convert into alternate image formats:
   -nofilter .... disable in-loop filtering
   -nodither .... disable dithering
   -dither <d> .. dithering strength (in 0..100)
-  -alpha_dither  use alpha-plane dithering if needed
   -mt .......... use multi-threading
   -crop <x> <y> <w> <h> ... crop output with the given rectangle
   -scale <w> <h> .......... scale the output (*after* any cropping)
-  -flip ........ flip the output vertically
   -alpha ....... only save the alpha plane
   -incremental . use incremental decoding (useful for tests)
   -h     ....... this help message

examples/dwebp.c

@@ -557,11 +557,15 @@ static void Help(void) {
          "  -nofilter .... disable in-loop filtering\n"
          "  -nodither .... disable dithering\n"
          "  -dither <d> .. dithering strength (in 0..100)\n"
+#if WEBP_DECODER_ABI_VERSION > 0x0203
          "  -alpha_dither  use alpha-plane dithering if needed\n"
+#endif
          "  -mt .......... use multi-threading\n"
          "  -crop <x> <y> <w> <h> ... crop output with the given rectangle\n"
          "  -scale <w> <h> .......... scale the output (*after* any cropping)\n"
+#if WEBP_DECODER_ABI_VERSION > 0x0203
          "  -flip ........ flip the output vertically\n"
+#endif
          "  -alpha ....... only save the alpha plane\n"
          "  -incremental . use incremental decoding (useful for tests)\n"
          "  -h     ....... this help message\n"
@@ -624,8 +628,10 @@ int main(int argc, const char *argv[]) {
       format = YUV;
     } else if (!strcmp(argv[c], "-mt")) {
       config.options.use_threads = 1;
+#if WEBP_DECODER_ABI_VERSION > 0x0203
     } else if (!strcmp(argv[c], "-alpha_dither")) {
       config.options.alpha_dithering_strength = 100;
+#endif
     } else if (!strcmp(argv[c], "-nodither")) {
       config.options.dithering_strength = 0;
     } else if (!strcmp(argv[c], "-dither") && c < argc - 1) {
@@ -640,8 +646,10 @@ int main(int argc, const char *argv[]) {
       config.options.use_scaling = 1;
       config.options.scaled_width  = strtol(argv[++c], NULL, 0);
       config.options.scaled_height = strtol(argv[++c], NULL, 0);
+#if WEBP_DECODER_ABI_VERSION > 0x0203
     } else if (!strcmp(argv[c], "-flip")) {
       config.options.flip = 1;
+#endif
     } else if (!strcmp(argv[c], "-v")) {
       verbose = 1;
 #ifndef WEBP_DLL

examples/vwebp.c

@@ -400,7 +400,9 @@ int main(int argc, char *argv[]) {
     return -1;
   }
   config->options.dithering_strength = 50;
+#if WEBP_DECODER_ABI_VERSION > 0x0203
   config->options.alpha_dithering_strength = 100;
+#endif
   kParams.use_color_profile = 1;
 
   for (c = 1; c < argc; ++c) {
@@ -413,8 +415,10 @@ int main(int argc, char *argv[]) {
       config->options.no_fancy_upsampling = 1;
     } else if (!strcmp(argv[c], "-nofilter")) {
       config->options.bypass_filtering = 1;
+#if WEBP_DECODER_ABI_VERSION > 0x0203
     } else if (!strcmp(argv[c], "-noalphadither")) {
       config->options.alpha_dithering_strength = 0;
+#endif
     } else if (!strcmp(argv[c], "-dither") && c + 1 < argc) {
       config->options.dithering_strength = strtol(argv[++c], NULL, 0);
     } else if (!strcmp(argv[c], "-info")) {

man/dwebp.1

@@ -1,5 +1,5 @@
 .\"                                      Hey, EMACS: -*- nroff -*-
-.TH DWEBP 1 "June 13, 2014"
+.TH DWEBP 1 "July 22, 2014"
 .SH NAME
 dwebp \- decompress a WebP file to an image file
 .SH SYNOPSIS
@@ -67,11 +67,12 @@ but it will make the decoding faster.
 Specify a dithering \fBstrength\fP between 0 and 100. Dithering is a
 post-processing effect applied to chroma components in lossy compression.
 It helps by smoothing gradients and avoiding banding artifacts.
-.TP
+.\" TODO(jzern): restore post-v0.4.1
-.BI \-alpha_dither
+.\" .TP
-If the compressed file contains a transparency plane that was quantized
+.\" .BI \-alpha_dither
-during compression, this flag will allow dithering the reconstructed plane
+.\" If the compressed file contains a transparency plane that was quantized
-in order to generate smoother transparency gradients.
+.\" during compression, this flag will allow dithering the reconstructed plane
+.\" in order to generate smoother transparency gradients.
 .TP
 .B \-nodither
 Disable all dithering (default).
@@ -86,9 +87,10 @@ This cropping area must be fully contained within the source rectangle.
 The top-left corner will be snapped to even coordinates if needed.
 This option is meant to reduce the memory needed for cropping large images.
 Note: the cropping is applied \fIbefore\fP any scaling.
-.TP
+.\" TODO(jzern): restore post-v0.4.1
-.B \-flip
+.\" .TP
-Flip decoded image vertically (can be useful for OpenGL textures for instance).
+.\" .B \-flip
+.\" Flip decoded image vertically (can be useful for OpenGL textures for instance).
 .TP
 .BI \-scale " width height
 Rescale the decoded picture to dimension \fBwidth\fP x \fBheight\fP. This

src/dec/buffer.c

@@ -195,10 +195,12 @@ VP8StatusCode WebPAllocateDecBuffer(int w, int h,
   status = AllocateBuffer(out);
   if (status != VP8_STATUS_OK) return status;
 
+#if WEBP_DECODER_ABI_VERSION > 0x0203
   // Use the stride trick if vertical flip is needed.
   if (options != NULL && options->flip) {
     status = WebPFlipBuffer(out);
   }
+#endif
   return status;
 }
 

src/dec/frame.c

@@ -177,6 +177,7 @@ void VP8InitDithering(const WebPDecoderOptions* const options,
         dec->dither_ = 1;
       }
     }
+#if WEBP_DECODER_ABI_VERSION > 0x0203
     // potentially allow alpha dithering
     dec->alpha_dithering_ = options->alpha_dithering_strength;
     if (dec->alpha_dithering_ > 100) {
@@ -184,6 +185,7 @@ void VP8InitDithering(const WebPDecoderOptions* const options,
     } else if (dec->alpha_dithering_ < 0) {
       dec->alpha_dithering_ = 0;
     }
+#endif
   }
 }
 

src/dec/idec.c

@@ -240,15 +240,17 @@ static int CheckMemBufferMode(MemBuffer* const mem, MemBufferMode expected) {
 
 // To be called last.
 static VP8StatusCode FinishDecoding(WebPIDecoder* const idec) {
+#if WEBP_DECODER_ABI_VERSION > 0x0203
   const WebPDecoderOptions* const options = idec->params_.options;
   WebPDecBuffer* const output = idec->params_.output;
 
   idec->state_ = STATE_DONE;
   if (options != NULL && options->flip) {
     return WebPFlipBuffer(output);
-  } else {
-    return VP8_STATUS_OK;
   }
+#endif
+  idec->state_ = STATE_DONE;
+  return VP8_STATUS_OK;
 }
 
 //------------------------------------------------------------------------------

src/dec/webp.c

@@ -521,9 +521,11 @@ static VP8StatusCode DecodeInto(const uint8_t* const data, size_t data_size,
     WebPFreeDecBuffer(params->output);
   }
 
+#if WEBP_DECODER_ABI_VERSION > 0x0203
   if (params->options != NULL && params->options->flip) {
     status = WebPFlipBuffer(params->output);
   }
+#endif
   return status;
 }
 

src/webp/decode.h

@@ -20,7 +20,7 @@
 extern "C" {
 #endif
 
-#define WEBP_DECODER_ABI_VERSION 0x0205    // MAJOR(8b) + MINOR(8b)
+#define WEBP_DECODER_ABI_VERSION 0x0203    // MAJOR(8b) + MINOR(8b)
 
 // Note: forward declaring enumerations is not allowed in (strict) C and C++,
 // the types are left here for reference.
@@ -442,13 +442,19 @@ struct WebPDecoderOptions {
   int scaled_width, scaled_height;    // final resolution
   int use_threads;                    // if true, use multi-threaded decoding
   int dithering_strength;             // dithering strength (0=Off, 100=full)
+#if WEBP_DECODER_ABI_VERSION > 0x0203
   int flip;                           // flip output vertically
   int alpha_dithering_strength;       // alpha dithering strength in [0..100]
+#endif
 
   // Unused for now:
   int force_rotation;                 // forced rotation (to be applied _last_)
   int no_enhancement;                 // if true, discard enhancement layer
+#if WEBP_DECODER_ABI_VERSION > 0x0203
   uint32_t pad[3];                    // padding for later use
+#else
+  uint32_t pad[5];                    // padding for later use
+#endif
 };
 
 // Main object storing the configuration for advanced decoding.