webp.c

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/*
 * File: webp.c
 *
 * Copyright (C) 2024 dogma
 * Copyright (C) 2024 Rodrigo Arias Mallo <rodarima@gmail.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 3 of the License, or
 * (at your option) any later version.
 */
 
#include <config.h>
#ifdef ENABLE_WEBP
 
#include <stdlib.h> /* For abort() */
 
#include <webp/decode.h>
 
#include "msg.h"
#include "image.hh"
#include "cache.h"
#include "dicache.h"
 
enum prog_state {
   IS_finished, IS_init, IS_nextdata
};
 
typedef struct {
   DilloImage *Image;           /* Image meta data */
   DilloUrl *url;               /* Primary Key for the dicache */
   int version;                 /* Secondary Key for the dicache */
   int bgcolor;                 /* Parent widget background color */
   int state;
   int y;
   WebPIDecoder* idec;
   WebPDecBuffer output_buffer; /* for RGBA */
} DilloWebp;
 
 
/*
 * Free up the resources for this image.
 */
static void Webp_free(DilloWebp *webp)
{
   _MSG("Webp_free: webp=%p\n", webp);
 
   WebPFreeDecBuffer(&webp->output_buffer);
   if (webp->idec)
      WebPIDelete(webp->idec);
   dFree(webp);
}
 
/*
 * Finish the decoding process (and free the memory)
 */
static void Webp_close(DilloWebp *webp, CacheClient_t *Client)
{
   _MSG("Webp_close\n");
   /* Let dicache know decoding is over */
   a_Dicache_close(webp->url, webp->version, Client);
   Webp_free(webp);
}
 
/*
 * Op:  Operation to perform.
 *   If (Op == 0)
 *      start or continue processing an image if image data exists.
 *   else
 *       terminate processing, cleanup any allocated memory,
 *       close down the decoding process.
 *
 * Client->CbData  : pointer to previously allocated work area.
 *  This holds the current state of the image processing and is kept
 *  across calls to this routine.
 * Client->Buf     : Pointer to data start.
 * Client->BufSize : the size of the data buffer.
 *
 * You have to keep track of where you are in the image data and
 * how much has been processed.
 *
 * It's entirely possible that you will not see the end of the data.  The
 * user may terminate transfer via a Stop button or there may be a network
 * failure.  This means that you can't just wait for all the data to be
 * presented before starting conversion and display.
 */
void a_Webp_callback(int Op, void *data)
{
   CacheClient_t *Client = data;
 
   if (Op == CA_Send) {
      uint8_t* output;
      VP8StatusCode ret;
 
      DilloWebp *webp = (DilloWebp *)Client->CbData;
 
      if (webp->state == IS_init) {
         WebPBitstreamFeatures features;
 
         ret = WebPGetFeatures(Client->Buf, Client->BufSize, &features);
         if (ret != VP8_STATUS_OK) {
            MSG("features ret is %d\n", ret);
            return;
         }
         if (features.has_alpha) {
            _MSG("WEBP: Alpha!\n");
         }
         webp->output_buffer.colorspace = features.has_alpha ? MODE_RGBA : MODE_RGB;
 
         a_Dicache_set_parms(webp->url, webp->version, webp->Image,
                             features.width, features.height,
                             DILLO_IMG_TYPE_RGB, 1 / 2.2);
 
         webp->idec = WebPINewDecoder(&webp->output_buffer);
         webp->state = IS_nextdata;
      }
 
      ret = WebPIUpdate(webp->idec, Client->Buf, Client->BufSize);
      /* SUSPENDED is a success state that means you don't have the entire file yet */
      if (ret == VP8_STATUS_SUSPENDED || ret == VP8_STATUS_OK) {
         /* last_y seems 1-based, which would be kind of crazy, but I would expect
          * crazy idiocy from google.
          */
         int last_y, width, height, stride;
 
         _MSG("webp completed. status: %s\n", ret == VP8_STATUS_SUSPENDED ? "suspended" : "ok (done)");
         output = WebPIDecGetRGB(webp->idec, &last_y, &width, &height, &stride);
         if (!output) {
            _MSG("webp decoding no output\n");
         } else {
            unsigned char *line;
            int row = webp->y;
 
            if (webp->output_buffer.colorspace == MODE_RGBA)
               line = dNew(unsigned char, width * 3);
            else
               line = output + row * stride;
 
            for (; row < last_y; row++) {
 
               if (webp->output_buffer.colorspace == MODE_RGBA) {
                  int j;
 
                  uint_t bg_blue  = (webp->bgcolor) & 0xFF;
                  uint_t bg_green = (webp->bgcolor>>8) & 0xFF;
                  uint_t bg_red   = (webp->bgcolor>>16) & 0xFF;
                  for (j = 0; j < width; j++) {
                     uchar_t alpha = output[row * stride + 4 * j + 3];
                     uchar_t r = output[row * stride + 4 * j];
                     uchar_t g = output[row * stride + 4 * j + 1];
                     uchar_t b = output[row * stride + 4 * j + 2];
                     line[3 * j] = (r * alpha + (bg_red * (0xFF - alpha))) / 0xFF;
                     line[3 * j + 1] = (g * alpha + (bg_green * (0xFF - alpha))) / 0xFF;
                     line[3 * j + 2] = (b * alpha + (bg_blue * (0xFF - alpha))) / 0xFF;
                  }
               } else {
                  line = output + row * stride;
               }
               a_Dicache_write(webp->url, webp->version, line, row);
            }
            webp->y = last_y;
 
            if (webp->output_buffer.colorspace == MODE_RGBA)
               dFree(line);
         }
      } else {
         MSG("webp WebPIUpdate failed with %d\n", ret);
      }
   } else if (Op == CA_Close) {
      Webp_close(Client->CbData, Client);
   } else if (Op == CA_Abort) {
      Webp_free(data);
   }
}
 
const char *a_Webp_version(char *buf, int n)
{
   /* Return the decoder's version number, packed in
    * hexadecimal using 8bits for each of major/minor/revision.
    * E.g: v2.5.7 is 0x020507. */
   int ver = WebPGetDecoderVersion();
 
   int major = (ver >> 16) & 0xff;
   int minor = (ver >>  8) & 0xff;
   int rev   = (ver >>  0) & 0xff;
 
   int k = snprintf(buf, n, "%d.%d.%d", major, minor, rev);
   if (k >= n)
      return "?";
   return buf;
}
 
/*
 * Create the image state data that must be kept between calls
 */
void *a_Webp_new(DilloImage *Image, DilloUrl *url, int version)
{
   DilloWebp *webp = dNew0(DilloWebp, 1);
   _MSG("a_Webp_new: webp=%p\n", webp);
 
   webp->Image = Image;
   webp->url = url;
   webp->version = version;
 
   webp->bgcolor = Image->bg_color;
   webp->state = IS_init;
   webp->y = 0;
   webp->idec = NULL;
   WebPInitDecBuffer(&webp->output_buffer);
 
   return webp;
}
 
#else /* ENABLE_WEBP */
 
void *a_Webp_new() { return 0; }
void a_Webp_callback() { return; }
const char *a_Webp_version(char *buf, int n) { return 0; }
 
#endif /* ENABLE_WEBP */