From b59ed4b7d10a6c74215fc9d7ded2f355ba713f09 Mon Sep 17 00:00:00 2001
From: Vincent Wei <vincent@minigui.org>
Date: Tue, 19 Oct 2021 18:46:53 +0800
Subject: [PATCH] implement __mg_check_webp, __mg_init_webp and
 __mg_cleanup_webp

---
 src/mybmp/webp.c | 117 ++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 115 insertions(+), 2 deletions(-)

diff --git a/src/mybmp/webp.c b/src/mybmp/webp.c
index 6f916a2b..9bc15fa6 100644
--- a/src/mybmp/webp.c
+++ b/src/mybmp/webp.c
@@ -59,26 +59,139 @@
 
 #ifdef _MGIMAGE_WEBP
 #include "gdi.h"
+#include "constants.h"
 
 #include <webp/decode.h>
 
+#define RIFF_HEADER_SIZE    12
+
+#define HEADER_CHUNK_SIZE   64
+#define READ_BUFF_SIZE      1024
+
+struct webp_decode_info {
+    WebPDecoderConfig   config;
+    size_t              sz_data;
+    char                buf[READ_BUFF_SIZE];
+};
+
 void* __mg_init_webp(MG_RWops *fp, MYBITMAP *mybmp, RGB *pal)
 {
+    int n;
+    size_t pitch;
+    struct webp_decode_info *info = NULL;
+
+    if ((info = malloc(sizeof(struct webp_decode_info))) == NULL) {
+        _ERR_PRINTF ("__mg_init_webp: failed to allocate memory\n");
+        return NULL;
+    }
+
+    if (!WebPInitDecoderConfig(&info->config)) {
+        _ERR_PRINTF ("__mg_init_webp: WebPInitDecoderConfig failed\n");
+        goto error;
+    }
+
+    info->sz_data = 0;
+    do {
+        VP8StatusCode sc;
+
+        if (info->sz_data + HEADER_CHUNK_SIZE > READ_BUFF_SIZE) {
+            _ERR_PRINTF ("__mg_init_webp: two small buffer\n");
+            goto error;
+        }
+
+        n = MGUI_RWread(fp, info->buf + info->sz_data, 1, HEADER_CHUNK_SIZE);
+        if (n > 0) {
+            info->sz_data += n;
+        }
+        else
+            goto error;
+
+        sc = WebPGetFeatures(info->buf, info->sz_data, &info->config.input);
+        if (sc == VP8_STATUS_OK) {
+            break;
+        }
+        else if (sc == VP8_STATUS_NOT_ENOUGH_DATA) {
+            continue;
+        }
+        else {
+            _ERR_PRINTF ("__mg_init_webp: WebPGetFeatures failed: %d\n", sc);
+            goto error;
+        }
+    } while (1);
+
+    if (info->config.input.has_animation) {
+        _ERR_PRINTF ("__mg_init_webp: animation not supported\n");
+        goto error;
+    }
+
+    mybmp->w = info->config.input.width;
+    mybmp->h = info->config.input.height;
+    mybmp->frames = 1;
+    if (info->config.input.has_alpha) {
+        info->config.output.colorspace = MODE_RGBA;
+
+        mybmp->depth = 32;
+        mybmp->flags |= MYBMP_FLOW_DOWN | MYBMP_ALPHA | MYBMP_TYPE_RGBA;
+        mybmp->flags |= MYBMP_RGBSIZE_4;
+
+        pitch = (size_t)info->config.input.width * 4;
+    }
+    else {
+        info->config.output.colorspace = MODE_RGB;
+
+        mybmp->depth = 24;
+        mybmp->flags |= MYBMP_FLOW_DOWN | MYBMP_ALPHA | MYBMP_TYPE_RGBA;
+        mybmp->flags |= MYBMP_RGBSIZE_4;
+
+        pitch = (size_t)info->config.input.width * 3;
+    }
+
+    pitch = ROUND_TO_MULTIPLE(pitch, 8);
+
+    // Have config.output point to an external buffer:
+    info->config.output.u.RGBA.rgba = (uint8_t*)malloc(pitch);
+    info->config.output.u.RGBA.stride = pitch;
+    info->config.output.u.RGBA.size = pitch;
+    info->config.output.is_external_memory = 1;
+
+    if (info->config.output.u.RGBA.rgba == NULL) {
+        _ERR_PRINTF ("__mg_init_webp: failed to allocate memory\n");
+        goto error;
+    }
+
+    return info;
+
+error:
+    if (info)
+        free(info);
     return NULL;
 }
 
 void __mg_cleanup_webp(void *init_info)
 {
+    struct webp_decode_info *info = init_info;
+
+    if (info) {
+        free(info->config.output.u.RGBA.rgba);
+        free(info);
+    }
 }
 
-int __mg_load_webp (MG_RWops *fp, void *init_info, MYBITMAP *my_bmp,
+int __mg_load_webp(MG_RWops *fp, void *init_info, MYBITMAP *my_bmp,
                 CB_ONE_SCANLINE cb, void *context)
 {
     return ERR_BMP_OK;
 }
 
-BOOL __mg_check_webp (MG_RWops* fp)
+BOOL __mg_check_webp(MG_RWops* fp)
 {
+    unsigned char header[RIFF_HEADER_SIZE];
+
+    MGUI_RWread(fp, header, RIFF_HEADER_SIZE, 1);
+    if (!WebPGetInfo(header, RIFF_HEADER_SIZE, NULL, NULL)) {
+    }
+
+    return WebPGetInfo(header, RIFF_HEADER_SIZE, NULL, NULL);
 }
 
 #endif /* _MGIMAGE_WEBP */