feat: recreate thumbnail if metadata changed

Signed-off-by: Rentib <[email protected]>

src/thumbnail.c

@@ -113,8 +113,6 @@ bool thumbnail_save(const struct pixmap* thumb, const char* source,
     uint32_t i;
     char path[PATH_MAX] = { 0 };
 
-    (void)params;
-
     if (!get_thumb_path(path, source)) {
         return false;
     }
@@ -127,8 +125,12 @@ bool thumbnail_save(const struct pixmap* thumb, const char* source,
         return false;
     }
 
-    // TODO: add alpha channel
     fprintf(fp, "P6\n%zu %zu\n255\n", thumb->width, thumb->height);
+    /* comment to store params */
+    fwrite("#", 1, 1, fp);
+    fwrite(params, sizeof(struct thumbnail_params), 1, fp);
+    fwrite("\n", 1, 1, fp);
+    // TODO: add alpha channel
     for (i = 0; i < thumb->width * thumb->height; ++i) {
         uint8_t color[] = { (((thumb->data[i] >> (8 * 2)) & 0xff)),
                             (((thumb->data[i] >> (8 * 1)) & 0xff)),
@@ -153,8 +155,7 @@ bool thumbnail_load(struct pixmap* thumb, const char* source,
     uint32_t i;
     char path[PATH_MAX] = { 0 };
     struct stat attr_img, attr_thumb;
-
-    (void)params;
+    struct thumbnail_params saved_params;
 
     if (!get_thumb_path(path, source) || stat(source, &attr_img) ||
         stat(path, &attr_thumb) ||
@@ -180,6 +181,15 @@ bool thumbnail_load(struct pixmap* thumb, const char* source,
         goto fail;
     }
 
+    /* comment to store params */
+    fread(header, 1, 1, fp); // '#'
+    fread(&saved_params, sizeof(struct thumbnail_params), 1, fp);
+    fread(header, 1, 1, fp); // '\n'
+
+    if (memcmp(params, &saved_params, sizeof(struct thumbnail_params))) {
+        goto fail;
+    }
+
     /* NOTE: It might be that we want the pixmap to have exact width and height
      * and return false if it doesn't match */
     if (!pixmap_create(thumb, thumb->width, thumb->height)) {

src/thumbnail.h

@@ -6,12 +6,15 @@
 #include "image.h"
 #include "pixmap.h"
 
-struct thumbnail_params {
-    size_t thumb_width, thumb_height;
-    ssize_t offset_x, offset_y;
-    bool fill;
-    bool antialias;
-    float scale;
+/** Thumbnail parameters.
+ * It is packed because we write it and we don't want any padding.
+ */
+struct __attribute__((packed)) thumbnail_params {
+    size_t thumb_width, thumb_height; ///< Thumbnail size
+    ssize_t offset_x, offset_y;       ///< Offset to center thumbnail
+    bool fill;                        ///< Scale mode (fill/fit)
+    bool antialias;                   ///< Use antialiasing
+    float scale;                      ///< Scale factor
 };
 
 /**