Moved dicache entry removal to a_Dicache_cleanup()

This allows keeping the decompressed image entry until a_Dicache_cleanup()
removes it. With the added SurvCleanup variable that controls how many
cleanup passes the entry is kept, it is now possible to tune the dicache.

For instance:
 SurvCleanup=0 same as without patch (negligible difference).
 SurvCleanup=1 allows Back and Forward reuse entries for adjacent pages.
 SurvCleanup=2 all the above, plus one more pass of lifetime.

The default is SurvCleanup=3 (experimental).
Example: If you read a newspaper with lots of images, this caching allows
to click an article, read it, and go back *quickly* using the same tab.

It is experimental because there may be other simple approaches that serve
well/better these kind of usage patterns.

1 files changed, 3 insertions, 2 deletions

diff --git a/src/dicache.h b/src/dicache.h
index f1819b12..0390d214 100644
--- a/src/dicache.h
+++ b/src/dicache.h
@@ -26,8 +26,9 @@ typedef enum {
 
 typedef struct DICacheEntry {
    DilloUrl *url;          /* Image URL for this entry */
-   uint_t width, height;   /* As taken from image data */
    DilloImgType type;      /* Image type */
+   uint_t width, height;   /* As taken from image data */
+   int SurvCleanup;        /* Cleanup-pass survival for unused images */
    uchar_t *cmap;          /* Color map */
    void *v_imgbuf;         /* Void pointer to an Imgbuf object */
    uint_t TotalSize;       /* Amount of memory the image takes up */
@@ -38,9 +39,9 @@ typedef struct DICacheEntry {
    int version;            /* Version number, used for different
                               versions of the same URL image */
 
+   uint_t DecodedSize;     /* Size of already decoded data */
    CA_Callback_t Decoder;  /* Client function */
    void *DecoderData;      /* Client function data */
-   uint_t DecodedSize;     /* Size of already decoded data */
 
    struct DICacheEntry *next; /* Link to the next "newer" version */
 } DICacheEntry;