Support for progressive jpeg in image_filter module

[Ruslan Ermilov]

On Wed, Mar 13, 2013 at 10:04:35PM +0400, ivan babrou wrote:
> This patch adds support for progressive jpeg and pgn encoding with
> image_filter_interlace on/off setting. Google suggests to use progressive
> jpegs so why not with nginx?

Your MUA broke the text patch, and HTML with the patch is generally
meaningless.  Please find a way to properly send patches (experiment
locally).

> diff --git a/ngx_http_image_filter_module.c b/ngx_http_image_filter_module.c
> index b086e3c..cc44d90 100644
> --- a/ngx_http_image_filter_module.c
> +++ b/ngx_http_image_filter_module.c
> @@ -52,6 +52,7 @@ typedef struct {
>      ngx_uint_t                   offset_y;
> 
>      ngx_flag_t                   transparency;
> +    ngx_flag_t                   interlace;
> 
>      ngx_http_complex_value_t    *wcv;
>      ngx_http_complex_value_t    *hcv;
> @@ -142,6 +143,13 @@ static ngx_command_t  ngx_http_image_filter_commands[]
> = {
>        0,
>        NULL },
> 
> +   { ngx_string("image_filter_interlace"),
> +      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_FLAG,
> +      ngx_conf_set_flag_slot,
> +      NGX_HTTP_LOC_CONF_OFFSET,
> +      offsetof(ngx_http_image_filter_conf_t, interlace),
> +      NULL },
> +

Please keep the same order here as in ngx_http_image_filter_conf_t and
ngx_http_image_filter_{create,merge}_conf().  That is (sharpen,
transparency, interlace).

>      { ngx_string("image_filter_sharpen"),
> 
>  NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_TAKE1,
>        ngx_http_image_filter_sharpen,
> @@ -1115,10 +1123,13 @@ ngx_http_image_out(ngx_http_request_t *r,
> ngx_uint_t type, gdImagePtr img,
> 
>      out = NULL;
> 
> +    conf = ngx_http_get_module_loc_conf(r, ngx_http_image_filter_module);
> +
> +    gdImageInterlace(img, conf->interlace);
> +

conf->interlace which is of type ngx_flag_t isn't the same
as "int" that this function expects.  This will cause warnings
if compiled with -Wshorten-64-to-32 on 64-bit platforms.
While nginx has several such issues at the moment, adding
another one is not welcome.  Cast it to "int" here.

>      switch (type) {
> 
>      case NGX_HTTP_IMAGE_JPEG:
> -        conf = ngx_http_get_module_loc_conf(r,
> ngx_http_image_filter_module);
> 
>          jq = ngx_http_image_filter_get_value(r, conf->jqcv,
> conf->jpeg_quality);
>          if (jq <= 0) {
> @@ -1237,6 +1248,7 @@ ngx_http_image_filter_create_conf(ngx_conf_t *cf)
>      conf->sharpen = NGX_CONF_UNSET_UINT;
>      conf->angle = NGX_CONF_UNSET_UINT;
>      conf->transparency = NGX_CONF_UNSET;
> +    conf->interlace = NGX_CONF_UNSET;
>      conf->buffer_size = NGX_CONF_UNSET_SIZE;
>      conf->offset_x = NGX_CONF_UNSET_UINT;
>      conf->offset_y = NGX_CONF_UNSET_UINT;
> @@ -1292,6 +1304,8 @@ ngx_http_image_filter_merge_conf(ngx_conf_t *cf, void
> *parent, void *child)
> 
>      ngx_conf_merge_value(conf->transparency, prev->transparency, 1);
> 
> +    ngx_conf_merge_value(conf->interlace, prev->interlace, 0);
> +
>      ngx_conf_merge_size_value(conf->buffer_size, prev->buffer_size,
>                                1 * 1024 * 1024);
>