Add support for customColor for SVG icons

[UtkarshVerma]

This commit implements customColor styling for SVG icons using librsvg. This is a rebased version of #1081 as master had changed quite a lot from that branch.

[bynect]

could this possibly be tweaked to allow a svg_stylesheet instead of just the color?

[UtkarshVerma]

I have implemented a version with a bit of templating as well. Please have a look. For now, it defaults to path: { fill: @foreground !important; }. I also allow the user to use @foreground and @background so that the color vary based on the active notification.

This is how the defaults look for me, for example.

Also, for the tests, I think librsvg needs to be added to the CI docker images.

[bynect]

Also, for the tests, I think librsvg needs to be added to the CI docker images

you are right I will do so

[bynect]

this seems to be a problem with librsvg itself?

[UtkarshVerma]

All tests pass for me. make test-valgrind reports some errors but they are also the on master so I doubt it is from this PR.

[UtkarshVerma]

How should I proceed with this PR?

[bynect]

The code seems good and I have no clue why the build is failing. It seems like the library includes are wrong??

[UtkarshVerma]

It couldn't be the library includes. As I've stated before, make test-valgrind fails on master without my changes.

[bynect]

make test and make test-valgrind work normally for me on master. you might just have some messed up library version.
what the ci is failing on is the build step:

pod2man --name=dunst -c "Dunst Reference" --section=1 --release="v1.13.0-16-g95321a8" docs/dunst.1.pod > docs/dunst.1
src/icon.c:236:17: error: implicit declaration of function 'rsvg_handle_set_stylesheet' is invalid in C99 [-Werror,-Wimplicit-function-declaration]
                rsvg_handle_set_stylesheet(handle, (guint8 *)resolved_css, strlen(resolved_css), &error);
                ^
In file included from test/icon.c:1:
test/../src/icon.c:236:17: error: implicit declaration of function 'rsvg_handle_set_stylesheet' is invalid in C99 [-Werror,-Wimplicit-function-declaration]
                rsvg_handle_set_stylesheet(handle, (guint8 *)resolved_css, strlen(resolved_css), &error);
                ^
src/icon.c:236:17: note: did you mean 'rsvg_handle_get_type'?
test/../src/icon.c:236:17: note: did you mean 'rsvg_handle_get_type'?
/usr/include/librsvg-2.0/librsvg/rsvg.h:53:7: note: 'rsvg_handle_get_type' declared here
GType rsvg_handle_get_type (void);
      ^
/usr/include/librsvg-2.0/librsvg/rsvg.h:53:7: note: 'rsvg_handle_get_type' declared here
GType rsvg_handle_get_type (void);
      ^
In file included from src/icon.c:239:30: error: expected ';' after expression
                RsvgRectangle viewport = {
                             ^
                             ;
src/icon.c:239:17: error: use of undeclared identifier 'RsvgRectangle'
                RsvgRectangle viewport = {
                ^
test/icon.c:1:
test/../src/icon.c:239:30: error: expected ';' after expression
                RsvgRectangle viewport = {
                             ^
                             ;
test/../src/icon.c:239:17: error: use of undeclared identifier 'RsvgRectangle'
                RsvgRectangle viewport = {
                ^
test/../src/icon.c:239:31: error: use of undeclared identifier 'viewport'
                RsvgRectangle viewport = {
                              ^
test/../src/icon.c:239:42: error: expected expression
                RsvgRectangle viewport = {
                                         ^
test/../src/icon.c:245:17: error: implicit declaration of function 'rsvg_handle_render_document' is invalid in C99 [-Werror,-Wimplicit-function-declaration]
                rsvg_handle_render_document(handle, cr, &viewport, &error);
                ^
src/icon.c:239:31: error: use of undeclared identifier 'viewport'
                RsvgRectangle viewport = {
                              ^
src/icon.c:239:42: error: expected expression
                RsvgRectangle viewport = {
                                         ^
src/icon.c:245:17: error: implicit declaration of function 'rsvg_handle_render_document' is invalid in C99 [-Werror,-Wimplicit-function-declaration]
                rsvg_handle_render_document(handle, cr, &viewport, &error);
                ^
clang -o dunstify dunstify.o -g -std=gnu11 -pedantic -Wall -Wno-overlength-strings -Os -Werror     -pthread -I/usr/include/gdk-pixbuf-2.0 -I/usr/include/libmount -I/usr/include/blkid -I/usr/include/uuid -I/usr/include/glib-2.0 -I/usr/lib/x86_64-linux-gnu/glib-2.0/include -lm -lrt  -lnotify -lgdk_pixbuf-2.0 -lgio-2.0 -lgobject-2.0 -lglib-2.0
src/icon.c:245:17: note: did you mean 'rsvg_handle_render_cairo'?
/usr/include/librsvg-2.0/librsvg/rsvg-cairo.h:37:13: note: 'rsvg_handle_render_cairo' declared here
gboolean    rsvg_handle_render_cairo     (RsvgHandle * handle, cairo_t * cr);
            ^
src/icon.c:245:58: error: use of undeclared identifier 'viewport'
                rsvg_handle_render_document(handle, cr, &viewport, &error);
                                                         ^
test/../src/icon.c:245:17: note: did you mean 'rsvg_handle_render_cairo'?
/usr/include/librsvg-2.0/librsvg/rsvg-cairo.h:37:13:7 errors generated.
 note: 'rsvg_handle_render_cairo' declared here
gboolean    rsvg_handle_render_cairo     (RsvgHandle * handle, cairo_t * cr);
            ^
In file included from test/icon.c:1:
test/../src/icon.c:245:58: error: use of undeclared identifier 'viewport'
                rsvg_handle_render_document(handle, cr, &viewport, &error);
                                                         ^
make: *** [Makefile:85: src/icon.o] Error 1
make: *** Waiting for unfinished jobs....
7 errors generated.
make: *** [Makefile:125: test/icon.o] Error 1

is this an old version of rsvg ? or an upstream bug? i never used the library myself so I can't tell at a glance