Enhance the -dpreview method for SVG output (issue 326960043 by address@hidden)

[pkx166h]

Reviewers: ,

Message:
Please note that *i* did the commit message - trying to interpret what
Etienne is trying to achieve, so if this is completely non-sensical,
blame me not him :)

Etienne knows this is a first 'draft' and sent me an email to say so,
any guidance would be appreciated:

---

From: Étienne Beaulé <address@hidden>
To: James <address@hidden>
Subject: Re: [Feature Request]: More flexible SVG snippet cropping
Date: Wed, 26 Jul 2017 20:24:41 -0300

I tried making a simple patch, but doesn't work. It's attached. I
wouldn't
know how, but if something like the "stack-stencils Y DOWN 0.0" section
from the output-preview-framework could be passed from output-framework
to
dump-page and there's a if statement for svg-begin for the -dcrop
option.
Guidance?

All the best
Étienne

Description:
Enhance the -dpreview method for SVG output

Issue 5165

Using SVG, the -dpreview option
has a limitation of only
outputting the first line.

This is a first attempt to merge the
dump-page and dump-preview methods
so that there is an option for
cropping pages that are not just
previews.

Please review this at https://codereview.appspot.com/326960043/

Affected files (+79, -0 lines):
  M Documentation/usage/running.itely
  M lily/paper-book.cc
  M scm/framework-svg.scm
  M scm/lily.scm


Index: Documentation/usage/running.itely
diff --git a/Documentation/usage/running.itely  
b/Documentation/usage/running.itely
index  
5ab8e1f37045abd4c4c4887c3b59a7a992a28a9d..b0c7ad2aa155f44877b14656505b98b2fdbb526f  
100644
--- a/Documentation/usage/running.itely
+++ b/Documentation/usage/running.itely
@@ -677,6 +677,10 @@ See @ref{Point and click}.
 @item @code{preview}
 @tab @code{#f}
 @tab Create preview images in addition to normal output.
+
address@hidden @code{crop}
address@hidden @code{#f}
address@hidden Match the size of the normal output to the typeset image for 
SVGs.
 @end multitable

 @noindent
Index: lily/paper-book.cc
diff --git a/lily/paper-book.cc b/lily/paper-book.cc
index  
c17ed576f1895c0a91febb29164ea9987dda1b0f..f1787e99550f2bb09eb001188b69384c69e5f004  
100644
--- a/lily/paper-book.cc
+++ b/lily/paper-book.cc
@@ -219,6 +219,25 @@ Paper_book::output (SCM output_channel)
         warning (_f ("program option -dpreview not supported by backend  
`%s'",
                      get_output_backend_name ()));
     }
+
+  if (get_program_option ("crop"))
+    {
+      SCM framework
+        = ly_module_lookup (mod, ly_symbol2scm ("output-crop-framework"));
+
+      if (scm_is_true (framework))
+        {
+          SCM func = scm_variable_ref (framework);
+          scm_call_4 (func,
+                      output_channel,
+                      self_scm (),
+                      scopes,
+                      dump_fields ());
+        }
+      else
+        warning (_f ("program option -dcrop not supported by backend `%s'",
+                     get_output_backend_name ()));
+    }
 }

 void
Index: scm/framework-svg.scm
diff --git a/scm/framework-svg.scm b/scm/framework-svg.scm
index  
a4cf2e996055305dbeb36730dc78247b0a1016a4..729f7ad1898451731f72c0967dc784c140a67499  
100644
--- a/scm/framework-svg.scm
+++ b/scm/framework-svg.scm
@@ -170,6 +170,37 @@ src: url('~a');
     (dump (svg-end))
     (ly:outputter-close outputter)))

+(define (dump-page-crop paper filename page page-number page-count stensil)
+  (let* ((outputter (ly:make-paper-outputter (open-file  
filename "wb") 'svg))
+         (dump (lambda (str) (display str (ly:outputter-port outputter))))
+         (lookup (lambda (x) (ly:output-def-lookup paper x)))
+         (unit-length (lookup 'output-scale))
+         (x-extent (ly:stencil-extent stencil X))
+         (y-extent (ly:stencil-extent stencil Y))
+         (left-x (car x-extent))
+         (top-y (cdr y-extent))
+         (device-width (interval-length x-extent))
+         (device-height (interval-length y-extent))
+         (output-scale (* lily-unit->mm-factor unit-length))
+         (svg-width (* output-scale device-width))
+         (svg-height (* output-scale device-height)))
+
+    (if (ly:get-option 'svg-woff)
+        (module-define! (ly:outputter-module outputter) 'paper paper))
+    (dump (svg-begin svg-width svg-height
+                     left-x (- top-y) device-width device-height))
+    (if (ly:get-option 'svg-woff)
+        (module-remove! (ly:outputter-module outputter) 'paper))
+    (if (ly:get-option 'svg-woff)
+        (dump (woff-header paper (dirname filename))))
+    (dump (comment (format #f "Page: ~S/~S" page-number page-count)))
+    (ly:outputter-output-scheme outputter
+                                `(begin (set!  
lily-unit-length ,unit-length)
+                                        ""))
+    (ly:outputter-dump-stencil outputter page)
+    (dump (svg-end))
+    (ly:outputter-close outputter)))
+

 (define (output-framework basename book scopes fields)
   (let* ((paper (ly:paper-book-paper book))
@@ -197,3 +228,25 @@ src: url('~a');
                                   (map paper-system-stencil
                                        (reverse to-dump-systems)))
                   (format #f "~a.preview.svg" basename))))
+
+(define (output-crop-framework basename book scopes fields)
+  (let* ((paper (ly:paper-book-paper book))
+       (systems (relevant-book-systems book))
+       (to-dump-systems (relevant-book-systems systems))
+       (page-stencils (map page-stencil (ly:paper-book-pages book)))
+       (page-number (1- (ly:output-def-lookup paper 'first-page-number)))
+       (page-count (length page-stencils))
+       (filename "")
+       (file-suffix (lambda (num)
+                      (if (= page-count 1) "" (format #f "-crop-page-~a"  
num)))))
+  (for-each
+   (lambda (page)
+     (set! page-number (1+ page-number))
+     (set! filename (format #f "~a~a.svg"
+                            basename
+                            (file-suffix page-number)))
+     (dump-page-crop paper filename page page-number page-count
+       (stack-stencils Y DOWN 0.0
+                       (map paper-system-stencil
+                            (reverse to-dump-systems)))))
+   page-stencils)))
Index: scm/lily.scm
diff --git a/scm/lily.scm b/scm/lily.scm
index  
4b3c9c7e1c4cad55c64a53fe611d1effcf692612..ff0cb0e0acf15808d3dab7006d681fa734837770  
100644
--- a/scm/lily.scm
+++ b/scm/lily.scm
@@ -338,6 +338,9 @@ to a music font.")
     (preview
      #f
      "Create preview images also.")
+    (crop
+     #f
+     "Match the size of the output to the image.")
     (print-pages
      #t
      "Print pages in the normal way.")