img: Add back support for SVG images, bypassing ImageMagick and simply passing the SVG through to the browser

SVG scaling by img directives has subtly changed; where before size=wxh
would preserve aspect ratio, this cannot be done when passing them through
and so specifying both a width and height can change the SVG's aspect
ratio.

(This patch looks significantly more complex than it was, because a large
block of code had to be indented.)

[smcv: drop trailing whitespace, fix some spelling]

IkiWiki/Plugin/img.pm

@@ -23,8 +23,8 @@ sub getsetup () {
 		},
 		img_allowed_formats => {
 			type => "string",
-			default => [qw(jpeg png gif)],
+			default => [qw(jpeg png gif svg)],
-			description => "Image formats to process (jpeg, png, gif, pdf, svg or 'everything' to accept all)",
+			description => "Image formats to process (jpeg, png, gif, svg, pdf or 'everything' to accept all)",
 			# ImageMagick has had arbitrary code execution flaws,
 			# and the whole delegates mechanism is scary from
 			# that perspective
@@ -36,7 +36,7 @@ sub getsetup () {
 sub allowed {
 	my $format = shift;
 	my $allowed = $config{img_allowed_formats};
-	$allowed = ['jpeg', 'png'] unless defined $allowed && @$allowed;
+	$allowed = ['jpeg', 'png', 'gif', 'svg'] unless defined $allowed && @$allowed;
 
 	foreach my $a (@$allowed) {
 		return 1 if $a eq $format || $a eq 'everything';
@@ -131,17 +131,7 @@ sub preprocess (@) {
 	error sprintf(gettext("%s image processing disabled in img_allowed_formats configuration"), $format ? $format : "\"$extension\"") unless allowed($format ? $format : "everything");
 
 	# Try harder to protect ImageMagick from itself
-	if ($format eq 'svg') {
+	if (defined $magic) {
-		my $content;
-		read($in, $content, 5) or error sprintf(gettext("failed to read %s: %s"), $file, $!);
-		# This is an over-simplification, but ?xml is the check that
-		# ImageMagick uses. We also accept <svg for the simplest
-		# possible SVGs.
-		if ($content !~ m/^(.\?xml|<svg)/is) {
-			error sprintf(gettext("\"%s\" does not seem to be a valid %s file"), $file, $format);
-		}
-	}
-	elsif ($magic) {
 		my $content;
 		read($in, $content, length $magic) or error sprintf(gettext("failed to read %s: %s"), $file, $!);
 		if ($magic ne $content) {
@@ -149,18 +139,38 @@ sub preprocess (@) {
 		}
 	}
 
-	my $issvg = $base=~s/\.svg$/.png/i;
 	my $ispdf = $base=~s/\.pdf$/.png/i;
 	my $pagenumber = exists($params{pagenumber}) ? int($params{pagenumber}) : 0;
 	if ($pagenumber != 0) {
 		$base = "p$pagenumber-$base";
 	}
 
+	my $imglink;
+	my $imgdatalink;
+	my ($dwidth, $dheight);
+
+	my ($w, $h);
+	if ($params{size} ne 'full') {
+		($w, $h) = ($params{size} =~ /^(\d*)x(\d*)$/);
+	}
+
+	if ($format eq 'svg') {
+		# svg images are not scaled using ImageMagick because the
+		# pipeline is complex. Instead, the image size is simply
+		# set to the provided values.
+		#
+		# Aspect ratio will be preserved automatically when
+		# only a width or only a height is specified.
+		# When both are specified, aspect ratio will not be
+		# preserved.
+		$imglink = $file;
+		$dwidth = $w if length $w;
+		$dheight = $h if length $h;
+	}
+	else {
 		eval q{use Image::Magick};
 		error gettext("Image::Magick is not installed") if $@;
 		my $im = Image::Magick->new();
-	my $imglink;
-	my $imgdatalink;
 		my $r = $im->Read("$format:$srcfile\[$pagenumber]");
 		error sprintf(gettext("failed to read %s: %s"), $file, $r) if $r;
 
@@ -168,13 +178,10 @@ sub preprocess (@) {
 			error sprintf(gettext("failed to get dimensions of %s"), $file);
 		}
 
-	my ($dwidth, $dheight);
+		if (! length $w && ! length $h) {
-
-	if ($params{size} eq 'full') {
 			$dwidth = $im->Get("width");
 			$dheight = $im->Get("height");
 		} else {
-		my ($w, $h) = ($params{size} =~ /^(\d*)x(\d*)$/);
 			error sprintf(gettext('wrong size format "%s" (should be WxH)'), $params{size})
 				unless (defined $w && defined $h &&
 				        (length $w || length $h));
@@ -213,7 +220,7 @@ sub preprocess (@) {
 				$r = $im->Resize(geometry => "${dwidth}x${dheight}");
 				error sprintf(gettext("failed to resize: %s"), $r) if $r;
 
-			$im->set(($issvg || $ispdf) ? (magick => 'png') : ());
+				$im->set($ispdf ? (magick => 'png') : ());
 				my @blob = $im->ImageToBlob();
 				# don't actually write resized file in preview mode;
 				# rely on width and height settings
@@ -238,6 +245,7 @@ sub preprocess (@) {
 		if (! defined($dwidth) || ! defined($dheight)) {
 			error sprintf(gettext("failed to determine size of image %s"), $file)
 		}
+	}
 
 	my ($fileurl, $imgurl);
 	my $urltobase = $params{preview} ? undef : $params{destpage};
@@ -255,10 +263,10 @@ sub preprocess (@) {
 		}
 	}
 	
-	my $imgtag='<img src="'.$imgurl.
+	my $imgtag='<img src="'.$imgurl.'"';
-		'" width="'.$dwidth.
+	$imgtag.=' width="'.$dwidth.'"' if defined $dwidth;
-		'" height="'.$dheight.'"'.
+	$imgtag.=' height="'.$dheight.'"' if defined $dheight;
-		$attrs.
+	$imgtag.= $attrs.
 		(exists $params{align} && ! exists $params{caption} ? ' align="'.$params{align}.'"' : '').
 		' />';
 

debian/changelog

@@ -16,6 +16,13 @@ ikiwiki (3.20160122) UNRELEASED; urgency=medium
   * d/control: add Vcs-Browser
 
   [ Joey Hess ]
+  * img: Add back support for SVG images, bypassing ImageMagick and
+    simply passing the SVG through to the browser, which is supported by all
+    commonly used browsers these days.
+    SVG scaling by img directives has subtly changed; where before
+    size=wxh would preserve aspect ratio, this cannot be done when passing
+    them through and so specifying both a width and height can change
+    the SVG's aspect ratio.
   * loginselector: When only openid and emailauth are enabled, but
     passwordauth is not, avoid showing a "Other" box which opens an
     empty form.

doc/ikiwiki/directive/img.mdwn

@@ -12,11 +12,13 @@ providing a link to a full-size version.
 The image file will be searched for using the same rules as used to find
 the file pointed to by a [[ikiwiki/WikiLink]].
 
-The `size` parameter is optional, defaulting to full size. Note that the
+The `size` parameter is optional, defaulting to full size.
-original image's aspect ratio is always preserved, even if this means
+You can specify only the width or the height, and the other value will
-making the image smaller than the specified size. You can also specify only
+be calculated based on it: "200x", "x200".
-the width or the height, and the other value will be calculated based on
+
-it: "200x", "x200"
+If you specify both the width and height, the original image's aspect
+ratio will be preserved, even if this means making the image smaller
+than the specified size. (However, this is not done for svg images.)
 
 You can also pass `alt`, `title`, `class`, `align`, `id`, `hspace`, and
 `vspace` parameters.