Import Ghostscript 9.52ghostscript-9.52

Signed-off-by: Thomas Deutschmann <whissi@gentoo.org>

1 files changed, 56 insertions, 5 deletions

diff --git a/doc/Language.htm b/doc/Language.htm
index 0b35e236..15f39e37 100644
--- a/doc/Language.htm
+++ b/doc/Language.htm
@@ -438,8 +438,15 @@ The garbage collector doesn't reclaim portions of arrays obtained with
 
 <h3><a name="Graphics_and_text"></a>Graphics and text operators</h3>
 
-<h4><a name="Transparency"></a>Transparency</h4>
-
+<h4><u><a name="Transparency"></a>Transparency</u></h4>
+<p><b><u>NOTE:</u></b> The following paragraphs describe non-standard operators
+for accessing the PDF 1.4 and later transparent imaging model through Postscript.
+If used incorrectly, they can have unexpected side effects and result in undefined
+behavior. As a result, these operators are disabled when <a href="Use.htm#Safer"><b>SAFER</b></a>
+is in force (as it is by default from version 9.50 onwards). To utilise these operators
+you will either have to disable <code>SAFER</code> (<code>-dNOSAFER</code>) or use
+the command line parameter <code>-dALLOWPSTRANSPARENCY</code>. The latter will make
+the custom operators available, but leave the file access controls active.
 <p>
 Ghostscript provides a set of operators for implementing the transparency
 and compositing facilities of PDF 1.4.  These are defined only if the
@@ -456,10 +463,34 @@ Ghostscript's model generalizes that of PDF 1.4 in that Ghostscript
 maintains separate alpha and mask values for opacity and shape, rather than
 a single value with a Boolean that says whether it represents opacity or
 shape.</p>
+<p>
+What follows is a subset of all the custom operators related to transparency, but
+covers the most useful, most common requirements.
+</p>
 
 <h5><a name="Transparency_graphics_state_operators"></a>Graphics state
 operators</h5>
 
+<p>Pushing the compositor device must be done before any other marking
+operations are made on the current page, and must be done per page.
+Popping the compositor should be done after the last marking operation
+of the page, and before the call to <code>showpage</code>. Any marking
+operations made after the compositor is popped will bypass the transparent
+imaging model, and may produce unexpected output.
+
+<dl>
+<dt><code>&lt;depth&gt; .pushpdf14devicefilter -</code></dt>
+<dd>Installs the transparency compositor device into the graphics state. At
+present the <code>depth</code> parameter should always be zero (<b>Subject
+To Change.</b>)
+</dl>
+<dl>
+<dt><code>- .popdf14devicefilter -</code></dt>
+<dd>Removes (or, more accuracately, disables) the transparency compositor in
+graphics state.
+</dl>
+
+
 <dl>
 <dt><code>&lt;modename&gt; .setblendmode -</code></dt>
 <dd>Sets the blending mode in the graphics state.  If the mode name is not
@@ -468,23 +499,43 @@ the blending mode is <code>/Compatible</code>.</dd>
 </dl>
 
 <dl>
+<dt><code>- .currentblendmode &lt;modename&gt;</code></dt>
+<dd>Returns the graphics state blend mode on the stack.
+</dl>
+
+<dl>
 <dt><code>&lt;0..1&gt; .setopacityalpha -</code></dt>
 <dd>Sets the opacity alpha value in the graphics state.
 The initial opacity alpha value is 1.</dd>
 </dl>
 
 <dl>
+<dt><code>- .currentopacityalpha &lt;0..1&gt;</code></dt>
+<dd>Returns the graphics state opacity alpha on the stack.</dd>
+</dl>
+
+<dl>
 <dt><code>&lt;0..1&gt; .setshapealpha -</code></dt>
 <dd>Sets the shape alpha value in the graphics state.
 The initial shape alpha value is 1.</dd>
 </dl>
 
 <dl>
+<dt><code>- .currentshapealpha &lt;0..1&gt;</code></dt>
+<dd>Returns the graphics state shape alpha on the stack.</dd>
+</dl>
+
+<dl>
 <dt><code>&lt;bool&gt; .settextknockout -</code></dt>
 <dd>Sets the text knockout flag in the graphics state.
 The initial value of the text knockout flag is <code>true</code>.</dd>
 </dl>
 
+<dl>
+<dt><code>- .currenttextknockout &lt;bool&gt;</code></dt>
+<dd>Returns the graphics state text knockout on the stack..</dd>
+</dl>
+
 <h5><a name="Transparency_rendering_stack_operators"></a>Rendering stack
 operators</h5>
 
@@ -496,7 +547,7 @@ accumulate only a coverage value.  Layers must be properly nested, i.e., the
 'end' or 'discard' operator must match the corresponding 'begin' operator.</p>
 
 <p>
-Beginning and ending layers must nest properly with respect to
+Beginning and ending groups must nest properly with respect to
 <code>save</code> and <code>restore</code>: <code>save</code> and
 <code>restore</code> do not save and restore the layer stack.  Currently,
 layers are not required to nest with respect to <code>gsave</code> and
@@ -1969,12 +2020,12 @@ implied.
 
 This software is distributed under license and may not be copied, modified
 or distributed except as expressly authorized under the terms of that
-license.  Refer to licensing information at http://www.artifex.com/
+license.  Refer to licensing information at <a href="https://www.artifex.com">https://www.artifex.com</a>
 or contact Artifex Software, Inc.,  1305 Grant Avenue - Suite 200,
 Novato, CA 94945, U.S.A., +1(415)492-9861, for further information.
 
 <p>
-<small>Ghostscript version 9.50, 15 October 2019
+<small>Ghostscript version 9.52, 19 March 2020
 
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