Attachment 50481 Details for Bug 4536 – set minimum line width to 1

[patch] set minimum line width to 1

0001-cairo-fix-stroking-of-very-thin-lines.patch (text/plain), 2.70 KB, created by Adrian Johnson on 2011-08-23 04:52:24 UTC

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Creator: Adrian Johnson

Created: 2011-08-23 04:52:24 UTC

Size: 2.70 KB

patch

obsolete

>From 223e7458d7ccb95ef9bad3884b9841cbc260d295 Mon Sep 17 00:00:00 2001
>From: Adrian Johnson <ajohnson@redneon.com>
>Date: Tue, 23 Aug 2011 20:46:24 +0930
>Subject: [PATCH 1/2] cairo: fix stroking of very thin lines
>
>Lines with a width less than 1.0 are almost invisible in cairo output
>due to antialising. The PDF standard states that when the Stroke
>Adjust graphics parameter is true, all lines must be at least one pixel wide.
>
>Add a stroke_adjust flag to the CairoOuputDev. Like splash, use the
>globalParam strokeAdjust setting (which defaults to true) to
>initialize the flag and ignore the Stroke Adjust settng in PDF
>files. This emulates Acrobat behavior.
>
>When stroke_adjust is true, find the line width in device pixels and
>if less than 0.5 set the line width to 0.5 device pixels. The value
>0.5 pixels seems to make horizontal and vertical lines look better
>because integer aligned 1.0 wide lines in cairo are rendered two
>pixels wide which looks too fat.
>---
> poppler/CairoOutputDev.cc |   20 +++++++++++++++++++-
> poppler/CairoOutputDev.h  |    1 +
> 2 files changed, 20 insertions(+), 1 deletions(-)
>
>diff --git a/poppler/CairoOutputDev.cc b/poppler/CairoOutputDev.cc
>index 968788e..272ae55 100644
>--- a/poppler/CairoOutputDev.cc
>+++ b/poppler/CairoOutputDev.cc
>@@ -153,6 +153,10 @@ CairoOutputDev::CairoOutputDev() {
> 
>   text = NULL;
>   actualText = NULL;
>+
>+  // the SA parameter supposedly defaults to false, but Acrobat
>+  // apparently hardwires it to true
>+  stroke_adjust = globalParams->getStrokeAdjust();
> }
> 
> CairoOutputDev::~CairoOutputDev() {
>@@ -420,7 +424,21 @@ void CairoOutputDev::updateLineWidth(GfxState *state) {
>     cairo_device_to_user_distance(cairo, &x, &y);
>     cairo_set_line_width (cairo, MIN(fabs(x),fabs(y)));
>   } else {
>-    cairo_set_line_width (cairo, state->getLineWidth());
>+    double width = state->getLineWidth();
>+    if (stroke_adjust && !printing) {
>+      double x, y;
>+      x = y = width;
>+
>+      /* find out line width in device units */
>+      cairo_user_to_device_distance(cairo, &x, &y);
>+      if (x < 0.5 && y < 0.5) {
>+	/* adjust width to at least one device pixel */
>+	x = y = 0.5;
>+	cairo_device_to_user_distance(cairo, &x, &y);
>+	width = MIN(fabs(x),fabs(y));
>+      }
>+    }
>+    cairo_set_line_width (cairo, width);
>   }
>   if (cairo_shape)
>     cairo_set_line_width (cairo_shape, cairo_get_line_width (cairo));
>diff --git a/poppler/CairoOutputDev.h b/poppler/CairoOutputDev.h
>index ca64ad5..7cf4157 100644
>--- a/poppler/CairoOutputDev.h
>+++ b/poppler/CairoOutputDev.h
>@@ -287,6 +287,7 @@ protected:
>   cairo_pattern_t *fill_pattern, *stroke_pattern;
>   double fill_opacity;
>   double stroke_opacity;
>+  GBool stroke_adjust;
>   CairoFont *currentFont;
> 
>   struct StrokePathClip {
>-- 
>1.7.4.1
>

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