Bug 9190

Summary:	[PATCH] Cairo transform matrix reset in poppler_page_render
Product:	poppler	Reporter:	Daniel Colascione <danc>
Component:	cairo backend	Assignee:	poppler-bugs <poppler-bugs>
Status:	RESOLVED FIXED	QA Contact:
Severity:	major
Priority:	high
Version:	unspecified
Hardware:	All
OS:	Linux (All)
URL:	http://code.magicprints.com/poppler-render.patch
Whiteboard:
i915 platform:		i915 features:

Description Daniel Colascione 2006-11-28 18:21:06 UTC

cairo_scale and other cairo transformation functions have no effect on a
subsequent call to poppler_render_page, since the Cairo backend sets the
transform matrix instead of adding to it. Since poppler_render_page doesn't take
a scaling parameter, it is impossible to use it to render a PDF at anything
other than 72 DPI.

The simple referenced patch(in the URL field) makes CairoOutputDev not reset the
transform matrix, so
cairo_scale(cairo, dpi_x / 72.0, dpi_y / 72.0); poppler_page_render(...) will do
the correct thing.

Comment 1 Kouhei Sutou 2006-12-10 06:25:19 UTC

I want poppler to accept the patch too.

I want to make a PDF file which includes thumbnail image for each page of
original PDF. To do the thing, I wrote the following code:

columns = 3;
rows = 2;

for (i = 0; i < poppler_document_get_n_pages(doc); i ++) {
  cairo_save(cr);
  column = i % columns;
  row = i / columns;
  x = (width / columns) * column;
  y = (height / rows) * row;
  cairo_translate(x, y);
  cairo_scale(cr, 1.0 / columns, 1.0 / rows);
  poppler_page_render(poppler_document_get_page(doc, i), cr);
  cairo_restore(cr);
}

I wrote a patch and started to find similar bug. And I found this bug and filed
patch was same as mine.

I'm happy if the patch is applied.f

Comment 2 Jeff Muizelaar 2006-12-11 21:24:38 UTC

Thanks for the patch.
Fixed in cvs.

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