From 318ef6fa612b610b83f763a67588af1283692ab8 Mon Sep 17 00:00:00 2001
From: Carlos Garcia Campos <carlosgc@gnome.org>
Date: Sun, 29 Nov 2009 15:34:40 +0100
Subject: [PATCH] [libdocument] Add a function to invert colors of an image
cairo surface
See bgo#321823.
---
libdocument/ev-document-misc.c | 38 ++++++++++++++++++++++++++++++++++
libdocument/ev-document-misc.h | 1 +
2 files changed, 39 insertions(+)
diff --git a/libdocument/ev-document-misc.c b/libdocument/ev-document-misc.c
index ced1ca11..14bc3a35 100644
--- a/libdocument/ev-document-misc.c
+++ b/libdocument/ev-document-misc.c
@@ -296,6 +296,44 @@ ev_document_misc_surface_rotate_and_scale (cairo_surface_t *surface,
return new_surface;
}
+void
+ev_document_misc_invert_surface (cairo_surface_t *surface) {
+#if CAIRO_VERSION > CAIRO_VERSION_ENCODE(1, 9, 2)
+ cairo_t *cr;
+
+ cr = cairo_create (surface);
+
+ /* white + DIFFERENCE -> invert */
+ cairo_set_operator (cr, CAIRO_OPERATOR_DIFFERENCE);
+ cairo_set_source_rgb (cr, 1., 1., 1.);
+ cairo_paint(cr);
+ cairo_destroy (cr);
+#else
+ guchar *data;
+ gint rowstride;
+ gint width, height;
+ gint x, y;
+
+ data = cairo_image_surface_get_data (surface);
+ rowstride = cairo_image_surface_get_stride (surface);
+ width = cairo_image_surface_get_width (surface);
+ height = cairo_image_surface_get_height (surface);
+
+ for (y = 0; y < height; y++) {
+ guchar *p = data + y * rowstride;
+
+ for (x = 0; x < width; x++) {
+ p[0] = 255 - p[0];
+ p[1] = 255 - p[1];
+ p[2] = 255 - p[2];
+ p += 4;
+ }
+ }
+
+ cairo_surface_mark_dirty (surface);
+#endif
+}
+
void
ev_document_misc_invert_pixbuf (GdkPixbuf *pixbuf)
{
diff --git a/libdocument/ev-document-misc.h b/libdocument/ev-document-misc.h
index 47e3c417..8e929836 100644
--- a/libdocument/ev-document-misc.h
+++ b/libdocument/ev-document-misc.h
@@ -51,6 +51,7 @@ cairo_surface_t *ev_document_misc_surface_rotate_and_scale (cairo_surface_t *sur
gint dest_width,
gint dest_height,
gint dest_rotation);
+void ev_document_misc_invert_surface (cairo_surface_t *surface);
void ev_document_misc_invert_pixbuf (GdkPixbuf *pixbuf);
G_END_DECLS
--
2.47.1