Commit 085a27d3 authored by Havoc Pennington's avatar Havoc Pennington Committed by Havoc Pennington
Browse files

In docs, explain what a dither offset is for.

1999-11-04  Havoc Pennington  <hp@pobox.com>

* src/gdk-pixbuf-render.c (gdk_pixbuf_render_to_drawable): In
docs, explain what a dither offset is for.
(gdk_pixbuf_render_to_drawable_alpha): Explain why you would use
this function vs. gdk_pixbuf_render_to_drawable().
parent 38abc0de
1999-11-04 Havoc Pennington <hp@pobox.com>
* src/gdk-pixbuf-render.c (gdk_pixbuf_render_to_drawable): In
docs, explain what a dither offset is for.
(gdk_pixbuf_render_to_drawable_alpha): Explain why you would use
this function vs. gdk_pixbuf_render_to_drawable().
1999-11-04 Havoc Pennington <hp@pobox.com>
* configure.in: Use libart-config correctly; find gnome-config
......
......@@ -43,6 +43,7 @@
* Takes the opacity values in a rectangular portion of a pixbuf and thresholds
* them to produce a bi-level alpha mask that can be used as a clipping mask for
* a drawable.
*
**/
void
gdk_pixbuf_render_threshold_alpha (GdkPixbuf *pixbuf, GdkBitmap *bitmap,
......@@ -174,6 +175,11 @@ remove_alpha (ArtPixBuf *apb, int x, int y, int width, int height, int *rowstrid
* the GdkRGB visual and colormap. Note that this function will ignore the
* opacity information for images with an alpha channel; the GC must already
* have the clipping mask set if you want transparent regions to show through.
*
* For an explanation of dither offsets, see the GdkRGB documentation. In brief, the
* dither offset is important when scrolling (so you can redraw half an image but keep the
* dithering "lined up" between the part you drew first and the part you drew previously).
* For unscrolled images, the offset can always be 0.
**/
void
gdk_pixbuf_render_to_drawable (GdkPixbuf *pixbuf,
......@@ -247,6 +253,13 @@ gdk_pixbuf_render_to_drawable (GdkPixbuf *pixbuf,
*
* Renders a rectangular portion of a pixbuf to a drawable. This is done using
* GdkRGB, so the specified drawable must have the GdkRGB visual and colormap.
*
* This function has a performance penalty; it makes two synchronous
* round trips to the X server (creating a bitmask and a GC), and it
* draws the contents of the bitmask. If performance is crucial,
* consider handling alpha yourself and using
* gdk_pixbuf_render_to_drawable(). On the other hand it's more convenient
* than gdk_pixbuf_render_to_drawable() because it handles the alpha channel.
**/
void
gdk_pixbuf_render_to_drawable_alpha (GdkPixbuf *pixbuf, GdkDrawable *drawable,
......
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