EXO中图标透明的小例子

/**
?* exo_gdk_pixbuf_lucent:
?* @source? : the source #GdkPixbuf.
?* @percent : the percentage of translucency.
?*
?* Returns a version of @source, whose pixels translucency is
?* @percent of the original @source pixels.
?*
?* The caller is responsible to free the returned object
?* using g_object_unref() when no longer needed.
?*
?* Returns: a translucent version of @source.
?*
?* Since: 0.3.1.3
?**/
GdkPixbuf*
exo_gdk_pixbuf_lucent (const GdkPixbuf *source,
?????????????????????? guint??????????? percent)
{
? GdkPixbuf *dst;
? guchar??? *dst_pixels;
? guchar??? *src_pixels;
? guchar??? *pixdst;
? guchar??? *pixsrc;
? gint?????? dst_row_stride;
? gint?????? src_row_stride;
? gint?????? width;
? gint?????? height;
? gint?????? i, j;

? g_return_val_if_fail (GDK_IS_PIXBUF (source), NULL);
? g_return_val_if_fail ((gint) percent >= 0 && percent <= 100, NULL);

? /* determine source parameters */
? width = gdk_pixbuf_get_width (source);
? height = gdk_pixbuf_get_height (source);

? /* allocate the destination pixbuf */
? dst = gdk_pixbuf_new (gdk_pixbuf_get_colorspace (source), TRUE, gdk_pixbuf_get_bits_per_sample (source), width, height);

? /* determine row strides on src/dst */
? dst_row_stride = gdk_pixbuf_get_rowstride (dst);
? src_row_stride = gdk_pixbuf_get_rowstride (source);

? /* determine pixels on src/dst */
? dst_pixels = gdk_pixbuf_get_pixels (dst);
? src_pixels = gdk_pixbuf_get_pixels (source);

? /* check if the source already contains an alpha channel */
? if (G_LIKELY (gdk_pixbuf_get_has_alpha (source)))
??? {
????? for (i = height; --i >= 0; )
??????? {
????????? pixdst = dst_pixels + i * dst_row_stride;
????????? pixsrc = src_pixels + i * src_row_stride;

????????? for (j = width; --j >= 0; )
??????????? {
????????????? *pixdst++ = *pixsrc++;
????????????? *pixdst++ = *pixsrc++;
????????????? *pixdst++ = *pixsrc++;
????????????? *pixdst++ = ((guint) *pixsrc++ * percent) / 100u;
??????????? }
??????? }
??? }
? else
??? {
????? /* pre-calculate the alpha value */
????? percent = (255u * percent) / 100u;

????? for (i = height; --i >= 0; )
??????? {
????????? pixdst = dst_pixels + i * dst_row_stride;
????????? pixsrc = src_pixels + i * src_row_stride;

????????? for (j = width; --j >= 0; )
??????????? {
????????????? *pixdst++ = *pixsrc++;
????????????? *pixdst++ = *pixsrc++;
????????????? *pixdst++ = *pixsrc++;
????????????? *pixdst++ = percent;
??????????? }
??????? }
??? }

? return dst;
}