--- Begin Message ---
- To: Debian Bug Tracking System <submit@bugs.debian.org>
- Subject: g3data: fails to correctly refresh images with transparency
- From: "Francesco Poli \(t1000\)" <frx@firenze.linux.it>
- Date: Mon, 18 May 2009 22:44:38 +0200
- Message-id: <20090518204438.6056.51142.reportbug@homebrew>
Package: g3data
Version: 1:1.5.1-1
Severity: normal
Hi!
I noticed a problem with how g3data handles images with transparent
pixels (such as PNG images using the alpha channel).
If you try to load such an image with a transparent background:
$ g3data transp-bg-image.png
the image is shown on a gray area and thus its transparent
background looks gray.
I am not sure if the gray color depends on the window manager
theme: if this is the case, it may be an issue with some themes
which may result in unreadable plots...
But anyway, the problem I am experiencing is another one:
as soon as I move the mouse over the image, the zoom area begins to
show the enlarged view of the mouse cross neighborhood in a messed
up way, with all plot lines drawn over each other.
I think this bug is caused by the refreshing strategy used by g3data:
it probably draws the updated zoom view *over* the previous one,
*without* first blanking the zoom area! This obviously works fine,
as long as there are no transparent pixels; but an image with
transparent background will fail to refresh properly, unless the
area is blanked before the repainting occurs.
The same refreshing strategy seems to be used on the main area, with
the loaded image: after laying some points down, I click on the
"Remove all points" button; the previously layed down points are
still visible on the transparent background, even though they appear
as if they were *under* the non-transparent plot lines.
This is confusing at best.
In summary, the zoom area is mostly unusable when dealing with
images having a transparent background. Moreover, understanding
which points are still present and which were effectively removed
is almost impossible, when dealing with transparent background images.
I think a refresh strategy with explicit blanking should be implemented
in order to avoid such issues.
Please forward this bug report to upstream, if appropriate.
Thanks in advance.
-- System Information:
Debian Release: squeeze/sid
APT prefers testing
APT policy: (800, 'testing'), (500, 'unstable')
Architecture: amd64 (x86_64)
Kernel: Linux 2.6.26-2-amd64 (SMP w/2 CPU cores)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/bash
Versions of packages g3data depends on:
ii libatk1.0-0 1.24.0-2 The ATK accessibility toolkit
ii libc6 2.9-4 GNU C Library: Shared libraries
ii libcairo2 1.8.6-2+b1 The Cairo 2D vector graphics libra
ii libfontconfig1 2.6.0-3 generic font configuration library
ii libfreetype6 2.3.9-4.1 FreeType 2 font engine, shared lib
ii libglib2.0-0 2.20.0-2 The GLib library of C routines
ii libgtk2.0-0 2.16.1-2 The GTK+ graphical user interface
ii libpango1.0-0 1.24.0-3+b1 Layout and rendering of internatio
g3data recommends no packages.
g3data suggests no packages.
-- no debconf information
--- End Message ---