how to get rid of padding around Gtk.Image in Gtk.Box / Gtk.Grid in gtk4?

Question

I'm trying to write a simple GUI using Gtk4 (in Python), but I'm having trouble with getting rid of padding (and I don't understand why the padding is there).

The goal is pretty simple - I need a Gtk.Grid showing a bunch of images with some basic metadata. AFAICS a good way to do that is Window -> ScrollWindow -> Grid -> Box -> (Image + Label). And in general this works, except that the images have a lot of top/bottom padding, so the labels have a lot of empty space around, which I don't like but can't get rid of it :-(

See this screenshot

Here's a simple example demonstrating this:

import gi
import sys

gi.require_version('Gtk', '4.0')

from gi.repository import Gtk, GdkPixbuf


def create_image(file_name, img_width, cssProvider = None):

    info = 'file:' + file_name

    box = Gtk.Box(orientation=Gtk.Orientation.VERTICAL)

    # box.get_style_context().add_provider(cssProvider, Gtk.STYLE_PROVIDER_PRIORITY_USER)
    # box.add_css_class('thumbnail')

    box.set_hexpand(True)

    # add image to top
    pixbuf = GdkPixbuf.Pixbuf.new_from_file(file_name)

    # calculate height to keep width and aspect ratio
    img_height = pixbuf.get_height() * img_width / pixbuf.get_width()

    image = Gtk.Image.new_from_pixbuf(pixbuf)
    image.set_size_request(img_height, img_width)

    # image.get_style_context().add_provider(cssProvider, Gtk.STYLE_PROVIDER_PRIORITY_USER)
    # image.add_css_class('thumbnail-image')

    box.append(image)

    # add label to bottom
    label = Gtk.Label(label=info)

    # label.get_style_context().add_provider(cssProvider, Gtk.STYLE_PROVIDER_PRIORITY_USER)
    # label.add_css_class('thumbnail-label')

    box.append(label)

    return box


class MainWindow(Gtk.ApplicationWindow):

    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)

        self.cssProvider = None
#       self.cssProvider = Gtk.CssProvider()
#       self.cssProvider.load_from_data(b"""
#.thumbnail {background-color: white; color: black; border: 1px solid #ddd; margin: 5px; padding: 0; }
#.thumbnail-label { font-size: 12pt; margin: 0; padding: 0; }
#.thumbnail-image { margin: 0; padding: 0; }
#.green { background-color: #bfb; }""")

        self.set_default_size(900, 600)
        self.set_title("MyApp")

        self.grid = Gtk.Grid()

        self.window = Gtk.ScrolledWindow()
        self.window.set_child(self.grid)

        self.set_child(self.window)

        idx = 0
        prev = None

        for idx in range(0,20):
            # 4 columns
            i = int(idx / 4)
            j = int(idx % 4)

            image = create_image('frog.jpg', 1920/4 - 10, self.cssProvider)

            self.grid.attach(image, j, i, 1, 1)


class MyApp(Gtk.Application):
    def __init__(self, **kwargs):
        super().__init__(**kwargs)
        self.connect('activate', self.on_activate)
    
    def on_activate(self, app):
        self.win = MainWindow(application=app)
        self.win.present()

app = MyApp(application_id="com.example.GtkApplication")
app.run(sys.argv)

This needs an image called 'frog.jpg', e.g. this one.

The sizes are meant to work on 1920x1080, with 4 columns. I'm sure it could be done more dynamic (i.e. to work better with resized windows etc.), but I believe that's a separate issue.

I've tried a bunch of things, including styling using CSS, etc. (which is commented-out in the sample).

I also experimented with setting hexpand/vexpand on different widgets, not adding the label, and various similar things.

I've tried to build the interface in a visual tool (instead of building it by hand).In Glade it works pretty much exactly the way I wanted (images are maximal size), but Glade supports only GTK3 and I planned to use GTK4. For GTK4 the only tool I found is Cambalache (flathub.org/apps/details/ar.xjuan.Cambalache) and that seems to always produce a layout with the empty space. So perhaps this is something that changed between GTK3 and GTK4? However, Cambalache seems to be somewhat new/quirky and harder to use than Glade, so maybe it just sets some properties differently. — TomasV
– TomasV, Commented Dec 2, 2022 at 16:50

TomasV · Accepted Answer · 2022-12-05 11:59:56Z

1

Apparently using Gtk.Picture instead of Gtk.Image solves the issue - with Picture there's no unwanted empty space/padding. Seems a bit confusing, considering Picture/Image are often used as synonyms. Maybe it's in the gtk docs somewhere, but I don't see it - certainly not without reading between the lines. I see some discussion of "natural size" but I don't see how'd that imply this behavior. Anyway, if others face the same issue, try using Gtk.Picture.

answered Dec 5, 2022 at 11:59

TomasV

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1 Comment

J-L Over a year ago

Thanks for this "self answer" I was trying to solve a similar problem and using Gtk.Picture worked for me! I'm making a grid of thumbnail that when clicked will play a video so my design is a bit similar but I'm using ScrolledWindow -> flowbox. You might want to look at flowbox I think its better suited to automatically adjust to different screen sizes

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