Add background chooser text box

osu.Game/Screens/Edit/Setup/SetupScreenHeaderBackground.cs

@@ -0,0 +1,76 @@
+// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
+// See the LICENCE file in the repository root for full licence text.
+
+using osu.Framework.Allocation;
+using osu.Framework.Bindables;
+using osu.Framework.Graphics;
+using osu.Framework.Graphics.Containers;
+using osu.Framework.Graphics.Shapes;
+using osu.Game.Beatmaps;
+using osu.Game.Beatmaps.Drawables;
+using osu.Game.Graphics;
+using osu.Game.Graphics.Containers;
+
+namespace osu.Game.Screens.Edit.Setup
+{
+    public class SetupScreenHeaderBackground : CompositeDrawable
+    {
+        [Resolved]
+        private OsuColour colours { get; set; }
+
+        [Resolved]
+        private IBindable<WorkingBeatmap> working { get; set; }
+
+        private readonly Container content;
+
+        public SetupScreenHeaderBackground()
+        {
+            InternalChild = content = new Container
+            {
+                RelativeSizeAxes = Axes.Both,
+                Masking = true
+            };
+        }
+
+        [BackgroundDependencyLoader]
+        private void load()
+        {
+            UpdateBackground();
+        }
+
+        public void UpdateBackground()
+        {
+            LoadComponentAsync(new BeatmapBackgroundSprite(working.Value)
+            {
+                RelativeSizeAxes = Axes.Both,
+                Anchor = Anchor.Centre,
+                Origin = Anchor.Centre,
+                FillMode = FillMode.Fill,
+            }, background =>
+            {
+                if (background.Texture != null)
+                    content.Child = background;
+                else
+                {
+                    content.Children = new Drawable[]
+                    {
+                        new Box
+                        {
+                            Colour = colours.GreySeafoamDarker,
+                            RelativeSizeAxes = Axes.Both,
+                        },
+                        new OsuTextFlowContainer(t => t.Font = OsuFont.Default.With(size: 24))
+                        {
+                            Text = "Drag image here to set beatmap background!",
+                            Anchor = Anchor.Centre,
+                            Origin = Anchor.Centre,
+                            AutoSizeAxes = Axes.Both
+                        }
+                    };
+                }
+
+                background.FadeInFromZero(500);
+            });
+        }
+    }
+}