mirror of
https://github.com/Ellpeck/MLEM.git
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226 lines
No EOL
11 KiB
C#
226 lines
No EOL
11 KiB
C#
using System;
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using System.Collections.Generic;
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using System.Linq;
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using Microsoft.Xna.Framework;
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using Microsoft.Xna.Framework.Graphics;
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using MLEM.Extensions;
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using MLEM.Misc;
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using MLEM.Textures;
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using MLEM.Ui.Style;
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namespace MLEM.Ui.Elements {
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/// <summary>
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/// A panel element to be used inside of a <see cref="UiSystem"/>.
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/// The panel is a complex element that displays a box as a background to all of its child elements.
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/// Additionally, a panel can be set to <see cref="scrollOverflow"/> on construction, which causes all elements that don't fit into the panel to be hidden until scrolled to using a <see cref="ScrollBar"/>.
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/// As this behavior is accomplished using a <see cref="RenderTarget2D"/>, scrolling panels need to have their <see cref="DrawEarly"/> methods called using <see cref="UiSystem.DrawEarly"/>.
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/// </summary>
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public class Panel : Element {
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/// <summary>
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/// The texture that this panel should have, or null if it should be invisible.
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/// </summary>
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public StyleProp<NinePatch> Texture;
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/// <summary>
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/// The scroll bar that this panel contains.
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/// This is only nonnull if <see cref="scrollOverflow"/> is true.
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/// </summary>
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public readonly ScrollBar ScrollBar;
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private readonly bool scrollOverflow;
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private RenderTarget2D renderTarget;
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private readonly List<Element> relevantChildren = new List<Element>();
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private bool relevantChildrenDirty;
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/// <summary>
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/// Creates a new panel with the given settings.
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/// </summary>
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/// <param name="anchor">The panel's anchor</param>
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/// <param name="size">The panel's default size</param>
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/// <param name="positionOffset">The panel's offset from its anchor point</param>
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/// <param name="setHeightBasedOnChildren">Whether the panel should automatically calculate its height based on its children's size</param>
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/// <param name="scrollOverflow">Whether this panel should automatically add a scroll bar to scroll towards elements that are beyond the area this panel covers</param>
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/// <param name="scrollerSize">The size of the <see cref="ScrollBar"/>'s scroller</param>
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/// <param name="autoHideScrollbar">Whether the scroll bar should be hidden automatically if the panel does not contain enough children to allow for scrolling</param>
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public Panel(Anchor anchor, Vector2 size, Vector2 positionOffset, bool setHeightBasedOnChildren = false, bool scrollOverflow = false, Point? scrollerSize = null, bool autoHideScrollbar = true) : base(anchor, size) {
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this.PositionOffset = positionOffset;
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this.SetHeightBasedOnChildren = setHeightBasedOnChildren;
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this.scrollOverflow = scrollOverflow;
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this.ChildPadding = new Vector2(5);
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this.CanBeSelected = false;
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if (scrollOverflow) {
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var scrollSize = scrollerSize ?? Point.Zero;
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this.ScrollBar = new ScrollBar(Anchor.TopRight, new Vector2(scrollSize.X, 1), scrollSize.Y, 0) {
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StepPerScroll = 10,
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OnValueChanged = (element, value) => this.ScrollChildren(),
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CanAutoAnchorsAttach = false,
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AutoHideWhenEmpty = autoHideScrollbar,
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IsHidden = autoHideScrollbar
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};
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// modify the padding so that the scroll bar isn't over top of something else
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this.ScrollBar.PositionOffset -= new Vector2(scrollSize.X + 1, 0);
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if (autoHideScrollbar)
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this.ScrollBar.OnAutoHide += e => this.ChildPadding += new Padding(0, scrollSize.X, 0, 0) * (e.IsHidden ? -1 : 1);
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// handle automatic element selection, the scroller needs to scroll to the right location
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this.OnSelectedElementChanged += (element, otherElement) => {
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if (!this.Controls.IsAutoNavMode)
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return;
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if (otherElement == null || !otherElement.GetParentTree().Contains(this))
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return;
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var firstChild = this.Children.First(c => c != this.ScrollBar);
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this.ScrollBar.CurrentValue = (otherElement.Area.Bottom - firstChild.Area.Top - this.Area.Height / 2) / this.Scale;
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};
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this.AddChild(this.ScrollBar);
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}
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}
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/// <inheritdoc />
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public override void ForceUpdateArea() {
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if (this.scrollOverflow) {
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// sanity check
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if (this.SetHeightBasedOnChildren)
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throw new NotSupportedException("A panel can't both set height based on children and scroll overflow");
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foreach (var child in this.Children) {
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if (child != this.ScrollBar && child.Anchor < Anchor.AutoLeft)
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throw new NotSupportedException($"A panel that handles overflow can't contain non-automatic anchors ({child})");
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if (child is Panel panel && panel.scrollOverflow)
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throw new NotSupportedException($"A panel that scrolls overflow cannot contain another panel that scrolls overflow ({child})");
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}
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}
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base.ForceUpdateArea();
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this.ScrollChildren();
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this.ScrollSetup();
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}
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private void ScrollChildren() {
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if (!this.scrollOverflow)
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return;
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var offset = -this.ScrollBar.CurrentValue;
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foreach (var child in this.GetChildren(c => c != this.ScrollBar, true))
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child.ScrollOffset = new Vector2(0, offset);
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this.relevantChildrenDirty = true;
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}
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/// <inheritdoc />
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public override void ForceUpdateSortedChildren() {
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base.ForceUpdateSortedChildren();
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if (this.scrollOverflow)
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this.relevantChildrenDirty = true;
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}
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/// <inheritdoc />
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protected override List<Element> GetRelevantChildren() {
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var relevant = base.GetRelevantChildren();
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if (this.scrollOverflow) {
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if (this.relevantChildrenDirty) {
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this.relevantChildrenDirty = false;
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var visible = this.GetRenderTargetArea();
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this.relevantChildren.Clear();
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foreach (var child in this.SortedChildren) {
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if (child.Area.Intersects(visible)) {
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this.relevantChildren.Add(child);
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} else {
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foreach (var c in child.GetChildren(regardGrandchildren: true)) {
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if (c.Area.Intersects(visible)) {
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this.relevantChildren.Add(child);
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break;
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}
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}
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}
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}
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}
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relevant = this.relevantChildren;
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}
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return relevant;
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}
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/// <inheritdoc />
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public override void Draw(GameTime time, SpriteBatch batch, float alpha, BlendState blendState, SamplerState samplerState, Matrix matrix) {
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if (this.Texture.HasValue())
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batch.Draw(this.Texture, this.DisplayArea, Color.White * alpha, this.Scale);
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// if we handle overflow, draw using the render target in DrawUnbound
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if (!this.scrollOverflow || this.renderTarget == null) {
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base.Draw(time, batch, alpha, blendState, samplerState, matrix);
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} else {
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// draw the actual render target (don't apply the alpha here because it's already drawn onto with alpha)
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batch.Draw(this.renderTarget, this.GetRenderTargetArea(), Color.White);
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}
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}
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/// <inheritdoc />
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public override void DrawEarly(GameTime time, SpriteBatch batch, float alpha, BlendState blendState, SamplerState samplerState, Matrix matrix) {
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this.UpdateAreaIfDirty();
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if (this.scrollOverflow && this.renderTarget != null) {
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// draw children onto the render target
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using (batch.GraphicsDevice.WithRenderTarget(this.renderTarget)) {
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batch.GraphicsDevice.Clear(Color.Transparent);
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// offset children by the render target's location
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var area = this.GetRenderTargetArea();
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var trans = Matrix.CreateTranslation(-area.X, -area.Y, 0);
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// do the usual draw, but within the render target
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batch.Begin(SpriteSortMode.Deferred, blendState, samplerState, null, null, null, trans);
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base.Draw(time, batch, alpha, blendState, samplerState, trans);
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batch.End();
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// also draw any children early within the render target with the translation applied
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base.DrawEarly(time, batch, alpha, blendState, samplerState, trans);
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}
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} else {
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base.DrawEarly(time, batch, alpha, blendState, samplerState, matrix);
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}
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}
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/// <inheritdoc />
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public override Element GetElementUnderPos(Vector2 position) {
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// if overflow is handled, don't propagate mouse checks to hidden children
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if (this.scrollOverflow && !this.GetRenderTargetArea().Contains(position))
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return null;
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return base.GetElementUnderPos(position);
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}
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private RectangleF GetRenderTargetArea() {
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var area = this.ChildPaddedArea;
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area.X = this.DisplayArea.X;
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area.Width = this.DisplayArea.Width;
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return area;
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}
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/// <inheritdoc />
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protected override void InitStyle(UiStyle style) {
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base.InitStyle(style);
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this.Texture.SetFromStyle(style.PanelTexture);
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}
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/// <summary>
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/// Prepares the panel for auto-scrolling, creating the render target and setting up the scroll bar's maximum value.
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/// </summary>
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protected virtual void ScrollSetup() {
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if (!this.scrollOverflow || this.IsHidden)
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return;
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// if there is only one child, then we have just the scroll bar
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if (this.Children.Count == 1)
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return;
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// the "real" first child is the scroll bar, which we want to ignore
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var firstChild = this.Children.First(c => c != this.ScrollBar);
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var lowestChild = this.GetLowestChild(e => !e.IsHidden);
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// the max value of the scrollbar is the amount of non-scaled pixels taken up by overflowing components
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var childrenHeight = lowestChild.Area.Bottom - firstChild.Area.Top;
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this.ScrollBar.MaxValue = (childrenHeight - this.Area.Height) / this.Scale + this.ChildPadding.Height;
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// update the render target
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var targetArea = (Rectangle) this.GetRenderTargetArea();
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if (targetArea.Width <= 0 || targetArea.Height <= 0)
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return;
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if (this.renderTarget == null || targetArea.Width != this.renderTarget.Width || targetArea.Height != this.renderTarget.Height) {
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if (this.renderTarget != null)
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this.renderTarget.Dispose();
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this.renderTarget = targetArea.IsEmpty ? null : new RenderTarget2D(this.System.GraphicsDevice, targetArea.Width, targetArea.Height);
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}
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}
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}
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} |