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Fix ScrollViewer.
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Use calculated values for scrollbar properties where possible.
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@grokys
grokys committed Mar 9, 2016
1 parent e332d3f commit 46b3ce2
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Showing 2 changed files with 129 additions and 53 deletions.
2 changes: 1 addition & 1 deletion src/Perspex.Base/PerspexObject.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -515,7 +515,7 @@ protected void RaisePropertyChanged(
PerspexProperty property,
object oldValue,
object newValue,
BindingPriority priority)
BindingPriority priority = BindingPriority.LocalValue)
{
Contract.Requires<ArgumentNullException>(property != null);
VerifyAccess();
Expand Down
180 changes: 128 additions & 52 deletions src/Perspex.Controls/ScrollViewer.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -2,9 +2,7 @@
// Licensed under the MIT license. See licence.md file in the project root for full license information.

using System;
using System.Collections.Specialized;
using System.Linq;
using System.Reactive.Disposables;
using System.Reactive.Linq;
using Perspex.Controls.Presenters;
using Perspex.Controls.Primitives;
Expand Down Expand Up @@ -51,37 +49,44 @@ public class ScrollViewer : ContentControl
/// Defines the HorizontalScrollBarMaximum property.
/// </summary>
/// <remarks>
/// There is no C# accessor for this property as it is intended to be bound to by a
/// There is no public C# accessor for this property as it is intended to be bound to by a
/// <see cref="ScrollContentPresenter"/> in the control's template.
/// </remarks>
public static readonly StyledProperty<double> HorizontalScrollBarMaximumProperty =
PerspexProperty.Register<ScrollViewer, double>("HorizontalScrollBarMaximum");
public static readonly DirectProperty<ScrollViewer, double> HorizontalScrollBarMaximumProperty =
PerspexProperty.RegisterDirect<ScrollViewer, double>(
nameof(HorizontalScrollBarMaximum),
o => o.HorizontalScrollBarMaximum);

/// <summary>
/// Defines the HorizontalScrollBarValue property.
/// </summary>
/// <remarks>
/// There is no C# accessor for this property as it is intended to be bound to by a
/// There is no public C# accessor for this property as it is intended to be bound to by a
/// <see cref="ScrollContentPresenter"/> in the control's template.
/// </remarks>
public static readonly StyledProperty<double> HorizontalScrollBarValueProperty =
PerspexProperty.Register<ScrollViewer, double>("HorizontalScrollBarValue");
public static readonly DirectProperty<ScrollViewer, double> HorizontalScrollBarValueProperty =
PerspexProperty.RegisterDirect<ScrollViewer, double>(
nameof(HorizontalScrollBarValue),
o => o.HorizontalScrollBarValue,
(o, v) => o.HorizontalScrollBarValue = v);

/// <summary>
/// Defines the HorizontalScrollBarViewportSize property.
/// </summary>
/// <remarks>
/// There is no C# accessor for this property as it is intended to be bound to by a
/// There is no public C# accessor for this property as it is intended to be bound to by a
/// <see cref="ScrollContentPresenter"/> in the control's template.
/// </remarks>
public static readonly StyledProperty<double> HorizontalScrollBarViewportSizeProperty =
PerspexProperty.Register<ScrollViewer, double>("HorizontalScrollBarViewportSize");
public static readonly DirectProperty<ScrollViewer, double> HorizontalScrollBarViewportSizeProperty =
PerspexProperty.RegisterDirect<ScrollViewer, double>(
nameof(HorizontalScrollBarViewportSize),
o => o.HorizontalScrollBarViewportSize);

/// <summary>
/// Defines the <see cref="HorizontalScrollBarVisibility"/> property.
/// </summary>
/// <remarks>
/// There is no C# accessor for this property as it is intended to be bound to by a
/// There is no public C# accessor for this property as it is intended to be bound to by a
/// <see cref="ScrollContentPresenter"/> in the control's template.
/// </remarks>
public static readonly AttachedProperty<ScrollBarVisibility> HorizontalScrollBarVisibilityProperty =
Expand All @@ -93,31 +98,38 @@ public class ScrollViewer : ContentControl
/// Defines the VerticalScrollBarMaximum property.
/// </summary>
/// <remarks>
/// There is no C# accessor for this property as it is intended to be bound to by a
/// There is no public C# accessor for this property as it is intended to be bound to by a
/// <see cref="ScrollContentPresenter"/> in the control's template.
/// </remarks>
public static readonly StyledProperty<double> VerticalScrollBarMaximumProperty =
PerspexProperty.Register<ScrollViewer, double>("VerticalScrollBarMaximum");
public static readonly DirectProperty<ScrollViewer, double> VerticalScrollBarMaximumProperty =
PerspexProperty.RegisterDirect<ScrollViewer, double>(
nameof(VerticalScrollBarMaximum),
o => o.VerticalScrollBarMaximum);

/// <summary>
/// Defines the VerticalScrollBarValue property.
/// </summary>
/// <remarks>
/// There is no C# accessor for this property as it is intended to be bound to by a
/// There is no public C# accessor for this property as it is intended to be bound to by a
/// <see cref="ScrollContentPresenter"/> in the control's template.
/// </remarks>
public static readonly StyledProperty<double> VerticalScrollBarValueProperty =
PerspexProperty.Register<ScrollViewer, double>("VerticalScrollBarValue");
public static readonly DirectProperty<ScrollViewer, double> VerticalScrollBarValueProperty =
PerspexProperty.RegisterDirect<ScrollViewer, double>(
nameof(VerticalScrollBarValue),
o => o.VerticalScrollBarValue,
(o, v) => o.VerticalScrollBarValue = v);

/// <summary>
/// Defines the VerticalScrollBarViewportSize property.
/// </summary>
/// <remarks>
/// There is no C# accessor for this property as it is intended to be bound to by a
/// There is no public C# accessor for this property as it is intended to be bound to by a
/// <see cref="ScrollContentPresenter"/> in the control's template.
/// </remarks>
public static readonly StyledProperty<double> VerticalScrollBarViewportSizeProperty =
PerspexProperty.Register<ScrollViewer, double>("VerticalScrollBarViewportSize");
public static readonly DirectProperty<ScrollViewer, double> VerticalScrollBarViewportSizeProperty =
PerspexProperty.RegisterDirect<ScrollViewer, double>(
nameof(VerticalScrollBarViewportSize),
o => o.VerticalScrollBarViewportSize);

/// <summary>
/// Defines the <see cref="VerticalScrollBarVisibility"/> property.
Expand Down Expand Up @@ -149,43 +161,25 @@ public ScrollViewer()
this.GetObservable(ExtentProperty),
this.GetObservable(ViewportProperty))
.Select(x => new { Extent = x[0], Viewport = x[1] });

Bind(
VerticalScrollBarViewportSizeProperty,
extentAndViewport.Select(x => Max((x.Viewport.Height / x.Extent.Height) * (x.Extent.Height - x.Viewport.Height), 0)));

Bind(
HorizontalScrollBarViewportSizeProperty,
extentAndViewport.Select(x => Max((x.Viewport.Width / x.Extent.Width) * (x.Extent.Width - x.Viewport.Width), 0)));

Bind(
HorizontalScrollBarMaximumProperty,
extentAndViewport.Select(x => Max(x.Extent.Width - x.Viewport.Width, 0)));

Bind(
VerticalScrollBarMaximumProperty,
extentAndViewport.Select(x => Max(x.Extent.Height - x.Viewport.Height, 0)));

this.GetObservable(OffsetProperty).Subscribe(x =>
{
SetValue(HorizontalScrollBarValueProperty, x.X);
SetValue(VerticalScrollBarValueProperty, x.Y);
});

var scrollBarOffset = Observable.CombineLatest(
this.GetObservable(HorizontalScrollBarValueProperty),
this.GetObservable(VerticalScrollBarValueProperty))
.Select(x => new Vector(x[0], x[1]))
.Subscribe(x => Offset = x);
}

/// <summary>
/// Gets the extent of the scrollable content.
/// </summary>
public Size Extent
{
get { return _extent; }
private set { SetAndRaise(ExtentProperty, ref _extent, value); }
get
{
return _extent;
}

private set
{
if (SetAndRaise(ExtentProperty, ref _extent, value))
{
CalculatedPropertiesChanged();
}
}
}

/// <summary>
Expand All @@ -201,7 +195,11 @@ public Vector Offset
set
{
value = ValidateOffset(this, value);
SetAndRaise(OffsetProperty, ref _offset, value);

if (SetAndRaise(OffsetProperty, ref _offset, value))
{
CalculatedPropertiesChanged();
}
}
}

Expand Down Expand Up @@ -241,6 +239,72 @@ public ScrollBarVisibility VerticalScrollBarVisibility
set { SetValue(VerticalScrollBarVisibilityProperty, value); }
}

/// <summary>
/// Gets the maximum horizontal scrollbar value.
/// </summary>
protected double HorizontalScrollBarMaximum
{
get { return Max(_extent.Width - _viewport.Width, 0); }
}

/// <summary>
/// Gets or sets the horizontal scrollbar value.
/// </summary>
protected double HorizontalScrollBarValue
{
get { return _offset.X; }
set
{
if (_offset.X != value)
{
var old = Offset.X;
Offset = Offset.WithX(value);
RaisePropertyChanged(HorizontalScrollBarValueProperty, old, value);
}
}
}

/// <summary>
/// Gets the size of the horizontal scrollbar viewport.
/// </summary>
protected double HorizontalScrollBarViewportSize
{
get { return Max((_viewport.Width / _extent.Width) * (_extent.Width - _viewport.Width), 0); }
}

/// <summary>
/// Gets the maximum vertical scrollbar value.
/// </summary>
protected double VerticalScrollBarMaximum
{
get { return Max(_extent.Height - _viewport.Height, 0); }
}

/// <summary>
/// Gets or sets the vertical scrollbar value.
/// </summary>
protected double VerticalScrollBarValue
{
get { return _offset.Y; }
set
{
if (_offset.Y != value)
{
var old = Offset.Y;
Offset = Offset.WithY(value);
RaisePropertyChanged(VerticalScrollBarValueProperty, old, value);
}
}
}

/// <summary>
/// Gets the size of the vertical scrollbar viewport.
/// </summary>
protected double VerticalScrollBarViewportSize
{
get { return Max((_viewport.Height / _extent.Height) * (_extent.Height - _viewport.Height), 0); }
}

internal static Vector CoerceOffset(Size extent, Size viewport, Vector offset)
{
var maxX = Math.Max(extent.Width - viewport.Width, 0);
Expand Down Expand Up @@ -274,5 +338,17 @@ private static Vector ValidateOffset(PerspexObject o, Vector value)
return value;
}
}

private void CalculatedPropertiesChanged()
{
// Pass old values of 0 here because we don't have the old values at this point,
// and it shouldn't matter as only the template uses these properies.
RaisePropertyChanged(HorizontalScrollBarMaximumProperty, 0, HorizontalScrollBarMaximum);
RaisePropertyChanged(HorizontalScrollBarValueProperty, 0, HorizontalScrollBarValue);
RaisePropertyChanged(HorizontalScrollBarViewportSizeProperty, 0, HorizontalScrollBarViewportSize);
RaisePropertyChanged(VerticalScrollBarMaximumProperty, 0, VerticalScrollBarMaximum);
RaisePropertyChanged(VerticalScrollBarValueProperty, 0, VerticalScrollBarValue);
RaisePropertyChanged(VerticalScrollBarViewportSizeProperty, 0, VerticalScrollBarViewportSize);
}
}
}

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