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chore: refactor ZoomContentControl.cs
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@vatsashah45
vatsashah45 committed Oct 4, 2024
1 parent 524839e commit 81f4bc1
Showing 1 changed file with 86 additions and 132 deletions.
218 changes: 86 additions & 132 deletions src/Uno.Toolkit.UI/Controls/ZoomContentControl/ZoomContentControl.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -31,7 +31,6 @@
using Windows.Devices.Input;
#endif


namespace Uno.Toolkit.UI;

[TemplatePart(Name = TemplateParts.RootGrid, Type = typeof(Grid))]
Expand All @@ -43,23 +42,35 @@ public partial class ZoomContentControl : ContentControl
private static class TemplateParts
{
public const string RootGrid = "PART_RootGrid";

public const string Presenter = "PART_Presenter";

public const string HorizontalScrollBar = "PART_ScrollH";
public const string VerticalScrollBar = "PART_ScrollV";
}

// Fields
private ContentPresenter? _presenter;
private ScrollBar? _scrollV;
private ScrollBar? _scrollH;

private Point _lastPosition = new Point(0, 0);

private (bool Horizontal, bool Vertical) _movementDirection = (false, false);

private bool IsAllowedToWork => (IsEnabled && IsActive && _presenter is not null);
private double _previousVerticalScrollValue = double.MinValue;
private double _previousHorizontalScrollValue = double.MinValue;
private uint _capturedPointerId;
private Point _referencePosition;

// Constructor
public ZoomContentControl()
{
DefaultStyleKey = typeof(ZoomContentControl);
Loaded += OnLoaded;
SizeChanged += OnSizeChanged;
}

// Events
public event EventHandler<EventArgs>? RenderedContentUpdated;

// Dependency Properties
public bool ResetWhenNotActive { get; set; } = true;

public Size AvailableSize
Expand All @@ -72,8 +83,7 @@ public Size AvailableSize
}
}

public event EventHandler<EventArgs>? RenderedContentUpdated;

// Methods
private async Task RaiseRenderedContentUpdated()
{
await Task.Yield();
Expand Down Expand Up @@ -103,12 +113,6 @@ private async void OnZoomLevelChanged()
await RaiseRenderedContentUpdated();
}

public record BoundsVisibilityData(bool LeftEdge, bool TopEdge, bool RightEdge, bool BottomEdge)
{
public static BoundsVisibilityData None => new BoundsVisibilityData(false, false, false, false);
public bool AllEdgesVisible => LeftEdge && TopEdge && RightEdge && BottomEdge;
}

private void UpdateContentBoundsVisibility()
{
if (_presenter?.Content is FrameworkElement fe)
Expand All @@ -118,8 +122,8 @@ private void UpdateContentBoundsVisibility()
ContentBoundsVisibility = new BoundsVisibilityData(
m.OffsetX >= 0,
m.OffsetY >= 0,
this.ActualWidth >= (fe.ActualWidth * ZoomLevel) + m.OffsetX,
this.ActualHeight >= (fe.ActualHeight * ZoomLevel) + m.OffsetY);
ActualWidth >= (fe.ActualWidth * ZoomLevel) + m.OffsetX,
ActualHeight >= (fe.ActualHeight * ZoomLevel) + m.OffsetY);
}
}

Expand All @@ -146,21 +150,16 @@ private bool CanMoveIn((bool Horizontal, bool Vertical) _movementDirection)
}

private bool CanScrollUp() => !ContentBoundsVisibility.TopEdge;

private bool CanScrollDown() => !ContentBoundsVisibility.BottomEdge;

private bool CanScrollLeft() => !ContentBoundsVisibility.LeftEdge;

private bool CanScrollRight() => !ContentBoundsVisibility.RightEdge;

//Slide move is always on the opposite direction of the drag
private async void UpdateVerticalScrollBarValue()
{
VerticalScrollValue = VerticalOffset;
await RaiseRenderedContentUpdated();
}

//Slide move is always on the opposite direction of the drag
private async void UpdateHorizontalScrollBarValue()
{
HorizontalScrollValue = -1 * HorizontalOffset;
Expand Down Expand Up @@ -188,9 +187,6 @@ private void UpdateScrollLimits()
{
if (_presenter?.Content is FrameworkElement fe)
{
// If Actual Width/Height * Zoom < ViewPort Width/Height there should be no scroll
// If Actual Width/Height * Zoom > ViewPort Width/Height the amount of scroll should
// be based on the difference between the two values
var verticalScroll = Math.Max(0, (fe.ActualHeight * ZoomLevel) - ViewPortHeight);
var horizontalScroll = Math.Max(0, (fe.ActualWidth * ZoomLevel) - ViewPortWidth);

Expand All @@ -207,14 +203,25 @@ private void CoerceZoomLevel()
ZoomLevel = Math.Clamp(ZoomLevel, MinZoomLevel, MaxZoomLevel);
}

public ZoomContentControl()
// Template handling
protected override void OnApplyTemplate()
{
DefaultStyleKey = typeof(ZoomContentControl);
T FindTemplatePart<T>(string name) where T : class =>
(GetTemplateChild(name) ?? throw new Exception($"Expected template part not found: {name}"))
as T ?? throw new Exception($"Expected template part '{name}' to be of type: {typeof(T)}");

_presenter = FindTemplatePart<ContentPresenter>(TemplateParts.Presenter);
_scrollV = FindTemplatePart<ScrollBar>(TemplateParts.VerticalScrollBar);
_scrollH = FindTemplatePart<ScrollBar>(TemplateParts.HorizontalScrollBar);

ResetOffset();
ResetZoom();

this.Loaded += OnLoaded;
this.SizeChanged += OnSizeChanged;
RegisterToControlEvents();
RegisterPointerHandlers();
}

// Event handlers
private void OnLoaded(object sender, RoutedEventArgs e)
{
CenterContent();
Expand All @@ -229,24 +236,6 @@ private void OnSizeChanged(object sender, SizeChangedEventArgs args)
}
}

protected override void OnApplyTemplate()
{
T FindTemplatePart<T>(string name) where T : class =>
(GetTemplateChild(name) ?? throw new Exception($"Expected template part not found: {name}"))
as T ?? throw new Exception($"Expected template part '{name}' to be of type: {typeof(T)}");
_presenter = FindTemplatePart<ContentPresenter>(TemplateParts.Presenter);
_scrollV = FindTemplatePart<ScrollBar>(TemplateParts.VerticalScrollBar);
_scrollH = FindTemplatePart<ScrollBar>(TemplateParts.HorizontalScrollBar);

ResetOffset();
ResetZoom();

RegisterToControlEvents();
RegisterPointerHandlers();
}

#region ScrollBars Events

private void RegisterToControlEvents()
{
if (_presenter?.Content is FrameworkElement { } fe)
Expand All @@ -271,11 +260,19 @@ private void RegisterToControlEvents()
}
}

private double _previousVerticalScrollValue = double.MinValue;
private void RegisterPointerHandlers()
{
PointerPressed -= OnPointerPressed;
PointerReleased -= OnPointerReleased;
PointerMoved -= OnPointerMoved;
PointerWheelChanged -= OnPointerWheelChanged;

private double _previousHorizontalScrollValue = double.MinValue;
PointerPressed += OnPointerPressed;
PointerReleased += OnPointerReleased;
PointerMoved += OnPointerMoved;
PointerWheelChanged += OnPointerWheelChanged;
}

//TemplateBinding doesn't support TwoWay mode. We need to manually update the values
private void ScrollV_Scroll(object sender, ScrollEventArgs e)
{
if ((_previousVerticalScrollValue > e.NewValue && !CanScrollUp()) ||
Expand All @@ -300,51 +297,22 @@ private void ScrollH_Scroll(object sender, ScrollEventArgs e)
_previousHorizontalScrollValue = e.NewValue;
}

#endregion

private uint _capturedPointerId;
private Point _referencePosition;

private void RegisterPointerHandlers()
{
// Register for pointer events.
PointerPressed -= OnPointerPressed;
PointerReleased -= OnPointerReleased;
PointerMoved -= OnPointerMoved;
PointerWheelChanged -= OnPointerWheelChanged;

PointerPressed += OnPointerPressed;
PointerReleased += OnPointerReleased;
PointerMoved += OnPointerMoved;
PointerWheelChanged += OnPointerWheelChanged;
}

// Additional private methods for pointer handling
private void OnPointerPressed(object sender, PointerRoutedEventArgs e)
{
if (!IsAllowedToWork)
{
return; // Don't handle the event when the control is disabled.
}

if (!IsAllowedToWork) return;
var pointerPoint = e.GetCurrentPoint(this);
var pointerProperties = pointerPoint.Properties;

// If the middle button of a mouse is pressed, then we want to handle the event.
if (pointerProperties.IsMiddleButtonPressed
#if IS_WINUI
&& pointerPoint.PointerDeviceType == PointerDeviceType.Mouse)
#else
&& pointerPoint.PointerDevice.PointerDeviceType == PointerDeviceType.Mouse)
#endif
if (pointerProperties.IsMiddleButtonPressed &&
pointerPoint.PointerDeviceType == PointerDeviceType.Mouse)
{
e.Handled = true;

// Capture the pointer so that we can track its movement even if it leaves the bounds of the control.
var pointer = e.Pointer;
var captured = CapturePointer(pointer);
var captured = CapturePointer(e.Pointer);
if (captured)
{
_capturedPointerId = pointer.PointerId;
_capturedPointerId = e.Pointer.PointerId;
_referencePosition = pointerPoint.Position;
_lastPosition = _referencePosition;
}
Expand All @@ -359,81 +327,39 @@ private void OnPointerReleased(object sender, PointerRoutedEventArgs e)

private void OnPointerMoved(object sender, PointerRoutedEventArgs e)
{
if (!(IsAllowedToWork && _capturedPointerId > 0 && IsPanAllowed))
{
return;
}
if (!(IsAllowedToWork && _capturedPointerId > 0 && IsPanAllowed)) return;

var currentPosition = e.GetCurrentPoint(this).Position;
_movementDirection = (currentPosition.X > _lastPosition.X, currentPosition.Y > _lastPosition.Y);
_lastPosition = currentPosition;

if (CanMoveIn(_movementDirection))
{
// If the pointer is captured, then we want to handle the event.
e.Handled = true;

var pointerPoint = e.GetCurrentPoint(this);

// Adjust the offsets based on the pointer's movement.
var position = pointerPoint.Position;
var deltaX = position.X - _referencePosition.X;
var deltaY = position.Y - _referencePosition.Y;

TryUpdateOffsets(deltaX, deltaY);

// Update the starting position for next time.
_referencePosition = position;
}
}

private void TryUpdateOffsets(double deltaX, double deltaY)
{
if ((deltaX > 0 && CanScrollLeft()) ||
(deltaX < 0 && CanScrollRight()))
{
var offset = HorizontalOffset + deltaX;
var max = HorizontalMaxScroll * ZoomLevel;

HorizontalOffset = Math.Clamp(offset, 0, max);
}

if ((deltaY > 0 && CanScrollUp()) ||
(deltaY < 0 && CanScrollDown()))
{
var offset = VerticalOffset + deltaY;

var max = VerticalMaxScroll * ZoomLevel;

VerticalOffset = Math.Clamp(offset, 0, max);
}
}

private void OnPointerWheelChanged(object sender, PointerRoutedEventArgs e)
{
if (!IsAllowedToWork)
{
return; // Don't handle the event when the control is disabled.
}
if (!IsAllowedToWork) return;

var pointerPoint = e.GetCurrentPoint(this);
var pointerProperties = pointerPoint.Properties;

var changeRatio = GetZoomDelta(pointerProperties);

//Zoom In/Out
if (
#if IS_WINUI
pointerPoint.PointerDeviceType == PointerDeviceType.Mouse &&
#else
pointerPoint.PointerDevice.PointerDeviceType == PointerDeviceType.Mouse &&
#endif
if (pointerPoint.PointerDeviceType == PointerDeviceType.Mouse &&
e.KeyModifiers.HasFlag(Windows.System.VirtualKeyModifiers.Control) &&
IsZoomAllowed)
{
e.Handled = true;

// Pointer relative to the content
var relativeX = (pointerPoint.Position.X - HorizontalOffset) / ZoomLevel;
var relativeY = (pointerPoint.Position.Y - VerticalOffset) / ZoomLevel;

Expand All @@ -444,15 +370,13 @@ private void OnPointerWheelChanged(object sender, PointerRoutedEventArgs e)
return;
}

//Horizontal Scroll
if (e.KeyModifiers.HasFlag(Windows.System.VirtualKeyModifiers.Shift))
{
var deltaX = GetPanDelta(pointerProperties);
TryUpdateOffsets(deltaX, 0);
return;
}

//Vertical Scroll
var deltaY = GetPanDelta(pointerProperties);
TryUpdateOffsets(0, deltaY);
}
Expand All @@ -469,6 +393,26 @@ private double GetPanDelta(PointerPointProperties pointerProperties)
return delta;
}

private void TryUpdateOffsets(double deltaX, double deltaY)
{
if ((deltaX > 0 && CanScrollLeft()) ||
(deltaX < 0 && CanScrollRight()))
{
var offset = HorizontalOffset + deltaX;
var max = HorizontalMaxScroll * ZoomLevel;
HorizontalOffset = Math.Clamp(offset, 0, max);
}

if ((deltaY > 0 && CanScrollUp()) ||
(deltaY < 0 && CanScrollDown()))
{
var offset = VerticalOffset + deltaY;
var max = VerticalMaxScroll * ZoomLevel;
VerticalOffset = Math.Clamp(offset, 0, max);
}
}

// Public methods
public void Initialize()
{
if (_presenter?.Content is FrameworkElement { } fe)
Expand Down Expand Up @@ -515,5 +459,15 @@ public void FitToCanvas()
CenterContent();
}
}
private static Matrix GetPositionMatrix(FrameworkElement element, FrameworkElement rootElement) => ((MatrixTransform)element.TransformToVisual(rootElement)).Matrix;

// Record for BoundsVisibilityData
public record BoundsVisibilityData(bool LeftEdge, bool TopEdge, bool RightEdge, bool BottomEdge)
{
public static BoundsVisibilityData None => new BoundsVisibilityData(false, false, false, false);
public bool AllEdgesVisible => LeftEdge && TopEdge && RightEdge && BottomEdge;
}

// Static helper
private static Matrix GetPositionMatrix(FrameworkElement element, FrameworkElement rootElement)
=> ((MatrixTransform)element.TransformToVisual(rootElement)).Matrix;
}

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