Điều này sẽ phóng to và thu nhỏ cũng như xoay nhưng giữ hình ảnh trong giới hạn của container. Viết như một điều khiển để thêm phong cách App.xamltrực tiếp hoặc thông qua Themes/Viewport.xaml.
Để dễ đọc, tôi cũng đã tải nó lên trên gist và github
Tôi cũng đã đóng gói cái này trên nuget
PM > Install-Package Han.Wpf.ViewportControl
./Controls/Viewport.cs:
public class Viewport : ContentControl
{
private bool _capture;
private FrameworkElement _content;
private Matrix _matrix;
private Point _origin;
public static readonly DependencyProperty MaxZoomProperty =
DependencyProperty.Register(
nameof(MaxZoom),
typeof(double),
typeof(Viewport),
new PropertyMetadata(0d));
public static readonly DependencyProperty MinZoomProperty =
DependencyProperty.Register(
nameof(MinZoom),
typeof(double),
typeof(Viewport),
new PropertyMetadata(0d));
public static readonly DependencyProperty ZoomSpeedProperty =
DependencyProperty.Register(
nameof(ZoomSpeed),
typeof(float),
typeof(Viewport),
new PropertyMetadata(0f));
public static readonly DependencyProperty ZoomXProperty =
DependencyProperty.Register(
nameof(ZoomX),
typeof(double),
typeof(Viewport),
new FrameworkPropertyMetadata(0d, FrameworkPropertyMetadataOptions.BindsTwoWayByDefault));
public static readonly DependencyProperty ZoomYProperty =
DependencyProperty.Register(
nameof(ZoomY),
typeof(double),
typeof(Viewport),
new FrameworkPropertyMetadata(0d, FrameworkPropertyMetadataOptions.BindsTwoWayByDefault));
public static readonly DependencyProperty OffsetXProperty =
DependencyProperty.Register(
nameof(OffsetX),
typeof(double),
typeof(Viewport),
new FrameworkPropertyMetadata(0d, FrameworkPropertyMetadataOptions.BindsTwoWayByDefault));
public static readonly DependencyProperty OffsetYProperty =
DependencyProperty.Register(
nameof(OffsetY),
typeof(double),
typeof(Viewport),
new FrameworkPropertyMetadata(0d, FrameworkPropertyMetadataOptions.BindsTwoWayByDefault));
public static readonly DependencyProperty BoundsProperty =
DependencyProperty.Register(
nameof(Bounds),
typeof(Rect),
typeof(Viewport),
new FrameworkPropertyMetadata(default(Rect), FrameworkPropertyMetadataOptions.BindsTwoWayByDefault));
public Rect Bounds
{
get => (Rect) GetValue(BoundsProperty);
set => SetValue(BoundsProperty, value);
}
public double MaxZoom
{
get => (double) GetValue(MaxZoomProperty);
set => SetValue(MaxZoomProperty, value);
}
public double MinZoom
{
get => (double) GetValue(MinZoomProperty);
set => SetValue(MinZoomProperty, value);
}
public double OffsetX
{
get => (double) GetValue(OffsetXProperty);
set => SetValue(OffsetXProperty, value);
}
public double OffsetY
{
get => (double) GetValue(OffsetYProperty);
set => SetValue(OffsetYProperty, value);
}
public float ZoomSpeed
{
get => (float) GetValue(ZoomSpeedProperty);
set => SetValue(ZoomSpeedProperty, value);
}
public double ZoomX
{
get => (double) GetValue(ZoomXProperty);
set => SetValue(ZoomXProperty, value);
}
public double ZoomY
{
get => (double) GetValue(ZoomYProperty);
set => SetValue(ZoomYProperty, value);
}
public Viewport()
{
DefaultStyleKey = typeof(Viewport);
Loaded += OnLoaded;
Unloaded += OnUnloaded;
}
private void Arrange(Size desired, Size render)
{
_matrix = Matrix.Identity;
var zx = desired.Width / render.Width;
var zy = desired.Height / render.Height;
var cx = render.Width < desired.Width ? render.Width / 2.0 : 0.0;
var cy = render.Height < desired.Height ? render.Height / 2.0 : 0.0;
var zoom = Math.Min(zx, zy);
if (render.Width > desired.Width &&
render.Height > desired.Height)
{
cx = (desired.Width - (render.Width * zoom)) / 2.0;
cy = (desired.Height - (render.Height * zoom)) / 2.0;
_matrix = new Matrix(zoom, 0d, 0d, zoom, cx, cy);
}
else
{
_matrix.ScaleAt(zoom, zoom, cx, cy);
}
}
private void Attach(FrameworkElement content)
{
content.MouseMove += OnMouseMove;
content.MouseLeave += OnMouseLeave;
content.MouseWheel += OnMouseWheel;
content.MouseLeftButtonDown += OnMouseLeftButtonDown;
content.MouseLeftButtonUp += OnMouseLeftButtonUp;
content.SizeChanged += OnSizeChanged;
content.MouseRightButtonDown += OnMouseRightButtonDown;
}
private void ChangeContent(FrameworkElement content)
{
if (content != null && !Equals(content, _content))
{
if (_content != null)
{
Detatch();
}
Attach(content);
_content = content;
}
}
private double Constrain(double value, double min, double max)
{
if (min > max)
{
min = max;
}
if (value <= min)
{
return min;
}
if (value >= max)
{
return max;
}
return value;
}
private void Constrain()
{
var x = Constrain(_matrix.OffsetX, _content.ActualWidth - _content.ActualWidth * _matrix.M11, 0);
var y = Constrain(_matrix.OffsetY, _content.ActualHeight - _content.ActualHeight * _matrix.M22, 0);
_matrix = new Matrix(_matrix.M11, 0d, 0d, _matrix.M22, x, y);
}
private void Detatch()
{
_content.MouseMove -= OnMouseMove;
_content.MouseLeave -= OnMouseLeave;
_content.MouseWheel -= OnMouseWheel;
_content.MouseLeftButtonDown -= OnMouseLeftButtonDown;
_content.MouseLeftButtonUp -= OnMouseLeftButtonUp;
_content.SizeChanged -= OnSizeChanged;
_content.MouseRightButtonDown -= OnMouseRightButtonDown;
}
private void Invalidate()
{
if (_content != null)
{
Constrain();
_content.RenderTransformOrigin = new Point(0, 0);
_content.RenderTransform = new MatrixTransform(_matrix);
_content.InvalidateVisual();
ZoomX = _matrix.M11;
ZoomY = _matrix.M22;
OffsetX = _matrix.OffsetX;
OffsetY = _matrix.OffsetY;
var rect = new Rect
{
X = OffsetX * -1,
Y = OffsetY * -1,
Width = ActualWidth,
Height = ActualHeight
};
Bounds = rect;
}
}
public override void OnApplyTemplate()
{
base.OnApplyTemplate();
_matrix = Matrix.Identity;
}
protected override void OnContentChanged(object oldContent, object newContent)
{
base.OnContentChanged(oldContent, newContent);
if (Content is FrameworkElement element)
{
ChangeContent(element);
}
}
private void OnLoaded(object sender, RoutedEventArgs e)
{
if (Content is FrameworkElement element)
{
ChangeContent(element);
}
SizeChanged += OnSizeChanged;
Loaded -= OnLoaded;
}
private void OnMouseLeave(object sender, MouseEventArgs e)
{
if (_capture)
{
Released();
}
}
private void OnMouseLeftButtonDown(object sender, MouseButtonEventArgs e)
{
if (IsEnabled && !_capture)
{
Pressed(e.GetPosition(this));
}
}
private void OnMouseLeftButtonUp(object sender, MouseButtonEventArgs e)
{
if (IsEnabled && _capture)
{
Released();
}
}
private void OnMouseMove(object sender, MouseEventArgs e)
{
if (IsEnabled && _capture)
{
var position = e.GetPosition(this);
var point = new Point
{
X = position.X - _origin.X,
Y = position.Y - _origin.Y
};
var delta = point;
_origin = position;
_matrix.Translate(delta.X, delta.Y);
Invalidate();
}
}
private void OnMouseRightButtonDown(object sender, MouseButtonEventArgs e)
{
if (IsEnabled)
{
Reset();
}
}
private void OnMouseWheel(object sender, MouseWheelEventArgs e)
{
if (IsEnabled)
{
var scale = e.Delta > 0 ? ZoomSpeed : 1 / ZoomSpeed;
var position = e.GetPosition(_content);
var x = Constrain(scale, MinZoom / _matrix.M11, MaxZoom / _matrix.M11);
var y = Constrain(scale, MinZoom / _matrix.M22, MaxZoom / _matrix.M22);
_matrix.ScaleAtPrepend(x, y, position.X, position.Y);
ZoomX = _matrix.M11;
ZoomY = _matrix.M22;
Invalidate();
}
}
private void OnSizeChanged(object sender, SizeChangedEventArgs e)
{
if (_content?.IsMeasureValid ?? false)
{
Arrange(_content.DesiredSize, _content.RenderSize);
Invalidate();
}
}
private void OnUnloaded(object sender, RoutedEventArgs e)
{
Detatch();
SizeChanged -= OnSizeChanged;
Unloaded -= OnUnloaded;
}
private void Pressed(Point position)
{
if (IsEnabled)
{
_content.Cursor = Cursors.Hand;
_origin = position;
_capture = true;
}
}
private void Released()
{
if (IsEnabled)
{
_content.Cursor = null;
_capture = false;
}
}
private void Reset()
{
_matrix = Matrix.Identity;
if (_content != null)
{
Arrange(_content.DesiredSize, _content.RenderSize);
}
Invalidate();
}
}
./Theme/Viewport.xaml:
<ResourceDictionary ... >
<Style TargetType="{x:Type controls:Viewport}"
BasedOn="{StaticResource {x:Type ContentControl}}">
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type controls:Viewport}">
<Border BorderBrush="{TemplateBinding BorderBrush}"
BorderThickness="{TemplateBinding BorderThickness}"
Background="{TemplateBinding Background}">
<Grid ClipToBounds="True"
Width="{TemplateBinding Width}"
Height="{TemplateBinding Height}">
<Grid x:Name="PART_Container">
<ContentPresenter x:Name="PART_Presenter" />
</Grid>
</Grid>
</Border>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
</ResourceDictionary>
./App.xaml
<Application ... >
<Application.Resources>
<ResourceDictionary>
<ResourceDictionary.MergedDictionaries>
<ResourceDictionary Source="./Themes/Viewport.xaml"/>
</ResourceDictionary.MergedDictionaries>
</ResourceDictionary>
</Application.Resources>
</Application>
Sử dụng:
<viewers:Viewport>
<Image Source="{Binding}"/>
</viewers:Viewport>
Bất kỳ vấn đề, cho tôi một tiếng hét.
Chúc mừng mã hóa :)