我有包含照片的内容页面。我想添加放大和缩小选项,但是当我尝试添加捏合手势时,它只是放大而不是缩小?如何添加缩小选项?
这是我的XAML:
<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
x:Class="ComplexInstructionApp.ShowProgram"
Title="dsa">
<ContentPage.Content>
</ContentPage.Content>
<Grid>
<Image x:Name="IMI" Aspect="Fill"
RelativeLayout.WidthConstraint=
"{ConstraintExpression Type=RelativeToParent, Property=Width}"
RelativeLayout.HeightConstraint=
"{ConstraintExpression Type=RelativeToParent, Property=Height}"
/>
</Grid>
</ContentPage>
这是我的代码: public partial class ShowProgram:ContentPage {
private double currentScale = 1;
private double startScale = 1;
private double xOffset = 0;
private double yOffset = 0;
public ShowProgram(string txt)
{
InitializeComponent();
switch (txt)
{
case "קובני":
IMI.Source = "Cuben_Expend.png";
break;
case "קובני מצומצם":
IMI.Source = "Cuben_short.png";
break;
case "אל איי":
IMI.Source = "LA_Expend.png";
break;
case "אל איי מצומצם":
IMI.Source = "LA_short.png";
break;
case "בצ'אטה":
IMI.Source = "bachata.png";
break;
case "זוק":
IMI.Source = "zouk.png";
break;
}
var pinchGesture = new PinchGestureRecognizer();
pinchGesture.PinchUpdated += (s, e) =>
{
if (e.Status == GestureStatus.Started)
{
// Store the current scale factor applied to the wrapped user interface element,
// and zero the components for the center point of the translate transform.
startScale = Content.Scale;
Content.AnchorX = 0;
Content.AnchorY = 0;
}
if (e.Status == GestureStatus.Running)
{
// Calculate the scale factor to be applied.
currentScale += (e.Scale - 1) * startScale;
currentScale = Math.Max(1, currentScale);
// The ScaleOrigin is in relative coordinates to the wrapped user interface element,
// so get the X pixel coordinate.
double renderedX = Content.X + xOffset;
double deltaX = renderedX / Width;
double deltaWidth = Width / (Content.Width * startScale);
double originX = (e.ScaleOrigin.X - deltaX) * deltaWidth;
// The ScaleOrigin is in relative coordinates to the wrapped user interface element,
// so get the Y pixel coordinate.
double renderedY = Content.Y + yOffset;
double deltaY = renderedY / Height;
double deltaHeight = Height / (Content.Height * startScale);
double originY = (e.ScaleOrigin.Y - deltaY) * deltaHeight;
// Calculate the transformed element pixel coordinates.
double targetX = xOffset - (originX * Content.Width) * (currentScale - startScale);
double targetY = yOffset - (originY * Content.Height) * (currentScale - startScale);
// Apply translation based on the change in origin.
Content.TranslationX = Clamp1(targetX ,- Content.Width * (currentScale - 1), 0);
Content.TranslationY = Clamp1(targetY, -Content.Height * (currentScale - 1), 0);
// Apply scale factor.
Content.Scale = currentScale;
}
if (e.Status == GestureStatus.Completed)
{
// Store the translation delta's of the wrapped user interface element.
xOffset = Content.TranslationX;
yOffset = Content.TranslationY;
}
};
IMI.GestureRecognizers.Add(pinchGesture);
}
public double Clamp1(double self, double min, double max)
{
return Math.Min(max, Math.Max(self, min));
}
}