/// <summary>
/// Event raised when the 'ContentOffsetY' property has changed value.
/// </summary>
private static void ContentOffsetY_PropertyChanged(DependencyObject o, DependencyPropertyChangedEventArgs e)
{
ZoomPanControl c = (ZoomPanControl)o;
c.UpdateTranslationY();
if (!c._disableContentFocusSync)
{
//
// Normally want to automatically update content focus when content offset changes.
// Although this is disabled using 'disableContentFocusSync' when content offset changes due to in-progress zooming.
//
c.UpdateContentZoomFocusY();
}
if (c.ContentOffsetYChanged != null)
{
//
// Raise an event to let users of the control know that the content offset has changed.
//
c.ContentOffsetYChanged(c, EventArgs.Empty);
}
if (!c._disableScrollOffsetSync && c._scrollOwner != null)
{
//
// Notify the owning ScrollViewer that the scrollbar offsets should be updated.
//
c._scrollOwner.InvalidateScrollInfo();
}
}
/// <summary>
/// Method called to clamp the 'ContentScale' value to its valid range.
/// </summary>
private static object ContentScale_Coerce(DependencyObject d, object baseValue)
{
ZoomPanControl c = (ZoomPanControl)d;
double value = (double)baseValue;
value = Math.Min(Math.Max(value, c.MinContentScale), c.MaxContentScale);
return(value);
}
/// <summary>
/// Event raised when the 'ContentScale' property has changed value.
/// </summary>
private static void ContentScale_PropertyChanged(DependencyObject o, DependencyPropertyChangedEventArgs e)
{
ZoomPanControl c = (ZoomPanControl)o;
if (c._contentScaleTransform != null)
{
//
// Update the content scale transform whenever 'ContentScale' changes.
//
c._contentScaleTransform.ScaleX = c.ContentScale;
c._contentScaleTransform.ScaleY = c.ContentScale;
}
//
// Update the size of the viewport in content coordinates.
//
c.UpdateContentViewportSize();
if (c._enableContentOffsetUpdateFromScale)
{
try
{
//
// Disable content focus synchronization. We are about to update content offset whilst zooming
// to ensure that the viewport is focused on our desired content focus point. Setting this
// to 'true' stops the automatic update of the content focus when content offset changes.
//
c._disableContentFocusSync = true;
//
// Whilst zooming in or out keep the content offset up-to-date so that the viewport is always
// focused on the content focus point (and also so that the content focus is locked to the
// viewport focus point - this is how the Google maps style zooming works).
//
double viewportOffsetX = c.ViewportZoomFocusX - (c.ViewportWidth / 2);
double viewportOffsetY = c.ViewportZoomFocusY - (c.ViewportHeight / 2);
double contentOffsetX = viewportOffsetX / c.ContentScale;
double contentOffsetY = viewportOffsetY / c.ContentScale;
c.ContentOffsetX = (c.ContentZoomFocusX - (c.ContentViewportWidth / 2)) - contentOffsetX;
c.ContentOffsetY = (c.ContentZoomFocusY - (c.ContentViewportHeight / 2)) - contentOffsetY;
}
finally
{
c._disableContentFocusSync = false;
}
}
if (c.ContentScaleChanged != null)
{
c.ContentScaleChanged(c, EventArgs.Empty);
}
if (c._scrollOwner != null)
{
c._scrollOwner.InvalidateScrollInfo();
}
}
/// <summary>
/// Method called to clamp the 'ContentOffsetY' value to its valid range.
/// </summary>
private static object ContentOffsetY_Coerce(DependencyObject d, object baseValue)
{
ZoomPanControl c = (ZoomPanControl)d;
double value = (double)baseValue;
double minOffsetY = 0.0;
double maxOffsetY = Math.Max(0.0, c._unScaledExtent.Height - c._constrainedContentViewportHeight);
value = Math.Min(Math.Max(value, minOffsetY), maxOffsetY);
return(value);
}
/// <summary>
/// Method called to clamp the 'ContentOffsetX' value to its valid range.
/// </summary>
private static object ContentOffsetX_Coerce(DependencyObject d, object baseValue)
{
ZoomPanControl c = (ZoomPanControl)d;
double value = (double)baseValue;
double minOffsetX = 0.0;
double maxOffsetX = Math.Max(0.0, c.unScaledExtent.Width - c.constrainedContentViewportWidth);
value = Math.Min(Math.Max(value, minOffsetX), maxOffsetX);
return(value);
}
/// <summary>
/// Event raised 'MinContentScale' or 'MaxContentScale' has changed.
/// </summary>
private static void MinOrMaxContentScale_PropertyChanged(DependencyObject o, DependencyPropertyChangedEventArgs e)
{
ZoomPanControl c = (ZoomPanControl)o;
c.ContentScale = Math.Min(Math.Max(c.ContentScale, c.MinContentScale), c.MaxContentScale);
}