I'm working on a custom grid-like panel where one element can be zoomed.
First, all elements have the same size. If one should be zoomed, it gets twice its previous size and the rest of the elements fill the remaining space uniformly (so, all elements except the ones in the same row or column with the zoomed element get smaller height and width, the ones in the same row get a smaller width and zoomed height, etc.).
Everything worked fine until I added animations for the zoom.
I'm calculating the size of each element in the measure pass and at first I was measuring each element with its calculated size. The elements itself have NaN as size until they get zoomed. I'm zooming them by setting them to their final size and then start doubleanimations from old to new.
However when I added animations, measure and arrange were only called for the first animation step.
And when I tried to measure the elements with availableSize or an infinite size the animation worked fine but the elements didn't proper resize in the dimensions where they got smaller.
Does anyone know how to solve either one of those behaviors?
Regards
Tobias
Edit: Code for animations:
Size normalSize = GetNormalElementSize(new Size(ActualWidth, ActualHeight));
DoubleAnimation widthAnimation = new DoubleAnimation
{
From = normalSize.Width,
To = normalSize.Width * 2,
Duration = TimeSpan.FromMilliseconds(750),
EasingFunction = new QuadraticEase { EasingMode = EasingMode.EaseInOut }
};
DoubleAnimation heightAnimation = new DoubleAnimation
{
From = normalSize.Height,
To = normalSize.Height * 2,
Duration = TimeSpan.FromMilliseconds(750),
EasingFunction = new QuadraticEase { EasingMode = EasingMode.EaseInOut }
};
ZoomedElement.Height = normalSize.Height;
ZoomedElement.Width = normalSize.Width;
Storyboard.SetTargetProperty(widthAnimation, new PropertyPath(FrameworkElement.WidthProperty));
Storyboard.SetTarget(widthAnimation, ZoomedElement);
Storyboard.SetTargetProperty(heightAnimation, new PropertyPath(FrameworkElement.HeightProperty));
Storyboard.SetTarget(heightAnimation, ZoomedElement);
Storyboard zoomStoryboard = new Storyboard();
zoomStoryboard.Children.Add(heightAnimation);
zoomStoryboard.Children.Add(widthAnimation);
zoomStoryboard.CurrentTimeInvalidated += zoomStoryboard_CurrentTimeInvalidated;
zoomStoryboard.Begin();
I guess you are using RenderTransformation, try LayoutTransformation instead.
Related
I have the following ChartArea Annotation settings set up:
private void chart1_PrePaint(object sender, ChartPaintEventArgs e)
{
if (e.ChartElement is ChartArea)
{
var ta = new TextAnnotation();
ta.IsMultiline = true;
ta.Text = "Results of Calculation\n%";
ta.Width = e.Position.Width;
ta.Height = e.Position.Height;
ta.X = e.Position.X;
ta.Y = e.Position.Y;
ta.Font = new Font("Candara", e.Position.Height / 10, FontStyle.Regular);
chart1.Annotations.Add(ta);
}
}
A few issues with this, and with the Legend in relation to my other posted question:
My other Pie Chart Legend/ChartArea question
With this PrePaint setup, I'm not sure if my position is correct for the TextAnnotation. I'm using the e.Position but it's coming out not "exactly" centered in the middle of the doughnut of the pie chart area. I'd like it to be centered perfectly. Not sure what other property to use here.
A second issue is that when Legend text length changes, it "pushes" and makes the ChartArea itself smaller so the pie chart gets smaller. I'd like it to be the other way around, where the ChartArea pie chart stays the same size but the Legend gets pushes aside.
Is this possible?
The following is the position setup of the pie chart:
Thanks
I'm sorry I couldn't help more, last time. I tested the centering of the TextAnnotation and in fact it has problems when the InnerPlotPosition is set to auto. Moreover, the answer found at link creates a new instance of the TextAnnotation at every PrePaint, causing the overlapping of TextAnnotations and the blurrying of the centered text.
I couldn't find a way to avoid the resizing of the doughnut (I'm not sure it's even possible, at this point...I'll wait for some other answers) but maybe this can work out as a workaround.
First I created a dictionary to store the centered TextAnnotations references (the key is the graph name, in case you have more than one), then in the PrePaint event I get the correct reference of the TextAnnotation used in the graph and update the coordinates of that one.
Second, I set the InnerPlotPosition manually, this seems to solve the problem of the centering of the TextAnnotation. Of course, you need to specify coordinates and size for the InnerPlot like I did with the line:
chart1.ChartAreas[0].InnerPlotPosition = new ElementPosition(0, 0, 60.65f, 94.99f);
Lastly, I set the position and the size of the legend manually and, with the extension method WrapAt I set a "line break" every _maxLegendTextBeforeWrap in the legend items text. Couldn't find a way to make it dynamically change with the width of the legend area, so it has to be set manually.
Below there's a GIF of the resulting effect. Don't know if this suits you as a solution (too much tweaking and code, for my taste), but anyway. Maybe this can trigger some new ideas on how to solve.
To do so I created these global variables:
/// <summary>
/// Saves the currently doughnut centered annotations per graph.
/// </summary>
private IDictionary<string, TextAnnotation> _annotationsByGraph;
/// <summary>
/// Number of characters
/// </summary>
private int _maxLegendTextBeforeWrap = 10;
/// <summary>
/// Legend area width.
/// </summary>
private int _legendWidth = 20;
/// <summary>
/// Legend area height.
/// </summary>
private int _legendHeight = 90;
This is the handler of the Load event:
private void ChartTest_Load(object sender, EventArgs e)
{
// ** Start of test data **
chart1.Series["Series1"].Points.AddXY("A", 33);
chart1.Series["Series1"].Points[0].LegendText = "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA";
chart1.Series["Series1"].Points.AddXY("B", 33);
chart1.Series["Series1"].Points[1].LegendText = "BBBBBBBBBBBBBBBBBBBB";
chart1.Series["Series1"].Points.AddXY("C", 34);
chart1.Series["Series1"].Points[2].LegendText = "CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC";
// ** End of test data **
// Creates a new instance of the dictionary storing the references to the annotations.
_annotationsByGraph = new Dictionary<string, TextAnnotation>();
// Createa a new instance of an annotation for the chart1 graph.
_annotationsByGraph.Add(chart1.Name, new TextAnnotation());
// Manually setting the position of the chart area prevents the imperfect positioning of the
// TextAnnotation at the center of the doughnut.
chart1.ChartAreas[0].Position.Auto = true;
// Manually set the position of the InnerPlotPosition area prevents the imperfect positioning of the
// TextAnnotation at the center of the doughnut.
chart1.ChartAreas[0].InnerPlotPosition.Auto = false;
chart1.ChartAreas[0].InnerPlotPosition = new ElementPosition(0, 0, 60.65f, 94.99f);
// Minimum size for the legend font.
chart1.Legends[0].AutoFitMinFontSize = 5;
// Set the legend style as column.
chart1.Legends[0].LegendStyle = LegendStyle.Column;
// Splits the legend texts with the space char every _maxLegendTextBeforeWrap characters.
chart1.Series["Series1"].Points.ToList().ForEach(p => p.LegendText = p.LegendText.WrapAt(_maxLegendTextBeforeWrap));
}
This is the handler of the PrePaint event:
private void chart1_PrePaint(object sender, ChartPaintEventArgs e)
{
if (e.ChartElement is ChartArea)
{
// Get the reference to the corresponding text annotation for this chart.
// We need this, otherwise we are creating and painting a new instance of a TextAnnotation
// at every PrePaint, with the resulting blurrying effect caused by the overlapping of the text.
var ta = _annotationsByGraph[e.Chart.Name];
// Check if the annotation has already been added to the chart.
if (!e.Chart.Annotations.Contains(ta))
e.Chart.Annotations.Add(ta);
// Set the properties of the centered TextAnnotation.
ta.IsMultiline = true;
ta.Text = "Results of Calculation\nx%";
ta.Font = new Font("Candara", e.Position.Height / 10, FontStyle.Regular);
ta.Width = e.Position.Width;
ta.Height = e.Position.Height;
ta.X = e.Position.X;
ta.Y = e.Position.Y;
// Move the legend manually to the right of the doughnut.
e.Chart.Legends[0].Position = new ElementPosition(e.Position.X + e.Position.Width, e.Position.Y, _legendWidth, _legendHeight);
}
}
This is what the button does:
private void BtnChangeLegendItemLength_Click(object sender, EventArgs e)
{
if (chart1.Series["Series1"].Points[1].LegendText.StartsWith("DD"))
chart1.Series["Series1"].Points[1].LegendText = "BBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBB".WrapAt(_maxLegendTextBeforeWrap);
else
chart1.Series["Series1"].Points[1].LegendText = "DDDDDD".WrapAt(_maxLegendTextBeforeWrap);
}
This is the extension method definition:
internal static class ExtensionMethods
{
public static string WrapAt(this string legendText, int maxLengthBeforeWrap)
{
if (legendText.Length <= maxLengthBeforeWrap)
return legendText;
// Integer division to get how many times we have to insert a space.
var times = legendText.Length / maxLengthBeforeWrap;
// Counter of added spaces.
var spacesAdded = 0;
// Iterate for each space char needed.
for (var i = 1; i <= times; i++)
{
// Insert a space char every maxLengthBeforeWrap positions.
legendText = legendText.Insert(maxLengthBeforeWrap * i + spacesAdded, new string(' ', 1));
spacesAdded++;
}
return legendText;
}
}
My linear algebra is weak. WPF is a great system for Rendering different transformations upon an image. However, the standard ScaleTransform will only scale the image's along the x-y axes. When the edges have first been rotated, the result of applying the ScaleTransform will result in a skewed transformation (as shown below) since the edges are no longer aligned.
So, if I have an image that has undergone several different transforms with the result being shown by the WPF rendering system, how do I calculate the correct matrix transform to take the (final rotated image) and scale it along the axes of the rendered image?
Any help or suggestions will be most appreciated.
TIA
(For the complete code, please see my previous question.)
Edit #1: To see the above effect:
Drop image onto Inkcavas. -- no skewing seen.
Rotate image counterclockwise (to about 45deg) -- no skewing seen.
Make the image larger (about twice its prescaled size -- no skewing seen.
Rotate the image clockwise (about back to where it started) -- skewing is
immediately seen during and after the rotation.
If step 3 is skipped, simple rotation -- no matter how many times done -- will not cause the skewing effect. Actually, this makes sense. The ScaleTransform preserves the distance from center from the edges of the image. If the image is at an angle, the x-y distance from the edges of the transform are no longer constant through the width and length of the rendered image. So the edges get appropriately scaled, but the angles are changed.
Here is the most relevant code:
private ImageResizing(Image image)
{
if (image == null)
throw new ArgumentNullException("image");
_image = image;
TransformGroup tg = new TransformGroup();
image.RenderTransformOrigin = new Point(0.5, 0.5); // All transforms will be based on the center of the rendered element.
tg.Children.Add(image.RenderTransform); // Keeps whatever transforms have already been applied.
image.RenderTransform = tg;
_adorner = new MyImageAdorner(image); // Create the adorner.
InstallAdorner(); // Get the Adorner Layer and add the Adorner.
}
Note: The image.RenderTransformOrigin = new Point(0.5, 0.5) is set to the center
of the rendered image. All transforms will be based on the center of the image at the time it is seem by the transform.
public MyImageAdorner(UIElement adornedElement)
: base(adornedElement)
{
visualChildren = new VisualCollection(this);
// Initialize the Movement and Rotation thumbs.
BuildAdornerRotate(ref moveHandle, Cursors.SizeAll);
BuildAdornerRotate(ref rotateHandle, Cursors.Hand);
// Add handlers for move and rotate.
moveHandle.DragDelta += new DragDeltaEventHandler(moveHandle_DragDelta);
moveHandle.DragCompleted += new DragCompletedEventHandler(moveHandle_DragCompleted);
rotateHandle.DragDelta += new DragDeltaEventHandler(rotateHandle_DragDelta);
rotateHandle.DragCompleted += new DragCompletedEventHandler(rotateHandle_DragCompleted);
// Initialize the Resizing (i.e., corner) thumbs with specialized cursors.
BuildAdornerCorner(ref topLeft, Cursors.SizeNWSE);
// Add handlers for resizing.
topLeft.DragDelta += new DragDeltaEventHandler(TopLeft_DragDelta);
topLeft.DragCompleted += TopLeft_DragCompleted;
// Put the outline border arround the image. The outline will be moved by the DragDelta's
BorderTheImage();
}
#region [Rotate]
/// <summary>
/// Rotate the Adorner Outline about its center point. The Outline rotation will be applied to the image
/// in the DragCompleted event.
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
void rotateHandle_DragDelta(object sender, DragDeltaEventArgs e)
{
// Get the position of the mouse relative to the Thumb. (All cooridnates in Render Space)
Point pos = Mouse.GetPosition(this);
// Render origin is set at center of the adorned element. (all coordinates are in rendering space).
double CenterX = AdornedElement.RenderSize.Width / 2;
double CenterY = AdornedElement.RenderSize.Height / 2;
double deltaX = pos.X - CenterX;
double deltaY = pos.Y - CenterY;
double angle;
if (deltaY.Equals(0))
{
if (!deltaX.Equals(0))
angle = 90;
else
return;
}
else
{
double tan = deltaX / deltaY;
angle = Math.Atan(tan); angle = angle * 180 / Math.PI;
}
// If the mouse crosses the vertical center,
// find the complementary angle.
if (deltaY > 0)
angle = 180 - Math.Abs(angle);
// Rotate left if the mouse moves left and right
// if the mouse moves right.
if (deltaX < 0)
angle = -Math.Abs(angle);
else
angle = Math.Abs(angle);
if (double.IsNaN(angle))
return;
// Apply the rotation to the outline. All Transforms are set to Render Center.
rotation.Angle = angle;
rotation.CenterX = CenterX;
rotation.CenterY = CenterY;
outline.RenderTransform = rotation;
}
/// Rotates image to the same angle as outline arround the render origin.
void rotateHandle_DragCompleted(object sender, DragCompletedEventArgs e)
{
// Get Rotation Angle from outline. All element rendering is set to rendering center.
RotateTransform _rt = outline.RenderTransform as RotateTransform;
// Add RotateTransform to the adorned element.
TransformGroup gT = AdornedElement.RenderTransform as TransformGroup;
RotateTransform rT = new RotateTransform(_rt.Angle);
gT.Children.Insert(0, rT);
AdornedElement.RenderTransform = gT;
outline.RenderTransform = Transform.Identity; // clear transform from outline.
}
#endregion //Rotate
#region [TopLeft Corner
// Top Left Corner is being dragged. Anchor is Bottom Right.
void TopLeft_DragDelta(object sender, DragDeltaEventArgs e)
{
ScaleTransform sT = new ScaleTransform(1 - e.HorizontalChange / outline.ActualWidth, 1 - e.VerticalChange / outline.ActualHeight,
outline.ActualWidth, outline.ActualHeight);
outline.RenderTransform = sT; // This will immediately show the new outline without changing the Image.
}
/// The resizing outline for the TopLeft is based on the bottom right-corner. The resizing transform for the
/// element, however, is based on the render origin being in the center. Therefore, the Scale transform
/// received from the outling must be recalculated to have the same effect--only from the rendering center.
///
/// TopLeft_DragCompleted resize the element rendering.
private void TopLeft_DragCompleted(object sender, DragCompletedEventArgs e)
{
// Get new scaling from the Outline.
ScaleTransform _sT = outline.RenderTransform as ScaleTransform;
scale.ScaleX *= _sT.ScaleX; scale.ScaleY *= _sT.ScaleY;
Point Center = new Point(AdornedElement.RenderSize.Width/2, AdornedElement.RenderSize.Height/2);
TransformGroup gT = AdornedElement.RenderTransform as TransformGroup;
ScaleTransform sT = new ScaleTransform( _sT.ScaleX, _sT.ScaleY, Center.X, Center.Y);
gT.Children.Insert(0, sT);
AdornedElement.RenderTransform = gT;
outline.RenderTransform = Transform.Identity; // Clear outline transforms. (Same as null).
}
#endregion
Note: I am adding each new transform to the first of the children list. This makes calculations on the image easier.
I could not find with Google or in text all the elements needed to answer this question completely. So, for all other newbies like my self, I will post this (very long) answer. (Editors and Gurus please feel free to correct).
A word toward setup. I have an inkcanvas onto which an image is dropped and added as a child of the inkcanvas. At the time of the drop, an adorner containing a Thumb on each corner for resizing, a Top-Middle thumb for rotating, and a middle thumb for translation is added for final positioning of the image. Along with a "outline" designed as a path element, the Thumbs and outline complete the Adorner and create a kind of wire frame around the adorned element.
There are multiple key points:
WPF first uses a layout pass to position elements within their parent container, followed by a rendering pass to arrange the element. Transforms can be applied to either or both the layout and rendering passes. However, it needs to be noted that the layout pass uses an x-y coordinate system with the origin on the top left of the parent, where as the rendering system inherently references the top left of the child element. If the layout position of the dropped element is not specifically defined, it will by default be added to the "origin" of the parent container.
The RenderTransform is by default a MatrixTransform but can be replaced by a TransformGroup. Using either or both of these allows for Matrices (in the MatrixTransform) or Transforms (in the TransformGroup) to be applied in any order. My preference was to use the MatrixTransforms to better see the relationship between scaling, rotation, and translation.
The rendering of the adorner follows the element it adorns. That is, the element's rendering will also be applied to the Adorner. This behavior can be overriden by use of
public override GeneralTransform GetDesiredTransform(GeneralTransform transform)
As noted in the initial question, I had avoided using SetTop() and SetLeft() as they messed up my other matrices. In hindsight, the reason my matrices failed was because SetTop() and SetLeft() apparently work during the layout phase--so all my coordinates for rendering were off. (I was using a TransalateTransform to position the image upon drag-drop.) However, using SetTop() and SetLeft() apparently act during the Layout Phase. Using this greatly simplified the calculations needed for the Rendering Phase since all coordinates could refer to the image without regard to the position on the canvas.
private void IC_Drop(object sender, DragEventArgs e)
{
InkCanvas ic = sender as InkCanvas;
// Setting InkCanvasEditingMode.None is necessary to capture DrawingLayer_MouseDown.
ic.EditingMode = InkCanvasEditingMode.None;
ImageInfo image_Info = e.Data.GetData(typeof(ImageInfo)) as ImageInfo;
if (image_Info != null)
{
// Display enlarged image on ImageLayer
// This is the expected format for the Uri:
// ImageLayer.Source = new BitmapImage(new Uri("/Images/Female - Front.png", UriKind.Relative));
// Source = new BitmapImage(image_Info.Uri);
Image image = new Image();
image.Width = image_Info.Width * 4;
// Stretch.Uniform keeps the Aspect Ratio but totally screws up resizing the image.
// Stretch.Fill allows for resizing the Image without keeping the Aspect Ratio.
image.Stretch = Stretch.Fill;
image.Source = new BitmapImage(image_Info.Uri);
// Position the drop. Note that SetLeft and SetTop are active during the Layout phase of the image drop and will
// be applied before the Image hits its Rendering stage.
Point position = e.GetPosition(ic);
InkCanvas.SetLeft(image, position.X);
InkCanvas.SetTop(image, position.Y);
ic.Children.Add(image);
ImageResizing imgResize = ImageResizing.Create(image);
}
}
Since I want to be able to resize the image from any direction, the image is set with Stretch.Fill. When Stretch.Uniform was used, the image appeared to first be resized then jump back to its initial size.
Since I am using MatrixTransform, the order of the Matrices is important. So when applying the Matrices, for my use
// Make new render transform. The Matrix order of multiplication is extremely important.
// Scaling should be done first, followed by (skewing), rotation and translation -- in
// that order.
MatrixTransform gT = new MatrixTransform
{
Matrix = sM * rM * tM
};
ele.RenderTransform = gT;
Scaling (sM), is performed before Rotation (rM). Translation is applied last. (C# does matrix multiplication from left to right).
In review of the matrices, it is apparent that the Rotation Matrix also involves skewing elements. (Which makes sense since apparently the RotationTransform is intended to keep the angles at the edges constant). Thus, the Rotation Matrix depends on the size of the image.
In my case, the reason scaling after rotation was causing skewing is because the Scaling transform multiplies the distance between points of the image and the x-y axes. So if the edge of the image is not of constant distance to the x-y axes, scaling will distort (i.e., skew) the image.
Putting this together, results in the following method to resize the image:
Action<Matrix, Vector> DragCompleted = (growthMatrix, v) =>
{
var ele = AdornedElement;
// Get the change vector. Transform (i.e, Rotate) change vector into x-y axes.
// The Horizontal and Vertical changes give the distance between the the current cursor position
// and the Thumb.
Matrix m = new Matrix();
m.Rotate(-AngleDeg);
Vector v1 = v * m;
// Calculate Growth Vector.
var gv = v1 * growthMatrix;
// Apply new scaling along the x-y axes to obtain the rendered size.
// Use the current Image size as the reference to calculate the new scaling factors.
var scaleX = sM.M11; var scaleY = sM.M22;
var W = ele.RenderSize.Width * scaleX; var H = ele.RenderSize.Height * scaleY;
var sx = 1 + gv.X/ W; var sy = 1 + gv.Y / H;
// Change ScalingTransform by applying the new scaling factors to the existing scaling transform.
// Do not add offsets to the scaling transform matrix as they will be included in future scalings.
// With RenderTransformOrigin set to the image center (0.5, 0.5), scalling occurs from the center out.
// Move the new center of the new resized image to its correct position such that the image's thumb stays
// underneath the cursor.
sM.Scale(sx, sy);
tM.Translate(v.X / 2, v.Y / 2);
// New render transform. The order of the transform's is extremely important.
MatrixTransform gT = new MatrixTransform
{
Matrix = sM * rM * tM
};
ele.RenderTransform = gT;
outline.RenderTransform = Transform.Identity; // clear this transform from the outline.
};
Just to be clear, my "Growth Matrix" is defined in such a manner as to result in "Positive" growth as the cursor is moved away from the center of the image. For Example, the TopLeft corner will "grow" the image when moved to the left and up. Hence
growth matrix = new Matrix(-1, 0, 0, -1, 0, 0) for top-left corner.
The last problem is that of correctly calculating the rotation center (i.e., I want to spin, not orbit). This becomes greatly simplified by using
// All transforms will be based on the center of the rendered element.
AdornedElement.RenderTransformOrigin = new Point(0.5, 0.5);
Lastly, since I am scaling from a corner, the center of the image needs to be translated to keep the corner underneath the cursor.
Sorry for the length of this answer, but there is much to cover (and learn :) ). Hope this helps somebody.
I'm looking to create a scrolling surfacelistbox which automatically snaps into a position after a drag is finished so that the center item on the screen is centered itself in the viewport.
I've gotten the center item, but now as usual the way that WPF deals with sizes, screen positions, and offsets has me perplexed.
At the moment I've chosen to subscribe to the SurfaceScrollViewer's ManipulationCompleted event, as that seems to consistently fire after I've finished a scroll gesture (whereas the ScrollChanged event tends to fire early).
void ManipCompleted(object sender, ManipulationCompletedEventArgs e)
{
FocusTaker.Focus(); //reset focus to a dummy element
List<FrameworkElement> visibleElements = new List<FrameworkElement>();
for (int i = 0; i < List.Items.Count; i++)
{
SurfaceListBoxItem item = List.ItemContainerGenerator.ContainerFromIndex(i) as SurfaceListBoxItem;
if (ViewportHelper.IsInViewport(item) && (List.Items[i] as string != "Dummy"))
{
FrameworkElement el = item as FrameworkElement;
visibleElements.Add(el);
}
}
int centerItemIdx = visibleElements.Count / 2;
FrameworkElement centerItem = visibleElements[centerItemIdx];
double center = ss.ViewportWidth / 2;
//ss is the SurfaceScrollViewer
Point itemPosition = centerItem.TransformToAncestor(ss).Transform(new Point(0, 0));
double desiredOffset = ss.HorizontalOffset + (center - itemPosition.X);
ss.ScrollToHorizontalOffset(desiredOffset);
centerItem.Focus(); //this also doesn't seem to work, but whatever.
}
The list snaps, but where it snaps seems to be somewhat chaotic. I have a line down the center of the screen, and sometimes it looks right down the middle of the item, but other times it's off to the side or even between items. Can't quite nail it down, but it seems that the first and fourth quartile of the list work well, but the second and third are progressively more off toward the center.
Just looking for some help on how to use positioning in WPF. All of the relativity and the difference between percentage-based coordinates and 'screen-unit' coordinates has me somewhat confused at this point.
After a lot of trial and error I ended up with this:
void ManipCompleted(object sender, ManipulationCompletedEventArgs e)
{
FocusTaker.Focus(); //reset focus
List<FrameworkElement> visibleElements = new List<FrameworkElement>();
for (int i = 0; i < List.Items.Count; i++)
{
SurfaceListBoxItem item = List.ItemContainerGenerator.ContainerFromIndex(i) as SurfaceListBoxItem;
if (ViewportHelper.IsInViewport(item))
{
FrameworkElement el = item as FrameworkElement;
visibleElements.Add(el);
}
}
Window window = Window.GetWindow(this);
double center = ss.ViewportWidth / 2;
double closestCenterOffset = double.MaxValue;
FrameworkElement centerItem = visibleElements[0];
foreach (FrameworkElement el in visibleElements)
{
double centerOffset = Math.Abs(el.TransformToAncestor(window).Transform(new Point(0, 0)).X + (el.ActualWidth / 2) - center);
if (centerOffset < closestCenterOffset)
{
closestCenterOffset = centerOffset;
centerItem = el;
}
}
Point itemPosition = centerItem.TransformToAncestor(window).Transform(new Point(0, 0));
double desiredOffset = ss.HorizontalOffset - (center - itemPosition.X) + (centerItem.ActualWidth / 2);
ss.ScrollToHorizontalOffset(desiredOffset);
centerItem.Focus();
}
This block of code effectively determines which visible list element is overlapping the center line of the list and snaps that element to the exact center position. The snapping is a little abrupt, so I'll have to look into some kind of animation, but otherwise I'm fairly happy with it! I'll probably use something from here for animations: http://blogs.msdn.com/b/delay/archive/2009/08/04/scrolling-so-smooth-like-the-butter-on-a-muffin-how-to-animate-the-horizontal-verticaloffset-properties-of-a-scrollviewer.aspx
Edit: Well that didn't take long. I expanded the ScrollViewerOffsetMediator to include HorizontalOffset and then simply created the animation as suggested in the above post. Works like a charm. Hope this helps someone eventually.
Edit2: Here's the full code for SnapList:
SnapList.xaml
SnapList.xaml.cs
Note that I got pretty lazy as this project went on an hard-coded some of it. Some discretion will be needed to determine what you do and don't want from this code. Still, I think this should work pretty well as a starting point for anyone who wants this functionality.
The code has also changed from what I pasted above; I found that using Windows.GetWindow gave bad results when the list was housed in a control that could move. I made it so you can assign a control for your movement to be relative to (recommended that be the control just above your list in the hierarchy). I think a few other things changed as well; I've added a lot of customization options including being able to define a custom focal point for the list.
I've got a custom (and getting complex) TabControl. It's a gathering of many sources, plus my own wanted features. In it is a custom Panel to show the headers of the TabControl. Its features are to compress the size of the TabItems until they reached their minimum, and then activates scrolling features (in the Panel, again). There is also another custom panel to hold a single button, that renders on the right of the TabItems (it's a "new tab" button).
It all works great, until I try to animate the scrolling.
Here are some relevant snippets :
In the CustomTabPanel (C#, overriding Panel and implementing IScrollInfo):
private readonly TranslateTransform _translateTransform = new TranslateTransform();
public void LineLeft()
{
FirstVisibleIndex++;
var offset = HorizontalOffset + _childRects[0].Width;
if (offset < 0 || _viewPort.Width >= _extent.Width)
offset = 0;
else
{
if (offset + _viewPort.Width > _extent.Width)
offset = _extent.Width - _viewPort.Width;
}
_offset.X = offset;
if (_scrollOwner != null)
_scrollOwner.InvalidateScrollInfo();
//Animate the new offset
var aScrollAnimation = new DoubleAnimation(_translateTransform.X, -offset,
new Duration(this.AnimationTimeSpan), FillBehavior.HoldEnd) { AccelerationRatio = 0.5, DecelerationRatio = 0.5 };
aScrollAnimation.Completed += ScrollAnimationCompleted;
_translateTransform.BeginAnimation(TranslateTransform.XProperty, aScrollAnimation , HandoffBehavior.SnapshotAndReplace);
//End of animation
// These lines are the only ones needed if we remove the animation
//_translateTransform.X = -offset;
//InvalidateMeasure();
}
void ScrollAnimationCompleted(object sender, EventArgs e)
{
InvalidateMeasure();
}
the _translateTransform is initialized in the constructor :
base.RenderTransform = _translateTransform;
Again, everything is fine if I remove the animation part and just replace it with the commented out lines at the end.
I must also point out that the problem is NOT with the animation itself. That part works out well. The problem is about when I remove some tab items : all the layout then screws up. The TranslateTransformation seems to hold on some wrong value, or something.
Thanks in advance.
Well. As it's often the case, I kept working on the thing, and... answered myself.
Could still be useful for other people, so here was the catch. In the line :
var aScrollAnimation = new DoubleAnimation(_translateTransform.X, -offset, new Duration(this.AnimationTimeSpan), FillBehavior.HoldEnd)
{ AccelerationRatio = 0.5, DecelerationRatio = 0.5 };
the FillBehavior should have been FillBehavior.Stop.
As easy as that!
I want to change the direction of my marquee on changeDirection button click.
My code for changing direction is :
private void changeDirection_click(object sender, RoutedEventArgs e)
{
if (_marqueeType == MarqueeType.RightToLeft)
{
_marqueeType = MarqueeType.LeftToRight;
StartMarqueeing(_marqueeType);
}
else if (_marqueeType == MarqueeType.LeftToRight)
{
_marqueeType = MarqueeType.RightToLeft;
StartMarqueeing(_marqueeType);
}
}
And code for start marquee is :
public void StartMarqueeing(MarqueeType marqueeType)
{
double height = canMain.ActualHeight - marqueeList.ActualHeight;
marqueeList.Margin = new Thickness(0, 0, 0, 0);
doubleAnimation.From = -marqueeList.ActualWidth;
doubleAnimation.To = canMain.ActualWidth;
doubleAnimation.RepeatBehavior = RepeatBehavior.Forever;
doubleAnimation.Duration = new Duration(TimeSpan.FromSeconds(_marqueeTimeInSeconds));
if (marqueeType == MarqueeType.RightToLeft)
{
Storyboard.SetTargetProperty(doubleAnimation, new PropertyPath("(Canvas.Right)"));
_storyBoard.Children.Add(doubleAnimation);
_storyBoard.Begin(marqueeList, true);
}
else if (marqueeType == MarqueeType.LeftToRight)
{
Storyboard.SetTargetProperty(doubleAnimation, new PropertyPath("(Canvas.Left)"));
_storyBoard.Children.Add(doubleAnimation);
_storyBoard.Begin(marqueeList, true);
}
}
Now here I am able to change the direction from Right to Left only first time.
But when I am change it from Left to Right it’s not changing the marquee position Left to Right.
It looks like you left out a _storyboard = new Storyboard(), perhaps at the top of the StartMarqueeing method.
From what I see it appears that every call to StartMarqueeing will add an additional DoubleAnimation to the storyboard, then start it again. So all the old DoubleAnimations will be recreated, and it looks like they take precedence.
Try creating a new Storyboard object each time, not just re-using it and adding to its children collection.
Update
Oh, now I see the problem. You should not be setting both (Canvas.Left) and (Canvas.Right). Use only one of the two: That's all you need anyway, and using both will give the Canvas conflicting instructions. Traditionally people use (Canvas.Left). I think that's what Canvas selects, which is what is causing your asymmetry.
You may wonder why I say you are using both when you don't think your two animations every run at the same time. Actually they do: The first animation runs then holds the value on the animated property until it is removed or bumped off by another animation. If the second animation then runs and modifies a different property it doesn't bump off the first animation so the first animation's value is still present.
The bottom line is, using (Canvas.Left) on both animations should fix it as long as you are using the default HandoffBehavior.SnapshotAndReplace.