In my program I would like to make two different things, one with the single touch, second with the two finger touch. But I don’t know how to handle the difference between single touch and two finger touch.
What should I do to achive that ?
Thanks.
UIElement has the ManipulationStarted event. The ManipulationStartedEventArgs has a property named Manipulators (IEnumerable). The count of Manipulators is the number of contacts being used (e.g. 2 elements would mean 2 fingers).
Also available is the ManipulationDelta event. The args there also has a Manipulators property.
Related
Is there a way in WPF to get active touch points? I need to determine if user is touching screen, similar to Mouse classes' Pressed -property?
I just need to know if any touch is present on the screen - don't mind what UIElement it's touching.
Here are two options, but they may not be the most correct way to do it:
1) You could subscribe to the MainWindow.PreviewTouchDown and MainWindow.PreviewTouchUp and maintain a list of all the current touch devices. It would be easy to implement but could make your code messy.
2) Subscribe to Touch.FrameReported which you can get a collection of touch points from the TouchFrameEventArgs.GetTouchPoints(null);. This will happen on every touch event firing, so it may be too often, but it would allow you to handle this event from any class.
You can subscribe to your main windows ManipulationStarting event (when the first finger makes contact with the screen), ManipulationInertiaStarting event (when the last finger lifts off the screen) and/or ManipulationDelta event (when any finger moves).
Within your event handlers you can get a list of all current touchpoints via ManipulationDeltaEventArgs.Manipulators
Don't forget to set your main window's IsManipulationEnabled to true.
This way you just have to remember whether a manipulation is currently in progress or not. You don't have to keep track of all the individual touch points yourself.
I want an event handler that handles the event when the grid splitter is being moved, Im not sure if there is one, if not, I guess I can generated an event when the size of the rows are changed?
Thanks.
You could do the rows changing size, but GridSplitter itself is a Thumb and so has its own events such as DragStarted and DragCompleted. More details here.
Edit: If you make the GridSplitter focusable and allow it to be moved with the keyboard, read the answer by Benlitz for more information.
I didn't tested, but I'm pretty sure that the currently accepted answer from AresAvatar won't work if you're resizing the rows/columns using keyboard arrows (by giving the focus to the grid splitter). This is a rare but possible case that you should anticipate in your application.
When the grid splitter is moved (either by drag'n'drop or using keyboard arrows), it changes the Width/Height dependency properties of the ColumnDefinitions/RowDefinitions of the grid. You can easily register a handler on this property change:
var heightDescriptor = DependencyPropertyDescriptor.FromProperty(RowDefinition.HeightProperty, typeof(ItemsControl));
heightDescriptor.AddValueChanged(myGrid.RowDefinitions[0], HeightChanged);
(This snippet will for instance track size change in the first row of the grid).
Then you can handle resize in an handler that will work in every case.
private void HeightChanged(object sender, EventArgs e)
{
// TODO: handle row resize
}
Generally, it is really not advised to rely on the user input action (mouse dragging, keyboard inputs...) to handle a logical or visual actions/events, since there are almost always several ways to do the same actions using different inputs (mouse, keyboards, touchscreen, ease-of-use tools...).
Use DragDelta. Be aware that if you want to change the size, use as the Actual property as the current size like ActualWidth instead of Width.
A WPF window should have hundreds of objects (rows of rectangles) and mouse clicking on each of them should fire similar actions. These actions differ only by several parameters (say "No. of Row" and "No. of position in a row").
Should I have hundreds of almost the same event handlers or how I could optimize my code?
Please give me some tips, just to move to the right direction.
Best regards.
WPF mitigates this problem by introducing Routed Events. At any level in the element hierarchy you may intercept events from its child elements and base your logic depending on the actual element that received this event in the first place (as presented by the Source property of RoutedEventArgs).
I'm no expert in WPF, but in event handling you could write 1 dans point every similar event to this handler. In the handler use the senter parameter to know whish control it came from.
Instead of 100's of similar event hander you could have a big one with a switch
Hope that's help
Can't you just use an instance of ICommand on your viewmodel and use the command parameter to determine which rectangle was clicked?
I hope this makes sense.
I have created several WPF User Controls. The lowest level item is 'PostItNote.xaml'. Next, I have a 'NotesGroup.xaml' file that has an ItemsControl bound to a List of PostItNotes. Above that, I have a 'ProgrammerControl.xaml' file. Each ProgrammerControl has a grid with four different NotesGroup user controls on it (and each NotesGroup contains 0-many PostItNotes.
Then, I have my main window. It also has an ItemsControl, bound to a list of Programmers.
So, you end up with a high level visual view of a list of programmers, each programmer has four groups of tickets, each group of tickets has many PostItNotes.
The trouble I'm having, is that I want to respond to a mouse click event in my mainWindow's code behind file.
I can add a MouseClick event into my PostItNote.xaml.vb file and that is getting called when the user clicks a PostItNote, and I can re-raise the event; but I can't seem to get the NotesGroup to listen for that event. I'm not sure if that's even the correct approach.
When the user clicks the PostItNote, I'm going to do a bunch of business-logic type stuff that the PostItNote control doesn't have a reference to/doesn't know about it.
Can anyone point me in the right direction?
You have a couple choices:
Use the PreviewXXX events which are fired during the "tunneling" phase of WPF event routing. The parent controls can always preview the events going down through them to children.
Use the more advanced approach to hooking up events leveraging the AddHandler method to which you can pass a parameter called "handledEventsToo" which basically means you want to know when the event happened "within" you even if some descendent element handled the event itself.
I am going to take a flyer here. You probably don't want to be handling the event that high up; not really anyway. You are catching the event at the lower levels, which is unavoidable. Consider invoking a routed command from the PostItNote click event handler.
The routed commands bubble up and tunnel down through the tree. You can have an architecture where a high-level handler can listen to a logical event (Opening a postit note perhaps?). The handler for this doesn't need to care where the command originates from. It might be from you clicking something, it might be from clicking on a toolbar button. Both are valid scenarios.
It sounds like you are creating some kind of custom UI, am I right? You want the application to respond to the users interactions. That is what the RoutedCommands are for.
My app has many controls on its surface, and more are added dynamically at runtime.
Although i am using tabs to limit the number of controls shown, and double-buffering too, it still flickers and stutters when it has to redraw (resize, maximize, etc).
What are your tips and tricks to improve WinForms app performance?
I know of two things you can do but they don't always apply to all situations.
You're going to get better performance if you're using absolute positioning for each control (myNewlyCreatedButton.Location.X/Y) as opposed to using a flow layout panel or a table layout panel. WinForms has to do a lot less math trying to figure out where controls should be placed.
If there is a single operation in which you're adding/removing/modifying a lot of controls, call "SuspendLayout()" on the container of the affected controls (whether it is a panel or the whole form), and when you're done with your work call "ResumeLayout()" on the same panel. If you don't, the form will have to do a layout pass each and every time you add/remove/modify a control, which cost a lot more time. see: http://msdn.microsoft.com/en-us/library/system.windows.forms.control.suspendlayout(VS.80).aspx
Although, I'm not sure how these approaches could apply when resizing a window.
Although more general than some of the other tips, here is mine:
When using a large number of "items", try to avoid creating a control for each one of them, rather reuse the controls. For example if you have 10 000 items, each corresponding to a button, it is very easy to (programatically) create a 10 000 buttons and wire up their event handlers, such that when you enter in the event handler, you know exactly which element you must work on. However it is much more efficient if you create, lets say, 500 buttons (because you know that only 500 buttons will be visible on the screen at any one time) and introduce a "mapping layer" between the buttons and the items, which dynamically reassigns the buttons to different items every time the user does something which would result in changing the set of buttons which should be visible (like moving a scrollbar for example).
Although, I'm not sure how these approaches could apply when resizing a window.
Handle the ResizeBegin and ResizeEnd events to call SuspendLayout() and ResumeLayout(). These events are only on the System.Windows.Form class (although I wish they were also on Control).
Are you making good use of SuspendLayout() and ResumeLayout()?
http://msdn.microsoft.com/en-us/library/system.windows.forms.control.suspendlayout(VS.80).aspx