Updated 10 Nov 2022
I have the following code in a Winforms program:
void CreateCheckBoxes(Control parentControl, int left, int top, int lineSpace)
{
List<string> listVariables = new List<string>() { "AllowColumnReorder", "CaptureFocusClick", "ColScaleMode", "ColumnTracking", "RowTracking", "EnsureVisible", "FullRowSelect", "GridLines", "HideSelection", "HoverSelection", "IsFocused", "LabelEdit", "MultiSelect", "Scrollable", "VisualStyles" };
foreach (string varName in listVariables)
{
CheckBox ctlTemp = new CheckBox { Name = "chk" + varName, Text = varName, Top = top, Left = left };
parentControl.Controls.Add(ctlTemp);
top += lineSpace;
}
chkAllowColumnReorder.CheckedChanged += new EventHandler(chkAllowColumnReorder_CheckedChanged);
// The name 'chkAllowColumnReorder' does not exist in the current context
}
It works to the extent that I can create as many CheckBoxes as I like based on the length of listVariables. However, I want the name of the CheckedChanged event handler to be based on the name of the control.
As well as my original question I now find I cannot refer to the CheckBox by the name provided in { Name = "chk" + varName, in the debugger a watch on "Name" returns the name of the form. I have not used this form of constructor before and am struggling to find any documentation on it. Can anybody help on this before I try to move on again please?
Is there a way to do this?
The code itself is produced by a small program where I just past in the names of variables from the main program and it produces the above, and all the vent handlers, which is an enormous time saver.
jimi - I've posted this as an answer as it's too long for a comment.
I ended up with:
Dictionary<string, Action<CheckBox>> m_Actions = new Dictionary<string, Action<CheckBox>>();
then loop through:
m_Actions.Add("chkAllowColumnReorder", (c) => containerListView1.AllowColumnReorder = c.Checked); etc.
and then:
void chkTemp_CheckedChanged(object sender, EventArgs e)
{
CheckBox chkTemp = ((CheckBox)sender);
m_Actions[chkTemp.Name](chkTemp);
}
This is completely new to me and I'm still not sure how (or why) it works but thank you very much for telling me about it - I can now paste variables in to my app's form and produce all the code to add controls to the app I need to test.
I did it because my heart sank at the thought of adding heaps of CheckBoxes to an app to test an ExtendeListView, in the end writing this to produce the code was much more interesting than the testing!
Related
Derived from Jeff S's methodology found here, I can add a "Checkbox" to a PDF page like so:
PdfPTable tblFirstRow = new PdfPTable(5);
tblFirstRow.SpacingBefore = 4f;
tblFirstRow.HorizontalAlignment = Element.ALIGN_LEFT;
. . . // code where textboxes are added has been elided for brevity
PdfPCell cell204Submitted = new PdfPCell()
{
CellEvent = new DynamicCheckbox("checkbox204Submitted", "204 Submitted or on file")
};
tblFirstRow.AddCell(cell204Submitted);
doc.Add(tblFirstRow);
The DynamicCheckbox class, based on Jeff S's CustomCellLayout class, is:
public class DynamicCheckbox : IPdfPCellEvent
{
private string fieldname;
private string cap;
public DynamicCheckbox(string name, String caption)
{
fieldname = name;
cap = caption;
}
public void CellLayout(PdfPCell cell, Rectangle rectangle, PdfContentByte[] canvases)
{
PdfWriter writer = canvases[0].PdfWriter;
RadioCheckField ckbx = new RadioCheckField(writer, rectangle, fieldname, "Yes");
ckbx.CheckType = RadioCheckField.TYPE_CHECK;
ckbx.Text = cap;
PdfFormField field = ckbx.CheckField;
writer.AddAnnotation(field);
}
}
My problem is that the checkbox's text (the string assigned to ckbx.Text) is not displaying. The checkbox (outsized) occupies the last cell in the table row, but there is no (visible) accompanying text.
What's missing from my code?
Note: I tried to reduce the size of the checkbox by doing this:
Rectangle tangle = new Rectangle(20, 20);
//RadioCheckField ckbx = new RadioCheckField(writer, rectangle, fieldname, "Yes");
RadioCheckField ckbx = new RadioCheckField(writer, tangle, fieldname, "Yes");
...but that attempt failed - with that code, I can't even "find" the checkbox in the generated PDF file - clicking willy-nilly in column 5 conjures up no checkbox...
Others have answered the label part. The Rectangle that you have called "tangle" needs to be calculated off of the rectangle that comes into the event handler, similar to
Rectangle tangle = new Rectangle(
rectangle.Left,
rectangle.Top - PDFStyle.boxsize - 4.5f,
rectangle.Left + PDFStyle.boxsize,
rectangle.Top - 4.5f
);
Where PDFStyle.boxsize is the width/height of the checkbox and 4.5f is the padding the edge of the cell. Basically the rectangle isn't relative to the cell, but absolute to the page.
As described in ISO-32000-1, a check box is a field of type Button. If you define text for a button, you want to define the text that is displayed on the button. However: in the case of a check box, there is no such text! Instead, you have two appearances, one for the Off value and one for the Yes value.
An educated guess made by an attentive reader would be that you don't want to add text (to the button), but that you want to add a label (for a checkbox). Again you should consult ISO-32000-1 and you'll discover that the spec doesn't say anything about labels for check boxes. The concept just doesn't exist at the level of an AcroForm.
This doesn't mean the concept doesn't exist in general. Many PDF tools allow you to define check boxes that are preceded by a label. When you look inside the PDF, you'll discover that this label is just part of the content, whereas the check box is represented by a widget orientation.
Let's take a look at the official documentation instead of frustrating ourselves searching on every place of the web except on the official web site. More specifically: let's take a look at the Buttons example from Chapter 7 of my book. You'll see that one can set text for a real button:
PushbuttonField button = new PushbuttonField(writer, rect, "Buttons");
button.setText("Push me");
This isn't possible with check boxes (for the obvious reason that the appearance of a check box is completely different). If we want to add a label, we can add it for instance like this:
checkbox = new RadioCheckField(writer, rect, LANGUAGES[i], "Yes");
field = checkbox.getCheckField();
field.setAppearance(PdfAnnotation.APPEARANCE_NORMAL, "Off", onOff[0]);
field.setAppearance(PdfAnnotation.APPEARANCE_NORMAL, "Yes", onOff[1]);
writer.addAnnotation(field);
ColumnText.showTextAligned(canvas, Element.ALIGN_LEFT,
new Phrase(LANGUAGES[i], font), 210, 790 - i * 40, 0);
You can find the C# version of these examples here: http://tinyurl.com/itextsharpIIA2C07
Creating a checkbox, and then accompanying text to its right, can be done like this:
PdfPCell cell204Submitted = new PdfPCell()
{
CellEvent = new DynamicCheckbox("checkbox204Submitted")
};
tblFirstRow.AddCell(cell204Submitted);
// . . . Chunks and an anchor created; that code has been elided for brevity
Paragraph parCkbxText = new Paragraph();
parCkbxText.Add(Chunk204SubmittedPreamble);
parCkbxText.Add(ChunkBoldNote);
parCkbxText.Add(Chunk204Midsection);
parCkbxText.Add(anchorPayeeSetup204);
PdfPCell cellCkbxText = new PdfPCell(parCkbxText);
cellCkbxText.BorderWidth = PdfPCell.NO_BORDER;
tblFirstRow.AddCell(cellCkbxText);
public class DynamicCheckbox : IPdfPCellEvent
{
private string fieldname;
public DynamicCheckbox(string name)
{
fieldname = name;
}
public void CellLayout(PdfPCell cell, Rectangle rectangle, PdfContentByte[] canvases)
{
PdfWriter writer = canvases[0].PdfWriter;
RadioCheckField ckbx = new RadioCheckField(writer, rectangle, fieldname, "Yes");
ckbx.CheckType = RadioCheckField.TYPE_CHECK;
ckbx.BackgroundColor = BaseColor.ORANGE;
ckbx.FontSize = 6;
ckbx.TextColor = BaseColor.WHITE;
PdfFormField field = ckbx.CheckField;
writer.AddAnnotation(field);
}
}
Summary:
I'm creating a simple application for practice, where the user can maintain and query a collection of Things. On the UI are several TextBoxes and ComboBoxes with which they can filter the collection.
The three buttons I'm concerned with are [Filter], [Random], and [All]. [Filter] applies the current filter options. [Random] applies the current filter options (if any), and then only shows one random entry from the filtered results. [All], as expected, shows the unfiltered collection.
To fully understand the background for the question, I'll provide the relevant code.
Here is where anything having to do with the CollectionViewSource (or any relevant code I'm posting) gets declared:
//Members
private ObservableCollection<Thing> _myDataCollection;
private CollectionViewSource _CVS;
private Thing _randomThing;
//Properties
public ObservableCollection<Thing> MyDataCollection
{
get { return _myDataCollection; }
set
{
if (_myDataCollection!= value)
{
_myDataCollection= value;
RaisePropertyChanged(() => MyDataCollection);
}
}
}
public CollectionViewSource CVS
{
get { return _CVS; }
set
{
if (_CVS != value)
{
_CVS = value;
RaisePropertyChanged(() => CVS);
}
}
}
public ICollectionView CVSView
{
get { return CVS.View; }
}
Here is where the CVS is initialized (in the window view-model's constructor). For now, the data collection is populated with a ton of random things (that's all that RandomizeData() does).
MyDataCollection = new ObservableCollection<Thing>();
RandomizeData();
CVS = new CollectionViewSource();
CVS.Source = MyDataCollection;
Here is the code for the [Filter] button's command:
//Clear any stale filter options and rebuild with the most current ones.
CVSView.Filter = null;
//IF THE FOLLOWING LINE IS UNCOMMENTED, THE ISSUE OCCURS.
//CVS.Filter -= new FilterEventHandler(SingleRandomFromCollectionFilter);
BuildCVSFilter();
The code for the [All] button literally just clears the filter:
CVSView.Filter = null;
The code for the [Random] button. I suspect the issue is coming from the handler added here.
//Clear any stale filter options and rebuild with the most current ones.
CVSView.Filter = null;
//IF THE FOLLOWING LINE IS UNCOMMENTED, THE ISSUE OCCURS.
//CVS.Filter -= new FilterEventHandler(SingleRandomFromCollectionFilter);
BuildCVSFilter();
//Only proceed if there are actually results in the filtered collection.
int resultsCount = CVSView.Cast<Thing>().Count();
if (resultsCount > 0)
{
//Point to a random thing in the filtered collection.
CVSView.MoveCurrentToPosition(random.Next(0, resultsCount));
_randomThing = CVSView.CurrentItem as Thing;
//Add another filter event that further constrains the collection to only contain the random thing.
CVS.Filter += new FilterEventHandler(SingleRandomFromCollectionFilter);
}
And here is the code for that BuildCVSFilter() I've been calling. I use this so that I can use multiple filters concurrently. The "FilterOption" strings are properties that are bound to the values of the UI controls.
if (!string.IsNullOrEmpty(FilterOption1))
{
CVS.Filter += new FilterEventHandler(Fitler1);
}
if (!string.IsNullOrEmpty(FilterOption2) && FilterOption2 != "ignore")
{
CVS.Filter += new FilterEventHandler(Fitler2);
}
if (!string.IsNullOrEmpty(FilterOption3))
{
CVS.Filter += new FilterEventHandler(Filter3);
}
Each filter that gets added this way only sets e.Accepted to false, if applicable, and leaves it alone if it's true.
Issue:
If I click on [Random] at all, it seems like the FilterEventHandler that gets added there does not go away. This makes it so that selecting [Filter] after [Random] won't work as expected, because it's only going to filter from the current collection of one thing. Additionally, selecting [Random] a second time seems to reuse the same random thing (instead of finding a new one). Interestingly enough, clicking [All] still works just fine. It shows everything.
When I go into those [Filter] and [Random] OnCommand methods and explicitly add a line to remove that SingleRandomFromCollectionFilter handler, everything works as expected.
Why would NameEntriesView.Filter = null; work to clear the filter on [All], but not on [Filter] or [Random]? Is there something about the CollectionViewSource and its implementation that I'm not fully understanding?
I would like to override the text displayed when an item is added to a checked list box. Right now it is using obj.ToString(), but I want to append some text, without changing the objects ToString method. I have seen examples of handling the DrawItem event for ListBoxs, but when I try to implement them, my event handler is not called. I have noted that the Winforms designer does not seem to allow me to assign a handler for the DrawItem event. Being stubborn, I just added the code myself
listbox1.DrawMode = DrawMode.OwnerDrawVariable;
listbox1.DrawItem += listbox1_DrawItem;
Am I trying to do the impossible?
Not impossible, but incredibly difficult. What you suggest will not work, note the meta-data in class CheckedListBox for method DrawItem:
// Summary:
// Occurs when a visual aspect of an owner-drawn System.Windows.Forms.CheckedListBox
// changes. This event is not relevant to this class.
[Browsable(false)]
[EditorBrowsable(EditorBrowsableState.Never)]
public event DrawItemEventHandler DrawItem;
Therefore, your only option is to derive your own class from CheckedListBox, and in my limited testing, this will be a long road. You can handle the drawing simply enough, as such:
public class CustomCheckedListBox : CheckedListBox
{
protected override void OnDrawItem(DrawItemEventArgs e)
{
String s = Items[e.Index].ToString();
s += "APPEND"; //do what you like to the text
CheckBoxState state = GetCheckBoxState(e.State); // <---problem
Size glyphSize = CheckBoxRenderer.GetGlyphSize(e.Graphics, state);
CheckBoxRenderer.DrawCheckBox(
e.Graphics,
e.Bounds.Location,
new Rectangle(
new Point(e.Bounds.X + glyphSize.Width, e.Bounds.Y),
new Size(e.Bounds.Width - glyphSize.Width, e.Bounds.Height)),
s,
this.Font,
false,
state);
}
}
Note the method GetCheckBoxState(). What you get in the DrawItemEventArgs is a DrawItemState, not the CheckBoxState you need, so you have to translate, and that's where things started to go downhill for me.
Soldier on, if you like, this should get you started. But I think it'll be a messy, long road.
I continued the work in DonBoitnotts answer.
The "GetCheckBoxState" is implemented using a very limited set with only two states.
var state = GetItemChecked(e.Index) ? CheckBoxState.CheckedNormal : CheckBoxState.UncheckedNormal;
Vertically aligned the checkbox and left aligned the text.
var b = e.Bounds;
int checkPad = (b.Height - glyphSize.Height) / 2;
CheckBoxRenderer.DrawCheckBox(g, new Point(b.X + checkPad, b.Y + checkPad),
new Rectangle(
new Point(b.X + b.Height, b.Y),
new Size(b.Width - b.Height, b.Height)),
text, this.Font, TextFormatFlags.Left, false, state);
In DataGridView, how to bind an array or list (with n elements) to n DataGridViewTextBoxColumn's?
Maybe it's not so clear, for example, I have a class:
public class DynamicNumberFieldsClass
{
public string FullName { get; set; }
public int[] Years { get; set; }
}
The expected form a DataGridView should display:
FullName Year1 Year2 Year3...
Peter 11 12 13
Bryan 21 22 23
If I have to use reflection, it's okay for me.
Any idea?
Thanks!
Peter
P.S.: We can assume the array field will never be null.
we can even assume that the number of elements in the array is fixed once a session is started, but the user can change it in Settings, so in the next session, the number of elements might not be the same.
I am assuming you are working in Windows Forms. I was able to at least display the data in the format you've shown by putting the DataGridView in Virtual Mode. You had best follow the entire walkthrough for a complete solution, but here is what I did in a quick test (hacked up from the samples in the walkthough):
CellValueNeeded handler:
private void dataGridView1_CellValueNeeded(object sender, DataGridViewCellValueEventArgs e)
{
// If this is the row for new records, no values are needed.
if (e.RowIndex == this.dataGridView1.RowCount - 1) return;
DynamicNumberFieldsClass objectInRow = (DynamicNumberFieldsClass)this._people[e.RowIndex];
// Set the cell value to paint using the DynamicNumberFieldsClass object retrieved.
switch (this.dataGridView1.Columns[e.ColumnIndex].Name)
{
case "FullName":
e.Value = objectInRow.FullName;
break;
default:
e.Value = objectInRow.Years[e.ColumnIndex - 1];
break;
}
}
where _people is a collection of DynamicNumberFieldsClass.
Form Load:
private void Form1_Load(object sender, EventArgs e)
{
this.dataGridView1.VirtualMode = true;
this.dataGridView1.CellValueNeeded += new DataGridViewCellValueEventHandler(dataGridView1_CellValueNeeded);
// Add columns to the DataGridView.
DataGridViewTextBoxColumn fullNameColumn = new
DataGridViewTextBoxColumn();
fullNameColumn.HeaderText = "FullName";
fullNameColumn.Name = "FullName";
this.dataGridView1.Columns.Add(fullNameColumn);
for (int i = 0; i < _numYears; i++)
{
DataGridViewTextBoxColumn yearIColumn = new
DataGridViewTextBoxColumn();
yearIColumn.HeaderText = "Year" + (i+1);
yearIColumn.Name = "Year" + (i+1);
this.dataGridView1.Columns.Add(yearIColumn);
}
this.dataGridView1.AutoSizeColumnsMode =
DataGridViewAutoSizeColumnsMode.AllCells;
// Set the row count, including the row for new records.
this.dataGridView1.RowCount = 3; //two objects in _people and the empty row
}
where _numYears is the fixed value you mentioned. If you have at least one instance of the object available, you could use the size of the Years array in that instance as the loop limiter, so that it is completely dynamic.
You would need to expand the switch statement if any other properties are included in the class, and of course add more error checking in general. The walkthrough shows how to support editing in the DataGridView, as well.
(I know you asked how to bind the columns, not force their values, so you probably wanted to be able to decorate the class definition, assign the data source, and go. To that end, I first looked into doing this with Reflection via CustomTypeDescriptor and TypeDescriptionProvider, etc., which is how second-level properties can be bound. Of course, the individual elements of the array are not exposed as properties, so this doesn't work. I can't think of a way to support auto-generation of the columns the way you want, but maybe someone else will find one.)
question 1. I have this issue of "Object reference not set to an instance of an object" when my Majorlabel is empty and this occurs after i try to do a save button click on xml serialization. How can i fix this?
private void SaveButton_Click(object sender, RoutedEventArgs e)
{
string savepath;
SaveFileDialog DialogSave = new SaveFileDialog();
// Default file extension
DialogSave.DefaultExt = "txt";
// Available file extensions
DialogSave.Filter = "XML file (*.xml)|*.xml|All files (*.*)|*.*";
// Adds a extension if the user does not
DialogSave.AddExtension = true;
// Restores the selected directory, next time
DialogSave.RestoreDirectory = true;
// Dialog title
DialogSave.Title = "Where do you want to save the file?";
// Startup directory
DialogSave.InitialDirectory = #"C:/";
DialogSave.ShowDialog();
savepath = DialogSave.FileName;
DialogSave.Dispose();
DialogSave = null;
FormSaving abc = new FormSaving();
if (!string.IsNullOrEmpty(MajorversionresultLabel.Content.ToString()))
{
abc.Majorversion = MajorversionresultLabel.Content.ToString();
}
abc.Startzbuildfrom = StartzbuildcomboBox.SelectedItem.ToString();
using (Stream savestream = new FileStream(savepath, FileMode.Create))
{
XmlSerializer serializer = new XmlSerializer(typeof(FormSaving));
serializer.Serialize(savestream, abc);
}
}
As recommended,
here is the line of error:
if (!string.IsNullOrEmpty(MajorversionresultLabel.Content.ToString()))
{
abc.Majorversion = MajorversionresultLabel.Content.ToString();
}
Question 2. I used this line to save my combo box selection:
abc.Startzbuildfrom = StartzbuildcomboBox.SelectedItem.ToString();
and in my load i have this line:
StartzbuildcomboBox.SelectedItem = abc.Startzbuildfrom
why wont it select the combobox selection previously?
As a first note, I'd recommend only putting one question into a single query here. Makes it easier.
For your second question, my guess is that you're running into a reference variable problem. I think that calling the ToString() method on the SelectedItem actually creates an entirely new string variable. Then, when you try to set the selected item later, it can't find the new string as a possible item to select because, even though the two strings have the same value, they are different objects. I would maybe recommend that you either:
1) Set the selected item by searching through your combo box contents to find a string whose value matches the one you've saved
or
2) Save the actual reference by saying abc.Startzbuildfrom = StartzbuildcomboBox.SelectedItem. Then set the selected item from that reference.
I suspect that MajorversionresultLabel is null, or MajorversionresultLabel.Content is null. Thus your statement
if (!string.IsNullOrEmpty(MajorversionresultLabel.Content.ToString()))
will throw a NullReferenceException. Try this instead:
if (MajorversionresultLabel != null && MajorversionresultLabel.Content != null && MajorversionLabel.Content.ToString() != string.Empty)
I bet your NullReferenceException will go away.