I have different kinds of cells in a single DataGridView column.
When the user clicks on the box it used to turn entirely black.
Now I am able to capture the Entered event from the EditingControlShowing event and set the backgroundColor to white.
private void ATextBoxHasBeenEntered(object sender, EventArgs e)
{
((TextBox)sender).BackColor = Color.White;
((TextBox)sender).TextAlign = HorizontalAlignment.Left;
((TextBox)sender).BorderStyle = System.Windows.Forms.BorderStyle.None;
}
But I still see this black box!
So I went crazy trying to grab every related object and setting it to white. I've tried setting the associated DataGridViewTextBox's background to white, removing the border from everything, etc.
Nothing works :(
I can't tell if this black box is the DataGridViewTextBox or the editing control. I can't tell what event changes the color either.
What can I do?
Related
For a Winforms textbox, when you click and drag over the text, it highlights it. Is there a way to determine which direction the user dragged over?
There is no way to get this info using the Windows TextBox selection API. For example, the EM_GETSEL message defines the starting and ending character positions of the selection, but in a predefined (sorted) order.
However you could get this info by handling the control's MouseMove event. For example:
textBox1.MouseMove += new MouseEventHandler(textBox1_MouseMove);
void textBox1_MouseMove(object sender, MouseEventArgs e)
{
Control tbCtrl = sender as Control;
// the mouse coordinate values here are relative to the coordinates of the control that raised the event
int mouseX = e.X;
...
}
By applying some logic to mouseX you could potentially discover the average direction the cursor is moving. It would work best if the user is making a linear motion. You could also handle the textbox's drag-and-drop event for similar mouse information if you only wanted the event raised while the user was dragging the mouse.
The following code produces a black flicker on the screen right before the form is displayed (transparently), I'm wondering what my options are for removing that flicker?
Form f = new Form();
f.BackColor = Color.Lime;
f.TransparencyKey = f.BackColor;
f.StartPosition = FormStartPosition.Manual;
f.Bounds = Screen.PrimaryScreen.WorkingArea;
f.Show();
I get the same results if I create a new project, set the background of the form to Lime and the TransparencyKey to Lime, then click Run.
Things I've tried:
Set Opacity to 99% -- same flicker
Force WS_EX_COMPOSITED in OnCreateParams or using SetWindowLong -- same flicker
Show the window smaller, or 0 width, or off screen, then move to desired location -- causes bad display issues where the windows behind my form do not redraw correctly.
Setting ControlStyles.Opaque, ControlStyles.UserPaint, and several other ControlStyles combos and overriding different paint/background-paint events -- various results, either same flicker, worse flicker, or form not transparent.
Moving to WPF might be an option, but not really looking for "use WPF" as an answer.
Set the Opacity to 0.01.
If you need the form (or parts of it) visible - then re-set the Opacity once the form creation is complete:
Form f = new Form { Opacity = 0.01 };
f.Show();
f.BeginInvoke( new Action(() => f.Opacity = 0.99 ));
EDIT: Updated cleaner as Tergiver suggested
I have an MdiClient derived from Form and I use the surface of this control for GDI+ drawing. I run into troubles implementing my own scrolling for this control. I set both AutoScroll and AutoSize properties to false and try to use form's own horizontal/vertical scrollbars instead of placing my own. Observed form's behavior is quite confusing. To begin with there are two properties (A) HScroll and (B) HorizontalScroll that also allows access to Visible attribute.
I ended up setting HorizontalScroll.Visible = true and leaving HScroll = false (same for vertical) but am curious why there are two of them. Documentation implies that both control visibility of horizontal scroll bar but they do not appear to access the same data. Besides, it looks like HScroll is being reset on every paint. At the moment I ignore existence of HScroll/VScroll. Is it OK for my application?
What is more critical for me is the ability control placement of the thumb on scroll bars. I set VerticalScroll attributes Minimum = 0, Maximum = 100, and Value = 50 but when form is displayed thumb is positioned at the start of scrollbar not in the middle. Why? Also when user clicks on horizontal scrollbar an event handler for horizontal scrolling is invoked but meanwhile form has already reset VerticalScroll.Value to 0 (without raising vertical scroll event). What is going on?
I probably don't understand how framework expects me to implement what I need. Can someone shed some light.
Credit goes to LarsTech who pointed me towards good solution. Setting large AutoScrollMinSize automatically does whatever needs to be done enabling and controlling form scrollbars. There is one potential trap to watch for. Be aware that programmatic attempts to set AutoScrollPosition will be ignored until form is shown. So if you want your form to open with scrollbars not in the default (0,0) position then place your code inside form_shown event handler.
Just set the AutoScrollMinSize to your desired canvas.
Quick example:
using System.Drawing;
using System.Drawing.Drawing2D;
private void Form1_Load(object sender, EventArgs e)
{
this.AutoScrollMinSize = new Size(1200, 1200);
}
private void Form1_Paint(object sender, PaintEventArgs e)
{
e.Graphics.Clear(SystemColors.Window);
using (Matrix mx = new Matrix(1, 0, 0, 1, this.AutoScrollPosition.X, this.AutoScrollPosition.Y))
{
e.Graphics.Transform = mx;
e.Graphics.FillEllipse(Brushes.Red, new Rectangle(250, 250, 100, 100));
}
}
See these links: Understanding Windows Forms AutoScroll and How to back-track the mouse to the virtual page.
I have a panel and on that I've a picturebox. There are around 20 labels that I've to show in the panel. I want the background of Label to be transparent ie the image in picturebox is shown and the label displays only the text.
Now since labels do not exhibit true transparency I made the labels child of picturebox
this.lbl1.Parent = pictureBox1;
This has solved my immediate problem but now when the form loads, all the labels take a while to become visible and do so one at a time. I'd appreciate if you guys can give some solution for this.
Thanks in advance
The standard cure for flicker is double-buffering. But that cannot solve this kind of flicker. It is a different kind, caused by having multiple windows overlapping each other. Each label is its own window. When the form needs to paint itself, it draws its background leaving holes for the child windows. Each child window then takes a turn drawing itself. And their child windows draw themselves next. Etcetera.
This becomes noticeable when one control takes a while to draw, no doubt your picture box. Especially when it displays a large image that needs to be resized. The holes for the child windows stay unpainted while the picture box draws. They have a white background, black when you use the form's TransparencyKey or Opacity property. This can contrast badly with the image in your picture box, that effect is perceived by the user as flicker.
One immediate cure is to not use controls so you don't pay for their window. A Label is very convenient but it is a massive waste of system resources to burn up a window just to display a string. You can simply implement the picture box' Paint event and draw the strings with TextRenderer.DrawText(). PictureBox has double-buffering turned on by default so the image as well as the text is drawn completely smoothly, no more flicker. The obvious disadvantage is that you lose the convenience of point-and-click, you have to write code.
There are other fixes possible. One of them is to prevent the picture box from leaving holes for the child windows. It will draw the entire image, the labels pop on top of them. That's still flicker but not nearly as noticeable. Add a new class to your project and paste this code:
using System;
using System.Windows.Forms;
internal class MyPictureBox : PictureBox {
protected override CreateParams CreateParams {
get {
var parms = base.CreateParams;
parms.Style &= ~0x02000000; // Turn off WS_CLIPCHILDREN
return parms;
}
}
}
Compile and drop the new picture box control from the top of the toolbox onto your form.
Yet another possible workaround is to make the form and all of its children double-buffered. This doesn't speed up the painting at all but all of the windows get rendered into a memory buffer, the result is blitted to the screen. You'll notice a delay but the window suddenly pops on the screen. This is called compositing. Winforms doesn't support this directly since it can have side-effects but it is easy to enable. Paste this code into your form class:
protected override CreateParams CreateParams {
get {
CreateParams cp = base.CreateParams;
cp.ExStyle |= 0x02000000; // Turn on WS_EX_COMPOSITED
return cp;
}
}
Supported by XP and later. Watch out for painting artifacts.
or you can ditch the labels and draw the text yourself:
private void pictureBox1_Paint(object sender, PaintEventArgs e)
{
TextRenderer.DrawText(e.Graphics, "Label1", SystemFonts.DefaultFont,
new Point(10, 10), Color.Black, Color.Empty);
}
The label does not support transparency, you must create your own unique custom control, you can see these code examples.
http://www.codeproject.com/KB/dotnet/transparent_controls_net.aspx http://www.codeproject.com/KB/vb/uLabelX.aspx
Bye
I've searched for examples for this, but the ones I've ran across seem to focus on simpler stuff like setting the InkCanvas DefaultDrawingAttributes such as Width, Height, Color etc. Doesn't seem like there's a lot of material for this.
For example, if I hold down the mouse button I can see it drawing lines. What if I want to draw ellipses instead of lines, or draw ellipses around sampled points between the start and end of the line?
I know I can get new points with the StrokeCollected event, but beyond that I have no idea where to go. This guy seemed like he got msdn's code working, but I couldn't do it. I only know how to build the interface using XAML, and there doesn't seem to be a sample either.
edit
Created a StrokeCollection class variable called thisIsNotNice, initialized in the constructor and did this:
private void InkCanvas_StrokeCollected(object sender, InkCanvasStrokeCollectedEventArgs e)
{
myInkCanvas.Strokes = thisIsNotNice;
foreach (StylusPoint p in e.Stroke.StylusPoints)
{
StylusPointCollection spc = new StylusPointCollection();
spc.Add(p);
Stroke s = new Stroke(spc);
s.DrawingAttributes.Height = 3;
s.DrawingAttributes.Width = 3;
thisIsNotNice.Add(s);
}
e.Handled = true;
}
But it doesn't work as it should. The ellipses are drawn, but the lines drawn by the mouse are still there. Also, for some reason, the first time it works as it should, drawing just the ellipses, but afterward it draws both the ellipses and the lines. But, if I do this instead:
private void InkCanvas_StrokeCollected(object sender, InkCanvasStrokeCollectedEventArgs e)
{
myInkCanvas.Strokes = new System.Windows.Ink.StrokeCollection();
e.Handled = true;
}
The lines aren't kept on the screen. So, I don't understand why they aren't being erased in the above code.
If I do this:
private void InkCanvas_StrokeCollected(object sender, InkCanvasStrokeCollectedEventArgs e)
{
foreach (Stroke s in myInkCanvas.Strokes)
System.Diagnostics.Trace.WriteLine(s);
e.Handled = true;
}
I can also see that the canvas contains the line strokes.
While erasing the strokes after they have been added to the collection is far from ideal, it at least does what I want. I could set up the line color to be the same of the background, but then I wouldn't be able to retrieve just the ellipses. I could copy them to a separate collection too, but that's just awful.
It sounds like you want to customize the way strokes appear on your inkCanvas. There are two separate things to consider here:
1) The way they look as the ink flows off the pen, before it is lifted (the DynamicRenderer, who runs on another thread to ensure that ink is always fast, is responsible for this. It sounds like you're happy with your solution to this already.
2) The way the eventual stroke sitting on the canvas looks. To customize this you might try subclassing Stroke, overriding:
protected override void DrawCore(DrawingContext drawingContext, DrawingAttributes drawingAttributes);
Each time you get a strokeCollected (and here's the same horrible thing you were worried about but there you go), you remove the incoming stroke from the canvas and replace it with your custom implementation, stealing the stroke data from the incoming one.
Your implementation of DrawCore would look something like (pseudocode):
foreach(sp in this.StylusPoints)
drawingContext.DrawEllipse(RADIUS, sp.X, sp.Y)
And so as not to get the lines that normally happen you would not call base.DrawCore(context,attributes) at any point.