Develop Reference

Unable to create ellipse on mouse double click event

I am trying to create a elipse in a textbox on double click. But it doesnt seem to happen.
panel.MouseClick += create_terms;
private void create_terms(object sender, EventArgs arg)
{
if (Phys_terms_check.Checked == true)
{
MouseEventArgs e = (MouseEventArgs)arg;
Graphics g = CreateGraphics();
SolidBrush p = new SolidBrush(Color.Red);
Pen erase = new Pen(Color.White);
Panel panel = (Panel)sender;
g.FillEllipse(p, e.X+panel.Left,e.Y+panel.Top,10,10);
}
}
The e.x and e.y seem to be giving relative coordinates from the sender. How to get point relative to the form.

add sender's top and left coordinates.
g.FillEllipse(p, e.X + textbox.Left, e.Y + textbox.Top, 10, 10);
but, this won't show, because textbox paint event fill fire and repaint textbox.

First of all: TextBoxes are old legacy and rather special Controls that do not support all things normal controls let you do.
Among the things that won't work are
Setting a BackgroundImage
Owner-drawing them
The latter includes any drawing in its Paint/OnPaint events.
You can code and hook-up the Paint event, but it won't get called.
You still can draw onto a TextBox using CreateGraphics, if you do it right, but as always with this function the result is non-persistent and will go away as soon as the system refreshes the TextBox itself, which is super-fast: as soon as you move your cursor over it the circle you draw may disappear..
The code to do it would have to look similar to this:
Graphics g = yourTextBox.CreateGraphics();
g.FillEllipse(Brushes.Red, yourTextBox.Width - 22, 2, 11, 11);
But as I said this will not persist, so it has little or no value.
If you want to draw onto something with a visible Text property you can use a Label:
private void yourLabel_Paint(object sender, PaintEventArgs e)
{
e.Graphics.FillEllipse(Brushes.Red, yourLabel.Width - 22, 2, 11, 11);
}
The result looks the same, but only the dot in the Label will persist, e.g. a Minimize-Maximize of the form.. In fact the dot in the TextBox didn't even survive calling my screenshot program, so I had use resort to pressing the Print-Key !
For drawing circles upon mouseclicks onto normal controls see this post!

Drawing over a 3D rendered scene using C#

UPDATE: Since originally asking this question, I have changed my approach slightly. Rather than drawing using System.Drawing.Graphics, I am hosting a WPF user control with an InkCanvas. That does everything I need it to do. The problem still is that I cannot get the background of the ElementHost to be transparent. I see the same black square I was seeing before.
ORIGINAL QUESTION: I have a C# WinForms application that renders a 3D scene using Ogre3D to a panel in the form using that panel's handle. I am trying to add the ability to draw on top of that scene (imagine Madden drawing over the TV screen) using C#'s System.Drawing.Graphics.
I'm using the BufferedGraphics class to do this. As a test, I'm trying to simply draw a rectangle on top of the 3D scene. Below is a snippet of the code I'm using to set everything up.
namespace TestApp
{
public partial class TestForm
{
private BufferedGraphics graphicsBuffer;
private BufferedGraphicsContext bufferContext = BufferedGraphicsManager.Current;
public TestForm()
{
InitializeComponent();
UpdateGraphicsBuffer();
}
private void UpdateGraphicsBuffer()
{
bufferContext.MaximumBuffer = new Size(panelRender.Width + 1, panelRender.Height + 1);
graphicsBuffer = bufferContext.Allocate(Graphics.FromHwnd(panelRender.Handle), new Rectangle(49, 49, 100, 100));
graphicsBuffer.Graphics.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
}
private void TestForm_Load(object sender, EventArgs e)
{
graphicsBuffer.Graphics.DrawRectangle(new Pen(Color.Red), 50, 50, 50, 50);
}
}
}
I've left out a lot of the proprietary code (there is a call to graphicsBuffer.Render(); in part of that proprietary code) and renamed some stuff but hopefully what I have provided will give you the gist. Also, the 3D scene is also using panelRender.Handle to draw into that panel, and the panelRender.BackColor is black.
In a nutshell, what I am seeing is a chunk of my 3D scene missing (specifically a 100x100 chunk) with the 50x50 red rectangle drawn inside it, as pictured here:
Obviously I don't want to lose the scene that I'm trying to draw on top of. Right now, I'm at a loss as to why this is happening. Is what I'm trying to do just not possible? If any additional information/code is needed, I will be happy to provide it, if possible.
EDIT:
To try and simplify matters, I created a really simple WinForms app that has a single panel and used the code above to recreate the issue. The code-behind for that is here:
using System.Drawing;
using System.Windows.Forms;
namespace DoubleBufferTest
{
public partial class Form1 : Form
{
private BufferedGraphics graphicsBuffer = null;
private BufferedGraphicsContext bufferContext = BufferedGraphicsManager.Current;
public Form1()
{
this.SetStyle(ControlStyles.SupportsTransparentBackColor | ControlStyles.UserPaint, true);
this.UpdateStyles();
InitializeComponent();
UpdateGraphicsBuffer();
}
private void UpdateGraphicsBuffer()
{
bufferContext.MaximumBuffer = new Size(panel1.Width + 1, panel1.Height + 1);
graphicsBuffer = bufferContext.Allocate(Graphics.FromHwnd(panel1.Handle), new Rectangle(10, 10, 50, 50));
}
protected override void OnPaint(PaintEventArgs e)
{
base.OnPaint(e);
graphicsBuffer.Graphics.DrawRectangle(new Pen(Color.Red, 3.0f), 20, 20, 10, 10);
graphicsBuffer.Render();
}
}
}
The panel's backcolor is set to transparent. Here is the result:
That black square corresponds to the graphics buffer that is getting allocated by the context. Why it always shows up as black is basically what is confusing me now...

Thank you to #Ron Beyer for answering this for me in a different question I posted.
So I was on the right track with the ElementHost control, but because of the transparency issues, Ron suggested that I try using a new WPF window that I could overlay on top of the application (link). The WPF window's background is set to transparent, so drawing on the InkCanvas results in the desired effect.

Highlight the Rectangular Area while Dragging it

I am creating a image viewer sort of application. I am on Windows and using .Net
In my app, I am trying to highlight a Particular area while dragging.
I have created a Rectangle.
Rectangle areaRect = new Rectangle(100,100, 300, 300);
Point ptOld = new Point(0, 0);
Pen rectPen = new Pen(Brushes.White, 3);
protected override void OnPaint(PaintEventArgs e)
{
Graphics dcPaint = e.Graphics;
dcPaint.DrawRectangle(rectPen, areaRect);
}
Now I am dragging this rectangular area along with my mouse movements.
protected override void OnMouseMove(MouseEventArgs e)
{
Point ptNew = new Point(e.X, e.Y);
int dx = ptNew.X - ptOld.X;
int dy = ptNew.Y - ptOld.Y;
areaRect.Offset(dx, dy);
MoveRect(ptNew);
ptOld = ptNew;
}
Here I am trying to move this rect along with my mouse
void MoveRect(Point point)
{
Graphics grfxClient = CreateGraphics();
Rectangle tempRectangle = new Rectangle(areaRect.Left, areaRect.Top, areaRect.Width, areaRect.Height);
grfxClient.DrawRectangle(rectPen, tempRectangle);
this.Invalidate();
grfxClient.Dispose();
}
My Code till this point is working fine.
Now I would like to darken the INVERSE drag Area (The area which is outside the drag region), I mean the area which is within this Rectangle should gets highlighted while dragging.
Any idea how to proceed.
Thanks.
-Pankaj

I suppose you can do it by creating a Region object that covers the outside of the rectangle and fill it with a semi-transparent SolidBrush to make it look darkened.
You also don't have to create a graphics and draw in OnMouseMove event, but just shift the rectangle and invalidate the surface of the control you are drawing on.
The code I used looks more or less like this:
Rectangle areaRect = new Rectangle(100,100, 300, 300);
Point ptOld = new Point(0, 0);
Pen rectPen = new Pen(Brushes.White, 3);
//A new field with a semi-transparent brush to paint the outside of the rectangle
Brush dimmingBrush = new SolidBrush(Color.FromArgb(128, 0, 0, 0));
protected override void OnPaint(PaintEventArgs e)
{
Region outsideRegion = new System.Drawing.Region(e.ClipRectangle);
outsideRegion.Exclude(areaRect);
Graphics dcPaint = e.Graphics;
dcPaint.FillRegion(dimmingBrush, outsideRegion);
dcPaint.DrawRectangle(rectPen, areaRect);
}
protected override void OnMouseMove(MouseEventArgs e)
{
Point ptNew = new Point(e.X, e.Y);
int dx = ptNew.X - ptOld.X;
int dy = ptNew.Y - ptOld.Y;
areaRect.Offset(dx, dy);
ptOld = ptNew;
this.Invalidate();
}
The method named MoveRect is not needed.
It now seems to work as you wanted it to.
Suggestions
I also have some suggestions. You don't have to use them, maybe they will be helpful for you.
You haven't written what kind of control you are using to draw on (or overriding Form methods and painting directly on it), but I suggest you to use a PictureBox control, create a custom control derived from it and override its events. This should make the painting process smooth and prevent flickering. To do it this way:
Create a new user control by selecting Add and User Control... and name a new control i.e. MyPictureBox
change the parent class of the control, so it should now contain the line:
public partial class MyPictureBox : PictureBox
open file MyPictureBox.Designer.cs and comment out these lines:
//this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 13F);
//this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
copy the code I posted in this answer and add line base.OnPaint(e); and the beginning of OnPaint method
compile the project
now you should be able to open designer of your main form, drag MyPictureBox control from the toolbox and use it without additional code needed
You also might consider changing the behaviour of the highlighted area, so mouse cursor was in the center of it. I suppose it would be more intuitive to the user.
If you have any issues with the code, just write it in the comments and I'll try to help :).

Redrawing and custom shaped windows question

I'm using C#2.0 and I want to create a facebook style tooltip window. I currently made it with 2 windows and transparent key. One for the triangle arrow pointer and one for the square. The whole picture looks like that:
I have problem with the redrawing (as shown in the picture).
Is there a way to use whole shaped window on that? (While I need to make it sizeable)
If no, is this the proper way to make that? Or I need to 'glue' the triangle to the rectangle

Two ways to solve --
Using transparency: Irregular shaped Windows Form (C#)
Or using Control.Region which is the actual shaping of the window. Plenty of samples or:
How do I make a genuinely transparent Control?
protected override void OnSizeChanged(EventArgs e)
{
base.OnSizeChanged(e);
const int ArrowSize = 25;
Point[] points = new[] {
new Point(ArrowSize, 0),
new Point(this.Width, 0),
new Point(this.Width, this.Height),
new Point(ArrowSize, this.Height),
new Point(ArrowSize, ArrowSize),
new Point(0, ArrowSize/2)
// don't need - autocloses
// ,new Point(ArrowSize, 0)
};
GraphicsPath path = new GraphicsPath();
path.AddLines(points);
this.Region = new Region(path);
}

Delete rectangle using .NET?

Can I delete the old rectangle which I have drawn and draw a new rectangle?
private void panel1_MouseClick(object sender, MouseEventArgs e)
{
Graphics g = this.panel1.CreateGraphics();
Pen pen = new Pen(Color.Black, 2);
g.DrawRectangle(pen, 100,100, 100, 200);
g.dispose();
}

No, you cannot "delete" something that's already been drawn. You can overwrite it with something else, but drawing with Graphics objects is like painting in real-life: once the paint is dry, you can only paint over it with another colour, you can't "erase" it.
You probably shouldn't be drawing things in response to a MouseClick, either. It's best to only draw things in response to a Paint event. What I would do in this situation is add a Rectangle structure to a list on the MouseClick and then call panel1.Invalidate() to ask it to redraw itself. Then in the Paint event for the panel, do the drawing there.
This will kill two birds with one stone, because you will be able to "erase" thing by simply removing them from the list of stuff to draw.

This is usually done by maintaining a collection of objects you want drawn. The mouse click should update this collection and then tell the window (or the affect region) to refresh. This has the enormous advantage of preserving whatever you've drawn if the window is moved off-screen, hidden behind other windows, minimized, etc.
For a rudimentary solution, create a hierarchy of drawable shape types derived from a common abstract Shape class, and use, e.g., a List for the collection. The base Shape class will have an abstract Draw method that the derived classes override.
For a more industrial-strength solution, look around for 2-D scene graphs.

One can use Graphics.Save() and Graphics.Restore(state) methods for that. For example:
private void SaveRestore2(PaintEventArgs e)
{
// Translate transformation matrix.
e.Graphics.TranslateTransform(100, 0);
// Save translated graphics state.
GraphicsState transState = e.Graphics.Save();
// Reset transformation matrix to identity and fill rectangle.
e.Graphics.ResetTransform();
e.Graphics.FillRectangle(new SolidBrush(Color.Red), 0, 0, 100, 100);
// Restore graphics state to translated state and fill second
// rectangle.
e.Graphics.Restore(transState);
e.Graphics.FillRectangle(new SolidBrush(Color.Blue), 0, 0, 100, 100);
}
http://msdn.microsoft.com/en-us/library/system.drawing.graphics.restore.aspx

Also, depending on the application, you might look at using DrawReversibleFrame. You can change the rectangle location by calling the Offset method.

Instead of calling g.DrawRectangle(pen, 100,100, 100, 200); , maintain the rectangle as a object which will be drawn by the graphics object. Each time you will update this rectangle object with new one and graphics object will draw the new one.
The refresh should clear the old rectangle and graphics will draw the new one.

You can just use VisualBasic PowerPacks, it is included with my version of Visual Studio 2008
Here's a sample code that will draw a rectangle over a TextBox, i.e. I am giving it a custom border
Dim x = TextBox1.Location.X
Dim y = TextBox1.Location.Y
Dim width = TextBox1.Width
Dim height = TextBox1.Height
Dim ShapeContainer1 As New Microsoft.VisualBasic.PowerPacks.ShapeContainer
Me.Controls.Add(ShapeContainer1)
Dim RectangleShape1 As New Microsoft.VisualBasic.PowerPacks.RectangleShape
ShapeContainer1.Shapes.AddRange(New Microsoft.VisualBasic.PowerPacks.Shape() {RectangleShape1})
RectangleShape1.Location = New System.Drawing.Point(x - 1, y - 1)
RectangleShape1.Size = New System.Drawing.Size(width + 1, height + 1)
RectangleShape1.BorderColor = Color.MistyRose
ShapeContainer1.Refresh()
Code is self describing but if you'd have any problem, just leave a message...

I think using DrawReversibleFrame is the right solution.
The first call draw the rectangle, the second call undraw it and so on.
Here is a sample code, a clic on the button will make the rectangle appear/disapper.
Rectangle pRect = new Rectangle(10, 10, 20, 20);
private void rect_Click(object sender, EventArgs e)
{
ControlPaint.DrawReversibleFrame(pRect, this.BackColor, FrameStyle.Thick);
}