I have drawn a circle in windows form
Pen pen = new Pen(Color.Black, 3);
Graphics gr = this.CreateGraphics();
gr.DrawEllipse(pen, 5,5,20,20);
How to delete it...
You have to clear your Graphic:
Graphics.Clear();
But all drawn figures will be cleared. Simply, you will then need to redraw all figures except that circle.
Also, you can use the Invalidate method:
Control.Invalidate()
It indicates a region to be redrawn inside your Graphics. But if you have intersecting figures you will have to redraw the figures you want visible inside the region except the circle.
This can become messy, you may want to check out how to design a control graph or use any graph layout library.
You can invalidate the draw region you want to refresh for example:
this.Invalidate();
on the form...
Assuming you're subscribing to the Paint event or overriding the protected OnPaint routine, then you will need to perform something like this:
bool paint = false;
protected override void OnPaint(object sender, PaintEventArgs e)
{
if (paint)
{
// Draw circle.
}
}
Then when you want to stop painting a circle:
paint = false;
this.Invalidate(); // Forces a redraw
You can make a figure of same dimensions using the backColor of your control in which you are drawing
use after your code to clear your figure.
Pen p = new Pen(this.BackColor);
gr.DrawEllipse(p, 5,5,20,20);
In fact, you can delete your circle and nothing but your circle.
Everything you need is something like a screenshot of the "before state" of the area you want to clear, to make a TextureBrush from it. You can achieve that step by something like this:
Bitmap _Background = new Bitmap(this.Width, this.Height);
Graphics.FromImage(_Background).CopyFromScreen(this.Left, this.Top, 0, 0, this.Size);
The first line will give you a bitmap in your windows forms size. The second line will save a screenshot of it in the _Background-bitmap.
Now you create a TextureBrush out of it:
Brush brsBackground = new TextureBrush(_Background);
The next thing you need are the dimensions of your circle, so you should save them into a variable, if they are not a fix value. When you got them at hand, you can clear the specific area like this:
Graphics gr = this.CreateGraphics();
gr.FillEllipse(brsBackground, 5, 5, 20, 20); // values referred to your example
Done!
Even complex figures are able to be deleted by this, like a GraphicsPath for example:
GraphicsPath gp = new GraphicsPath(); // any kind of GraphicsPath
gr.FillRegion(brsBackground, new Region(gp));
You don't "delete" it per se, there's nothing to delete. It's a drawing, you draw something else over it or you can call the Graphics.Clear() method.
If u are using Invalidate() and is not working, make a panel.Refresh().
That will work on you.
just make another control with the attributes etc. that you want, make the visibility to false and set the region of the control to the other control like this:
pen.Region = pen2.Region;
It is very simple to delete a drawn circle from c.
There is only four steps:-
Open turbo app
go to the command where you had drawn the circle
drag the command
click on delete button
Related
so I've created a custom control and I wanted to draw on that control
now the problem is that I can't use OnPaint event because I want to
draw at different times with different conditions.
here is the custom control function to draw a rectangle
public void DrawARectangle(int x,int y,int height,int width)
{
Graphics g = this.CreateGraphics();
g.DrawRectangle(Pens.Black, x, y, height, width);
g.FillRectangle(Brushes.Black, x, y, height, width);
}
and I basically call it from my form , but it doesn't draw anything even after using the update() method.
You must use Control.OnPaint to do your custom drawing. Otherwise all of your drawings will be erased after the next repaint of your control.
The idea is you may store your rectangles in a list. Then in your Control.OnPaint, you do the drawing based on that list.
Graphics g = this.CreateGraphics(); This is almost always wrong.
Use the Paint/OnPaint event and its e.Graphics parameter! Store the coordinates somewhere and be prepared to always draw everthing..
I can't use OnPaint event because I want to draw at different times with different conditions. Yes. But you must!
This is how graphics work in winforms. This only sounds wasteful but..: The system also needs to call this event when the window must be restored, so there is no way around it if you want your drawing to persist..
Only non-persistent graphics operations like displaying a dynamic rubber-band rectangle or a line that follows the mouse, are ok with a Graphics object you get from control.CreateGraphics(). And measurements without drawing...
Trigger re-drawing by calling Invalidate on your control whenever your data have changed.
C# Beginner here.
I'm making a 2D Tanks game, and everything's working out nicely so far.
Both of my tanks are Picture Boxes, and so is my Missile.
The image of the missile and tanks in the PictureBoxes have transparent BackColour properties. The problem is, the background of the missile & tanks are not transparent while on top of the other picturebox (pbBackground). It looks like this.
I'm aware that using different PB's is an inefficient way of going about it, but I've come pretty far and I don't really know any better. Anyways, as you can see, the Missile and Tank PB backgrounds show the form colour. When I downloaded the images, the backgrounds were transparent, I'm sure of it. How do I go about making the background of my PB's truly transparent? (Matching the background of the Overlapped PB?)
I saw this but it doesn't really match my scenario and I don't understand the solution.
UPDATE: Okay, I followed Tommy's advice, is this the right way to go about moving it along pbBackground in a timer constantly changing MissileX and MissileY? Currently this does nothing.
using (Graphics drawmissile = Graphics.FromImage(pbBackground.Image))
{
drawmissile.DrawImage(pbMissile.Image, new Point(MissileX,Convert.ToInt32(MissileY)));
}
PictureBox is opaque. And PictureBox is not efficient.
For making games, you should study Paint event which directly draws on your form.
Bitmap backgroundBitmap = new Bitmap("background");
Bitmap tankBitmap = new Bitmap("tank");
private void Form1_Paint(object sender, PaintEventArgs e)
{
e.Graphics.DrawImage(backgroundBitmap, 0, 0);
e.Graphics.DrawImage(tankBitmap, 30, 30);
}
private void timer1_Tick(object sender, EventArgs e)
{
this.Invalidate(); //trigger Form1_Paint to draw next frame
}
Don't layer multiple PictureBox instances on top of each other. It will get very confusing, very quickly.
Instead, use one single PictureBox and use Paint to draw your images to it. In this way, you can have much more control over the graphics operations happening.
Have a look at this
private void DrawIt()
{
System.Drawing.Graphics graphics = this.CreateGraphics();
System.Drawing.Rectangle rectangle = new System.Drawing.Rectangle(
50, 50, 150, 150);
graphics.DrawEllipse(System.Drawing.Pens.Black, rectangle);
graphics.DrawRectangle(System.Drawing.Pens.Red, rectangle);
}
In this example they demonstrate how to draw shapes directly onto a Form. You would use your PictureBox there instead. You can also draw images.
There's lots of ways to draw shapes onto a form using a System.Drawing.Graphics object. Try taking a look at this question for a comparison.
Tommy's answer is right, however, if you're dead set on using pictureboxes (a bad idea), set the overlapping picturebox backgroundcolour to Transparent and the Form's Background to whatever image. TIL the Transparent BackColour just uses the form colour / image. Tommy actually has the right answer here, but this is what I did to fix my problem (the lazy way).
I want to use a PictureBox as a canvas and draw some text on it and save.
I wrote this piece of code but I'm not sure if im doing this the correct way:
Bitmap b = new Bitmap(pictureBox1.Width, pictureBox1.Height);
Graphics g = Graphics.FromImage(b);
g.FillRectangle(new SolidBrush(Color.White), new Rectangle(0, 0, pictureBox1.Width, pictureBox1.Height)); // i used this code to make the background color white
g.DrawString("some text", new Font("Times New Roman", 20), new SolidBrush(Color.Red), new PointF(10, 10));
pictureBox1.Image = b;
This code works well but when I want to change the background color of the image I have to redraw the text.
Is there a way to change the background color without having to redraw the text?
Writing a Paint program is a lot of fun, but you need to plan ahead for all or most of the features you want.
So far you have these:
A background you can change
A way to modify an image by drawing text on it
The need to save it all to a file
Here are a few more things you will need:
Other tools than just text, like lines, rectangles etc..
A choice of colors and pens with widths
A way to undo one or more steps
Here are few thing that are nice to have:
A way to help with drawing and positioning with the mouse
Other type backgrounds like a canvas or pergament paper
The ability to draw with some level of tranparency
A redo feature (*)
Rotation and scaling (***)
Levels (*****)
Some things are harder (*) or a lot harder (***) than others, but all get hard when you decide to patch them on too late..
Do read this post (starting at 'actually') about PictureBoxes, which explain how it is the ideal choice for a Paint program.
Your original piece of code and your question have these problems:
You seem to think that repeating anything, like redrawing the text is wrong. It is not. Windows redraws huge numbers of things all the time..
You have mixed two of the tasks which really should be separate.
You have not parametrizied anything, most notably the drawing of the text should use several variables:
Font
Brush
Position
the text itself
The same will be true once you draw lines or rectangles..
So here are the hints how do get it right:
Use the BackgroundColor and/or the BackgroundImage of the Picturebox to dynamically change the background!
Collect all things to draw in a List<someDrawActionclass>
Combine all drawings by drawing it into he Picturebox's Image
Use the Paint event to draw supporting things like the temporary rectangle or line while moving the mouse. On MouseUp you add it to the list..
So, coming to the end, let's fix your code..:
You set the backgound with a function like this:
void setBackground(Color col, string paperFile)
{
if (paperFile == "") pictureBox1.BackColor = col;
else pictureBox1.BackgroundImage = Image.FromFile(paperFile);
}
you can call it like this: setBackground(Color.White, "");
To draw a piece of text into the Image of the PictureBox, first make sure you have one:
void newCanvas()
{
Bitmap bmp = new Bitmap(pictureBox1.ClientSize.Width, pictureBox1.ClientSize.Height);
pictureBox1.Image = bmp;
}
Now you can write a function to write text. You really should not hard-code any of the settings, let alone the text! This is just a quick and very dirty example..:
void drawText()
{
using (Font font = new Font("Arial", 24f))
using (Graphics G = Graphics.FromImage(pictureBox1.Image))
{
// no anti-aliasing, please
G.TextRenderingHint = System.Drawing.Text.TextRenderingHint.SingleBitPerPixel;
G.DrawString("Hello World", font, Brushes.Orange, 123f, 234f);
}
pictureBox1.Invalidate();
}
See here and here for a few remarks on how to create a drawAction class to store all the things your drawing is made up from..!
The last point is how to save all layers of the PictureBox:
void saveImage(string filename)
{
using (Bitmap bmp = new Bitmap(pictureBox1.ClientSize.Width,
pictureBox1.ClientSize.Height))
{
pictureBox1.DrawToBitmap(bmp, pictureBox1.ClientRectangle);
bmp.Save("yourFileName.png", ImageFormat.Png);
}
}
I have a picturebox that has an image in it and a top of this image I am drawing some ellipses. However, only some of the ellipses show up. Code looks something like this:
Graphics g = Graphics.FromHwnd(pictureBox1.Handle);
g.FillEllipse(redBrush, rfidNode1.readerPos.X, rfidNode1.readerPos.Y, 15, 15);
EDIT: I'm sorry I copied and pasted the last line twice...so there is only one line that fills the ellipse. Also, x and y are within the range of the picture box.
Could you try something like this? (change the dimensions if needed)
Bitmap bmp = new Bitmap(pictureBox1.Width, pictureBox1.Height);
Graphics g = Graphics.FromImage(bmp);
g.FillEllipse(redBrush, rfidNode1.readerPos.X, rfidNode1.readerPos.Y, 15, 15);
pictureBox1.Image = bmp;
Or maybe I missed your intentions?
If the X and Y are same, you are drawing two ellipses one on top another, so only the last is visible. Also, it could be that the X and Y are out of bounds of picture box ?
try to override the paint event and place there your painting code. drawing processes run very often, and then your graphic just gets overdrawn.
Tutorial - Drawing with C#
For drawing on a control, try to register with the paint-event and use the graphics object provided in the paint event args.
Look here for details and an example.
I' m not very sure if it really possible in secure way draw over picture box. Secure I mean: to be sure that all your ellipses are visible when you want. If you want some custom behaviuor, PictureBox is not so good solution, by me.
Like a solution I would suggest to draw an image manually in place where now you have picture box.
Hope this helps.
Regards.
Hey everyone, a new guy here in C#.Net.
I'm trying to make an application like Ms Paint, of course much simpler, and I'm stuck.
The problem is this.
In pictureBox, I'm drawing grid lines on the PictureBox, after that I'm reading a .map(A Mapper3 file) and want to draw onto grid lines, but When I draw the map, The grid lines disappers.
I think the problem is because of the PictureBox Image becomes null while I'm drawing the map. How can I overcome this, is there any tricks?
Thanks for the replies from now on, and sorry for my bad English...
My best Regards...
Do you using winforms? If yes, you actually dont need picture box for working area. I think more appropriate would be Graphics class on form or panel. You have lost lines because of form repaint circle, put your drawing code into form paint handler and picture would be repainted when it needed. In some cases you can need to manual trigger repaint circle, for this purposes you should use Invalidate method of your form.
For example, add this code to paint handler:
private void Form1_Paint(object sender, PaintEventArgs e)
{
// Drawing vertical lines
for (int x = 5; x < this.ClientRectangle.Width; x+=5)
{
e.Graphics.DrawLine(Pens.Gray, new Point(x, 0), new Point(x, this.ClientRectangle.Height));
}
// Drawing horisontal lines
for (int y = 5; y < this.ClientRectangle.Width; y += 5)
{
e.Graphics.DrawLine(Pens.Gray, new Point(0, y), new Point(this.ClientRectangle.Width,y));
}
}
You also may use Graphics in button click handler this way:
Graphics g = Graphics.FromHwnd(this.Handle);
g.FillEllipse(Brushes.Beige, new Rectangle(10, 10, 10, 10));
But in this case all you have drawn would be erased during form's repaint circle and you will have to repeint it in form paint handler
[EDIT]
Ok, for example you have pictureBox1 on your form, you can easly draw into it with help of Bitmap class in this way:
// Draw into bitmap
Bitmap bmp = new Bitmap(150, 150);
Graphics g = Graphics.FromImage(bmp);
g.FillRectangle(Brushes.Green, new Rectangle(25, 75, 10, 30));
// Set bitmap into picture box
pictureBox1.Image = bmp;
In this case you have no need to redraw your paintings, picture box would do it for you. Dont forget to set BackColor ot picture box to Transparent if you prefer to show paintings from below of picture box.
You have to draw everything including the grid lines whenever the paint event raised, if you are concerned about performance you may detect the clipping area and only draw that portion.
Good luck.