i try to draw line on form:
protected override void OnPaint(PaintEventArgs e)
{
base.OnPaint(e);
Graphics g;
g = e.Graphics;
g.PageUnit = GraphicsUnit.Pixel;
g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.None;
Pen myPen = new Pen(Color.Red);
myPen.Width = 1;
g.DrawLine(myPen, 100, 50, 200, 50);
g.DrawLine(myPen, 150, 0, 150, 100);
}
it looks like this: but after magnification it looks like this: - line width is 3 pixels ...
my question is: how to draw line width one pixel width ?
ok - i edited it but now it looks like this (in magnification): (wihtout pageunit looks the same)
What you are looking for is using the following before all your drawing calls:
g.SmoothingMode = SmoothingMode.None;
although the example in your question can not be reproduced.
Related
As suggested by #TaW on this previous question, I setted PenAlignment.Inset to draw the circle inside the Bitmap, but this caused another problem.
I want to draw a circle on a specified Bitmap with antialiasing.
SmoothingMode.AntiAlias
The problem is that, when I use PenAlignment.Inset, the antialiasing doesn't work correctly!
Instead, with PenAlignment.Center, it works correctly...
Any suggestion to resolve this problem?
Bitmap layer = new Bitmap(80, 80);
using (Graphics g = Graphics.FromImage(layer))
{
using (Pen p = new Pen(Color.Black, 4))
{
p.Alignment = PenAlignment.Inset;
g.SmoothingMode = SmoothingMode.AntiAlias;
g.DrawEllipse(p, new Rectangle(0, 0, layer.Width, layer.Height));
}
}
pictureBox3.Size = new Size(100, 100);
pictureBox3.Image = layer;
(Note the bugs on the left image)
Deflating the bounding rectangle by 1/2 of the pen's stroke width should solve this problem. By "deflate", I mean pull in all 4 sides towards the rectangle's center by 1/2 pen width:
float halfPenWidth = p.Width*0.5f;
g.DrawEllipse(p, new RectangleF(halfPenWidth, halfPenWidth, layer.Width - p.Width, layer.Height - p.Width));
or plugging in a hardcoded pen width of 4:
g.DrawEllipse(p, new Rectangle(2, 2, layer.Width - 4, layer.Height - 4));
Note that the full pen width must be subtracted from the rectangle's width and height in order to pull the right and bottom sides in by 1/2 pen width while keeping the rectangle centered on the same point.
Using this code with pen alignment centered, 1/2 of the stroke width will be drawn outside of the rectangle at the points where the ellipse touches the rectangle, but it will still be drawn inside the bitmap.
I am currently trying to draw a gradient filled rounded rectangle onto a panel bar in a form.
From some research I found some code that allowed me to create a custom rectangle :
static class CustomRectangle
{
public static GraphicsPath RoundedRect(Rectangle bounds, int radius)
{
int diameter = radius * 2;
Size size = new Size(diameter, diameter);
Rectangle arc = new Rectangle(bounds.Location, size);
GraphicsPath path = new GraphicsPath();
if (radius == 0)
{
path.AddRectangle(bounds);
return path;
}
// top left arc
path.AddArc(arc, 180, 90);
// top right arc
arc.X = bounds.Right - diameter;
path.AddArc(arc, 270, 90);
// bottom right arc
arc.Y = bounds.Bottom - diameter;
path.AddArc(arc, 0, 90);
// bottom left arc
arc.X = bounds.Left;
path.AddArc(arc, 90, 90);
path.CloseFigure();
return path;
}
public static void FillRoundedRectangle(this Graphics graphics, Brush brush, Rectangle bounds, int cornerRadius)
{
if (graphics == null)
throw new ArgumentNullException("graphics");
if (brush == null)
throw new ArgumentNullException("brush");
using (GraphicsPath path = RoundedRect(bounds, cornerRadius))
{
graphics.FillPath(brush, path);
}
}
Credit to this page
Next using this custom rectangle, I have tried using the paint method for the bar panel.
private void quickMenuBar_Paint(object sender, PaintEventArgs e)
{
LinearGradientBrush myBrush = new LinearGradientBrush(new Point(20, 20), new Point(120, 520), Color.DarkBlue, Color.RoyalBlue);
System.Drawing.Graphics formGraphics = this.CreateGraphics();
CustomRectangle.FillRoundedRectangle(formGraphics, myBrush, new System.Drawing.Rectangle(20, 20, 100, 500), 25);
myBrush.Dispose();
formGraphics.Dispose();
}
But after executing this code, it only prints a rounded rectangle directly onto the form and behind the bar panel.
I have other methods that fill a panel with a standard rectangle using PaintEventArgs e:
e.Graphics.FillRectangle(myBrush , otherBar.ClientRectangle);
So obviously I need to use PaintEventArgs e in my custom rectangle method, but I do not know how or where to.
If there are better ways than this way of drawing a rounded rectnagles, please share.
You generally should never be using CreateGraphics(). Simply remove this line:
System.Drawing.Graphics formGraphics = this.CreateGraphics();
And use e.Graphics where you would previously use formGraphics. The Paint event is basically asking you to "paint something for me, here's the graphics object to paint on".
Since you're already providing a Graphics object instance to your rounded rectangle method, no changes are required there.
I draw lines with the same pen, but the line widths are different in result. Why?
Bitmap b = new Bitmap(400, 400);
Graphics g = Graphics.FromImage(b);
g.PageUnit = GraphicsUnit.Point;
g.Clear(Color.White);
Pen pen = new Pen(Color.Red, 1.2f);
for (int i = 20; i < 200; i = i + 20)
{
g.DrawLine(pen, 10, i, 190, i);
}
g.Dispose();
b.Save("d:/temp/test.png", ImageFormat.Png);
b.Dispose()
Here is the result:
MSDN for GraphicsUnit
It's because you're working with Points and not Pixels and the variation in the width of the lines is the result of a rounding errors in the placement of the line and the width of the line in relation to how it gets rendered in pixels in the final product.
If you don't care about printing the image, it might be best to stick with Pixels.
Edit: If you want to continue using points, space things relative to your pen width:
Bitmap b = new Bitmap(400, 400);
Graphics g = Graphics.FromImage(b);
g.PageUnit = GraphicsUnit.Point;
g.Clear(Color.White);
Pen pen = new Pen(Color.Red, 1.2f);
for (float i = 20f * pen.Width; i < 200f * pen.Width; i = i + 20f * pen.Width)
{
g.DrawLine(pen, 10f, i, 190f, i);
}
g.Dispose();
b.Save("c:/temp/test.png", ImageFormat.Png);
b.Dispose();
I want to draw several figures on the PictureBox. I expected that the following code will draw a rectangle with it's full size diagonal, but it doesn't. Line do not connected with bottom-right corner of rectangle. I'm really curious what may be wrong?
private void onPaint(object sender, PaintEventArgs e)
{
Graphics g = e.Graphics;
Pen p = new Pen(System.Drawing.Color.Black, 2);
g.DrawRectangle(p, 50, 10, 400, 400);
g.DrawLine(p, 50, 10, 400, 400);
}
In DrawRectangle, the last two arguments are width and height. In DrawLine, the last two arguments are final x and final y.
So just add the starting x and starting y to the width and height to get your diagonal line:
g.DrawRectangle(p, 50, 10, 400, 400);
g.DrawLine(p, 50, 10, 450, 410);
Also, if you declare a Rectangle then you can change the values without needing to change the drawing code. Something like:
private void onPaint(object sender, PaintEventArgs e)
{
Graphics g = e.Graphics;
Rectangle rc = new Rectangle(50, 10, 400, 400);
using (Pen p = new Pen(System.Drawing.Color.Black, 2))
{
g.DrawRectangle(p, rc);
g.DrawLine(p, rc.Left, rc.Top, rc.Right, rc.Bottom);
}
}
In C# i have a picturebox. i would like to draw 4 colors. The default will be white, red, green, blue. How do i draw these 4 colors stritched in this picbox? or should i have 4 picbox? in that case how do i set the rgb color?
You need to specify what it is you would specifically like to draw. You can't draw a red - that makes no sense. You can, however, draw a red rectangle at location (0,0) which is 100 pixels tall and 100 wide. I will answer what I can, however.
If you want to set the outline of a shape to a specific color, you would create a Pen object. If you want to fill a shape with a color, however, then you would use a Brush object. Here's an example of how you would draw a rectangle filled with red, and a rectangle outlined in green:
private void pictureBox_Paint(object sender, PaintEventArgs e)
{
Graphics graphics = e.Graphics;
Brush brush = new SolidBrush(Color.Red);
graphics.FillRectangle(brush, new Rectangle(10, 10, 100, 100));
Pen pen = new Pen(Color.Green);
graphics.DrawRectangle(pen, new Rectangle(5, 5, 100, 100));
}
Add a PictureBox to the form, create an event handler for the paint event, and make it look like this:
private void PictureBox_Paint(object sender, PaintEventArgs e)
{
int width = myPictureBox.ClientSize.Width / 2;
int height = myPictureBox.ClientSize.Height / 2;
Rectangle rect = new Rectangle(0, 0, width, height);
e.Graphics.FillRectangle(Brushes.White, rect);
rect = new Rectangle(width, 0, width, height);
e.Graphics.FillRectangle(Brushes.Red, rect);
rect = new Rectangle(0, height, width, height);
e.Graphics.FillRectangle(Brushes.Green, rect);
rect = new Rectangle(width, height, width, height);
e.Graphics.FillRectangle(Brushes.Blue, rect);
}
This will divide the surface into 4 rectangles and paint each of them in the colors White, Red, Green and Blue.
If you want to use non-predefined colors, then you need to get a Color object from the static method Color.FromArgb().
int r = 100;
int g = 200;
int b = 50;
Color c = Color.FromArgb(r, g, b);
Brush brush = new SolidBrush(c);
//...
Best RegardsOliver Hanappi