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
Related
I want to draw a circle with DrawEllipse on a specified Bitmap, with the same size of the Bitmap, but the result is that the circle appears clipped at the edges.
Why this problem?
Bitmap layer = new Bitmap(80, 80);
using (Graphics g = Graphics.FromImage(layer))
{
using (Pen p = new Pen(Color.Black, 4))
{
g.DrawEllipse(p, new Rectangle(0, 0, layer.Width, layer.Height));
}
}
pictureBox3.Size = new Size(100, 100);
pictureBox3.Image = layer;
By default a Pen has a PenAlignment.Center.
This means that half of its widh will draw outside the bounding rectangle.
You can simply avoid the issue by changing it to PenAlignment.Inset:
using (Pen p = new Pen(Color.Black, 4) { Alignment = PenAlignment.Inset})
{
g.DrawEllipse(p, new Rectangle(0, 0, layer.Width, layer.Height));
}
Update: If you want to turn on smoothing for the Graphics object you will need 1 or 2 extra pixels on both sides of the pen stroke for the anti-aliasing pixels. Using a smaller bounding rectanlge can't be avoided now. But..:
Rectangle rect = new Rectangle(Point.Empty, layer.Size);
rect.Inflate(-1, -1); // or -2
..should do..
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.
In the code below:
void f13(Graphics g)
{
g.FillRectangle(new SolidBrush(Color.Black), pictureBox1.ClientRectangle);
g.InterpolationMode = InterpolationMode.HighQualityBicubic;
var zf = .0143;
const int w = 6000, h = 10, margin = 40;
var bmp = new Bitmap(w + 2 * margin, h + 2 * margin);
var bmpG = Graphics.FromImage(bmp);
bmpG.FillRectangle(new SolidBrush(Color.White), 0, 0, bmp.Width, bmp.Height);
var srcRect = new RectangleF(margin - .5f, margin - .5f, w, h);
zf = (float)Convert.ToInt32(w * zf) / w;
var destRect = new Rectangle(0, 0, Convert.ToInt32(w * zf), Convert.ToInt32(w * zf));
g.DrawImage(bmp, destRect, srcRect, GraphicsUnit.Pixel);
destRect.X += destRect.Width;
g.DrawImage(bmp, destRect, srcRect, GraphicsUnit.Pixel);
}
private void pictureBox1_Paint(object sender, PaintEventArgs e)
{
f13(e.Graphics);
}
I get a gap between two rectangles:
micro http://www.uploadup.com/di-0HXM.png
macro http://www.uploadup.com/di-G1O5.png
why is that?
If the gap line is not so clear, you may decrease margin. if you set it to 10 you'll get:
macro, less margin http://www.uploadup.com/di-P2ZT.png
That'll happen if your rectangles' boundaries aren't integers. Gradient has nothing to do with it.
Consider: Let's say you're drawing a rectangle whose right side is at X=100.5, and you're filling it with white (with the existing background being black). So the graphics library (this isn't specific to GDI+) will "half-fill" those rightmost pixels (at X=100) with white, meaning they blend the existing black with a 50% mix of white, for a result of gray.
Then you draw another rectangle whose left side is at X=100.5. Now you're once again filling the pixels at X=100 halfway with white, so the graphics library will take the existing color (gray) and blend it with a 50% white, leaving you with 75% white.
If you don't want this kind of seam, you have to either (a) make sure your rectangles overlap a little bit, or (b) manually round your coordinates to the nearest pixel, so all the pixels are getting completely written instead of blended with what's already there.
I draw the ellipse with the code as shown below. How can I make the height of the red color is inside the ellipse can be changed for example from 0% -100%. If 0% the meanings the level of red height is empty. If 50% the meanings height level of the red color is half of the ellipse. If 100% the meanings height level of the red color is full. Thank You.
private void panel1_Paint(object sender, PaintEventArgs e)
{
Rectangle r1= new Rectangle(10, 130, 60, 60);
// Create solid brush.
SolidBrush redBrush = new SolidBrush(Color.Red);
// Create location and size of ellipse.
float x = 20F;
float y = 20F;
float width = 80.0F;
float height = 200.0F;
// Fill ellipse on screen.
e.Graphics.FillEllipse(redBrush, x, y, width, height);
}
Please, try the following code:
void panel1_Paint(object sender, PaintEventArgs e)
float percent = 0.75f;
RectangleF bounds = new RectangleF(20, 20, 80, 200);
FillEllipse(e.Graphics, bounds, percent);
}
static void FillEllipse(Graphics g, RectangleF bounds, float percent) {
g.DrawEllipse(Pens.Red, bounds);
g.SetClip(new RectangleF(
bounds.X,
bounds.Y + (1f - percent) * bounds.Height,
bounds.Width,
percent * bounds.Height));
g.FillEllipse(Brushes.Red, bounds);
g.ResetClip();
}
When I want to draw a rectangle in c# using pen tools If the rectangle width and height is less then the pens width then program draw nothing in from if pens alignment property Inset.But when I set alignment center then It print a rectangle. which is not size of my rectangle. Actually what happened at that time?
example:
Pen p = new Pen(Color.Black, 300);
p.Alignment = PenAlignment.Center;
g.DrawRectangle(p, 100, 100,10, 10);
p.Dispose();
The output figure is:
But how it is possible to draw a rectangle of 1o pixel width,hight with a pen of 300 pixel width?
So, basically, when the rectangle width or height smaller then 300px, you want to draw a black filled rectangle?
void DrawRectangle(Graphics g, Color pencolor, int penwidth, Rectangle x)
{
if(x.Width < penwidth || x.Height < penHeight)
{
Pen p = new Pen(pencolor);
p.Alignment = PenAlignment.Inset;
g.FillRectangle(p, x);
p.Dispose();
}
else
{
Pen p = new Pen(pencolor, penwidth);
p.Alignment = PenAlignment.Inset;
g.DrawRectangle(p, x);
p.Dispose();
}
}
Hope that helps.