I'm completely new to Winforms and GDI+, I come from a WPF background. Using the simple code below to draw 1000 Lines I noticed that it doesn't draw the Lines at once like WPF does. It is slow and the process of drawing is actually noticable. Am I missing something in the code below?
private void button1_Click(object sender, EventArgs e)
{
Graphics g;
g = CreateGraphics();
var pn = new Pen(Color.Wheat, 1);
var x = 0;
var y = 0;
var n = 0;
while (n < 1000)
{
x = x + 5;
if (x > 1200)
{
x = 0;
y = y + 15;
}
g.DrawLine(pn, x, y, x, y + 10);
n++;
}
}
Related
I'm trying to create some simple graphics ("plasma" effect) with C# and Winforms.
I have two classes in my code, (main)Form1 and Plasmadraw.
In Plasmadraw I have following setup:
class Plasmadraw
{
int y;
int x;
double i;
double pii = 3.1415;
public void Draw(Graphics gfx, int addition)
{
for (int i = 0; i < 23040; i++)
{
x = x + 10;
if (x == 1920)
{
x = 0;
y = y + 10;
}
if (y == 1200)
{
y = 0;
}
double v = Math.Sin((x * 0.5) + i * 0.001 * addition);
double c = v * pii;
double d = c + (2 * pii / 3);
double f = c + (6 * pii / 3);
double r = 255 * Math.Abs(Math.Sin(c));
double g = 255 * Math.Abs(Math.Sin(d));
double b = 255 * Math.Abs(Math.Sin(f));
int r1 = (int)r;
int g1 = (int)g;
int b1 = (int)b;
Color e = Color.FromArgb(r1, g1, b1);
SolidBrush brush = new SolidBrush(e);
Rectangle rect = new Rectangle(x, y, 10, 10);
gfx.FillRectangle(brush, rect);
}
}
}
and then in Form1 I have Paint event:
private void Form1_Paint(object sender, PaintEventArgs e)
{
Plasmadraw plasmaeffect = new Plasmadraw();
for (int a = 0; a < 30; a++)
{
plasmaeffect.Draw(e.Graphics, a);
Invalidate();
}
Is this somehow completely wrong way to build the logic ? I've managed to create some graphics effects (moving sprites etc.) by creating a list and then running through the list with Foreach in Paint event (& Invalidate()). However, I'd like to learn some new way to do things, rather than copying the old way.
I am trying to detect light from 2 LED lights (red and blue) I did that using Bernsen thresholding technique. However, I applied that to an image. Now I want to apply that same technique but to a live video from my webcam. Is there anyway I could simply edit the code for this technique on the image to make it work on a video from the webcam? I will add below the code I used for this thresholding technique.
private ArrayList getNeighbours(int xPos, int yPos, Bitmap bitmap)
{
//This goes around the image in windows of 5
ArrayList neighboursList = new ArrayList();
int xStart, yStart, xFinish, yFinish;
int pixel;
xStart = xPos - 5;
yStart = yPos - 5;
xFinish = xPos + 5;
yFinish = yPos + 5;
for (int y = yStart; y <= yFinish; y++)
{
for (int x = xStart; x <= xFinish; x++)
{
if (x < 0 || y < 0 || x > (bitmap.Width - 1) || y > (bitmap.Height - 1))
{
continue;
}
else
{
pixel = bitmap.GetPixel(x, y).R;
neighboursList.Add(pixel);
}
}
}
return neighboursList;
}
private void button5_Click_1(object sender, EventArgs e)
{
//The input image
Bitmap image = new Bitmap(pictureBox2.Image);
progressBar1.Minimum = 0;
progressBar1.Maximum = image.Height - 1;
progressBar1.Value = 0;
Bitmap result = new Bitmap(pictureBox2.Image);
int iMin, iMax, t, c, contrastThreshold, pixel;
contrastThreshold = 180;
ArrayList list = new ArrayList();
for (int y = 0; y < image.Height; y++)
{
for (int x = 0; x < image.Width; x++)
{
list.Clear();
pixel = image.GetPixel(x, y).R;
list = getNeighbours(x, y, image);
list.Sort();
iMin = Convert.ToByte(list[0]);
iMax = Convert.ToByte(list[list.Count - 1]);
// These are the calculations to test whether the
current pixel is light or dark
t = ((iMax + iMin) / 2);
c = (iMax - iMin);
if (c < contrastThreshold)
{
pixel = ((t >= 160) ? 0 : 255);
}
else
{
pixel = ((pixel >= t) ? 0 : 255);
}
result.SetPixel(x, y, Color.FromArgb(pixel, pixel, pixel));
}
progressBar1.Value = y;
}
pictureBox3.Image =result;
}
I'm having some trouble reading back pixel values from a Bitmap that I'm generating. I first generate a bitmap named maskBitmap in my class using this code:
void generateMaskBitmap()
{
if (inputBitmap != null)
{
Bitmap tempBitmap = new Bitmap(inputBitmap.Width, inputBitmap.Height, System.Drawing.Imaging.PixelFormat.Format32bppArgb);
using (Graphics g = Graphics.FromImage(tempBitmap))
{
Brush brush = Brushes.Black;
for (int y = 0; y < tempBitmap.Height; y += circleSpacing)
{
for (int x = 0; x < tempBitmap.Width; x += circleSpacing)
{
g.FillEllipse(brush, x, y, circleDiameter, circleDiameter);
}
}
g.Flush();
}
maskBitmap = (Bitmap)tempBitmap.Clone();
}
}
I then try to apply the mask to my original image using the following code:
void generateOutputBitmap()
{
if (inputBitmap != null && maskBitmap != null)
{
Bitmap tempBitmap = new Bitmap(inputBitmap.Width, inputBitmap.Height);
for (int y = 0; y < tempBitmap.Height; y++)
{
for (int x = 0; x < tempBitmap.Width; x++)
{
Color tempColor = maskBitmap.GetPixel(x, y);
if (tempColor == Color.Black)
{
tempBitmap.SetPixel(x, y, inputBitmap.GetPixel(x, y));
}
else
{
tempBitmap.SetPixel(x, y, Color.White);
}
}
}
outputBitmap = tempBitmap;
}
}
The mask bitmap is successfully generated and visible in a picture box, however the color values for every pixel when testing "tempColor" show empty (A = 0, R = 0, G = 0, B = 0). I am aware of the performance problems with getpixel/setpixel, but this is not an issue for this project. I'm also aware that "tempColor == Color.Black" is not a valid test, but that is just a place holder for my comparison code.
I am unable to reproduce your problem. I copy-and-pasted your code and made some modifications to make it work for me. I am able to confirm that tempColor is sometimes #FF000000.
I suspect you mixed up your bitmap references somewhere. Are you really sure you are never getting any value other than #00000000? Do your circleDiameter and circleSpacing have sensible values? And most importantly: are you absolutely sure that you are reading from the correct bitmap?
Here's my version of your code, which I know works:
using System;
using System.Drawing;
namespace Test
{
class Program
{
static void Main()
{
var bitmap = GenerateMaskBitmap(100, 100);
TestMaskBitmap(bitmap);
}
const int CircleDiameter = 10;
const int CircleSpacing = 10;
static Bitmap GenerateMaskBitmap(int width, int height)
{
Bitmap maskBitmap = new Bitmap(width, height, System.Drawing.Imaging.PixelFormat.Format32bppArgb);
using (Graphics g = Graphics.FromImage(maskBitmap))
{
Brush brush = Brushes.Black;
for (int y = 0; y < maskBitmap.Height; y += CircleSpacing)
{
for (int x = 0; x < maskBitmap.Width; x += CircleSpacing)
{
g.FillEllipse(brush, x, y, CircleDiameter, CircleDiameter);
}
}
g.Flush();
}
return maskBitmap;
}
static void TestMaskBitmap(Bitmap maskBitmap)
{
for (int y = 0; y < maskBitmap.Height; y++)
{
for (int x = 0; x < maskBitmap.Width; x++)
{
Color tempColor = maskBitmap.GetPixel(x, y);
if (tempColor.ToArgb() != 0)
throw new Exception("It works!");
}
}
}
}
}
Im doing a normalization for my image and i've already gotten done the RGB values for the image. can anyone help me with the RGB normalization for the c# codes like maybe some starters on how to write out the normalization code. thanks!
private void normalization_Click(object sender, EventArgs e)
{
// for (int x = 0; x < pictureBox1.Width; x++)
{
// for (int y = 0; y < pictureBox1.Height; y++)
{
try
{
Bitmap img = new Bitmap(pictureBox1.Image);
Color c;
for (int i = 0; i < img.Width; i++)
{
for (int j = 0; j < img.Height; j++)
{
c = img.GetPixel(i, j);
int r = Convert.ToInt16(c.R);
int g = Convert.ToInt16(c.G);
int b = Convert.ToInt16(c.B);
d = r / (r + g + b);
h = g / (r + g + b);
f = b / (r + g + b);
img.SetPixel(i, j, Color.FromArgb(d, h, f));
Color pixelColor = img.GetPixel(i, j);
float normalizedPixel = (d + h + f);
Color normalizedPixelColor = System.Drawing.ColorConverter.(normalizedPixel);
img.SetPixel(x, y, normalizedPixelColor);
}
}
}
catch (Exception ex) { }
Hi. I've done the formulaes and all for normalization. The problem that I am facing now is that I'm having trouble getting the values of the RGB pixels out of the listbox and normalizing it with the formulae and then putting the pixels back into picturebox/image. Above is the code that i've tried to do to put the normalized RGB pixels back into the picturebox. Can I ask for some help with this because it still doesn't normalize my image. Thanks.
Have a look at AForge.NET if you do not mind having a dependency in your project. As a bonus you'll have plenty of other algorithms at your availability without the need for you to re-invent the for loop...
I was trying to create simple program that would perform some trivial operation with given image.
For some reason, it works only for the first time (when the app is launched):
//pseudo code
Bitmap im=Bitmap.FromFile("D:\\x.BMP");
Color [,] ColorArray=new [im.Width,im.Height];
private override voide OnPaint(EventArgs e)
{
for(int X=0;X<im.Width;X++)
{
for(int Y=0;Y<im.Height;Y++)
{
ColorArray[X,Y]=im.GetPixel[X,Y];
}
}
for(int X=0;X<im.Width;X++)
{
for(int Y=0;Y<im.Height;Y++)
{
Color c=ColorArray[X,Y];
...
//some code that adds 100 to R,G,B
im.SetPixel(X,Y,c);
}
}
e.Graphics.DrawImage(im);
}
[EDIT]
I have modified my sample code. With the previous version, it could be hard to see the difference from one iteration to the next (especially with the bmp I was using for testing). This one allows you to change color gradually by pressing 1, 2, or 3 on the Num Pad. As others have mentioned, SetPixel/GetPixel is slow, so each KeyUp event does take some time to run.
This works fine for me.
Create a new Windows Forms project. Drop this code in. Make sure you have "x.bmp" available. Each time you press 1, 2, or 3 on the number pad (you might need turn on Num Lock), the colors of the bitmap change slightly:
public partial class Form1 : Form
{
Bitmap bm;
Color [,] colors;
public Form1()
{
bm = (Bitmap)Bitmap.FromFile("x.bmp");
colors = new Color[bm.Width, bm.Height];
InitializeComponent();
}
private void Form1_Paint(object sender, PaintEventArgs e)
{
e.Graphics.DrawImage(bm,new Point(0,0));
}
private void Form1_KeyUp(object sender, KeyEventArgs e)
{
//Change the colors a little bit on each KeyUp.
//On NumPad1, change red.
//On NumPad2, change green.
//On NumPad3, change blue.
//Mod with 256 to ensure a value between 0 and 255.
int rInc = 0;
int gInc = 0;
int bInc = 0;
switch (e.KeyCode)
{
case Keys.NumPad1:
rInc = 20;
break;
case Keys.NumPad2:
gInc = 20;
break;
case Keys.NumPad3:
bInc = 20;
break;
default:
break;
}
for (int x = 0; x < bm.Width; x++)
{
for (int y = 0; y < bm.Height; y++)
{
colors[x, y] = bm.GetPixel(x, y);
}
}
for (int x = 0; x < bm.Width; x++)
{
for (int y = 0; y < bm.Height; y++)
{
Color c = colors[x, y];
int r = (c.R + rInc) % 256;
int g = (c.G + gInc) % 256;
int b = (c.B + bInc) % 256;
c = Color.FromArgb(255, r, g, b);
bm.SetPixel(x, y, c);
}
}
Invalidate();
}
}
It's not very sophisticated, but it does what you asked with real code that closely matches your pseudocode.
You can improve your performance when looping over pixels, arrange the loops to access the pixels in row order (x coordinates) in the inner loop. That best matches the image memory layout so it will improve CPU cache performance
for ( y = 0, y < bm.Height; y++)
{
...
for ( x = 0, x < bm.Width; x++)
{
...
}
}