I could not fit exactly what I wanted to say in the title, it would be too long. Okay this is a multi-threaded app. What my app does is looks at a picture, find the edges of the picture, and finds the shape of that object from the edges. While it finds the shape, it constantly updates the image so we can get some sort of visual representation. I have created a very short (40 seconds) video demonstrating the issue: http://phstudios.com/projects/Programming/MultiThreadIssue/
As you can see, everything is working fine until the minute I move the window. This is always the case. I ran the program several times without moving the window and it ran fine. However, the minute I move the window, it will come up with that error. As you see, I am locking the specific image I would like to work with. Is the forms OnPaint overriding that somehow? Is there any way I can fix that?
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Threading;
using System.Drawing.Imaging;
namespace LineRecognition
{
public enum Shape
{
Unknown,
Quadrilateral,
Circle,
Triangle
}
public partial class Form1 : Form
{
Bitmap image, original, shapes;
List<Point> outlines;
Shape shape;
ShapeDetection detector;
public Form1()
{
InitializeComponent();
edgeDetection.WorkerReportsProgress = true;
shapeDetection.WorkerReportsProgress = true;
shape = Shape.Unknown;
}
private void Form1_Load(object sender, EventArgs e)
{
original = new Bitmap("photo1.png");
image = new Bitmap("photo1.png");
shapes = new Bitmap(image.Width, image.Height);
pictureBox1.Image = (Image)original;
}
private void findLines_Click(object sender, EventArgs e)
{
if (edgeDetection.IsBusy != true)
{
lblStatus.Text = "Finding Edges";
edgeDetection.RunWorkerAsync();
}
}
private void justTheOutlines(Bitmap image, List<Point> pixels, BackgroundWorker worker)
{
lock (image)
{
for (int i = 0; i < pixels.Count; i++)
{
image.SetPixel(pixels[i].X, pixels[i].Y, Color.Red);
worker.ReportProgress((int)((float)i * 100 / (float)pixels.Count));
}
}
}
private List<Point> outlineLines(Bitmap image, BackgroundWorker worker)
{
int w = image.Width;
int h = image.Height;
int alpha = 800000;
List<Point> changes = new List<Point>();
lock (image)
{
for (int i = 0; i < w; i++)
{
for (int j = 0; j < h; j++)
{
Color selected = image.GetPixel(i, j);
Color nextRight = selected;
Color nextDown = selected;
if (i < w - 1)
nextRight = image.GetPixel(i + 1, j);
if (j < h - 1)
nextDown = image.GetPixel(i, j + 1);
int iSelected = selected.ToArgb();
int iNextRight = nextRight.ToArgb();
int iNextDown = nextDown.ToArgb();
if (Math.Abs(iSelected - iNextRight) > alpha)
{
if (iSelected < iNextRight)
{
Point p = new Point(i, j);
if(!ContainsPoint(changes, p)) changes.Add(p);
}
else
{
Point p = new Point(i + 1, j);
if (!ContainsPoint(changes, p)) changes.Add(p);
}
}
if (Math.Abs(iSelected - iNextDown) > alpha)
{
if (iSelected < iNextDown)
{
Point p = new Point(i, j);
if (!ContainsPoint(changes, p)) changes.Add(p);
}
else
{
Point p = new Point(i, j + 1);
if (!ContainsPoint(changes, p)) changes.Add(p);
}
}
image.SetPixel(i, j, Color.White);
}
worker.ReportProgress((int)(((float)i / (float)w) * 100));
}
}
return changes;
}
private bool ContainsPoint(List<Point> changes, Point p)
{
foreach (Point n in changes)
{
if (n.Equals(p)) return true;
}
return false;
}
private void edgeDetection_DoWork(object sender, DoWorkEventArgs e)
{
BackgroundWorker worker = sender as BackgroundWorker;
outlines = outlineLines(image, worker);
justTheOutlines(image, outlines, worker);
pictureBox2.Image = (Image)image;
Thread.Sleep(100);
image.Save("photo-lines.jpg");
}
private void edgeDetection_ProgressChanged(object sender, ProgressChangedEventArgs e)
{
algorithmProgress.Value = e.ProgressPercentage;
}
private void edgeDetection_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
algorithmProgress.Value = 0;
findLines.Enabled = false;
determineShape.Enabled = true;
lblStatus.Text = "";
}
private void determineShape_Click(object sender, EventArgs e)
{
if (shapeDetection.IsBusy != true)
{
pictureBox1.Image = (Image)image;
lblStatus.Text = "Running Shape Detection: Circle -> Quadrilateral";
shapeDetection.RunWorkerAsync();
}
}
private void ShapeDetection_DoWork(object sender, DoWorkEventArgs e)
{
BackgroundWorker worker = sender as BackgroundWorker;
detector = new ShapeDetection(outlines, 40, 10);
detector.Worker = worker;
detector.circleChange += new ShapeDetection.CircleChangeEventHandler(circleChange);
if (detector.IsCircle())
{
MessageBox.Show("Object is a circle");
shape = Shape.Circle;
}
else if (detector.IsQuadrilateral())
{
MessageBox.Show("Object is a quadrilateral", "Number of edges: " + detector.Summits);
shape = Shape.Quadrilateral;
}
else
{
int sides = detector.Summits.Count;
if (sides == 3)
{
MessageBox.Show("Object is a triangle");
shape = Shape.Triangle;
}
else
{
MessageBox.Show("Number of edges: " + detector.Summits.Count, "Unknown");
}
}
BitmapDrawing.DrawLines(detector.Summits, shapes);
BitmapDrawing.DrawSummits(detector.Summits, shapes);
pictureBox2.Image = (Image)shapes;
Thread.Sleep(100);
}
private void ShapeDetection_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
if (detector != null)
{
lblSummits.Text += detector.Summits.Count;
lblType.Text += shape.ToString();
determineShape.Enabled = false;
lblStatus.Text = "";
}
}
void circleChange(object sender, CircleChangeEventArgs e)
{
lock (shapes)
{
Point p = detector.visited[detector.visited.Count - 1];
shapes.SetPixel(p.X, p.Y, Color.Blue);
pictureBox2.Image = (Image)shapes;
Thread.Sleep(10);
detector.Worker.ReportProgress((int)(e.percent * 100));
}
}
private void shapeDetection_ProgressChanged(object sender, ProgressChangedEventArgs e)
{
algorithmProgress.Value = e.ProgressPercentage;
}
}
}
Update
What Nick said before worked fine. I added that to my CircleChange event and it works. Can somebody explain why the invoke makes it work instead of setting the picturebox2.Image to the shapes image? I mean I call it after I call setpixel, so I should be done modifying the image right?
void circleChange(object sender, CircleChangeEventArgs e)
{
Point p = detector.visited[detector.visited.Count - 1];
shapes.SetPixel(p.X, p.Y, Color.Blue);
Image copyForPictureBox = shapes.Clone() as Image;
BeginInvoke(new Action(() => pictureBox2.Image = copyForPictureBox));
Thread.Sleep(15);
detector.Worker.ReportProgress((int)(e.percent * 100));
}
It appears that you're operating on the shapes bitmap on a thread separate to the GUI thread. When you move the window the OnPaint routine will run which will also access the image.
What you need to do to solve this is operate on a separate bitmap in your worker thread, and then pass a copy of that to the GUI thread using Invoke on the form. That way you're guaranteed only to have one thread accessing the picture box image at a time.
Edit:
void MyThreadFunction( )
{
Bitmap localThreadImage;
...
Image copyForPictureBox = localThreadImage.Clone( ) as Image;
BeginInvoke( new Action( () => pictureBox.Image = copyForPictureBox ) );
....
}
So the idea is that you create a Bitmap on the thread which is only ever accessed by that thread (i.e. your background worker thread). And when you get to a point when you want to update the image in the PictureBox you invoke onto the the GUI thread using BeginInvoke (which doesn't block your worker thread) passing a copy of the Bitmap to the PictureBox.
Locking the shapes object at only one point in your application does not accomplish anything. You also use this bitmap to draw to the window, and my guess is that you are not locking it for drawing. You can either lock it in OnPaint as well, or use a different bitmap for manipulation and display.
Related
I am trying to make a program that will draw waves with any given parameters and I want to have them oscillate in real time. I have a checkbox in my form and in the CheckedChanged event that will toggle the drawing of the wave and when toggled it is supposed to start constantly drawing and redrawing the given wave using my DrawWave function until I untick the box. Below is the code for the DrawWave function and the event for ticking the checkbox.
private void DrawWave(object waveinput)
{
var wave = (Wave)waveinput;
Graphics graphicsobj = this.CreateGraphics();
Point[] graphPoints = new Point[waveSizeConstant];
myPen = new Pen(Color.Red, 3f);
for (int i = 0; i < waveSizeConstant; i++)
{
int displacement = Convert.ToInt32(Math.Round(wave.getDisplacementDegrees(i, timer.Elapsed.TotalSeconds)));
graphPoints[i] = new Point(i + 30, displacement + 250);
}
for (int i = 0; i < waveSizeConstant - 1; i++)
{
graphicsobj.DrawLine(myPen, graphPoints[i], graphPoints[i + 1]);
}
graphicsobj.Dispose();
}
private void ToggleWave_CheckedChanged(object sender, EventArgs e)
{
var graphicsThread = new Thread(new ParameterizedThreadStart(DrawWave));
if (ToggleWave.Checked)
{
while (true)
{
graphicsThread.Start(wave1);
Thread.Sleep(1000);
graphicsThread.Abort();
Invalidate();
}
}
else
{
graphicsThread.Abort();
Invalidate();
}
}
So I have some code that creates a highlight effect on top of a picture box with gdi32.dll and I am wondering if there is a simpler way to do it with System.Drawing.Graphics? Basically with the gdi32.dll, I have to capture a screen shot after drawing, post that to my picturebox and then I am able to draw more stuff and change the color of the pen that I use. If I just try to change the pen thickness and color and draw on the screen again, if changes what I already drew.
Now I have a version of this that uses System.Drawing.Graphics and lots of math with FillPolygon but if I draw over an area I already drew on, it just makes the area I drew on darker. It does not do this with gdi32.dll which justr shades as long as you have not already shaded the area with the mouse. Any suggestions?
public partial class Form9 : Form
{
private bool is_mouse_down { get; set; } // Will check if the mouse is down or not.
private Color Pen_Color = new Color();
private int Pen_Type { get; set; }
private int Thickness { get; set; }
private bool Start { get; set; }
List<Point> Points = new List<Point>();
public Form9()
{
InitializeComponent();
pictureBox1.Dock = DockStyle.Fill;
Pen_Color = Color.Blue;
Pen_Type = 13; // Type = 9 for highlighter, Type = 13 for solid.
Thickness = 2;
Start = false;
pictureBox1.MouseDown += pictureBox1_MouseDown;
pictureBox1.MouseUp += pictureBox1_MouseUp;
pictureBox1.MouseMove += pictureBox1_MouseMove;
pictureBox1.Paint += pictureBox1_OnPaint;
}
private void DrawHighlight(Graphics g, Point[] usePoints, int brushSize, int penType, Color brushColor)
{
int useColor = System.Drawing.ColorTranslator.ToWin32(brushColor);
IntPtr pen = GetImage.GDI32.CreatePen(GetImage.GDI32.PS_SOLID, brushSize, (uint)useColor);
IntPtr hDC = g.GetHdc();
IntPtr xDC = GetImage.GDI32.SelectObject(hDC, pen);
GetImage.GDI32.SetROP2(hDC, penType);//GetImage.GDI32.R2_MASKPEN);
for (int i = 1; i <= usePoints.Length - 1; i++)
{
Point p1 = usePoints[i - 1];
Point p2 = usePoints[i];
GetImage.GDI32.MoveToEx(hDC, p1.X, p1.Y, IntPtr.Zero);
GetImage.GDI32.LineTo(hDC, p2.X, p2.Y);
}
GetImage.GDI32.SetROP2(hDC, GetImage.GDI32.R2_COPYPEN);
GetImage.GDI32.SelectObject(hDC, xDC);
GetImage.GDI32.DeleteObject(pen);
g.ReleaseHdc(hDC);
}
private void pictureBox1_OnPaint(object sender, PaintEventArgs e)
{
if (Start)
{
base.OnPaint(e);
if (is_mouse_down)
{
DrawHighlight(e.Graphics, Points.ToArray(), Thickness, Pen_Type, Pen_Color);
}
}
}
private void pictureBox1_MouseDown(object sender, MouseEventArgs e)
{
Points.Clear();
Start = true;
is_mouse_down = true;
}
private void pictureBox1_MouseUp(object sender, MouseEventArgs e)
{
is_mouse_down = false;
using (Image img = CaptureScreen())
{
try
{
if (System.IO.File.Exists(Program.ProgramPath + #"\Temp\marked.bmp"))
{
System.IO.File.Delete(Program.ProgramPath + #"\Temp\marked.bmp");
}
}
catch (Exception Ex)
{
MessageBox.Show("File Delete Error" + Environment.NewLine + Convert.ToString(Ex));
}
try
{
img.Save(Program.ProgramPath + #"\Temp\marked.bmp", System.Drawing.Imaging.ImageFormat.Bmp);
}
catch (Exception Ex)
{
MessageBox.Show("Unable to save Screenshot" + Environment.NewLine + Convert.ToString(Ex));
}
}
if (System.IO.File.Exists(Program.ProgramPath + #"\Temp\marked.bmp"))
{
using (FileStream fs = new System.IO.FileStream(Program.ProgramPath + #"\Temp\marked.bmp", System.IO.FileMode.Open, System.IO.FileAccess.Read, FileShare.Read))
{
pictureBox1.Image = Image.FromStream(fs);
}
}
pictureBox1.Invalidate(); // Refreshes picturebox image.
}
public Image CaptureScreen()
{
GetImage gi = new GetImage();
return gi.CaptureWindow(GetImage.User32.GetDesktopWindow());
}
private void pictureBox1_MouseMove(object sender, MouseEventArgs e)
{
if (is_mouse_down == true) // Check to see if the mouse button is down while moving over the form.
{
Points.Add(new Point(e.X, e.Y));
pictureBox1.Invalidate(); // Refreshes picturebox image.
}
}
Here are a couple photos of what I am talking about:
Using System.Drawing.Graphics:
Using gdi32.dll:
UPDATE
After testing some of your code...I got a some strange stuff.
This is a way to draw multiple independent stroke of semi-transparent color without piling up the alpha:
It uses tow lists, one for the strokes and one for the current stroke:
List<List<Point>> strokes = new List<List<Point>>();
List<Point> currentStroke = new List<Point>();
They are filled in the usual way
private void canvas_MouseDown(object sender, MouseEventArgs e)
{
if (e.Button.HasFlag(MouseButtons.Left))
{
currentStroke.Add(e.Location);
if (currentStroke.Count == 1)
currentStroke.Add(new Point(currentStroke[0].X + 1,
currentStroke[0].Y));
canvasInvalidate();
}
}
private void canvas_MouseMove(object sender, MouseEventArgs e)
{
if (e.Button.HasFlag(MouseButtons.Left))
{
currentStroke.Add(e.Location);
canvas.Invalidate();
}
}
private void canvas_MouseUp(object sender, MouseEventArgs e)
{
if (currentStroke.Count > 1)
{
strokes.Add(currentStroke.ToList());
currentStroke.Clear();
}
canvas.Invalidate();
}
In this version we avoid overlay effects of overlapping strokes by drawing all pixels in only one call. All the pixels are painted by creating a GraphicsPath from the strokes and and filling it:
private void canvas_Paint(object sender, PaintEventArgs e)
{
if (strokes.Count > 0 || currentStroke.Count > 0)
{
GraphicsPath gp = new GraphicsPath();
gp.FillMode = FillMode.Winding;
if (currentStroke.Count > 0)
{
gp.AddCurve(currentStroke.ToArray());
gp.CloseFigure();
}
foreach (var stroke in strokes)
{
gp.AddCurve(stroke.ToArray());
gp.CloseFigure();
}
using (SolidBrush b = new SolidBrush(Color.FromArgb(77, 177, 99, 22)))
{
e.Graphics.FillPath(b, gp);
}
}
}
Note that you should take care not to move back onto the current stroke while drawing it or else the croosing path parts will create holes!
A Clear or Save Button are simple, the former Clears the two list and invalidates, the latter would use DrawToBitmap to save the control..
Note: To avoid flicker do make sure the canval Panel is DoubleBuffered!
Update:
Here is another way that uses a Pen to draw the overlay. To avoid the piling up of alpha and changed color values (depending on the PixelFormat) it uses a fast function to modify all set pixels in the overlay to have the same overlay color:
The stroke collection code is the same. The Paint is reduced to calling a function to create an overlay bitmap and drawing it:
private void canvas_Paint(object sender, PaintEventArgs e)
{
using (Bitmap bmp = new Bitmap(canvas.ClientSize.Width,
canvas.ClientSize.Height, PixelFormat.Format32bppPArgb))
{
PaintToBitmap(bmp);
e.Graphics.DrawImage(bmp, 0, 0);
}
The first function does the drawing, pretty much like before, but with simple pen strokes:
private void PaintToBitmap(Bitmap bmp)
{
Color overlayColor = Color.FromArgb(77, 22, 99, 99);
using (Graphics g = Graphics.FromImage(bmp))
using (Pen p = new Pen(overlayColor, 15f))
{
p.MiterLimit = p.Width / 2;
p.EndCap = LineCap.Round;
p.StartCap = LineCap.Round;
p.LineJoin = LineJoin.Round;
g.SmoothingMode = SmoothingMode.AntiAlias;
if (currentStroke.Count > 0)
{
g.DrawCurve(p, currentStroke.ToArray());
}
foreach (var stroke in strokes)
g.DrawCurve(p, stroke.ToArray());
}
SetAlphaOverlay(bmp, overlayColor);
}
It also calls the function that 'flattens' all set pixels to the overlay color:
void SetAlphaOverlay(Bitmap bmp, Color col)
{
Size s = bmp.Size;
PixelFormat fmt = bmp.PixelFormat;
Rectangle rect = new Rectangle(Point.Empty, s);
BitmapData bmpData = bmp.LockBits(rect, ImageLockMode.ReadOnly, fmt);
int size1 = bmpData.Stride * bmpData.Height;
byte[] data = new byte[size1];
System.Runtime.InteropServices.Marshal.Copy(bmpData.Scan0, data, 0, size1);
for (int y = 0; y < s.Height; y++)
{
for (int x = 0; x < s.Width; x++)
{
int index = y * bmpData.Stride + x * 4;
if (data[index + 0] + data[index + 1] + data[index + 2] > 0)
{
data[index + 0] = col.B;
data[index + 1] = col.G;
data[index + 2] = col.R;
data[index + 3] = col.A;
}
}
}
System.Runtime.InteropServices.Marshal.Copy(data, 0, bmpData.Scan0, data.Length);
bmp.UnlockBits(bmpData);
}
It uses LockBits, so it is pretty fast..
Here it is in action:
Update 2:
Just for the fun of it here is an extension of only a few lines that adds the option of drawing filled curves:
The fill mode is stored in a cheapo hack by having the 1st element twice. These are the changes:
In the MouseDown:
currentStroke.Add(e.Location);
if (cbx_Fill.Checked)
currentStroke.Add(e.Location);
And in the PaintToBitmap:
g.SmoothingMode = SmoothingMode.AntiAlias;
if (currentStroke.Count > 0)
{
if (cbx_Fill.Checked)
g.FillClosedCurve(b, currentStroke.ToArray());
else
g.DrawCurve(p, currentStroke.ToArray());
}
foreach (var stroke in strokes)
if (stroke[0]==stroke[1])
g.FillClosedCurve(b, stroke.ToArray());
else
g.DrawCurve(p, stroke.ToArray());
And one more demo:
I have 2 picture objects.
I want both of them to move from right to left.
If one go out of the visible panel, I replace its position to the start point.
So there are always 2 pictures moving on the screen.
If I don't use timer, 2 pictures are painted. But if I use a timer with tick event updating their positions to make them move, there is only 1 picture is shown and it's keep flashing, lagging...
Below is my code so far. I'm not familiar with C#. Appreciate any help. Thank you.
Timer interval = 30;
Form 1:
public partial class Form1 : Form
{
Background bg1 = new Background();
Background bg2 = new Background(800);
public Form1()
{
InitializeComponent();
}
private void flowLayoutPanel1_Paint(object sender, PaintEventArgs e)
{
bg1.paint(e);
bg2.paint(e);
}
private void Timer_Tick(object sender, EventArgs e)
{
bg1.updatePosition();
bg2.updatePosition();
this.Refresh();
}
}
Background:
class Background
{
int bg_width = 800;
int bg_height = 500;
Image bg;
Rectangle wb;
private static int x = 0;
public Background()
{
bg = Properties.Resources.bg;
wb = new Rectangle(x, 0, bg_width, bg_height);
}
public Background(int custom_x)
{
x = custom_x;
bg = Properties.Resources.bg;
wb = new Rectangle(x, 0, bg_width, bg_height);
}
public void paint(PaintEventArgs e)
{
Graphics g = e.Graphics;
g.DrawImage(bg, wb);
}
public void updatePosition()
{
x--;
if (x == -800)
{
x = 801;
}
wb.Location = new Point(x, 0);
}
}
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Code running slow.. the code generates multiple circles have a center can be specified by first click then change the radius by moving the pointer to desired circle size then click to finish drawing the circle.. and repeat to draw another circle..I solved the problem by very simple step see the comments down
public partial class Form1 : Form
{
public class Seat
{
private string _SeatKey;
private Rectangle _SeatRectangle;
public Seat(string seatKey, Rectangle seatRectangle)
{
_SeatKey = seatKey;
_SeatRectangle = seatRectangle;
}
public string SeatKey
{
get { return _SeatKey; }
}
public Rectangle SeatRectangle
{
get { return _SeatRectangle; }
set { _SeatRectangle = value; }
}
}
List<Seat> _Seats = new List<Seat>();
List<Seat> _center = new List<Seat>();
public Form1()
{
InitializeComponent();
SetStyle(ControlStyles.OptimizedDoubleBuffer, true);
SetStyle(ControlStyles.AllPaintingInWmPaint, true);
for (int i = 0; i < 30; i = i + 1)
{
string mystring = "regctangle" + i.ToString();
_Seats.Add(new Seat(mystring, new Rectangle(50, 50, 50, 50)));
}
for (int i = 0; i < 30; i = i + 1)
{
string mystring = "center" + i.ToString();
_center.Add(new Seat(mystring, new Rectangle(50 , 50 , 3, 3)));
}
}
Bitmap background;
Graphics scG;
private Point clickCurrent = Point.Empty;
private Point clickPrev = Point.Empty;
int clikno = 1;
int xpos;
int ypos;
int clicknew = 0;
int radius=0;
int recH;
int recW;
int xcen;
int ycen;
protected override void OnMouseClick(MouseEventArgs e)
{
base.OnMouseClick(e);
clikno = clikno + 1;
clicknew = clicknew + 1;
}
private void Form1_Load(object sender, EventArgs e)
{
background = new Bitmap(Width, Height);
scG = Graphics.FromImage(background);
}
protected override void OnPaint(PaintEventArgs pe)
{
pe.Graphics.DrawImage(Draw(), 0, 0);
}
public Bitmap Draw()
{
Graphics scG = Graphics.FromImage(background);
Pen myPen = new Pen(System.Drawing.Color.Red, 1/2);
Pen mPen = new Pen(System.Drawing.Color.Black, 3);
scG.Clear(SystemColors.Control);
_Seats[clikno].SeatRectangle = new Rectangle(xpos, ypos, recH, recW);
_center[clikno].SeatRectangle = new Rectangle(xcen, ycen, 3, 3);
for (int i = 0; i < clikno+1; i = i + 1)
{
scG.DrawEllipse(myPen, _Seats[i].SeatRectangle);
scG.DrawEllipse(mPen, _center[i].SeatRectangle);
}
Refresh();//This what cause the code running slow
return background;
}
private void Form1_MouseDown(object sender, MouseEventArgs e)
{
AutoSize = true;
clickCurrent = this.PointToClient(Cursor.Position);
clickPrev = clickCurrent;
if (clickPrev == Point.Empty) return;
Refresh();
clickCurrent = Point.Empty;
}
protected override void OnMouseMove(MouseEventArgs e)
{
base.OnMouseMove(e);
double oradius = Math.Sqrt((Math.Pow(clickPrev.X - e.X, 2)) + (Math.Pow(clickPrev.Y - e.Y, 2)));
radius = Convert.ToInt32(oradius);
if (clicknew == 1)
{
recH = radius;
recW = radius;
xpos = clickPrev.X - recW / 2;
ypos = clickPrev.Y - recH / 2;
xcen = clickPrev.X - 3 / 2;
ycen = clickPrev.Y - 3 / 2;
Refresh();
}
if (clicknew == 2)
clicknew = 0;
Refresh();
}
}
The part that is so slow is your MouseMove.
Usually one checks for the left mousebutton to be pressed:
private void yourDrawingControl_MouseMove(object sender, MouseEventArgs e)
{
if (e.Button.HasFlag(MouseButtons.Left) )
{
// draw stuff
}
}
If that is not a condition that applies you should check for having moved for at least more than one pixel:
Point oldLocation = Point.Empty;
private void yourDrawingControl_MouseMove(object sender, MouseEventArgs e)
{
int minStep = 3;
if ( (Math.Abs(oldLocation.X - e.X) + Math.Abs(oldLocation.Y - e.Y) > minStep) )
{
// draw stuff
}
oldLocation = e.Location;
}
Also: While the graphics is being built up, do not draw into a Bitmap which you then draw with DrawImage in your Paint event. Instead in the Paint event draw directly onto the surfce of the control from a List<yourDrawingshapeClass> !
Drawing hundreds of Rectangles is extremely fast compared to drawing even one of your Bitmaps..
Also: It looks as if you are drawing onto the Form? Better draw onto a dedicated control with just the right size; the natural choice is a PictureBox, which is made for this and is double-buffered out-of-the-box. Instead your enforce the form to refresh all it controls..
Finally: Even if you refuse to change your convoluted code to something well-proven, at least make it not call Refresh in the MouseMove unconditionally (in the last line), even if nothing at all has changed!
I am writing an emulator program, and the virtual display is supposed to be able to take in 3 bytes of color data and display the correct color pixel, similar to how a real screen works. But when I set up some scroll bars to test the generation of pixels nothing happens. Here is my code and a screenshot of the form:
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
namespace TSC_Multi_System_Emulator
{
public partial class Form1 : Form
{
private PictureBox Display = new PictureBox();
string #emulationfolderpath = Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments);
Bitmap screen = new Bitmap(#Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments) + #"\Resource_Folder\" + #"FirstFrame.bmp");
int x = 0;
int y = 0;
public Form1()
{
InitializeComponent();
}
private void Form1_Load(object sender, System.EventArgs e) {
// Dock the PictureBox to the form and set its background to black.
Display.BackColor = Color.Black;
// Connect the Paint event of the PictureBox to the event handler method.
// Add the PictureBox control to the Form.
this.Controls.Add(Display);
}
public void DigitalGraphicsDisplay(int red, int green, int blue) {
Graphics g = Display.CreateGraphics();
screen.SetPixel(x, y, Color.FromArgb(red, green, blue));
g.DrawImage(screen, 0, 0, screen.Width, screen.Height);
g.Save();
if (x < screen.Width)
{
x = x + 1;
}
else if (x == screen.Width)
{
x = 0;
if (y < screen.Height)
{
y = y + 1;
}
else if (y == screen.Height)
{
y = 0;
}
}
}
private void button1_Click(object sender, EventArgs e){
int rchannel = redControl.Value;
int gchannel = greenControl.Value;
int bchannel = blueControl.Value;
DigitalGraphicsDisplay(rchannel, gchannel, bchannel);
}
}
}
UPDATE:
The code is now working somewhat, but I can't test the code using just a test button. I had to use the exact code given to me in the first answer, which only displayed a gradient, I wonder what I am doing wrong... :(
public partial class Form1 : Form
{
string #emulationfolderpath = Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments);
Bitmap screen = new Bitmap(#Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments) + #"\Resource_Folder\" + #"FirstFrame.bmp");
int x = 0;
int y = 0;
public Form1()
{
InitializeComponent();
}
private void Form1_Load(object sender, System.EventArgs e) {
// Dock the PictureBox to the form and set its background to black.
Display.BackColor = Color.Black;
// Connect the Paint event of the PictureBox to the event handler method.
// Add the PictureBox control to the Form.
this.Controls.Add(Display);
}
public void DigitalGraphicsDisplay(int red, int green, int blue)
{
if (Display.Image == null)
{
Bitmap NewBMP = new Bitmap(Display.ClientRectangle.Width, Display.ClientRectangle.Height);
using (Graphics g = Graphics.FromImage(NewBMP))
{
g.Clear(Color.White);
}
Display.Image = NewBMP;
}
(Display.Image as Bitmap).SetPixel(x, y, Color.FromArgb(red, green, blue));
Display.Invalidate();
x++;
if (x >= Display.Image.Width)
{
x = 0;
y++;
if (y >= Display.Image.Height)
{
y = 0;
}
}
}
private void button1_Click(object sender, EventArgs e){
Boolean a = false;
int b = 0;
do
{
DigitalGraphicsDisplay(51, 153, 102);
if (b == 10000)
{
a = true;
}
b = b + 1;
} while (a);
}
}
}
All I am getting is a white picturebox with nothing else in it...
(The gradient code did work though)
It looks like you are trying to draw directly on the PictureBox control itself.
Instead you should have an Image assigned to the PictureBox and then draw on the image.
Try changing your code as shown below. (Including the click event for testing.)
Note, the PictureBox keeps the reference to the image directly so you don't need a separate screen image in your class, unless you have a different purpose for it.
Also, this uses Bitmap.SetPixel() which is an extremely slow way to set pixels. There is a much faster but slightly more complex way, in these other links:
SetPixel is too slow. Is there a faster way to draw to bitmap?
Work with bitmaps faster in C#
Remember your button click will only draw one pixel at a time.
So be sure to look carefully:
Running my test code within the click event will yield this:
int x = 0;
int y = 0;
public void DigitalGraphicsDisplay(int red, int green, int blue)
{
if (Display.Image == null)
{
Bitmap NewBMP = new Bitmap(Display.ClientRectangle.Width, Display.ClientRectangle.Height);
using (Graphics g = Graphics.FromImage(NewBMP))
{
g.Clear(Color.White);
}
Display.Image = NewBMP;
}
(Display.Image as Bitmap).SetPixel(x, y, Color.FromArgb(red, green, blue));
Display.Invalidate();
x++;
if (x >= Display.Image.Width)
{
x = 0;
y++;
if (y >= Display.Image.Height)
{
y = 0;
}
}
}
private void button1_Click(object sender, EventArgs e)
{
// Temporary code to show that it works (Due to Bitmap.SetPixel() it will be slow)
for (int I = 1; I < Display.ClientRectangle.Width * Display.ClientRectangle.Height; I++)
DigitalGraphicsDisplay((I/255)%255, (I % Display.ClientRectangle.Width) % 255, 127);
}
UPDATE: Per your comment, try this sample code:
private void button1_Click(object sender, EventArgs e)
{
Boolean a = true;
int b = 0;
do
{
DigitalGraphicsDisplay(51, 153, 102);
if (b == 10000)
{
a = false;
}
b = b + 1;
} while (a);
}
public void DigitalGraphicsDisplay(int red, int green, int blue) {
Graphics g = Display.CreateGraphics();
screen.SetPixel(x, y, Color.FromArgb(red, green, blue));
g.DrawImage(screen, 0, 0, screen.Width, screen.Height);
g.Save();
All possible mistakes in one go..
Never use CreateGraphics to draw persistent Graphics! Always either go for the Paint event or draw into the Image.
Graphics.Save does not save any drawn pixels. It saves the state of the Graphics object, which does not contain graphics but is a tool to write into a related bitmap. The state includes scale, rotation, smoothing-mode and then some..
You already write into the Bitmap so you can simply make it your new PictureBox.Image..
Or the PictureBox.BackgroundImage.
And, as I said, you can instead write on top of both that is onto the PBox's surface. For this use the Paint event, Invalidate to trigger it and class level variables to hold the necessary data..
The latter is for graphics that will change a lot, the two former ones are for changes that accumulate.
Control.CreateGraphics is for transient graphics only, like a rubber-band line or a cursor cross..