Develop Reference

How do I loop the paint event in Windows Forms to create a simple game loop?

I'm attempting to create a simple snake game in C# visual studio as an exercise. I have very little knowledge of the Windows Forms App, but it seemed like the easiest way to access drawing and user input with the arrows.
Is this a good framework to use for a simple game like this in C#?
But here is my real question. I'm trying to create the game loop which loops about every second, and changes where the head of the snake is going to be drawn next. But I cannot figure out how to call the Paint event multiple times. It seems like it calls once, and then exits. If I put a while() loop inside of the paint method with Thread.Sleep(), it draws a rectangle every second, but I don't have access to the KeyEventArgs or anything else because the running code is trapped inside the Paint call.
I want the initial paint call to draw the starting point for the snake, and then looping paint calls, I'm guessing to another paint method(?) which asks the controller which button was pressed last, and then draws the next rectangle in that direction. What is the intended way to do this and create that game loop?
I would appreciate any information and knowledge to help teach me this process, and any other advice or input is welcome!
Here is my current code:
'''
public partial class FormMain : Form
{
private readonly int pixelSize;
private readonly int gridSize;
private readonly int center;
private string currDirection;
public FormMain()
{
pixelSize = 30;
currDirection = "right";
// Calculating size of the grid based on the size of the 'pixel'
gridSize = 640 / pixelSize;
// Calculating the starting position of the snake in the center of the screen
center = (gridSize / 2) * pixelSize;
InitializeComponent();
}
private void FormMain_Paint(object sender, PaintEventArgs e)
{
// referencing the Graphics object and setting the color of the snake
Graphics g = e.Graphics;
Pen seaPen = new Pen(Color.MediumSeaGreen);
// This draws the initial center rectangle
Point currentHeadLocation = new Point(center, center);
Rectangle r;
// Here's the loop that should happen every second or so, probably in another method.
while (true)
{
r = new Rectangle(currentHeadLocation, new Size(pixelSize, pixelSize));
g.DrawRectangle(seaPen, r);
if (currDirection.Equals("right"))
{
currentHeadLocation = new Point(currentHeadLocation.X + pixelSize, currentHeadLocation.Y);
}
else if (currDirection.Equals("left"))
{
currentHeadLocation = new Point(currentHeadLocation.X - pixelSize, currentHeadLocation.Y);
}
else if (currDirection.Equals("up"))
{
currentHeadLocation = new Point(currentHeadLocation.X, currentHeadLocation.Y - pixelSize);
}
else if (currDirection.Equals("down"))
{
currentHeadLocation = new Point(currentHeadLocation.X, currentHeadLocation.Y + pixelSize);
}
Thread.Sleep(1000);
}
}
private void FormMain_KeyDown(object sender, KeyEventArgs e)
{
switch(e.KeyCode)
{
case Keys.Left:
currDirection = "left";
break;
case Keys.Right:
currDirection = "right";
break;
case Keys.Up:
currDirection = "up";
break;
case Keys.Down:
currDirection = "down";
break;
}
}
}
'''

Using Thread.Sleep() in this context is almost always a bad idea, as it will freeze your only thread, which is also your UI thread.
You probably want to make use of a timer.
Quick example:
public FormMain()
{
//Any other init stuff here
System.Windows.Forms.Timer t = new System.Windows.Forms.Timer(); //Create a timer
t.interval = 1000; //interval time in ms
t.Tick += (s, e) => LoopFunctionName(); //Bind a function to the event whenever the timer reaches its interval
}
public void LoopFunctionName()
{
//Game loop
}
If you want to force your control to be repainted, you can simply call Invalidate().

Mouse Drag - C# bot

First time doing this. I am currently building a bot using C# and want my bot to be able to move the mouse to a given point in a way that looks human. By this I am referring to the dragging of the mouse when a human moves the cursor to a point they are trying to click on. Currently my C# bot moves the mouse instantly to the location which doesn't look human.
private static Point[] FindColor(Color color)
{
int searchValue = color.ToArgb();
List<Point> result = new List<Point>();
using (Bitmap bmp = GetScreenShot())
{
for (int x = 0; x < bmp.Width; x++)
{
for (int y = 0; y < bmp.Height; y++)
{
if (searchValue.Equals(bmp.GetPixel(x, y).ToArgb()))
result.Add(new Point(x, y));
}
}
}
return result.ToArray();
}
// FUNCTIONS OCCUR BELOW
// Error message if program could not find bitmap within screenshot show error message
Color myRgbColor = new Color(); // Creates new colour called myRgbColor
myRgbColor = Color.FromArgb(51, 90, 9); // This colour equals the RGB value
Point[] points = FindColor(myRgbColor); // Create an array called points which list all the points found in the screen where the RgB value matches.
if (points.Length > 0)
{
Cursor.Position = points[2]; // Move mouse cursor to first point (Point 0)
Thread.Sleep(0200);
MouseClick();
}
if (points.Length == 0)
{
MessageBox.Show("No matches!"); // Return error
goto checkore;
}

You're going to want to use some kind of Timer with a callback, to move the mouse incrementally, step by step. As for the movement itself, you have a world of possibilities, but it's all maths.
So, let's decompose the problem.
What is a natural mouse movement?
Position change rate
It doesn't necessarilly looks like it, but when you move your mouse, you're simply setting its position multiple times per seconds.
The amount of times the position changes per second is equivalent to the polling rate of your mouse. The default polling rate for USB mice is 125Hz (or 125 position changes per second, if you will). This is the value we'll use for our Timer: its callback will be called 125 times per second.
var timer = new Timer(1000 / 125d);
timer.Elapsed += MoveMouse;
void MoveMouse(object sender, ElpasedEventArgs e) { }
Speed and acceleration
When you move your mouse, the distance between two cursor positions is not constant, because you're fast when you start moving your mouse, but you slow down when you get close to the item you want your cursor to be on.
There are also two ways I personally usually move my mouse depending on the context/mood:
One fast uniform movement to get close to the destination, then one slow to correct and get on it (I'll usually go past the destination during the first move)
One medium-slow movement with a small deceleration, follow by a stronger deceleration at the end
The overall speed of the movement also depends on three factors:
The distance between your cursor and the destination
The size of the destination area
Your personal speed
I have absolutely NO IDEA how to work out the formula based on these factors, that's gonna be a work of trial and error for yourself.
This one is purely math and observation based, and will be tricky to get perfectly right, if ever; every person moves their mouse a different way.
The solution I can offer you is to simply forget about deceleration, correction and so on, and just divide your movement into equal steps. That has the merit of being simple.
using System;
using System.Timers;
using System.Drawing;
public class Program
{
static int stepCount = 0;
static int numberOfSteps = 0;
static float stepDistanceX = 0;
static float stepDistanceY = 0;
static PointF destinationPoint;
static Timer timer;
public static void Main()
{
int timerStepDurationMs = 1000 / 125;
PointF currentPoint = Cursor.Position;
destinationPoint = new PointF(2000, 1800); // or however you select your point
int movementDurationMs = new Random().Next(900, 1100); // roughly 1 second
int numberOfSteps = movementDurationMs / timerStepDurationMs;
stepDistanceX = (destinationPoint.X - currentPoint.X) / (float)numberOfSteps;
stepDistanceY = (destinationPoint.Y - currentPoint.Y) / (float)numberOfSteps;
timer = new Timer(timerStepDurationMs);
timer.Elapsed += MoveMouse;
timer.Start();
while (stepCount != numberOfSteps) { }
}
static void MoveMouse(object sender, ElapsedEventArgs e)
{
stepCount++;
if (stepCount == numberOfSteps)
{
Cursor.Position = destinationPoint;
timer.Stop();
}
Cursor.Position.X += stepDistanceX;
Cursor.Position.Y += stepDistanceY;
}
}
Note that I haven't tested with "Cursor", but with some PointF variable instead. It seems to work fine here: dotnetfiddle.

Dynamic drawing ants in winforms during execution of ant colony

After this question (Show trail of moving pixel in C# WinForm project) for my personal ant colony project in c#, I'm trying to apply the solution second suggested solution: the one that combines drawing the trail into a bitmap and the new ants onto the surface.
[...]Application.Run(new ShowAnts());[...]
public partial class ShowAnts : Form
{
Bitmap bmp;
int j = 0;
public ShowAnts()
{
InitializeAntProgram();
InitializeComponent();
bmp = new Bitmap(pictureBox1.ClientSize.Width, pictureBox1.ClientSize.Height);
pictureBox1.Image = bmp;
}
public void RenderAnts(object sender, PaintEventArgs e)
{
using (Graphics G = Graphics.FromImage(pictureBox1.Image))
{
while (j < 1000)
{
Map.EvaporatesPheromones();
foreach (Vector2D food in foodSrcs)
{
Map.SetMapPoint(food, 500);
}
foreach (Ant a in ants)
{
Brush c;
c = Brushes.DarkBlue;
if (a.role == AntRole.Scout)
{
a.Move(j);
c = Brushes.Red;
}
e.Graphics.FillRectangle(Brushes.DarkBlue, a.position.x, a.position.y, 1, 1);
G.FillRectangle(Brushes.Gray, a.position.x, a.position.y, 1, 1);
}
j++;
}
}
}
}
The code above shows the graphic attempt to draw the ant movement into a winform.
It works perfectly, but it shows only the final result. I would like to show the step by step evolution keeping the graphical trail information without reparsing my map info.
Please consider that a working console project on which I' developing this "graphic interface" already exists so:
some variables are set elsewhere (i.e.: food) in the project;the `a.Move(j);` refers to the ant logic itself (analysis, decision, new cell movement referring to the map array);the `j` counter is used to count steps and to set an arbitrary stop, but has no real use;I'm already storing into map array and some other variables all informations concerning pheromone, movement, positions etc.

Looking at your code and also the comments of the previous question, it seems that you are missing the part that would animate the movement. Instead you are looping inside what seems to be the Paint event.
Here is a quick fix for that. It adds a Timer that triggers the RenderAnts event, which seems to be hooked up to the pictureBox1.Paint handler..:
A few class level variables:
int counter = 0;
int limit = 1000;
Timer antTimer = new Timer();
Start code:
antTimer.Interval = 50; // <-- pick your speed !!
antTimer.Tick += (ss, ee) =>
{ pictureBox1.Invalidate(); counter++; if (counter > limit) antTimer.Stop(); };
antTimer.Start();
The speed is 50ms, which means 20 Ticks per second.
The Tick event is inlined with a tiny Lambda epression and has only one statement plus the loop logic. By Invalidating the pictureBox1 control its Paint event and thereby the RenderAnts event is triggered.
Also note that I called it a 'quick fix'. Usually you would discern between the rendering and the moving code of an animation; but in this case this fine difference doesn't matter much.
Now we change the RenderAnts method, taking out the loop:
public void RenderAnts(object sender, PaintEventArgs e)
{
using (Graphics G = Graphics.FromImage(pictureBox1.Image))
{
Map.EvaporatesPheromones();
foreach (Vector2D food in foodSrcs)
{
Map.SetMapPoint(food, 500);
}
foreach (Ant a in ants)
{
Brush c = Brushes.DarkBlue;
if (a.role == AntRole.Scout)
{
a.Move(j);
c = Brushes.Red;
}
e.Graphics.FillRectangle(c, a.position.x, a.position.y, 1, 1);
G.FillRectangle(Brushes.Gray, a.position.x, a.position.y, 1, 1);
}
}
}
You also may want to add a Start/Stop Button. Also a TrackBar to change the speed..
Now you should be able to watch the progress of your ants at 20Hz, leaving grey trails.

Event delayed when in a loop

I use the global mouse hooks from this page in a project. I want the mouse to move a specified path when it is clicked, but interupted if I let go of the mouse button, but for some reason the HookManager_MouseUp won't fire until round about 175 loops in my for-loop (forloop is for moving the mouse). (That should be about 0.4 seconds). No matter how long I press the mousebutton it will only stop the loop after those 0.4 seconds. If I wait longer than that it will stop the loop immediately when I let go of the mousebutton.
public void MoveMouse()
{
btm = new Bitmap(2000, 2000);
for (int i = 0; i < BézierPointList.Count; i++)
{
if (!run) { break; }
this.Cursor = new Cursor(Cursor.Current.Handle);
Cursor.Position = new Point((int)BézierPointList[i].X(), (int)BézierPointList[i].Y());
Graphics g = Graphics.FromImage(btm);
g.DrawRectangle(new Pen(Color.Red), (int)BézierPointList[i].X(), (int)BézierPointList[i].Y(), 1, 1);
Application.DoEvents();
System.Threading.Thread.Sleep(2);
}
CreateGraphics().DrawImage(btm, 0, 0);
}
(The graphics are for debugging).
Is there some way to update the events, or something else I can do to fix this? Thanks! (C#)
Edit:
My Form1.Designer.cs contains this code (among other)
Gma.UserActivityMonitor.HookManager.MouseDown += HookManager_MouseDown;
Gma.UserActivityMonitor.HookManager.MouseUp += HookManager_MouseUp;
And the methods HookManager_MouseUp and HookManager_MouseDown enters MoveMouse() and brakes it. The delay happens before HookManager_MouseUp (HookManager_MouseUp breaks the loop pretty much instantaneosly).

Window won't draw my Sprite when releasing Mouse Button

I am new to SFML and I am just playing around with an example at the moment. I try to draw a sprite where I last clicked my mouse in a window. But some reason the event fires and no sprite is drawn. I can't really figure out why.
I've been looking around in the Documentation but I don't seem to do anything wrong. Help me pretty please? :3
The event is called OnMouseLeftClick and I am trying to draw the mouseLeftClickSprite object. I have removed the bits of code that doesn't matter like the OnMouseMoved event and the OnClose event. They have nothing to do with this.
using System;
using SFML.Audio;
using SFML.Graphics;
using SFML.Window;
namespace SFMLExample
{
class Program
{
static Text xMouseCoord;
static Text yMouseCoord;
static Text statusMsg;
static float mouseX, mouseY;
static Texture mouseLeftClickTexture;
static Sprite mouseLeftClickSprite;
static void OnMouseLeftClick(object sender, EventArgs e)
{
if (Mouse.IsButtonPressed(Mouse.Button.Left))
{
statusMsg.DisplayedString = "Console: OnMouseLeftClick() Fired";
RenderWindow window = (RenderWindow)sender;
mouseLeftClickSprite.Position = new Vector2f(mouseX, mouseY);
window.Draw(mouseLeftClickSprite);
}
}
static void Main(string[] args)
{
mouseX = 0.0f;
mouseY = 0.0f;
// Create the main window
RenderWindow window = new RenderWindow(new VideoMode(800, 600), "SFML Window");
window.Closed += new EventHandler(OnClose);
window.MouseMoved += new EventHandler<MouseMoveEventArgs>(OnMouseMoved);
window.MouseButtonPressed += new EventHandler<MouseButtonEventArgs>(OnMouseLeftClick);
// Load a sprite to display
Texture texture = new Texture("cute_image.jpg");
Sprite sprite = new Sprite(texture);
mouseLeftClickTexture = new Texture("GM106.png");
mouseLeftClickSprite = new Sprite(mouseLeftClickTexture);
// Create a graphical string to display
Font font = new Font("arial.ttf");
Text text = new Text("Hello SFML.Net", font);
xMouseCoord = new Text("Mouse X: ", font);
yMouseCoord = new Text("Mouse Y: ", font);
statusMsg = new Text("Console: ", font);
// Play some Music
//Music music = new Music("nice_music.mp3");
//music.Play();
// Start the game loop
while (window.IsOpen())
{
// Process events
window.DispatchEvents();
// Clear screen
window.Clear();
sprite.Scale = new Vector2f(1.0f, 1.0f);
sprite.Position = new Vector2f(window.Size.X / 2, window.Size.Y / 2);
// Draw the sprite
window.Draw(sprite);
// Draw the strings
xMouseCoord.Position = new Vector2f(text.Position.X, text.Position.Y + 30);
yMouseCoord.Position = new Vector2f(xMouseCoord.Position.X, xMouseCoord.Position.Y + 30);
statusMsg.Position = new Vector2f(yMouseCoord.Position.X, yMouseCoord.Position.Y + 30);
window.Draw(text);
window.Draw(xMouseCoord);
window.Draw(yMouseCoord);
window.Draw(statusMsg);
// Update the window
window.Display();
}
}
}
}
Added this bit below for some clarification
static void OnMouseMoved(object sender, EventArgs e)
{
RenderWindow window = (RenderWindow)sender;
Vector2i vector = window.InternalGetMousePosition();
mouseX = vector.X;
mouseY = vector.Y;
xMouseCoord.DisplayedString = "Mouse X: " + mouseX;
yMouseCoord.DisplayedString = "Mouse Y: " + mouseY;
statusMsg.DisplayedString = "Console: ";
}

You only draw your sprite once. With approximately 60 frames per second, you might see it blink... or not. If you need it to stay permanent, you need to remember the point in your main program and then draw a sprite at that point every time your draw the other things.
You may want to look into game programming patterns. Normally, you have three big blocks that are repeated endlessly: you get user input, you act on user input, you draw the result.
In pseudo code:
while(isRunning)
{
HandleUserInput();
ChangeWorld():
Render();
}
That way, you can check yourself if what you do is correct. For example, in your scenario you would have drawn something while handling user input. Not good.

The events are dispatched and evaluated inside the so-called window.DispatchEvents(). When you click on your window, the event will be fired and your sprite will be drawn.
The thing is that you are calling window.Clear() after it, so you can not see the result. As nvoigt said, you must render everything at each frame, that is to say at each turn of your loop. This is why one uses Clear() method from Window, to clear the result of the previous frame.
What you could do is remember the position of the mouse when the event is fired or directly set the position of the sprite according to it. Then draw your sprite along with your text etc. If you don't want it to be displayed before any click of the mouse, just put its coordinates at a point outside the window so it will not be drawn.