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How to draw moving axis table

I'm trying to draw an axis table (x-y) in WPF from code-behind; and I want to give it drag and drop option which can see more of the axis table.
I had created static axis but I don't know how to create a dynamic one?
Can anybody help me with this stuff ?
Thanks.
for (int i = 10; i < 400; i+=10)
{
Line a = new Line();
a.X1 = 0;
a.Y1 = i;
a.X2 = canGraph.Width;
a.Y2 = a.Y1;
a.Stroke = System.Windows.Media.Brushes.Black;
a.StrokeThickness = 0.5;
canGraph.Children.Add(a);
Line b = new Line();
b.X1 = i;
b.Y1 = 0;
b.X2 = i;
b.Y2 = canGraph.Height;
b.Stroke = System.Windows.Media.Brushes.Black;
b.StrokeThickness = 0.5;
canGraph.Children.Add(b);
if (i % 50 == 0)
{
a.StrokeThickness = 1;
b.StrokeThickness = 1;
}
if (i == 200)
{
a.StrokeThickness = 2;
b.StrokeThickness = 2;
}
}

This should get you started. Add event handler(s) to your main axis and canGraph -
...
if (i == 200)
{
a.StrokeThickness = 2;
b.StrokeThickness = 2;
a.MouseLeftButtonDown += A_MouseLeftButtonDown;
}
}
canGraph.MouseLeftButtonUp += CanGraph_MouseLeftButtonUp;
canGraph.MouseMove += CanGraph_MouseMove;
Add following methods -
Line _selectedAxis = null;
private void CanGraph_MouseMove(object sender, MouseEventArgs e)
{
if (_selectedAxis != null)
{
var line = _selectedAxis;
var pos = e.GetPosition(line);
textBlock.Text = $"({pos.X}, {pos.Y})";
line.Y1 = pos.Y;
line.Y2 = pos.Y;
}
}
private void CanGraph_MouseLeftButtonUp(object sender, MouseButtonEventArgs e)
{
_selectedAxis = null;
}
private void A_MouseLeftButtonDown(object sender, MouseButtonEventArgs e)
{
var line = sender as Line;
_selectedAxis = line;
}
Now hold you main horizontal axis and drag it.
You can do the same for vertical axis as well.
For Zooming
Initialize canGraph.RenderTransform with ScaleTransform and subscribe to MouseWheel event. Note RenderTransformOrigin is set to (0.5, 0.5) to zoom from center instead of top left (default) -
canGraph.RenderTransformOrigin = new Point(0.5, 0.5);
canGraph.RenderTransform = new ScaleTransform();
canGraph.MouseWheel += CanGraph_MouseWheel;
And the function -
private void CanGraph_MouseWheel(object sender, MouseWheelEventArgs e)
{
var transform = canGraph.RenderTransform as ScaleTransform;
var factor = transform.ScaleX;
factor += (e.Delta > 0 ? 1 : (factor == 1 ? 0 : -1));
transform.ScaleX = factor;
transform.ScaleY = factor;
}

I'm guessing you have added Line type object to draw axes, then gave it to window content.
Then just add events, like MouseLeftButtonDown event, or MouseMove event.Add appropriate methods.
Change your object positions on MouseMove event, like:
(For a certain line)
private void MouseMoveMethod(object sender, MouseEventArgs e)
{
var obj = sender as Line;
obj.X1 = e.GetPosition(this).X; //Line start x coordinate
obj.Y1 = e.GetPosition(this).Y; //Line start y coordinate
...
}

c# Drawing with gdi32.dll vs System.Drawing.Graphics

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:

Which part of the code make Drawing on bitmap slow...C# [closed]

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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!

Graphical Timer control not working correctly

This is a custom control I have made, a graphical timer, however, it is not working correctly. As the time left decreases a pie is filled to represent the amount of time left decreasing, but it is decreasing with unexpected angles (which are output to the listbox for debugging purposes). How do I get it to work correctly? Also I'm very new to making Custom Controls (this is my first) so any pointers on good coding guidelines, what not to do, etc, would be very helpful.
using System;
using System.Drawing;
using System.Windows.Forms;
namespace TestCustomControl
{
class GraphicalTimer : Control
{
public Color Timer { get; set; }
public Color TimerEmpty { get; set; }
public Color BorderColor { get; set; }
private Timer t;
public int MaxTime { get; set; }
private int timeElapsed = 0;
public GraphicalTimer()
{
DoubleBuffered = true;
SetStyle(ControlStyles.SupportsTransparentBackColor, true);
BackColor = Color.Transparent;
t = new Timer();
t.Interval = 1000;
t.Tick += t_Tick;
}
public void Start()
{
t.Start();
}
public void Stop()
{
t.Stop();
}
public void Reset()
{
timeElapsed = 0;
Invalidate();
}
void t_Tick(object sender, EventArgs e)
{
timeElapsed += 1;
if (timeElapsed == MaxTime)
{
t.Dispose();
}
Invalidate();
}
private float getAngleFromTime()
{
if (timeElapsed == 0)
{
return 0;
}
else
{
MainWindow.lb.Items.Add((360 / (MaxTime / timeElapsed)).ToString());
return (360 / (MaxTime / timeElapsed));
}
}
protected override void OnPaint(PaintEventArgs e)
{
base.OnPaint(e);
Graphics g = e.Graphics;
Rectangle rc = ClientRectangle;
g.FillEllipse(new SolidBrush(Timer), rc);
g.FillPie(new SolidBrush(TimerEmpty), rc, -90, getAngleFromTime());
g.DrawEllipse(new Pen(BorderColor, 4), rc);
Font font = new Font("Arial", (float)rc.Height * 0.4f, FontStyle.Bold, GraphicsUnit.Pixel);
StringFormat sf = new StringFormat();
sf.Alignment = StringAlignment.Center;
sf.LineAlignment = StringAlignment.Center;
g.DrawString((MaxTime - timeElapsed).ToString("D2"), font, new SolidBrush(Color.Black), new RectangleF((rc.Width - rc.Width / 2) / 2, (rc.Height - rc.Height / 2) / 2, rc.Width * 0.7f, rc.Height * 0.7f));
}
}
class MainWindow : Form
{
GraphicalTimer gt;
Button startButton;
Button stopButton;
Button resetButton;
public static ListBox lb;
public MainWindow()
{
this.Text = "Test Application";
gt = new GraphicalTimer();
gt.MaxTime = 20;
gt.BorderColor = Color.BurlyWood;
gt.Timer = Color.Aqua;
gt.TimerEmpty = Color.White;
gt.Top = 10;
gt.Left = 10;
gt.Width = 50;
gt.Height = 50;
this.Controls.Add(gt);
startButton = new Button();
startButton.Top = 70;
startButton.Left = 30;
startButton.AutoSize = true;
startButton.Text = "Start Timer";
startButton.Click += startButton_Click;
this.Controls.Add(startButton);
stopButton = new Button();
stopButton.Top = 70;
stopButton.Left = startButton.Right + 10;
stopButton.AutoSize = true;
stopButton.Text = "Stop Timer";
stopButton.Click += stopButton_Click;
this.Controls.Add(stopButton);
resetButton = new Button();
resetButton.Top = 70;
resetButton.Left = stopButton.Right + 10;
resetButton.AutoSize = true;
resetButton.Text = "Reset Timer";
resetButton.Click += resetButton_Click;
this.Controls.Add(resetButton);
lb = new ListBox();
lb.Top = resetButton.Bottom + 10;
lb.Left = 10;
lb.Width = this.ClientSize.Width - 20;
lb.Height = this.ClientSize.Height - lb.Top - 10;
this.Controls.Add(lb);
}
void resetButton_Click(object sender, EventArgs e)
{
gt.Reset();
}
void stopButton_Click(object sender, EventArgs e)
{
gt.Stop();
}
void startButton_Click(object sender, EventArgs e)
{
gt.Start();
}
}
class StartClass
{
static void Main()
{
MainWindow form = new MainWindow();
Application.EnableVisualStyles();
Application.Run(form);
}
}
}

You are using integers to calculate the angle, and in a way that can cause quite some jitters.
360 / (MaxTime / timeElapsed) will first evaluate temp = MaxTime / timeElapsed in integer arithmetics, and then 360 / temp also using integer division.
Try using floating point numbers for the calculation and then converting the final result into an integer value if you need it that way. Even writing 360 * timeElapsed / MaxTime might reduce the artifacts as you then first multiply 360 * timeElapsed which is accurate (unless timeElapsed is very large).

The method of calculating AngleForTime is wrong. Just replace your method with below code and it should do your job.
;)
private float getAngleFromTime()
{
if (timeElapsed == 0)
{
return 0;
}
else
{
MainWindow.lb.Items.Add((360*timeElapsed) / MaxTime ).ToString();
return (360*timeElapsed) / MaxTime ;
}
}

winForm invalidate(rectangle)

I'd like to draw animation where the airplane crossing form from leftside to the right.
public partial class Form1 : Form
{
Bitmap sky, plane, background;
int currentX, currentY;
Random rndHeight;
Rectangle planeRect;
Graphics g;
public Form1()
{
InitializeComponent();
}
private void Form1_Load(object sender, EventArgs e)
{
try
{
sky = new Bitmap("sky.jpg");
plane = new Bitmap("plane1.png");
int planeWidth = plane.Width; int planeHeight = plane.Height;
}
catch (Exception) { MessageBox.Show("No files!"); }
this.ClientSize = new System.Drawing.Size(sky.Width, sky.Height);
this.FormBorderStyle = FormBorderStyle.FixedSingle;
background = new Bitmap(sky);
g = Graphics.FromImage(background);
rndHeight = new Random();
currentX = -plane.Width; currentY = rndHeight.Next(0, this.Height);
this.BackgroundImage = background;
timer1.Interval = 1;
timer1.Enabled = true;
timer1.Start();
}
protected override void OnPaint(PaintEventArgs e)
{
e.Graphics.DrawImage(sky, 0, 0);
e.Graphics.DrawImage(plane, planeRect);
}
private void timer1_Tick(object sender, EventArgs e)
{
g.DrawImage(sky, 0, 0);
planeRect.X = currentX; planeRect.Y = currentY; planeRect.Width = plane.Width; planeRect.Height = plane.Height;
g.DrawImage(plane, planeRect);
Rectangle myNewPlane = new Rectangle(planeRect.X - 10, planeRect.Y - 10, planeRect.Width + 20, planeRect.Height + 20);
this.Invalidate(myNewPlane);
if (currentX >= this.Width) currentX = -plane.Width; else currentX += 2;
currentY += rndHeight.Next(-2, 2);
}
}
This code works, but the Rectangle of plane flickers with the frequency of timer1.Interval. My question is: how can I avoid these flickers?
p.s.: background image resolution 1024x768; plane - 160x87. plane is transparent

You fix this by setting the DoubleBuffering style for your Form to remove the flicker, e.g.
DoubleBuffered = true;
You probably want to set a few more control styles as well for automatic double-buffering (after InitializeComponents)
this.SetStyle(
ControlStyles.AllPaintingInWmPaint |
ControlStyles.UserPaint |
ControlStyles.DoubleBuffer,true);
More information about automatic and manual double-buffering is on MSDN here