I want to draw a line on a panel and then move it as the mouse moves. To do so, I draw the line and when the mouse moves I redraw the line to the new location and remove the previous line by drawing a line with the background color on it. It works fine if I do not use the high quality smoothing mode. But if use high quality smoothing mode, it leave traces on the panel. Does anybody know how to fix this? Thank you.
Here is the code
int x_previous = 0;
int y_previous = 0;
private void panel1_MouseMove(object sender, MouseEventArgs e)
{
Pen pen1 = new System.Drawing.Pen(Color.Black, 3);
Pen pen2 = new System.Drawing.Pen(panel1.BackColor, 3);
Graphics g = panel1.CreateGraphics();
g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
g.DrawLine(pen2, new Point(0, 0), new Point(x_previous, y_previous));
g.DrawLine(pen1, new Point(0, 0), new Point(e.Location.X, e.Location.Y));
x_previous = e.Location.X;
y_previous = e.Location.Y;
}
Here is the snapshot with SmoothingMode
Here is the snapshot without SmoothingMode
Instead of drawing a line over a line, the safest option would be to clear the graphics using g.Clear(panel1.BackColor). This will wipe everything off that has been drawn, so that you can safely draw a new line:
private void panel1_MouseMove(object sender, MouseEventArgs e)
{
Pen pen1 = new System.Drawing.Pen(Color.Black, 3);
Pen pen2 = new System.Drawing.Pen(panel1.BackColor, 3);
Graphics g = panel1.CreateGraphics();
g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
// Clear the graphics, creating a blank area to draw on
g.Clear(panel1.BackColor);
g.DrawLine(pen1, new Point(0, 0), new Point(e.Location.X, e.Location.Y));
x_previous = e.Location.X;
y_previous = e.Location.Y;
}
Hope this helps!
Instead of drawing the line in the event handler for the mouse movement you should use it to Invalidate the panel and perform the line drawing in a handler for its Paint event. There will be no need to erase the old line.
I haven't used WinForms in a while, so you'll have to forgive me if this doesn't work.
I assume that anti-aliasing has slightly blurred the edges of the line so that the initial line extends slightly further out than the width of the pen. That also means that the edges of the white pen won't be completely opaque when drawing over the black line.
Try increasing the width of the white pen until it completely covers the black, and maybe see if you can leave the Graphics object with lower quality rendering for the white pen, and use the smoothing only for the black pen.
Related
I'm New in c sharp, i'm trying to make a circular button. the code below is making a ellipse for me but it is not looking smooth, also it is having partially hidden lines at right and bottom as shown in image
class ButtonEllipse: Button
{
protected override void OnPaint(PaintEventArgs e)
{
GraphicsPath graphics = new GraphicsPath();
Rectangle myEllipse = new Rectangle(0, 0, this.ClientSize.Width,this.ClientSize.Height);
graphics.AddEllipse(myEllipse);
Pen myPen = new Pen(Color.Black, 2);
this.Region = new System.Drawing.Region(graphics);
base.OnPaint(e);
}
}
can you please guide me how to get a exact and smooth circular button.
Try setting graphics.SmoothingMode = SmoothingMode.AntiAlias; Read more about antialiazing.
You should perhaps also paint the button graphics directly rather than using the Region. See DrawEllipse and FillEllipse.
I am trying to draw the YinYang symbol on C# windows Form Application. So far, I drew the big outer circle and the two innner circles.
I need help on drawing the curve part that runs down the middle of the circle
Also, how would I fill in the small circle and the other half of the circle to be black.
Also, it is possible to draw this without having to have a button (see code).
Here is a snippet of my code:
private void button1_Click(object sender, EventArgs e)
{
Graphics myGraphics = base.CreateGraphics();
Pen myPen = new Pen(Color.Black);
SolidBrush mySolidBrush = new SolidBrush(Color.Black);
myGraphics.DrawEllipse(myPen, 50,50, 150, 150);
Graphics innerCircle = base.CreateGraphics();
Pen myPen2 = new Pen(Color.Black);
SolidBrush mySolidBrush2 = new SolidBrush(Color.Black);
myGraphics.DrawEllipse(myPen, 118, 75, 20, 20);
Graphics innerCircle2 = base.CreateGraphics();
Pen myPen3 = new Pen(Color.Black);
SolidBrush mySolidBrush3 = new SolidBrush(Color.Black);
myGraphics.DrawEllipse(myPen, 118, 150, 20, 20);
}
You do not have to draw a curve, geometry of ying and yang is so beautiful that it lets you draw it only using circles.
Sorry for my paint skills, but I think you know what I mean by this pic. You said
I drew the big outer circle and the two innner circles.
So use this knowledge again without thinking about curves
Is there a method to draw on the panel in c# which not redraw what i've drawn? E.g. when I use refresh() or Invalidate() alway redraw me it, but I need something what not. :(
I have a simple Photoshop-made grid and i would like to use it as progress bar, i need to draw round ellipses from 1 to 100 (then probably about 100 times in x time).
If I use System.Graphic I have not persistent result.
Then I found the code to use the PaintEventArgs method by inserting instructions in the Paint Event of the form.
Unfortunately in my mind this is not a solution because I need to draw only when I need and only where I want.... in other word I need a simple Function able to draw desired ellipses when I need...
I tried also to override the OnPaint-base but I really don't understand how to use it and if may help to reach my goal.
Here some code:
With the paint event:
private void Main_Paint(object sender, PaintEventArgs e)
{
// Create pen.
Pen blackPen = new Pen(Color.Yellow, 3);
// Create rectangle for ellipse.
Rectangle rect = new Rectangle(355, 282, 9, 9);
e.Graphics.DrawEllipse(blackPen, rect);
}
With the Graphic mode:
private void lbl_help_Click(object sender, EventArgs e)
{
//SetStatus("BURNING PROCESS COMPLETED SUCCESSFULLY");
Graphics g = this.CreateGraphics();
// Create pen.
Pen blackPen = new Pen(Color.Yellow, 3);
// Create rectangle for ellipse.
Rectangle rect = new Rectangle(355, 282, 9, 9);
// Draw ellipse to screen.
g.DrawEllipse(blackPen, rect);
System.Threading.Thread.Sleep(3000);
}
And this one I found to override OnPaint(), but I really don't know how to use it, how to override the form-paint event or how to call it only when needed and passing values:
private void lbl_help_Click(object sender, EventArgs e)
{
//SetStatus("BURNING PROCESS COMPLETED SUCCESSFULLY",);
Graphics g = this.CreateGraphics();
// Create pen.
Pen blackPen = new Pen(Color.Yellow, 3);
// Create rectangle for ellipse.
Rectangle rect = new Rectangle(355, 282, 9, 9);
// Draw ellipse to screen.
g.DrawEllipse(blackPen, rect);
System.Threading.Thread.Sleep(3000);
}
Something other other:
I imagine if I use variables to store the percentage and call a paint-refresh of the form (maybe invalidate?) to update the result should work but I will lose any sort of animation, elsewhere I come-back to a non persistent state again... I need to use the grid as a progress bar, adding circles only at desired time, without losing the back drawings...
The grid I need to fill is very simple, here a screenshot:
Sry I should not post image for the reputation (i'm a new user!), here the link
EDIT:
I solved the smoothing problem (at least with the Graphic Mode):
g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
if i draw some rectangles in panel , how can i select one of them and delete it. My code here i have write it inside panel_OnClick event :
g = panel1.CreateGraphics();
Pen p = new Pen(Color.Black);
p.Width = 2;
g.DrawRectangle(p, e.X, e.Y, 100, 60);
p.Dispose();
g.Dispose();
Drawing on the panel is like drawing on a piece of paper - they are etched in and are no longer a rectangle, but a collection of pixels. Even though you could draw a rectangle over the one you want to clear using the background color, you won't be "removing the rectangle", you'll just draw a rectangle over the existing one.
Rectangle will have a Region.
You will need to subscribe to one of the following: MouseClick, MouseDown, MouseUp.
// assuming you keep a reference of the rectangle
void OnMouseClick(object sender, MouseEventArgs e) {
if(myRect.Region.IsVisible(e.Location) {
// perform action on myRect ...
// have window Invalidate(myRect)
// Refresh() the invalidated area.
}
}
This snippet assumes that no Rectangles overlap. You can also create a GraphicsPath from the points of the Rectangle and then from that path, I believe you can create a Region that enables the actual lines of the rectangle to be selected.
Update per comment
Region
GraphicsPath
I checked and I didn't see the Region property for Rectangle. So, to create the Region do the following:
var gPath = new GraphicsPath();
gPath.AddRectangle(rectangle);
var region = new Region(gPath);
I'm drawing directly onto a form with two FillPolygon statements to create two arrows - one black, one white. (The white arrow is slightly smaller and drawn over the black arrow.)
Here's the code in the form's OnPaint.
protected override void OnPaint(PaintEventArgs e)
{
Graphics g = e.Graphics;
g.FillPolygon(brushBlack, travelArrow);
g.FillPolygon(brushWhite, featureArrow);
}
Works great. Now since the white arrow is going to be drawn several times in different rotations, I decided to use double-buffering to avoid as much flicker as possible.
I first created a DrawFeatureArrow method that I call in OnPaint.
protected override void OnPaint(PaintEventArgs e)
{
Graphics g = e.Graphics;
g.FillPolygon(brushBlack, travelArrow);
DrawFeatureArrow(this, e);
}
Note: There's no rotation of the white arrow coded yet, I'm just trying to get the double-buffering set up.
DrawFeatureArrow looks like this.
private void DrawFeatureArrow(object sender, PaintEventArgs e)
{
Bitmap buffer = new Bitmap(60, 159);
Graphics gOff = Graphics.FromImage(buffer);
gOff.FillRectangle(brushGreen, 0, 0, buffer.Width, buffer.Height);
gOff.FillPolygon(brushWhite, featureArrow);
ImageAttributes attr = new ImageAttributes();
attr.SetColorKey(Color.Green, Color.Green);
Rectangle srcRect = new Rectangle(0, 0, bugger.Width, buffer.Height);
Rectangle destRect = new Rectangle(90, 66, 60, 159);
Graphics f = e.Graphics;
// Should draw green rectangle and white arrow
f.DrawImage(buffer, 90, 66); // Draws just a green rectangle
// If uncommented, should draw just white arrow (green rectangle hidden by SetColorKey)
// f.DrawImage(buffer, destRect, 0, 0, buffer.Width, buffer.Height, GraphicsUnit.Pixel, attr);
f.Dispose();
gOff.Dispose();
buffer.Dispose();
}
When run, the green rectangle is drawn but not the white arrow.
Strangely enough, in DrawFeatureArrow, if you replace this
gOff.FillPolygon(brushWhite, featureArrow);
With this
gOff.FillRectangle(brushWhite, 10, 10, 20, 20);
You get a tiny white rectangle in the upper left of the green rectangle.
Very strange behavior. Hope someone can point out what I'm doing incorrectly.
Thanks in advance for the help.
You're drawing your feature arrow over buffer that has dimensions of 60, 159. Maybe the location of the feature arrow is outside of those dimensions and therefore did not end in the bitmap.