On Wed, 07 May 2008 14:36:31 -0700, Macias <ma************@gmail.com
wrote:
I make drawing like this:
private void pb_MouseMove(object sender, MouseEventArgs e)
{
Point CurentCoord = new Point(e.X, e.Y);
if (md)
{
using (Graphics g = Graphics.FromImage(img))
{
g.CompositingMode = CompositingMode.SourceOver;
g.CompositingQuality =
CompositingQuality.HighSpeed;
Rectangle rect = this.ClientRectangle;
using (Pen p = new Pen(ColorBox.BackColor, 2))
{
g.DrawLine(p, ClickCoord, CurentCoord);
pb.Image = img;
}
}
}
but still I've a lot of lines when I moveing mouse. But I want to have
only one.
Please correct my pice of program.
What is the precise reason for using a PictureBox to contain the image?
Are you sure you really need that? Or would it suffice to override
OnPaint() in your form or a custom control class? I ask, because the use
of the PictureBox is going to necessarily impose additional overhead on
the redrawing.
The basic issue you've got is that you've apparently started with a given
Image instance, and to that you want to add a line. However, since you're
adding a new line every time the mouse moves, you get a lot of lines,
instead of just the one for the most recent mouse position.
One of the simplest approaches I see based on the code you posted would be
to not draw into the original Image, but rather create a new one:
private void pb_MouseMove(object sender, MouseEventArgs e)
{
Point CurentCoord = new Point(e.X, e.Y);
if (md)
{
Image imgT = new Bitmap(img);
using (Graphics g = Graphics.FromImage(imgT))
{
g.CompositingMode = CompositingMode.SourceOver;
g.CompositingQuality =
CompositingQuality.HighSpeed;
Rectangle rect = this.ClientRectangle;
using (Pen p = new Pen(ColorBox.BackColor, 2))
{
g.DrawLine(p, ClickCoord, CurentCoord);
pb.Image = imgT;
}
}
}
Optionally (and most likely) in the MouseUp event you'd replace the "img"
reference with the Image currently in the PictureBox.
This is far from an ideal solution though. It can get very expensive to
be creating a new bitmap every time the mouse moves. I haven't use the
PictureBox control much; it's possible you could create one temporary
image that you repeatedly copy your original image into, and then reassign
that to the PictureBox.Image property. That would at least avoid the
constant instantiation of Bitmaps, but you'd still have a little extra
overhead every time you copy the original image into the temporary image..
It would be much better if you weren't using the PictureBox, but instead
were drawing the Image directly yourself in the appropriate place (form or
custom control). This way you could simply draw both the base Image and
then the line each time the OnPaint() method was called. You'd still
override OnMouseMove() but the only thing you'd do there is update your
line coordinates and invalidate the area of the form or control containing
the old position of the line and the new position of the line.
This way, rather than creating new bitmaps every time the mouse moves, all
you have to do is redraw the relevant area based on the current mouse
position.
Without knowing more about the specific goal you have for your program,
it's hard to offer more detailed advice than the above. Hopefully that
gets you going in the right direction.
Pete
