我是一个新的开发人员。我正在尝试制作一个简单的程序，我们可以在其中绘制多个形状，如矩形、椭圆、直线等。我现在面临的问题是当我单击鼠标并拖动时绘制 mouseDown 和 mouseMove 事件我看不到形状。仅当我离开鼠标时，该形状才会出现在图片框上。
我希望形状在用户绘制时随着鼠标出现并移动，就像在 Microsoft 的绘画应用程序中一样。
我在绘制时尝试使用 Refresh() 函数，但它删除了已经在图片框中绘制的旧形状。
下面是我正在使用的代码。需要一些建议。
bool draw = false;
bool isMouseDown = false;
int x, y, lx, ly = 0;
Item currItem;
Pen pen = new Pen(Color.Red,1);
public enum Item
{
Rectangle, Ellipse, Line, Pencil, Eraser
}
private void btnROIDraw_Click(object sender, EventArgs e)
{
if (menuStripRoi.Visible == false)
{
menuStripRoi.Visible = true;
}
else
{
menuStripRoi.Visible = false;
draw = false;
}
}
private void pictureBoxROI_MouseDown(object sender, MouseEventArgs e)
{
x = e.X;
y = e.Y;
isMouseDown = true;
//draw = true;
}
private void pictureBoxROI_MouseUp(object sender, MouseEventArgs e)
{
lx = e.X;
ly = e.Y;
if (draw)
{
Graphics g = pictureBoxROI.CreateGraphics();
switch (currItem)
{
case Item.Rectangle:
g.DrawRectangle(pen, x, y, e.X - x, e.Y - y);
break;
case Item.Ellipse:
g.DrawEllipse(pen, x, y, e.X - x, e.Y - y);
break;
case Item.Line:
g.DrawLine(pen, x, y, e.X, e.Y);
break;
}
g.Dispose();
}
isMouseDown = false;
}
private void pictureBoxROI_MouseMove(object sender, MouseEventArgs e)
{
if (isMouseDown)
{
if (draw)
{
Graphics g = pictureBoxROI.CreateGraphics();
switch (currItem)
{
case Item.Pencil:
g.FillEllipse(new SolidBrush(Color.Red), e.X - x + x, e.Y - y + y, 2, 2);
break;
case Item.Eraser:
g.FillEllipse(new SolidBrush(pictureBoxROI.BackColor), e.X - x + x, e.Y - y + y, 20, 20);
break;
}
g.Dispose();
}
}
}
private void pictureBoxROI_Paint(object sender, PaintEventArgs e)
{
}
private void clearToolStripMenuItem_Click(object sender, EventArgs e)
{
pictureBoxROI.Refresh();
}
private void rectangleToolStripMenuItem_Click(object sender, EventArgs e)
{
currItem = Item.Rectangle;
draw = true;
}
private void ellipseToolStripMenuItem_Click(object sender, EventArgs e)
{
currItem = Item.Ellipse;
draw = true;
}
private void lineToolStripMenuItem_Click(object sender, EventArgs e)
{
currItem = Item.Line;
draw = true;
}
private void pencilToolStripMenuItem_Click(object sender, EventArgs e)
{
currItem = Item.Pencil;
draw = true;
}
private void eracerToolStripMenuItem_Click(object sender, EventArgs e)
{
currItem = Item.Eraser;
draw = true;
}
private void newToolStripMenuItem_Click(object sender, EventArgs e)
{
pictureBoxROI.Refresh();
pictureBoxROI.Image = null;
}
private void openToolStripMenuItem_Click(object sender, EventArgs e)
{
OpenFileDialog o = new OpenFileDialog();
o.Filter = "Png files|*.png|jpeg files|*jpg|bitmaps|*.bmp";
if (o.ShowDialog() == System.Windows.Forms.DialogResult.OK)
{
pictureBoxROI.Image = (Image)Image.FromFile(o.FileName).Clone();
}
}
private void saveToolStripMenuItem_Click(object sender, EventArgs e)
{
Bitmap bmp = new Bitmap(pictureBoxROI.Width, pictureBoxROI.Height);
Graphics g = Graphics.FromImage(bmp);
Rectangle rect = pictureBoxROI.RectangleToScreen(pictureBoxROI.ClientRectangle);
g.CopyFromScreen(rect.Location, Point.Empty, pictureBoxROI.Size);
g.Dispose();
SaveFileDialog s = new SaveFileDialog();
s.Filter = "Png files|*.png|jpeg files|*jpg|bitmaps|*.bmp";
if (s.ShowDialog() == System.Windows.Forms.DialogResult.OK)
{
if (File.Exists(s.FileName))
{
File.Delete(s.FileName);
}
if (s.FileName.Contains(".jpg"))
{
bmp.Save(s.FileName, ImageFormat.Jpeg);
}
else if (s.FileName.Contains(".png"))
{
bmp.Save(s.FileName, ImageFormat.Png);
}
else if (s.FileName.Contains(".bmp"))
{
bmp.Save(s.FileName, ImageFormat.Bmp);
}
}
}
最佳答案
找到了我的问题的解决方案。
本文详细解释了有关使用 GDI+ 绘图的所有内容。值得一看
http://www.codeproject.com/Articles/17893/Extensions-to-DrawTools
关于visual-studio-2005 - 在鼠标拖动 C# 上绘制时不可见的形状，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/32707744/