[英]Control not drawn on panel
我正在嘗試向面板添加控件。 在面板上的mouseDown下,該點被保存,而在mouseUp上,該點被保存。 但是在面板mouseUp上沒有繪制任何內容。 怎么解決呢?
橢圓類:
class Ellipse : Control
{
private int x;
private int y;
private int width;
private int height;
public Ellipse(int x, int y, int width, int height)
{
setY(y);
setX(x);
setWidth(width);
setHeight(height);
}
public int getX() { return x;}
public int getY() { return y; }
public int getWidth() { return width; }
public int getHeight() { return height; }
public void setX(int newx) { x = newx; }
public void setY(int newy) { y = newy; }
public void setWidth(int newwidth) { width = newwidth; }
public void setHeight(int newheight) { height = newheight; }
protected override void OnPaint(PaintEventArgs e)
{
base.OnPaint(e);
// Call methods of the System.Drawing.Graphics object.
// Declare and instantiate a new pen.
System.Drawing.Pen myPen = new System.Drawing.Pen(Color.Aqua);
// Draw an aqua rectangle in the rectangle represented by the control.
e.Graphics.FillEllipse(Brushes.Black,x,y,width,height);
}
}
Form1班
private void panel_MouseDown(object sender, MouseEventArgs e)
{
draw = true;
x = e.X;
y = e.Y;
}
private void panel_MouseUp(object sender, MouseEventArgs e)
{
draw = false;
xe = e.X;
ye = e.Y;
Item item;
Enum.TryParse<Item>(menuComboBoxShape.ComboBox.SelectedValue.ToString(), out item);
switch (item)
{
case Item.Pencil:
using (Graphics g = panel.CreateGraphics())
using (var pen = new Pen(System.Drawing.Color.Black)) //Create the pen used to draw the line (using statement makes sure the pen is disposed)
{
g.DrawLine(pen,new Point(x, y), new Point(xe, ye));
}
break;
case Item.Rectangle:
break;
case Item.Ellipse:
Ellipse el = new Ellipse(x,y,xe-x,ye-y);
panel.Controls.Add(el);
break;
default:
break;
}
}
您正在從Control繼承Ellipse
類,但實際上您沒有將其用作控件-您沒有將其添加到Controls
集合中,因此實際上它是不可見的,不活動的,並且沒有從表單接收任何事件。
從外部代碼繪制控件看起來也很糟糕。 控件應自行繪制,並且應從外部代碼設置其邊界。
以下是可幫助您正確選擇的代碼段:
class Ellipse : Control
{
Point mDown { get; set; }
public Ellipse()
{
MouseDown += shape_MouseDown;
MouseMove += shape_MouseMove;
}
protected override void OnPaint(PaintEventArgs e)
{
base.OnPaint(e);
e.Graphics.FillEllipse(Brushes.Black, this.Bounds);
}
private void shape_MouseDown(object sender, MouseEventArgs e)
{
mDown = e.Location;
}
private void shape_MouseMove(object sender, MouseEventArgs e)
{
if (e.Button == MouseButtons.Left)
{
Location = new Point(e.X + Left - mDown.X, e.Y + Top - mDown.Y);
}
}
}
並以以下形式創建它:
el = new Ellipse();
el.Bounds = new Rectangle(0, 0, 100, 100);
Controls.Add(el);
更新資料
根據您更新的代碼,我可以看到幾個問題:
實際上,您不需要Ellipse
類的x, y, width, height
屬性以及相應的getter / setter方法,因為它是Control
,並且具有自己的Location
和Width
, Height
公共屬性。
您繪制橢圓不正確。 假設它應填滿所有區域,則繪畫應為e.Graphics.FillEllipse(Brushes.Black,0,0,Width,Height)
(此處我假設使用Control.Width
而不是您的width
,依此類推)。 否則,您將另外移動繪制的橢圓。
panel_MouseUp
有關橢圓創建的代碼應類似於
var el = new Ellipse();
panel.Controls.Add(el);
el.Location = new Point(x, y);
el.Width = (xe - x);
el.Height = (ye - y);
或者,如果它應該是一個橢圓(現在每次都在創建一個新橢圓)-在mouseUp處理程序外部和處理程序內部創建一個橢圓形,只需更改其大小和位置即可。
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