c#.netwinformsgdi+picturebox
Creating Custom Picturebox with Draggable and Resizable Selection Window
I'm using the following code to draw a selection rectangle over a picturebox and allow the user to select and drag it to the desired position.
What I intend to achieve is to allow the user to adjust the rectangle size by implementing option to adjust the rectangle size. Currently I have managed to achieve the following.
How to solve this issue?
public class DraggablePictureBox : PictureBox
{
Boolean hit1 = false, hit2 = false;
public Boolean notagimg = true;
public Boolean editedflag = false;
public Boolean notext = false;
public Boolean tdrawflag = false, tdrawflag2 = false;
Bitmap l;
public Form1 LaunchOrigin2 { get; set; }
public Point point = new Point(0, 0);
public Point point2 = new Point(0, 0);
public int sizemode = 1;
public DraggablePictureBox()
{
this.Invalidate();
}
protected override void OnMouseMove(MouseEventArgs e)
{
this.Cursor = Cursors.Arrow;
if (e.Button == MouseButtons.Left)
{
point = e.Location;
base.OnMouseDown(e);
this.Invalidate();
}
}
protected override void OnMouseDown(MouseEventArgs e)
{
PointF x = new PointF(e.X, e.Y);
Pen p = new Pen(Brushes.Red, 2f);
RectangleF rect2 = new RectangleF(1, 1, 1, 1);
RectangleF rect = new RectangleF(1, 1, 1, 1);
if (e.Button == MouseButtons.Left)
{
this.Cursor = Cursors.Hand;
//Creating Rectangles to check to find the selected object
if (notext == false)
{
rect = new RectangleF(point, new Size(400,400));
}
if (rect.Contains(x) && notext == false)
{
hit1 = true;
}
if (hit1 == true )
{
this.Invalidate();
}
this.Invalidate();
}
}
protected override void OnMouseUp(MouseEventArgs e)
{
base.OnMouseUp(e);
tdrawflag = false;
}
if (e.Button == MouseButtons.Left)
{
point = e.Location;
base.OnMouseDown(e);
this.Invalidate();
}
}
protected override void OnPaint(PaintEventArgs pe)
{
base.OnPaint(pe);
Pen p = new Pen(Brushes.Red, 5);
p.DashStyle = System.Drawing.Drawing2D.DashStyle.Dot;
Pen p2 = new Pen(Brushes.LightYellow, 5);
p2.DashStyle = System.Drawing.Drawing2D.DashStyle.Dash;
if (!hit1)
{
pe.Graphics.DrawRectangle(p, new Rectangle(point, new Size(400, 400)));
}
else
{
pe.Graphics.DrawRectangle(p2, new Rectangle(point, new Size(400, 400)));
hit1 = false;
}
}
}
Solution
You have different options:
- You can draw a resizable frame on the picture box
- You can create a resizable control and add it to picture box
In this answer, I've taken the second option to be able to use built-in sizing features of the controls. Here is a screen capture which shows how it looks like in action:
Example - Creating a Frame Control
As an example, I'll create a resizable control and will add it to the picture box.
using System;
using System.Drawing;
using System.Windows.Forms;
public class FrameControl : Control
{
public FrameControl()
{
SetStyle(ControlStyles.SupportsTransparentBackColor, true);
DoubleBuffered = true;
ResizeRedraw = true;
BackColor = Color.Transparent;
}
protected override void OnPaint(PaintEventArgs e)
{
base.OnPaint(e);
using (var p = new Pen(Color.Black, 4))
{
p.DashStyle = System.Drawing.Drawing2D.DashStyle.Dash;
e.Graphics.DrawRectangle(p, 0, 0, Width - 1, Height - 1);
}
}
const int WM_NCHITTEST = 0x84;
const int WM_SETCURSOR = 0x20;
const int WM_NCLBUTTONDBLCLK = 0xA3;
protected override void WndProc(ref Message m)
{
int borderWidth = 10;
if (m.Msg == WM_SETCURSOR) /*Setting cursor to SizeAll*/
{
if ((m.LParam.ToInt32() & 0xffff) == 0x2 /*Move*/)
{
Cursor.Current = Cursors.SizeAll;
m.Result = (IntPtr)1;
return;
}
}
if ((m.Msg == WM_NCLBUTTONDBLCLK)) /*Disable Mazimiz on Double click*/
{
m.Result = (IntPtr)1;
return;
}
base.WndProc(ref m);
if (m.Msg == WM_NCHITTEST)
{
var pos = PointToClient(new Point(m.LParam.ToInt32() & 0xffff,
m.LParam.ToInt32() >> 16));
if (pos.X <= ClientRectangle.Left + borderWidth &&
pos.Y <= ClientRectangle.Top + borderWidth)
m.Result = new IntPtr(13); //TOPLEFT
else if (pos.X >= ClientRectangle.Right - borderWidth &&
pos.Y <= ClientRectangle.Top + borderWidth)
m.Result = new IntPtr(14); //TOPRIGHT
else if (pos.X <= ClientRectangle.Left + borderWidth &&
pos.Y >= ClientRectangle.Bottom - borderWidth)
m.Result = new IntPtr(16); //BOTTOMLEFT
else if (pos.X >= ClientRectangle.Right - borderWidth &&
pos.Y >= ClientRectangle.Bottom - borderWidth)
m.Result = new IntPtr(17); //BOTTOMRIGHT
else if (pos.X <= ClientRectangle.Left + borderWidth)
m.Result = new IntPtr(10); //LEFT
else if (pos.Y <= ClientRectangle.Top + borderWidth)
m.Result = new IntPtr(12); //TOP
else if (pos.X >= ClientRectangle.Right - borderWidth)
m.Result = new IntPtr(11); //RIGHT
else if (pos.Y >= ClientRectangle.Bottom - borderWidth)
m.Result = new IntPtr(15); //Bottom
else
m.Result = new IntPtr(2); //Move
}
}
}
Then add the control to the picture box:
var s = 100;
var c = new FrameControl();
c.Size = new Size(s, s);
c.Location = new Point((pictureBox1.Width - s) / 2, (pictureBox1.Height - s) / 2);
pictureBox1.Controls.Add(c);
To add a fancy effect of filling outside of the frame with semi-transparent color:
private void pictureBox1_Paint(object sender, PaintEventArgs e)
{
e.Graphics.ExcludeClip(pictureBox1.Controls[0].Bounds);
using (var b = new SolidBrush(Color.FromArgb(100, Color.Black)))
e.Graphics.FillRectangle(b, pictureBox1.ClientRectangle);
}
As you can see in the paint event, you can find the FrameControl using pictureBox1.Controls[0]. So you can find its location and size.
You can encapsulate all the logic of the picture box in a derived picture box.
Note: Flicker-free rendering
If you experience flickering when moving the frame, use the following code in your form:
protected override CreateParams CreateParams
{
get
{
CreateParams cp = base.CreateParams;
cp.ExStyle |= 0x02000000; // WS_EX_COMPOSITED
return cp;
}
}