Here is my code:
public Form1()
{
InitializeComponent();
pBox1.AllowDrop = true;
}
private void pBox1_DragDrop(object sender, DragEventArgs e)
{
var bmp = (Bitmap)e.Data.GetData(DataFormats.Bitmap);
pBox1.Image = bmp;
pBox1.Size = new Size(100, 100);
}
private void pBox2_MouseDown(object sender, MouseEventArgs e)
{
if (DoDragDrop(pBox2.Image, DragDropEffects.Move) == DragDropEffects.Move)
{
pBox2.Image = null;
}
}
pBox1 is the pictureBox that I would like to drag into, and pBox2 is the pictureBox I would like to drag from. The error I get is an object reference not set to instance of object error, on the line "if(DoDragDrop...." within the MouseDown method.
If what you have listed is the entire code listing, you are never setting pBox2.Image to an Image, which would cause the exception. May want to add:
private void pBox2_MouseDown(object sender, MouseEventArgs e)
{
if(pBox2.Image != null)
{
if (DoDragDrop(pBox2.Image, DragDropEffects.Move) == DragDropEffects.Move)
{
pBox2.Image = null;
}
}
}
To initialize the pBox2 to an image of some sort...
public Form1()
{
InitializeComponent();
pBox1.AllowDrop = true;
pBox2.Image = Image.FromFile(#"YourFilePath");
}
Edit
Just a note, this gets rid of your exception, but still does not implement drag drop properly. I am playing with it and will get back with you if I find a proper solution.
Edit
Possible duplicate to the following link:
Stack Overflow Thread
I got it working using the following:
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
this.AllowDrop = true;
pictureBox1.AllowDrop = true;
pictureBox2.AllowDrop = true;
pictureBox2.Image = Image.FromFile(#"C:\TitleBar.jpg");
}
private void pictureBox2_MouseDown(object sender, MouseEventArgs e)
{
if (pictureBox2.Image != null)
{
pictureBox2.DoDragDrop(pictureBox2.Image, DragDropEffects.Move);
pictureBox2.Image = null;
}
}
private void pictureBox1_DragEnter(object sender, DragEventArgs e)
{
e.Effect = DragDropEffects.Move;
}
private void pictureBox1_DragDrop(object sender, DragEventArgs e)
{
pictureBox1.Image = (Image)e.Data.GetData(DataFormats.Bitmap);
}
}
Related
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private void Button1_Click(object sender, EventArgs e)
{
VideoCapture capture = new VideoCapture();
var img = capture.QueryFrame();
imageBox1.Image = img;
}
}
}
This is my code and I can't seem to make it work. Everything seems fine, I am unable to Debug. My ImageBox is not streaming a video just showing an image.
I found the answer. Thank You!. Everyone :)
public partial class Form1 : Form
{
bool _streaming;
VideoCapture _capture;
public Form1()
{
InitializeComponent();
}
private void Form1_Load(object sender, EventArgs e)
{
_streaming = false;
_capture = new VideoCapture();
}
private void Button2_Click(object sender, EventArgs e)
{
if (_streaming == false)
{
//Start streaming
Application.Idle += streaming;
button2.Text = "Stop Streaming";
}
else
{
Application.Idle -= streaming;
button2.Text = "Start Streaming";
}
_streaming = !_streaming;
}
private void streaming(object sender, EventArgs e)
{
var img = _capture.QueryFrame();
imageBox2.Image = img;
}
private void Button1_Click(object sender, EventArgs e)
{
imageBox1.Image = imageBox2.Image;
}
I am doing a memory matching game in c#
when the user matches 2 images i want them to disappear or make them invisible
i am still new to coding and this is what i did so far but the images wont be invisible
private void apple1_Click(object sender, EventArgs e)
{
apple1.Image = Properties.Resources.apple;
bool condition = true;
if (apple1.Image==apple2.Image)
{
apple1.Visible = false;
apple2.Visible = false;
}
}
private void apple2_Click(object sender, EventArgs e)
{
apple2.Image = Properties.Resources.apple;
}
As others have stated you'll need to store all of the Resources just once. Here is a possible example:
class MyForm
{
private Dictionary<String, Image> images = new Dictionary<String, Image>();
public void Init()
{
images["apple"] = Properties.Resources.apple;
}
public void Dispose()
{
foreach(var item in myDictionary.Values)
{
item.Dispose();
}
}
private void apple1_Click(object sender, EventArgs e)
{
apple1.Image = images["apple"];
bool condition = true;
if (apple1.Image==apple2.Image)
{
apple1.Visible = false;
apple2.Visible = false;
}
}
private void apple2_Click(object sender, EventArgs e)
{
apple2.Image = images["apple"];
}
}
When you set apple1.Image = Properties.Resources.apple; Note that a copy of the value (Image) of the Properties.Resources.apple is set to apple1.Image, same thing happens when you assign to apple2.Image, so although visually they seem to have the same image, but they are pointing to different images (in memory).
You may do one of following:
1-Set your images to a dictionary and then load apple1.Image and apple2.Image from it:
Dictionary<string, Image> Images = new Dictionary<string, Image>();
Images.Add("apple", Properties.Resources.apple);
Image apple = Properties.Resources.apple;
private void apple1_Click(object sender, EventArgs e)
{
apple1.Image = Images["apple"];
if (apple1.Image==apple2.Image)
{
apple1.Visible = false;
apple2.Visible = false;
}
}
private void apple2_Click(object sender, EventArgs e)
{
apple2.Image = Images["apple"];
}
2-Just use another property to compare equality:
private void apple1_Click(object sender, EventArgs e)
{
apple1.Image = Properties.Resources.apple;
apple1.Tag = "apple";
if ((string)apple1.Tag==(string)apple2.Tag)
{
apple1.Visible = false;
apple2.Visible = false;
}
}
private void apple2_Click(object sender, EventArgs e)
{
apple2.Image = Properties.Resources.apple;
apple2.Tag = "apple";
}
I usually call this piece of code to show a form whenever a button is clicked.
private frmSelection _frmSelection;`
private void _frmSelection_FormClosing(object sender, FormClosingEventArgs e)
{
_frmSelection = null;
}
private void changeFeedOrderToolStripMenuItem_Click(object sender, EventArgs e)
{
if (_frmSelection == null)
{
_frmSelection = new frmSelection();
_frmSelection.FormClosing += _frmSelection_FormClosing;
_frmSelection.WindowState = FormWindowState.Minimized;
_frmSelection.Show();
_frmSelection.WindowState = FormWindowState.Normal;
}
else
{
_frmSelection.WindowState = FormWindowState.Minimized;
_frmSelection.WindowState = FormWindowState.Normal;
}
}
If the form is already open it will show the already opened instance instead of creating new instance. It is working fine.
But my problem is i need to copy paste and change the form name whenever i am adding a new form.
How it can be generalized and added to
Helper
class?
Something like this:
public sealed class ReusableFormContainer<T> : IDisposable
where T : Form, new()
{
private bool isDisposed;
private void HandleFormClosing(object sender, FormClosingEventArgs e)
{
Form = null;
}
public T Form { get; private set; }
public void Show()
{
if (isDisposed)
{
throw new ObjectDisposedException(null);
}
if (Form == null)
{
Form = new T { WindowState = FormWindowState.Minimized };
Form.FormClosing += HandleFormClosing;
Form.Show();
}
else
{
Form.WindowState = FormWindowState.Minimized;
}
Form.WindowState = FormWindowState.Normal;
}
public void Dispose()
{
// IDisposable.Dispose is implemented to handle cases, when you want to close
// wrapped form using code
if (!isDisposed)
{
Form?.Dispose();
isDisposed = true;
}
}
}
Usage:
// must be initialized somewhere in constructors
private readonly ReusableFormContainer<FormA> container_A;
private readonly ReusableFormContainer<FormB> container_B;
private void button1_Click(object sender, EventArgs e)
{
container_A.Show();
}
private void button2_Click(object sender, EventArgs e)
{
container_B.Show();
}
The following code might do what you want. Just thought about to use the Application functions because those can cover all forms that are on thread.
public partial class Form1 : Form
{
public int i;
private Form1 _frmSelection;
public Form1()
{
InitializeComponent();
i = Application.OpenForms.Count;
}
private void _frmSelection_FormClosing(object sender, FormClosingEventArgs e)
{
_frmSelection = null;
}
private void button1_Click(object sender, EventArgs e)
{
if (_frmSelection == null)
{
_frmSelection = new Form1();
_frmSelection.FormClosing += _frmSelection_FormClosing;
_frmSelection.WindowState = FormWindowState.Minimized;
_frmSelection.WindowState = FormWindowState.Normal;
_frmSelection.Show();
if (Application.OpenForms.Count > 1)
{
_frmSelection.Text = Application.OpenForms[i].Text + " and going";
}
}
else
{
_frmSelection.WindowState = FormWindowState.Minimized;
_frmSelection.WindowState = FormWindowState.Normal;
}
}
}
In my program I need to copy a Label in Windows Forms, and I implemented it the following way:
public partial class Resizer : Form
{
public Resizer()
{
InitializeComponent();
}
private Control toChange = new Control();
private Control selected = new Control();
private bool readyToMove = false;
private Point offset;
private void pictureBox4_Click(object sender, EventArgs e)
{
selected.Location = ((Control)sender).Location;
selected.Size = ((Control)sender).Size;
}
private void backClick(object sender, EventArgs e)
{
selected = null;
}
private void Resizer_Load(object sender, EventArgs e)
{
pictureBox4.MouseDown += new MouseEventHandler(this.dynamicMouseDown);
pictureBox4.MouseMove += new MouseEventHandler(this.dynamicMouseMove);
pictureBox4.MouseUp += new MouseEventHandler(this.dynamicMouseUp);
}
private void dynamicMouseDown(object sender, MouseEventArgs e)
{
toChange = (Control)sender;
selected.Location = ((Control)sender).Location;
selected.Size = ((Control)sender).Size;
readyToMove = true;
offset = new Point(PointToClient(MousePosition).X - selected.Location.X,
PointToClient(MousePosition).Y - selected.Location.Y);
}
private void dynamicMouseMove(object sender, MouseEventArgs e)
{
if (readyToMove)
{
selected.Location = new Point(PointToClient(MousePosition).X-offset.X,
PointToClient(MousePosition).Y- offset.Y);
this.Update();
}
}
private void dynamicMouseUp(object sender, MouseEventArgs e)
{
toChange.Location = selected.Location;
readyToMove = false;
}
private void button1_Click(object sender, EventArgs e)
{
PictureBox pBox = (PictureBox)CloneObject(this.pictureBox4);
this.Controls.Add(pBox);
//pBox.MouseDown += new MouseEventHandler(this.dynamicMouseDown);
//pBox.MouseMove += new MouseEventhandler(this.dynamicMouseMove);
//pBox.MouseUp += new MouseEventHandler(this.dynamicMouseUp);
//these eventhandlers did not help...
}
private object cloneObject(object o)
{
Type t = o.GetType();
System.Reflection.PropertyInfo[] properties = t.GetProperties();
Object p = t.InvokeMember("",
System.Reflection.BindingFlags.CreateInstance,
null,
o,
null);
foreach (PropertyInfo pi in properties)
{
if (pi.CanWrite)
pi.SetValue(p, pi.GetValue(o, null), null);
}
return p;
}
}
old problem:
The problem is that as soon as I click on the labelOrigin, the Window freezes and I can't close the form anymore. Why is that and how can I fix it?
Now:
As you can see, this implements a drag&drop where by pressing a button, you can duplicate a form..
the problem is, that the new pBox is not movable and does lead to graphical errors..
this code should work on a simple form after adding a button1 and a pictureBox4
I have this simple code in my DevExpress LookUp control (should be identical with a normal combobox)
private void lookUpUsers_EditValueChanged(object sender, EventArgs e)
{
lookUpRolesPréÉdit.EditValue = null;
}
private void lookUpRolesPréÉdit_EditValueChanged(object sender, EventArgs e)
{
lookUpUsers.EditValue = null;
}
The problem is that when I select a value in lookUpUsers, is resets the other lookup which then resets lookUpUsers. So when I pick a value, both combobox become null. What I want is that when you pick a value in combobox 1, combobox 2 resets its value.
How about this:
private void lookUpUsers_EditValueChanged(object sender, EventArgs e)
{
if(lookUpUsers.EditValue != null)
lookUpRolesPréÉdit.EditValue = null;
}
private void lookUpRolesPréÉdit_EditValueChanged(object sender, EventArgs e)
{
if(lookUpRolesPréÉdit.EditValue != null)
lookUpUsers.EditValue = null;
}
There might be an easier way than this, as my knowledge of C# is limited (especially their libraries like you are using them here). Nevertheless, this is an answer that uses no magic provided by libraries:
private bool localEdit = false;
private void lookUpUsers_EditValueChanged(object sender, EventArgs e)
{
if (!localEdit)
{
localEdit = true;
lookUpRolesPréÉdit.EditValue = null;
localEdit = false;
}
}
private void lookUpRolesPréÉdit_EditValueChanged(object sender, EventArgs e)
{
if (!localEdit)
{
localEdit = true;
lookUpUsers.EditValue = null;
localEdit = false;
}
}
Here's a solution I've come up with
private void lookUpUsers_EditValueChanged(object sender, EventArgs e)
{
if (!isEditFinished)
{
isEditFinished = true;
lookUpRolesPréÉdit.EditValue = null;
}
isEditFinished = false;
}
private void lookUpRolesPréÉdit_EditValueChanged(object sender, EventArgs e)
{
if (!isEditFinished)
{
isEditFinished = true;
lookUpUsers.EditValue = null;
}
isEditFinished = false;
}