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carallot
Asked: 2020-07-17 14:03:48 +0800 CST 2020-07-17 14:03:48 +0800 CST

How to replace a form control with one of the same type generated dynamically?

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I don't know if I've been too clear with the title so I apologize if I haven't. I put an example of what I mean, very simple, but I imagine that it will be extensible to any Windows Forms control. I create a textBoxin a "textBox1" form , now by code, I instantiate a textBoxand Textassign the value "test" to its property:

textBox cajaTextoDinamica = new textBox();
cajaTextoDinamica.Text = "prueba";

In my head, it made sense that if I typed : textBox1 = cajaTextoDinamica;the one on textBox1the form would be replaced by the dynamically generated one, but it doesn't. However, even though such a control is not displayed on the form, the property textnow txtBox1has the value "test" even though it does not display it. I hope I have explained myself well enough and I would appreciate it if you could tell me what I am doing wrong.

c#

1 Answers

  1. Best Answer

    What you suggest can be done. I don't see much point in changing one control for another of the same type, but since you mention that it's about learning, I can think of a hypothetical case that could be solved by changing one control for another.

    Let's say a form is required where the user has to choose option A or option B. If he chooses option A, he has to write some information in a TextBox, but if he chooses option B, he has to select a value in a ComboBox.

    To solve it, we place a Label control on the form that will serve to mark the position of the place where we want the final control to be, and we assign the following properties to it:

    • AutoSize = false, this will allow us to change the size that will be used to assign it to the final control.
    • TabIndexthis property defines the traversal order of the controls when the tab key is pressed.
    • Name = label1although it can be any name.

    The way to replace the control is as follows:

    private void CrearTextBox()
{
    // Instancia el nuevo control y de una vez se inicializan las propiedades de interés
    var cajaTextoDinamica = new TextBox()
    {
        Text = "prueba",
        Location = label1.Location,
        TabIndex = label1.TabIndex,
        Size = label1.Size
    };

    // Esta instrucción elimina el control Label del formulario
    this.Controls.Remove(label1);

    // Esta instrucción agrega el nuevo control al formulario
    this.Controls.Add(cajaTextoDinamica);

}

    This example should serve to replace any control. Note that it is necessary to add validations to ensure that the control exists before removing it or that it does not exist before adding it.
    For example:

    // Ejemplo para validar que el control existe antes de eliminarlo
if (this.Controls.IndexOf(label1) >= 0)
{
    this.Controls.Remove(label1);
}
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