syncfusion-winforms-double-textbox

# Implementing Syncfusion WinForms DoubleTextBox ## When to Use This Skill Use this skill when you need to: - Accept and display double-precision floating-point values in a Windows Forms application - Implement numeric input with customizable decimal places and group separators - Apply min/max value constraints to numeric input - Handle value change events or keyboard shortcuts for incrementing/decrementing values - Override the control's default keystroke handling for custom behavior - Apply visual styling based on positive, negative, or zero values ## Component Overview The **DoubleTextBox** is a specialized text box control derived from the Windows Forms Framework that handles double data type values. It provides: - Automatic double value validation and formatting - Customizable number display (decimal digits, separators, patterns) - Min/max value constraints - Event handling for value changes and keyboard input - Keyboard shortcut support for incrementing/decrementing values - Extensibility through method overrides ## Documentation Navigation Guide ### Getting Started 📄 **Read:** [references/getting-started.md](references/getting-started.md) - Assembly deployment and setup - Adding control via designer - Adding control via C# code - Setting maximum and minimum values - Customizing number format ### Number and Format Settings 📄 **Read:** [references/number-and-format-settings.md](references/number-and-format-settings.md) - Number formatting properties overview - Decimal digits and separators - Value range configuration (MaxValue/MinValue) - Banner text support - Hiding trailing zeros ### Appearance and Behavior 📄 **Read:** [references/appearance-and-behavior.md](references/appearance-and-behavior.md) - Border style settings - Color settings for value states - Keyboard support configuration - Overflow indicator display - Active when disabled behavior ### Event Handling and Customization 📄 **Read:** [references/event-handling-and-customization.md](references/event-handling-and-customization.md) - DoubleValueChanged event handling - Keyboard events for increment/decrement - Overriding control behavior - Custom HandleSubtractKey implementation - Extending control functionality ## Quick Start Example **Basic setup in C#:** ```csharp using Syncfusion.Windows.Forms.Tools; // Create instance DoubleTextBox doubleTextBox1 = new DoubleTextBox(); this.Controls.Add(doubleTextBox1); // Set value constraints doubleTextBox1.MaxValue = 100; doubleTextBox1.MinValue = 0; // Handle value changes doubleTextBox1.DoubleValueChanged += (s, e) => MessageBox.Show("Value changed"); ``` **Key properties:** - `DoubleValue` - Gets or sets the double value - `MaxValue` - Maximum allowed value - `MinValue` - Minimum allowed value - `NumberDecimalDigits` - Number of decimal places to display - `NumberDecimalSeparator` - Character used as decimal separator - `NumberGroupSeparator` - Character used as thousands separator ## Common Patterns ### Pattern 1: Accept Percentage Input (0-100) ```csharp doubleTextBox1.MinValue = 0; doubleTextBox1.MaxValue = 100; doubleTextBox1.NumberDecimalDigits = 2; doubleTextBox1.Text = "50"; ``` ### Pattern 2: Accept Currency Values ```csharp doubleTextBox1.NumberDecimalDigits = 2; doubleTextBox1.NumberGroupSeparator = ","; doubleTextBox1.NumberDecimalSeparator = "."; doubleTextBox1.Text = "1234.56"; ``` ### Pattern 3: Increment/Decrement with Keyboard ```csharp doubleTextBox1.KeyDown += (s, e) => { if (e.KeyCode == Keys.Up) doubleTextBox1.DoubleValue++; else if (e.KeyCode == Keys.Down) doubleTextBox1.DoubleValue--; }; ``` ### Pattern 4: Allow Null/Empty Values ```csharp doubleTextBox1.AllowNull = true; doubleTextBox1.NullString = ""; doubleTextBox1.Text = ""; ``` ## Key Properties | Property | Type | Purpose | |----------|------|---------| | `DoubleValue` | double | Gets or sets the double value of the textbox | | `MaxValue` | double | Maximum allowed value | | `MinValue` | double | Minimum allowed value | | `NumberDecimalDigits` | int | Number of decimal places to display | | `NumberDecimalSeparator` | string | Decimal separator character | | `NumberGroupSeparator` | string | Thousands separator character | | `NumberGroupSizes` | int[] | Sizes of number groups | | `NumberNegativePattern` | int | Pattern for negative numbers | | `HideTrailingZeros` | bool | Hide trailing zeros in display | | `AllowNull` | bool | Allow null/empty values | | `NullString` | string | String representation of null | ## Common Use Cases 1. **Financial Applications** - Currency input with two decimal places, value constraints 2. **Measurement Input** - Scientific data with variable decimal precision 3. **Percentage Fields** - Constrained to 0-100 range with validation 4. **Configuration Settings** - Numeric parameters for application tuning 5. **Data Entry Forms** - Validated numeric fields with formatting 6. **Calculate Totals** - Increment/decrement values with keyboard shortcuts