BreakableComponent.cs

using System;
using System.ComponentModel;
using System.Drawing.Design;
using FastReport.Utils;


namespace FastReport
{
    /// <summary>
    /// Base class for report components that can break across pages.
    /// </summary>
    public class BreakableComponent : ReportComponentBase
    {
        #region Fields
        private bool canBreak;
        private BreakableComponent breakTo;
        #endregion

        #region Properties
        /// <summary>
        /// Gets or sets a value that determines if the component can break its contents across pages.
        /// </summary>
        [DefaultValue(true)]
        [Category("Behavior")]
        public bool CanBreak
        {
            get { return canBreak; }
            set { canBreak = value; }
        }

        /// <summary>
        /// Gets or sets a reference to another similar object that will be used for displaying the
        /// text that not fit in this object.
        /// </summary>
        [Category("Behavior")]
        [TypeConverter(typeof(FastReport.TypeConverters.ComponentRefConverter))]
        [Editor("FastReport.TypeEditors.BandComponentRefEditor, FastReport", typeof(UITypeEditor))]
        public BreakableComponent BreakTo
        {
            get { return breakTo; }
            set
            {
                if (breakTo != value)
                {
                    if (breakTo != null)
                        breakTo.Disposed -= new EventHandler(BreakTo_Disposed);
                    if (value != null)
                        value.Disposed += new EventHandler(BreakTo_Disposed);
                }
                breakTo = value;
            }
        }
        #endregion

        #region Private Methods
        private void BreakTo_Disposed(object sender, EventArgs e)
        {
            breakTo = null;
        }
        #endregion

        #region Public Methods
        /// <inheritdoc/>
        public override void Assign(Base source)
        {
            base.Assign(source);

            BreakableComponent src = source as BreakableComponent;
            CanBreak = src.CanBreak;
            BreakTo = src.BreakTo;
        }

        /// <inheritdoc/>
        public override void Serialize(FRWriter writer)
        {
            BreakableComponent c = writer.DiffObject as BreakableComponent;
            base.Serialize(writer);

            if (CanBreak != c.CanBreak)
                writer.WriteBool("CanBreak", CanBreak);
            if (writer.SerializeTo != SerializeTo.Preview && writer.SerializeTo != SerializeTo.SourcePages &&
              BreakTo != c.BreakTo)
                writer.WriteRef("BreakTo", BreakTo);
        }

        /// <summary>
        /// Breaks the contents of the object.
        /// </summary>
        /// <param name="breakTo">Object to put the part of content to that does not fit in this object. These two 
        /// objects must have the same type.</param>
        /// <returns><b>true</b> if there is enough space in this object to display at least one text line.</returns>
        /// <remarks>
        /// <para>
        /// Do not call this method directly, it is used by the report engine. You should override it if
        /// you are writing a new FastReport object.
        /// </para>
        /// <para>
        /// This method must break the contents of the object. The part of content that fit in current object's
        /// bounds should remain in this object, the part that does not fit should be transferred to <b>breakTo</b>
        /// object. 
        /// </para>
        /// </remarks>
        public virtual bool Break(BreakableComponent breakTo)
        {
            return false;
        }

        #endregion

        /// <summary>
        /// Initializes a new instance of the <b>BreakableComponent</b> class with default settings. 
        /// </summary>
        public BreakableComponent()
        {
            CanBreak = true;
        }
    }
}