ScrollProperties.cs source code in C# .NET

Source code for the .NET framework in C#

                        
Code:

                         / DotNET / DotNET / 8.0 / untmp / whidbey / REDBITS / ndp / fx / src / WinForms / Managed / System / WinForms / ScrollProperties.cs / 1 / ScrollProperties.cs
                        

                        
                            //------------------------------------------------------------------------------ 
// 
//     Copyright (c) Microsoft Corporation.  All rights reserved.
// 
//----------------------------------------------------------------------------- 

namespace System.Windows.Forms { 
    using System.Runtime.InteropServices; 
    using System.Diagnostics;
    using System; 
    using System.Security.Permissions;
    using System.Runtime.Serialization.Formatters;
    using System.ComponentModel;
    using System.Drawing; 
    using Microsoft.Win32;
    using System.Windows.Forms; 
    using System.Globalization; 

    ///  
    /// 
    ///    
    ///       Basic Properties for Scrollbars.
    ///     
    /// 
    public abstract class ScrollProperties { 
 
        internal int minimum = 0;
        internal int maximum = 100; 
        internal int smallChange = 1;
        internal int largeChange = 10;
        internal int value = 0;
        internal bool maximumSetExternally; 
        internal bool smallChangeSetExternally;
        internal bool largeChangeSetExternally; 
 
        /// 
        private ScrollableControl parent; 

        protected ScrollableControl ParentControl {
            get
            { 
                return parent;
            } 
        } 

        ///  
        ///     Number of pixels to scroll the client region as a "line" for autoscroll.
        /// 
        /// 
        private const int SCROLL_LINE = 5; 

        internal bool visible = false; 
 
        //Always Enabled
        private bool enabled = true; 


        /// 
        protected ScrollProperties(ScrollableControl container)  { 
            this.parent = container;
        } 
 
        /// 
        ///  
        ///    
        ///       Gets or sets a bool value controlling whether the scrollbar is enabled.
        ///    
        ///  
        [
        SRCategory(SR.CatBehavior), 
        DefaultValue(true), 
        SRDescription(SR.ScrollBarEnableDescr)
        ] 
        public bool Enabled {
            get {
                return enabled;
            } 
            set {
                if (parent.AutoScroll) { 
                    return; 
                }
                if (value != enabled) { 
                    enabled = value;
                    EnableScroll(value);
                }
            } 
        }
 
 
        /// 
        ///  
        ///    
        ///       Gets or sets a value to be added or subtracted to the 
        ///       property when the scroll box is moved a large distance.
        ///     
        /// 
        [ 
        SRCategory(SR.CatBehavior), 
        DefaultValue(10),
        SRDescription(SR.ScrollBarLargeChangeDescr), 
        RefreshProperties(RefreshProperties.Repaint)
        ]
        public int LargeChange {
            get { 
                // We preserve the actual large change value that has been set, but when we come to
                // get the value of this property, make sure it's within the maximum allowable value. 
                // This way we ensure that we don't depend on the order of property sets when 
                // code is generated at design-time.
                // 
                return Math.Min(largeChange, maximum - minimum + 1);
            }
            set {
                if (largeChange != value ) { 
                    if (value < 0) {
                        throw new ArgumentOutOfRangeException("LargeChange", SR.GetString(SR.InvalidLowBoundArgumentEx, "LargeChange", (value).ToString(CultureInfo.CurrentCulture), (0).ToString(CultureInfo.CurrentCulture))); 
                    } 
                    largeChange = value;
                    largeChangeSetExternally = true; 
                    UpdateScrollInfo();
                }
            }
        } 

        ///  
        ///  
        ///    
        ///       Gets or sets the upper limit of values of the scrollable range. 
        ///    
        /// 
        [
        SRCategory(SR.CatBehavior), 
        DefaultValue(100),
        SRDescription(SR.ScrollBarMaximumDescr), 
        RefreshProperties(RefreshProperties.Repaint) 
        ]
        public int Maximum { 
            get {
                return maximum;
            }
            set { 
                if (parent.AutoScroll) {
                    return; 
                } 
                if (maximum != value) {
                    if (minimum > value) 
                        minimum = value;
                    // bring this.value in line.
                    if (value < this.value)
                        Value = value; 
                    maximum = value;
                    maximumSetExternally = true; 
                    UpdateScrollInfo(); 
                }
            } 
        }

        /// 
        ///  
        ///    
        ///       Gets or sets the lower limit of values of the scrollable range. 
        ///     
        /// 
        [ 
        SRCategory(SR.CatBehavior),
        DefaultValue(0),
        SRDescription(SR.ScrollBarMinimumDescr),
        RefreshProperties(RefreshProperties.Repaint) 
        ]
        public int Minimum { 
            get { 
                return minimum;
            } 

            set {
                if (parent.AutoScroll) {
                    return; 
                }
                if (minimum != value) { 
                    if (value < 0) { 
                        throw new ArgumentOutOfRangeException("Minimum", SR.GetString(SR.InvalidLowBoundArgumentEx, "Minimum", (value).ToString(CultureInfo.CurrentCulture), (0).ToString(CultureInfo.CurrentCulture)));
                    } 
                    if (maximum < value)
                        maximum = value;
                    // bring this.value in line.
                    if (value > this.value) 
                        this.value = value;
                    minimum = value; 
                    UpdateScrollInfo(); 
                }
            } 
        }

        internal abstract int PageSize  {
            get; 
        }
 
        internal abstract int Orientation  { 
            get;
        } 

        internal abstract int HorizontalDisplayPosition  {
            get;
        } 

 
        internal abstract int VerticalDisplayPosition  { 
            get;
        } 

        /// 
        /// 
        ///     
        ///       Gets or sets the value to be added or subtracted to the
        ///     
        ///    property when the scroll box is 
        ///    moved a small distance.
        ///  
        /// 
        [
        SRCategory(SR.CatBehavior),
        DefaultValue(1), 
        SRDescription(SR.ScrollBarSmallChangeDescr)
        ] 
        public int SmallChange { 
            get {
                // We can't have SmallChange > LargeChange, but we shouldn't manipulate 
                // the set values for these properties, so we just return the smaller
                // value here.
                //
                return Math.Min(smallChange, LargeChange); 
            }
            set { 
                if (smallChange != value) { 

                    if (value < 0) { 
                        throw new ArgumentOutOfRangeException("SmallChange", SR.GetString(SR.InvalidLowBoundArgumentEx, "SmallChange", (value).ToString(CultureInfo.CurrentCulture), (0).ToString(CultureInfo.CurrentCulture)));
                    }

                    smallChange = value; 
                    smallChangeSetExternally = true;
                    UpdateScrollInfo(); 
                } 
            }
        } 

        /// 
        /// 
        ///     
        ///       Gets or sets a numeric value that represents the current
        ///       position of the scroll box 
        ///       on 
        ///       the scroll bar control.
        ///     
        /// 
        [
        SRCategory(SR.CatBehavior),
        DefaultValue(0), 
        Bindable(true),
        SRDescription(SR.ScrollBarValueDescr) 
        ] 
        public int Value {
            get { 
                return value;
            }
            set {
                if (this.value != value) { 
                    if (value < minimum || value > maximum) {
                        throw new ArgumentOutOfRangeException("Value", SR.GetString(SR.InvalidBoundArgument, "Value", (value).ToString(CultureInfo.CurrentCulture), "'minimum'", "'maximum'")); 
                    } 
                    this.value = value;
                    UpdateScrollInfo(); 
                    parent.SetDisplayFromScrollProps(HorizontalDisplayPosition, VerticalDisplayPosition);
                }
            }
        } 

 
        ///  
        /// 
        ///     
        ///       Gets or sets a bool value controlling whether the scrollbar is showing.
        ///    
        /// 
        [ 
        SRCategory(SR.CatBehavior),
        DefaultValue(false), 
        SRDescription(SR.ScrollBarVisibleDescr) 
        ]
        public bool Visible { 
            get {
                return visible;
            }
            set { 
                if (parent.AutoScroll) {
                    return; 
                } 
                if (value != visible) {
                    visible = value; 
                    parent.UpdateStylesCore ();
                    UpdateScrollInfo();
                    parent.SetDisplayFromScrollProps(HorizontalDisplayPosition, VerticalDisplayPosition);
                } 
            }
        } 
 
        /// 
        ///  
        ///     Internal helper method
        /// 
        /// 
        internal void UpdateScrollInfo() { 
            if (parent.IsHandleCreated && visible) {
                NativeMethods.SCROLLINFO si = new NativeMethods.SCROLLINFO(); 
                si.cbSize = Marshal.SizeOf(typeof(NativeMethods.SCROLLINFO)); 
                si.fMask = NativeMethods.SIF_ALL;
                si.nMin = minimum; 
                si.nMax = maximum;
                si.nPage = (parent.AutoScroll) ? PageSize : LargeChange;
                si.nPos = value;
                si.nTrackPos = 0; 
                UnsafeNativeMethods.SetScrollInfo(new HandleRef(parent, parent.Handle), Orientation, si, true);
            } 
        } 

        ///  
        /// 
        ///     Internal helper method for enabling or disabling the Vertical Scroll bar.
        /// 
        ///  
        private void EnableScroll(bool enable)
        { 
            if (enable) { 
                UnsafeNativeMethods.EnableScrollBar(new HandleRef(parent, parent.Handle), Orientation, NativeMethods.ESB_ENABLE_BOTH);
            } 
            else {
                UnsafeNativeMethods.EnableScrollBar(new HandleRef(parent, parent.Handle), Orientation, NativeMethods.ESB_DISABLE_BOTH);
            }
 
        }
 
    } 
}
 

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
// Copyright (c) Microsoft Corporation. All rights reserved.

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