If you look at the Splitter Source Code , you will see that the selection is highlighted in the DrawSplitHelper private method.
Since splitter methods rely heavily on the private members of a control, redefining members or handling events on a control using this method simply does not provide such transparent highlighting. Also, if you decide to highlight a solid highlight, you cannot have graphics without a filter, because the halftone highlight that the control draws in private methods.
The idea of ββshowing transparent backlighting is based on showing the translucent window itself, which is not activated when showing. You can also use the PatBlt method to draw a reversible rectangle with a brush.
As an option, I started with Splitter.cs and changed it to draw the desired transparent color, as you see in the image below:
code
As an option, I started with Splitter.cs and changed it to draw the desired transparent hue. I used Form to show transparent highlighting. I showed the form without activation, as the topmost and with the appropriate opacity.
You might be able to create a splitter using less code, but I preferred using the Splitter source code instead of writing my own separator. Thanks to Microsoft for sharing source code.
using System; using System.ComponentModel; using System.Drawing; using System.Globalization; using System.Runtime.InteropServices; using System.Security; using System.Security.Permissions; using System.Windows.Forms; using System.Windows.Forms.Design; using System.Drawing.Drawing2D; using System.Reflection; [ComVisible(true)] [DefaultEvent("SplitterMoved")] [DefaultProperty("Dock")] [Designer(typeof(MySplitterDesigner))] public class MySplitter : Control { private Point anchor = Point.Empty; private System.Windows.Forms.BorderStyle borderStyle; private const int defaultWidth = 3; private const int DRAW_END = 3; private const int DRAW_MOVE = 2; private const int DRAW_START = 1; private static readonly object EVENT_MOVED = new object(); private static readonly object EVENT_MOVING = new object(); private int initTargetSize; private int lastDrawSplit = -1; private int maxSize; private int minExtra = 25; private int minSize = 25; private int splitSize = -1; private Control splitTarget; private SplitterMessageFilter splitterMessageFilter; private int splitterThickness = 3; [Category("Behavior")] [Description("Occurs when the splitter is done being moved.")] public event SplitterEventHandler SplitterMoved { add { base.Events.AddHandler(EVENT_MOVED, value); } remove { base.Events.RemoveHandler(EVENT_MOVED, value); } } [Category("Behavior")] [Description("Occurs when the splitter is being moved.")] public event SplitterEventHandler SplitterMoving { add { base.Events.AddHandler(EVENT_MOVING, value); } remove { base.Events.RemoveHandler(EVENT_MOVING, value); } } HighLight highlight; public MySplitter() { base.SetStyle(ControlStyles.Selectable, false); this.TabStop = false; this.minSize = 0x19; this.minExtra = 0x19; this.Dock = DockStyle.Left; highlight = new HighLight(); } private void ApplySplitPosition() { this.SplitPosition = this.splitSize; } private SplitData CalcSplitBounds() { SplitData data = new SplitData(); Control control = this.FindTarget(); data.target = control; if (control != null) { switch (control.Dock) { case DockStyle.Top: case DockStyle.Bottom: this.initTargetSize = control.Bounds.Height; break; case DockStyle.Left: case DockStyle.Right: this.initTargetSize = control.Bounds.Width; break; } Control parentInternal = this.Parent; Control.ControlCollection controls = parentInternal.Controls; int count = controls.Count; int num2 = 0; int num3 = 0; for (int i = 0; i < count; i++) { Control control3 = controls[i]; if (control3 != control) { switch (control3.Dock) { case DockStyle.Top: case DockStyle.Bottom: num3 += control3.Height; break; case DockStyle.Left: case DockStyle.Right: num2 += control3.Width; break; } } } Size clientSize = parentInternal.ClientSize; if (this.Horizontal) { this.maxSize = (clientSize.Width - num2) - this.minExtra; } else { this.maxSize = (clientSize.Height - num3) - this.minExtra; } data.dockWidth = num2; data.dockHeight = num3; } return data; } private Rectangle CalcSplitLine(int splitSize, int minWeight) { Rectangle bounds = base.Bounds; Rectangle rectangle2 = this.splitTarget.Bounds; switch (this.Dock) { case DockStyle.Top: if (bounds.Height < minWeight) { bounds.Height = minWeight; } bounds.Y = rectangle2.Y + splitSize; return bounds; case DockStyle.Bottom: if (bounds.Height < minWeight) { bounds.Height = minWeight; } bounds.Y = ((rectangle2.Y + rectangle2.Height) - splitSize) - bounds.Height; return bounds; case DockStyle.Left: if (bounds.Width < minWeight) { bounds.Width = minWeight; } bounds.X = rectangle2.X + splitSize; return bounds; case DockStyle.Right: if (bounds.Width < minWeight) { bounds.Width = minWeight; } bounds.X = ((rectangle2.X + rectangle2.Width) - splitSize) - bounds.Width; return bounds; } return bounds; } private int CalcSplitSize() { Control control = this.FindTarget(); if (control != null) { Rectangle bounds = control.Bounds; switch (this.Dock) { case DockStyle.Top: case DockStyle.Bottom: return bounds.Height; case DockStyle.Left: case DockStyle.Right: return bounds.Width; } } return -1; } private void DrawSplitBar(int mode) { if ((mode != 1) && (this.lastDrawSplit != -1)) { this.DrawSplitHelper(this.lastDrawSplit); this.lastDrawSplit = -1; } else if ((mode != 1) && (this.lastDrawSplit == -1)) { return; } if (mode != 3) { this.DrawSplitHelper(this.splitSize); this.lastDrawSplit = this.splitSize; } else { if (this.lastDrawSplit != -1) { this.DrawSplitHelper(this.lastDrawSplit); } this.lastDrawSplit = -1; highlight.Hide(); } Console.WriteLine(mode); } private void DrawSplitHelper(int splitSize) { if (this.splitTarget != null) { Rectangle rectangle = this.CalcSplitLine(splitSize, 3); var r = this.Parent.RectangleToScreen(rectangle); if (!highlight.Visible) highlight.ShowInactiveTopmost(); highlight.Location = r.Location; highlight.Size = r.Size; } } private Control FindTarget() { Control parentInternal = this.Parent; if (parentInternal != null) { Control.ControlCollection controls = parentInternal.Controls; int count = controls.Count; DockStyle dock = this.Dock; for (int i = 0; i < count; i++) { Control control2 = controls[i]; if (control2 != this) { switch (dock) { case DockStyle.Top: if (control2.Bottom != base.Top) { break; } return control2; case DockStyle.Bottom: if (control2.Top != base.Bottom) { break; } return control2; case DockStyle.Left: if (control2.Right != base.Left) { break; } return control2; case DockStyle.Right: if (control2.Left != base.Right) { break; } return control2; } } } } return null; } private int GetSplitSize(int x, int y) { int num; if (this.Horizontal) num = x - this.anchor.X; else num = y - this.anchor.Y; int num2 = 0; switch (this.Dock) { case DockStyle.Top: num2 = this.splitTarget.Height + num; break; case DockStyle.Bottom: num2 = this.splitTarget.Height - num; break; case DockStyle.Left: num2 = this.splitTarget.Width + num; break; case DockStyle.Right: num2 = this.splitTarget.Width - num; break; } return Math.Max(Math.Min(num2, this.maxSize), this.minSize); } protected override void OnKeyDown(KeyEventArgs e) { base.OnKeyDown(e); if ((this.splitTarget != null) && (e.KeyCode == Keys.Escape)) this.SplitEnd(false); } protected override void OnMouseDown(MouseEventArgs e) { base.OnMouseDown(e); if ((e.Button == MouseButtons.Left) && (e.Clicks == 1)) this.SplitBegin(eX, eY); } protected override void OnMouseMove(MouseEventArgs e) { base.OnMouseMove(e); if (this.splitTarget != null) { int x = eX + base.Left; int y = eY + base.Top; Rectangle rectangle = this.CalcSplitLine(this.GetSplitSize(eX, eY), 0); int splitX = rectangle.X; int splitY = rectangle.Y; this.OnSplitterMoving(new SplitterEventArgs(x, y, splitX, splitY)); } } protected override void OnMouseUp(MouseEventArgs e) { base.OnMouseUp(e); if (this.splitTarget != null) { Rectangle rectangle = this.CalcSplitLine(this.GetSplitSize(eX, eY), 0); this.SplitEnd(true); } } protected virtual void OnSplitterMoved(SplitterEventArgs sevent) { SplitterEventHandler handler = (SplitterEventHandler)base.Events[EVENT_MOVED]; if (handler != null) handler(this, sevent); if (this.splitTarget != null) this.SplitMove(sevent.SplitX, sevent.SplitY); } protected virtual void OnSplitterMoving(SplitterEventArgs sevent) { SplitterEventHandler handler = (SplitterEventHandler)base.Events[EVENT_MOVING]; if (handler != null) handler(this, sevent); if (this.splitTarget != null) this.SplitMove(sevent.SplitX, sevent.SplitY); } protected override void SetBoundsCore(int x, int y, int width, int height, BoundsSpecified specified) { if (this.Horizontal) { if (width < 1) width = 3; this.splitterThickness = width; } else { if (height < 1) height = 3; this.splitterThickness = height; } base.SetBoundsCore(x, y, width, height, specified); } private void SplitBegin(int x, int y) { SplitData data = this.CalcSplitBounds(); if ((data.target != null) && (this.minSize < this.maxSize)) { this.anchor = new Point(x, y); this.splitTarget = data.target; this.splitSize = this.GetSplitSize(x, y); try { if (this.splitterMessageFilter != null) this.splitterMessageFilter = new SplitterMessageFilter(this); Application.AddMessageFilter(this.splitterMessageFilter); } finally { } this.Capture = true; this.DrawSplitBar(1); } } private void SplitEnd(bool accept) { this.DrawSplitBar(3); this.splitTarget = null; this.Capture = false; if (this.splitterMessageFilter != null) { Application.RemoveMessageFilter(this.splitterMessageFilter); this.splitterMessageFilter = null; } if (accept) this.ApplySplitPosition(); else if (this.splitSize != this.initTargetSize) this.SplitPosition = this.initTargetSize; this.anchor = Point.Empty; } private void SplitMove(int x, int y) { int splitSize = this.GetSplitSize((x - base.Left) + this.anchor.X, (y - base.Top) + this.anchor.Y); if (this.splitSize != splitSize) { this.splitSize = splitSize; this.DrawSplitBar(2); } } public override string ToString() { string str = base.ToString(); string[] textArray1 = new string[] { str, ", MinExtra: ", this.MinExtra.ToString(CultureInfo.CurrentCulture), ", MinSize: ", this.MinSize.ToString(CultureInfo.CurrentCulture) }; return string.Concat(textArray1); } [DefaultValue(0)] [Category("Appearance")] [Description("The border type of the control.")] public System.Windows.Forms.BorderStyle BorderStyle { get { return this.borderStyle; } set { if (!IsEnumValid(value, (int)value, 0, 2)) throw new InvalidEnumArgumentException("value", (int)value, typeof(System.Windows.Forms.BorderStyle)); if (this.borderStyle != value) { this.borderStyle = value; base.UpdateStyles(); } } } protected override System.Windows.Forms.CreateParams CreateParams { get { System.Windows.Forms.CreateParams createParams = base.CreateParams; createParams.ExStyle &= -513; createParams.Style &= -8388609; System.Windows.Forms.BorderStyle borderStyle = this.borderStyle; if (borderStyle != System.Windows.Forms.BorderStyle.FixedSingle) { if (borderStyle == System.Windows.Forms.BorderStyle.Fixed3D) { createParams.ExStyle |= 0x200; } return createParams; } createParams.Style |= 0x800000; return createParams; } } protected override Cursor DefaultCursor { get { switch (this.Dock) { case DockStyle.Top: case DockStyle.Bottom: return Cursors.HSplit; case DockStyle.Left: case DockStyle.Right: return Cursors.VSplit; } return base.DefaultCursor; } } protected override System.Windows.Forms.ImeMode DefaultImeMode { get { return System.Windows.Forms.ImeMode.Disable; } } protected override Size DefaultSize { get { return new Size(3, 3); } } [Localizable(true), DefaultValue(3)] public override DockStyle Dock { get { return base.Dock; } set { if (((value != DockStyle.Top) && (value != DockStyle.Bottom)) && ((value != DockStyle.Left) && (value != DockStyle.Right))) throw new ArgumentException("Splitter control must be docked left, right, top, or bottom."); int splitterThickness = this.splitterThickness; base.Dock = value; switch (this.Dock) { case DockStyle.Top: case DockStyle.Bottom: if (this.splitterThickness == -1) break; base.Height = splitterThickness; return; case DockStyle.Left: case DockStyle.Right: if (this.splitterThickness != -1) base.Width = splitterThickness; break; default: return; } } } private bool Horizontal { get { DockStyle dock = this.Dock; if (dock != DockStyle.Left) return (dock == DockStyle.Right); return true; } } [Category("Behavior")] [Localizable(true)] [DefaultValue(25)] [Description("Specifies the minimum size of the undocked area.")] public int MinExtra { get { return this.minExtra; } set { if (value < 0) value = 0; this.minExtra = value; } } [Category("Behavior")] [Localizable(true)] [DefaultValue(25)] [Description("Specifies the minimum size of the control being resized.")] public int MinSize { get { return this.minSize; } set { if (value < 0) value = 0; this.minSize = value; } } [Category("Layout")] [Browsable(false)] [DesignerSerializationVisibility(DesignerSerializationVisibility.Hidden)] [Description("The current position of the splitter, or -1 if it is not bound to a control.")] public int SplitPosition { get { if (this.splitSize == -1) { this.splitSize = this.CalcSplitSize(); } return this.splitSize; } set { SplitData data = this.CalcSplitBounds(); if (value > this.maxSize) { value = this.maxSize; } if (value < this.minSize) { value = this.minSize; } this.splitSize = value; this.DrawSplitBar(3); if (data.target == null) { this.splitSize = -1; } else { Rectangle bounds = data.target.Bounds; switch (this.Dock) { case DockStyle.Top: bounds.Height = value; break; case DockStyle.Bottom: bounds.Y += bounds.Height - this.splitSize; bounds.Height = value; break; case DockStyle.Left: bounds.Width = value; break; case DockStyle.Right: bounds.X += bounds.Width - this.splitSize; bounds.Width = value; break; } data.target.Bounds = bounds; Application.DoEvents(); this.OnSplitterMoved(new SplitterEventArgs(base.Left, base.Top, base.Left + (bounds.Width / 2), base.Top + (bounds.Height / 2))); } } } private class SplitData { public int dockHeight = -1; public int dockWidth = -1; internal Control target; } private class SplitterMessageFilter : IMessageFilter { private MySplitter owner; public SplitterMessageFilter(MySplitter splitter) { this.owner = splitter; } public bool PreFilterMessage(ref Message m) { if ((m.Msg < 0x100) || (m.Msg > 0x108)) { return false; } if ((m.Msg == 0x100) && (((int)((long)m.WParam)) == 0x1b)) { this.owner.SplitEnd(false); } return true; } } private static bool IsEnumValid(Enum enumValue, int value, int minValue, int maxValue) { return ((value >= minValue) && (value <= maxValue)); } } public class MySplitterDesigner : ControlDesigner { public MySplitterDesigner() { base.AutoResizeHandles = true; } private void DrawBorder(Graphics graphics) { Color white; Control control = this.Control; Rectangle clientRectangle = control.ClientRectangle; if (control.BackColor.GetBrightness() < 0.5) white = Color.White; else white = Color.Black; using (Pen pen = new Pen(white)) { pen.DashStyle = DashStyle.Dash; clientRectangle.Width--; clientRectangle.Height--; graphics.DrawRectangle(pen, clientRectangle); } } protected override void OnPaintAdornments(PaintEventArgs pe) { base.OnPaintAdornments(pe); if (((MySplitter)base.Component).BorderStyle == BorderStyle.None) this.DrawBorder(pe.Graphics); } protected override void WndProc(ref Message m) { if (m.Msg == 0x47) this.Control.Invalidate(); base.WndProc(ref m); } }
Here is the selection form :
public class HighLight : Form { public HighLight() { FormBorderStyle = FormBorderStyle.None; BackColor = Color.Black; Opacity = 0; ShowInTaskbar = false; StartPosition = FormStartPosition.Manual; } protected override void OnDeactivate(EventArgs e) { base.OnDeactivate(e); this.Hide(); } private const int SW_SHOWNOACTIVATE = 4; private const int HWND_TOPMOST = -1; private const uint SWP_NOACTIVATE = 0x0010; [DllImport("user32.dll", EntryPoint = "SetWindowPos")] static extern bool SetWindowPos(int hWnd, int hWndInsertAfter, int X, int Y, int cx, int cy, uint uFlags); [DllImport("user32.dll")] static extern bool ShowWindow(IntPtr hWnd, int nCmdShow); public void ShowInactiveTopmost() { ShowWindow(this.Handle, SW_SHOWNOACTIVATE); SetWindowPos(this.Handle.ToInt32(), HWND_TOPMOST, this.Left, this.Top, this.Width, this.Height, SWP_NOACTIVATE); this.Opacity = 0.3; } }