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65 lines
2.1 KiB
C#
65 lines
2.1 KiB
C#
7 months ago
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using System;
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using System.Windows.Forms;
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namespace Mesnac.Docking
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{
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// Inspired by Chris Sano's article:
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// http://msdn.microsoft.com/smartclient/default.aspx?pull=/library/en-us/dnwinforms/html/colorpicker.asp
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// In Sano's article, the DragForm needs to meet the following criteria:
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// (1) it was not to show up in the task bar;
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// ShowInTaskBar = false
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// (2) it needed to be the top-most window;
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// TopMost = true (not necessary here)
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// (3) its icon could not show up in the ALT+TAB window if the user pressed ALT+TAB during a drag-and-drop;
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// FormBorderStyle = FormBorderStyle.None;
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// Create with WS_EX_TOOLWINDOW window style.
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// Compares with the solution in the artile by setting FormBorderStyle as FixedToolWindow,
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// and then clip the window caption and border, this way is much simplier.
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// (4) it was not to steal focus from the application when displayed.
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// User Win32 ShowWindow API with SW_SHOWNOACTIVATE
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// In addition, this form should only for display and therefore should act as transparent, otherwise
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// WindowFromPoint will return this form, instead of the control beneath. Need BOTH of the following to
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// achieve this (don't know why, spent hours to try it out :( ):
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// 1. Enabled = false;
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// 2. WM_NCHITTEST returns HTTRANSPARENT
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internal class DragForm : Form
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{
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public DragForm()
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{
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FormBorderStyle = FormBorderStyle.None;
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ShowInTaskbar = false;
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SetStyle(ControlStyles.Selectable, false);
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Enabled = false;
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}
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protected override CreateParams CreateParams
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{
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get
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{
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CreateParams createParams = base.CreateParams;
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createParams.ExStyle |= (int)Win32.WindowExStyles.WS_EX_TOOLWINDOW;
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return createParams;
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}
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}
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protected override void WndProc(ref Message m)
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{
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if (m.Msg == (int)Win32.Msgs.WM_NCHITTEST)
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{
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m.Result = (IntPtr)Win32.HitTest.HTTRANSPARENT;
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return;
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}
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base.WndProc (ref m);
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}
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public virtual void Show(bool bActivate)
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{
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if (bActivate)
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Show();
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else
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NativeMethods.ShowWindow(Handle, (int)Win32.ShowWindowStyles.SW_SHOWNOACTIVATE);
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}
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}
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}
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