Renamed the GreenshotPlugin to Greenshot.Base

src/Greenshot.Base/Controls/ThumbnailForm.cs

@@ -0,0 +1,156 @@
+/*
+ * Greenshot - a free and open source screenshot tool
+ * Copyright (C) 2007-2021 Thomas Braun, Jens Klingen, Robin Krom
+ * 
+ * For more information see: http://getgreenshot.org/
+ * The Greenshot project is hosted on GitHub https://github.com/greenshot/greenshot
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 1 of the License, or
+ * (at your option) any later version.
+ * 
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+using System;
+using System.Drawing;
+using System.Windows.Forms;
+using Greenshot.Base.Core;
+using Greenshot.Base.IniFile;
+using Greenshot.Base.UnmanagedHelpers;
+using Greenshot.Base.UnmanagedHelpers.Enums;
+using Greenshot.Base.UnmanagedHelpers.Structs;
+
+namespace Greenshot.Base.Controls
+{
+    /// <summary>
+    /// This form allows us to show a Thumbnail preview of a window near the context menu when selecting a window to capture.
+    /// Didn't make it completely "generic" yet, but at least most logic is in here so we don't have it in the mainform.
+    /// </summary>
+    public sealed class ThumbnailForm : FormWithoutActivation
+    {
+        private static readonly CoreConfiguration conf = IniConfig.GetIniSection<CoreConfiguration>();
+
+        private IntPtr _thumbnailHandle = IntPtr.Zero;
+
+        public ThumbnailForm()
+        {
+            ShowInTaskbar = false;
+            FormBorderStyle = FormBorderStyle.None;
+            TopMost = false;
+            Enabled = false;
+            if (conf.WindowCaptureMode == WindowCaptureMode.Auto || conf.WindowCaptureMode == WindowCaptureMode.Aero)
+            {
+                BackColor = Color.FromArgb(255, conf.DWMBackgroundColor.R, conf.DWMBackgroundColor.G, conf.DWMBackgroundColor.B);
+            }
+            else
+            {
+                BackColor = Color.White;
+            }
+
+            // cleanup at close
+            FormClosing += delegate { UnregisterThumbnail(); };
+        }
+
+        public new void Hide()
+        {
+            UnregisterThumbnail();
+            base.Hide();
+        }
+
+        private void UnregisterThumbnail()
+        {
+            if (_thumbnailHandle == IntPtr.Zero) return;
+
+            DWM.DwmUnregisterThumbnail(_thumbnailHandle);
+            _thumbnailHandle = IntPtr.Zero;
+        }
+
+        /// <summary>
+        /// Show the thumbnail of the supplied window above (or under) the parent Control
+        /// </summary>
+        /// <param name="window">WindowDetails</param>
+        /// <param name="parentControl">Control</param>
+        public void ShowThumbnail(WindowDetails window, Control parentControl)
+        {
+            UnregisterThumbnail();
+
+            DWM.DwmRegisterThumbnail(Handle, window.Handle, out _thumbnailHandle);
+            if (_thumbnailHandle == IntPtr.Zero) return;
+
+            var result = DWM.DwmQueryThumbnailSourceSize(_thumbnailHandle, out var sourceSize);
+            if (result.Failed())
+            {
+                DWM.DwmUnregisterThumbnail(_thumbnailHandle);
+                return;
+            }
+
+            if (sourceSize.IsEmpty)
+            {
+                DWM.DwmUnregisterThumbnail(_thumbnailHandle);
+                return;
+            }
+
+            int thumbnailHeight = 200;
+            int thumbnailWidth = (int) (thumbnailHeight * (sourceSize.Width / (float) sourceSize.Height));
+            if (parentControl != null && thumbnailWidth > parentControl.Width)
+            {
+                thumbnailWidth = parentControl.Width;
+                thumbnailHeight = (int) (thumbnailWidth * (sourceSize.Height / (float) sourceSize.Width));
+            }
+
+            Width = thumbnailWidth;
+            Height = thumbnailHeight;
+            // Prepare the displaying of the Thumbnail
+            var dwmThumbnailProperties = new DWM_THUMBNAIL_PROPERTIES
+            {
+                Opacity = 255,
+                Visible = true,
+                SourceClientAreaOnly = false,
+                Destination = new RECT(0, 0, thumbnailWidth, thumbnailHeight)
+            };
+            result = DWM.DwmUpdateThumbnailProperties(_thumbnailHandle, ref dwmThumbnailProperties);
+            if (result.Failed())
+            {
+                DWM.DwmUnregisterThumbnail(_thumbnailHandle);
+                return;
+            }
+
+            if (parentControl != null)
+            {
+                AlignToControl(parentControl);
+            }
+
+            if (!Visible)
+            {
+                Show();
+            }
+
+            // Make sure it's on "top"!
+            if (parentControl != null)
+            {
+                User32.SetWindowPos(Handle, parentControl.Handle, 0, 0, 0, 0, WindowPos.SWP_NOMOVE | WindowPos.SWP_NOSIZE | WindowPos.SWP_NOACTIVATE);
+            }
+        }
+
+        public void AlignToControl(Control alignTo)
+        {
+            var screenBounds = WindowCapture.GetScreenBounds();
+            if (screenBounds.Contains(alignTo.Left, alignTo.Top - Height))
+            {
+                Location = new Point(alignTo.Left + (alignTo.Width / 2) - (Width / 2), alignTo.Top - Height);
+            }
+            else
+            {
+                Location = new Point(alignTo.Left + (alignTo.Width / 2) - (Width / 2), alignTo.Bottom);
+            }
+        }
+    }
+}