Scale TreeViewAdv elements based on DPI

TreeViewAdv assumed a standard 96 DPI display. This commit fixes some
problems on high DPI displays, including some problems mentioned in
OHM issue 830.

- column header height
- checkboxes
- icons
- indentation

External/Aga.Controls/Tree/NodeControls/NodeCheckBox.cs

@@ -46,7 +46,9 @@ namespace Aga.Controls.Tree.NodeControls
 
 		public override Size MeasureSize(TreeNodeAdv node, DrawContext context)
 		{
-			return new Size(ImageSize, ImageSize);
+			int scaledX = node.Tree.GetScaledSize(ImageSize, false);
+			int scaledY = node.Tree.GetScaledSize(ImageSize);
+			return new Size(scaledX, scaledY);
 		}
 
 		public override void Draw(TreeNodeAdv node, DrawContext context)
@@ -56,13 +58,15 @@ namespace Aga.Controls.Tree.NodeControls
 			if (Application.RenderWithVisualStyles)
 			{
 				VisualStyleRenderer renderer;
+				int scaledX = node.Tree.GetScaledSize(ImageSize, false);
+				int scaledY = node.Tree.GetScaledSize(ImageSize);
 				if (state == CheckState.Indeterminate)
 					renderer = new VisualStyleRenderer(VisualStyleElement.Button.CheckBox.MixedNormal);
 				else if (state == CheckState.Checked)
 					renderer = new VisualStyleRenderer(VisualStyleElement.Button.CheckBox.CheckedNormal);
 				else
 					renderer = new VisualStyleRenderer(VisualStyleElement.Button.CheckBox.UncheckedNormal);
-				renderer.DrawBackground(context.Graphics, new Rectangle(bounds.X, bounds.Y, ImageSize, ImageSize));
+				renderer.DrawBackground(context.Graphics, new Rectangle(bounds.X, bounds.Y, scaledX, scaledY));
 			}
 			else
 			{

External/Aga.Controls/Tree/NodeControls/NodeIcon.cs

@@ -19,9 +19,15 @@ namespace Aga.Controls.Tree.NodeControls
 		{
 			Image image = GetIcon(node);
 			if (image != null)
-				return image.Size;
+			{
+				int scaledX = node.Tree.GetScaledSize(image.Size.Width, false);
+				int scaledY = node.Tree.GetScaledSize(image.Size.Height);
+				return new Size(scaledX, scaledY); ;
+			}
 			else
+			{
 				return Size.Empty;
+			}
 		}
 
 

External/Aga.Controls/Tree/NodeControls/NodePlusMinus.cs

@@ -46,7 +46,9 @@ namespace Aga.Controls.Tree.NodeControls
 
 		public override Size MeasureSize(TreeNodeAdv node, DrawContext context)
 		{
-			return new Size(Width, Width);
+			int scaledX = node.Tree.GetScaledSize(Width, false);
+			int scaledY = node.Tree.GetScaledSize(Width);
+			return new Size(scaledX, scaledY);
 		}
 
 		public override void Draw(TreeNodeAdv node, DrawContext context)
@@ -54,7 +56,9 @@ namespace Aga.Controls.Tree.NodeControls
 			if (node.CanExpand)
 			{
 				Rectangle r = context.Bounds;
-				int dy = (int)Math.Round((float)(r.Height - ImageSize) / 2);
+				int scaledX = node.Tree.GetScaledSize(ImageSize, false);
+				int scaledY = node.Tree.GetScaledSize(ImageSize);
+				int dy = (int)Math.Round((float)(r.Height - scaledY) / 2);
 				if (Application.RenderWithVisualStyles)
 				{
 					VisualStyleRenderer renderer;
@@ -62,7 +66,7 @@ namespace Aga.Controls.Tree.NodeControls
 						renderer = OpenedRenderer;
 					else
 						renderer = ClosedRenderer;
-					renderer.DrawBackground(context.Graphics, new Rectangle(r.X, r.Y + dy, ImageSize, ImageSize));
+					renderer.DrawBackground(context.Graphics, new Rectangle(r.X, r.Y + dy, scaledX, scaledY));
 				}
 				else
 				{

External/Aga.Controls/Tree/TreeViewAdv.Draw.cs

@@ -259,8 +259,9 @@ namespace Aga.Controls.Tree
 			while (curNode != _root && curNode != null)
 			{
 				int level = curNode.Level;
-				int x = (level - 1) * _indent + NodePlusMinus.ImageSize / 2 + LeftMargin;
+				int scaledIndent = node.Tree.GetScaledSize(_indent, false);
-				int width = NodePlusMinus.Width - NodePlusMinus.ImageSize / 2;
+				int x = (level - 1) * scaledIndent + NodePlusMinus.ImageSize / 2 + LeftMargin;
+				int width = node.Tree.GetScaledSize(NodePlusMinus.Width - NodePlusMinus.ImageSize / 2, false);
 				int y = rowRect.Y;
 				int y2 = y + rowRect.Height;
 

External/Aga.Controls/Tree/TreeViewAdv.cs

@@ -42,6 +42,11 @@ namespace Aga.Controls.Tree
 		private List<TreeNodeAdv> _expandingNodes = new List<TreeNodeAdv>();
 		private AbortableThreadPool _threadPool = new AbortableThreadPool();
 
+		private float dpiX;
+		private float dpiY;
+		private float dpiXscale = 1;
+		private float dpiYscale = 1;
+
 		#region Public Events
 
 		[Category("Action")]
@@ -204,6 +209,7 @@ namespace Aga.Controls.Tree
 		public TreeViewAdv()
 		{
 			InitializeComponent();
+			SetDPI();
 			SetStyle(ControlStyles.AllPaintingInWmPaint
 				| ControlStyles.UserPaint
 				| ControlStyles.OptimizedDoubleBuffer
@@ -216,6 +222,7 @@ namespace Aga.Controls.Tree
 				_columnHeaderHeight = 20;
 			else
 				_columnHeaderHeight = 17;
+			_columnHeaderHeight = GetScaledSize(_columnHeaderHeight);
 
 			//BorderStyle = BorderStyle.Fixed3D;
 			_hScrollBar.Height = SystemInformation.HorizontalScrollBarHeight;
@@ -245,6 +252,46 @@ namespace Aga.Controls.Tree
 			ExpandingIcon.IconChanged += ExpandingIconChanged;
 		}
 
+		public void SetDPI()
+		{
+			// https://msdn.microsoft.com/en-us/library/windows/desktop/dn469266(v=vs.85).aspx
+			const int _default_dpi = 96;
+			Graphics g = this.CreateGraphics();
+
+			try
+			{
+				this.dpiX = g.DpiX;
+				this.dpiY = g.DpiY;
+			}
+			finally
+			{
+				g.Dispose();
+			}
+			if (dpiX > 0)
+			{
+				this.dpiXscale = dpiX / _default_dpi;
+			}
+			if (dpiY > 0)
+			{
+				this.dpiYscale = dpiY / _default_dpi;
+			}
+		}
+
+		public int GetScaledSize(int size, bool useY = true)
+		{
+			int scaledsize = size;
+
+			if (useY && this.dpiYscale > 1)
+			{
+				scaledsize = (int)(this.dpiYscale * size);
+			}
+			else if (this.dpiXscale > 1)
+			{
+				scaledsize = (int)(this.dpiXscale * size);
+			}
+			return scaledsize;
+		}
+
 		void ExpandingIconChanged(object sender, EventArgs e)
 		{
 			if (IsHandleCreated && !IsDisposed)
@@ -543,11 +590,12 @@ namespace Aga.Controls.Tree
 			if (node == null)
 				yield break;
 
+			int scaledIndent = node.Tree.GetScaledSize(_indent, false);
 			int y = rowRect.Y;
-			int x = (node.Level - 1) * _indent + LeftMargin;
+			int x = (node.Level - 1) * scaledIndent + LeftMargin;
 			int width = 0;
 			if (node.Row == 0 && ShiftFirstNode)
-				x -= _indent;
+				x -= scaledIndent;
 			Rectangle rect = Rectangle.Empty;
 
 			if (ShowPlusMinus)