/// <summary>
/// Returns a TEXTMETRIC structure for the font selected in the device context
/// represented by this object, in units of pixels.
/// </summary>
public Gdi32.TEXTMETRICW GetTextMetrics()
{
// Set the mapping mode to MM_TEXT so we deal with units of pixels.
Gdi32.MM mapMode = DeviceContext.MapMode;
bool setupDC = mapMode != Gdi32.MM.TEXT;
if (setupDC)
{
// Changing the MapMode will affect viewport and window extent and origin, we save the dc
// state so all those properties can be properly restored once done.
DeviceContext.SaveHdc();
}
try
{
if (setupDC)
{
mapMode = DeviceContext.SetMapMode(Gdi32.MM.TEXT);
}
var tm = new Gdi32.TEXTMETRICW();
Gdi32.GetTextMetricsW(DeviceContext, ref tm);
return(tm);
}
finally
{
if (setupDC)
{
DeviceContext.RestoreHdc();
}
}
}
private void ActivateDropDown()
{
if (_editor != null)
{
try
{
object newValue = _editor.EditValue(TypeDescriptorContext, this, Value);
SetValue(newValue);
}
catch (Exception ex)
{
ActionPanel.ShowError(string.Format(SR.DesignerActionPanel_ErrorActivatingDropDown, ex.Message));
}
}
else
{
ListBox listBox = new ListBox
{
BorderStyle = BorderStyle.None,
IntegralHeight = false,
Font = ActionPanel.Font
};
listBox.SelectedIndexChanged += new EventHandler(OnListBoxSelectedIndexChanged);
listBox.KeyDown += new KeyEventHandler(OnListBoxKeyDown);
TypeConverter.StandardValuesCollection standardValues = GetStandardValues();
if (standardValues != null)
{
foreach (object o in standardValues)
{
string newItem = PropertyDescriptor.Converter.ConvertToString(TypeDescriptorContext, CultureInfo.CurrentCulture, o);
listBox.Items.Add(newItem);
if ((o != null) && o.Equals(Value))
{
listBox.SelectedItem = newItem;
}
}
}
// All measurement code borrowed from WinForms PropertyGridView.cs
int maxWidth = 0;
// The listbox draws with GDI, not GDI+. So, we use a normal DC here.
using (var hdc = new User32.GetDcScope(listBox.Handle))
{
using var hFont = new Gdi32.ObjectScope(listBox.Font.ToHFONT());
using var fontSelection = new Gdi32.SelectObjectScope(hdc, hFont);
var tm = new Gdi32.TEXTMETRICW();
if (listBox.Items.Count > 0)
{
foreach (string s in listBox.Items)
{
var textSize = new Size();
Gdi32.GetTextExtentPoint32W(hdc, s, s.Length, ref textSize);
maxWidth = Math.Max(textSize.Width, maxWidth);
}
}
Gdi32.GetTextMetricsW(hdc, ref tm);
// border + padding + scrollbar
maxWidth += 2 + tm.tmMaxCharWidth + SystemInformation.VerticalScrollBarWidth;
listBox.Height = Math.Max(tm.tmHeight + 2, Math.Min(ListBoxMaximumHeight, listBox.PreferredHeight));
listBox.Width = Math.Max(maxWidth, EditRegionSize.Width);
_ignoreDropDownValue = false;
}
try
{
ShowDropDown(listBox, SystemColors.ControlDark);
}
finally
{
listBox.SelectedIndexChanged -= new EventHandler(OnListBoxSelectedIndexChanged);
listBox.KeyDown -= new KeyEventHandler(OnListBoxKeyDown);
}
if (!_ignoreDropDownValue)
{
if (listBox.SelectedItem != null)
{
SetValue(listBox.SelectedItem);
}
}
}
}
