|
//------------------------------------------------------------------------------
// <copyright file="WindowsFont.cs" company="Microsoft">
// Copyright (c) Microsoft Corporation. All rights reserved.
// </copyright>
//------------------------------------------------------------------------------
#if WGCM_TEST_SUITE // Enable tracking when built for the test suites.
#define TRACK_HDC
#define GDI_FONT_CACHE_TRACK
#endif
#if Microsoft_NAMESPACE
namespace System.Windows.Forms.Internal
#elif DRAWING_NAMESPACE
namespace System.Drawing.Internal
#else
namespace System.Experimental.Gdi
#endif
{
using System;
using System.Collections.Generic;
using System.Internal;
using System.Diagnostics;
using System.Drawing;
using System.Threading;
using Microsoft.Win32;
/// <devdoc>
/// Keeps a cache of some graphics primitives.
/// Created to improve performance of TextRenderer.MeasureText methods that don't receive a WindowsGraphics.
/// This class mantains a cache of MRU WindowsFont objects in the process. (See VSWhidbey#301492).
/// </devdoc>
#if Microsoft_PUBLIC_GRAPHICS_LIBRARY
public
#else
internal
#endif
static class DeviceContexts
{
[ThreadStatic]
private static ClientUtils.WeakRefCollection activeDeviceContexts;
/// <devdoc>
/// WindowsGraphicsCacheManager needs to track DeviceContext
/// objects so it can ask them if a font is in use before they
/// it's deleted.
internal static void AddDeviceContext(DeviceContext dc) {
if (activeDeviceContexts == null) {
activeDeviceContexts = new ClientUtils.WeakRefCollection();
activeDeviceContexts.RefCheckThreshold = 20; // See DevDiv#82664 (the repro app attached to this bug was used to determine this number).
}
if (!activeDeviceContexts.Contains(dc)) {
dc.Disposing += new EventHandler(OnDcDisposing);
activeDeviceContexts.Add(dc);
}
}
private static void OnDcDisposing(object sender, EventArgs e)
{
DeviceContext dc = sender as DeviceContext;
if (dc != null)
{
dc.Disposing -= new EventHandler(OnDcDisposing);
RemoveDeviceContext(dc);
}
}
internal static void RemoveDeviceContext(DeviceContext dc) {
if (activeDeviceContexts == null) {
return;
}
activeDeviceContexts.RemoveByHashCode(dc);
}
#if !DRAWING_NAMESPACE
internal static bool IsFontInUse(WindowsFont wf) {
if (wf == null) {
return false;
}
for (int i = 0; i < activeDeviceContexts.Count; i++) {
DeviceContext dc = activeDeviceContexts[i] as DeviceContext;
if (dc != null && (dc.ActiveFont == wf || dc.IsFontOnContextStack(wf))) {
return true;
}
}
return false;
}
#endif
}
}
|