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Make the TreeView respect the DoubleBuffered property #7403

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merged 6 commits into from Jul 27, 2022
Merged

Make the TreeView respect the DoubleBuffered property #7403

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c36293f
Make the TreeView respect the DoubleBuffered property
0xC0000054 Jul 13, 2022
f4f00b3
Only update the extended styles if the value has changed
0xC0000054 Jul 19, 2022
0de6fb0
Do not change the styles that were set by external code
0xC0000054 Jul 19, 2022
052d21a
Allow the double buffering to be disabled
0xC0000054 Jul 19, 2022
89db47d
Fix the method ordering
0xC0000054 Jul 19, 2022
0956749
Track whether the DoubleBuffered property has been set
0xC0000054 Jul 19, 2022
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38 changes: 37 additions & 1 deletion src/System.Windows.Forms/src/System/Windows/Forms/TreeView.cs
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Expand Up @@ -436,7 +436,14 @@ protected override Size DefaultSize
protected override bool DoubleBuffered
{
get => base.DoubleBuffered;
set => base.DoubleBuffered = value;
set
{
if (DoubleBuffered != value)
{
base.DoubleBuffered = value;
UpdateTreeViewExtendedStyles();
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}
}
}

/// <summary>
Expand Down Expand Up @@ -1959,6 +1966,9 @@ protected override void OnHandleCreated(EventArgs e)

base.OnHandleCreated(e);

// The TreeView extended styles are independent of the window extended styles.
UpdateTreeViewExtendedStyles();

int version = (int)User32.SendMessageW(this, (User32.WM)CCM.GETVERSION);
if (version < 5)
{
Expand Down Expand Up @@ -2065,6 +2075,32 @@ protected override void OnHandleCreated(EventArgs e)
SelectedNode = savedSelectedNode;
}

private void UpdateTreeViewExtendedStyles()
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{
if (!IsHandleCreated)
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{
return;
}

TVS_EX extendedStyles = (TVS_EX)User32.SendMessageW(this, (User32.WM)TVM.GETEXTENDEDSTYLE);

SetExtendedStyle(ref extendedStyles, TVS_EX.DOUBLEBUFFER, DoubleBuffered);
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What are the default extended styles for TreeView here? why do we have to negate when DoubleBuffered is not enabled? It would default back to current behavior. Did you notice any change in behavior here?

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The default extended styles appeared to be 0 (None) when I was debugging.

But now that I think about it the code is incorrect and would not clear the style anyway, the first SendMessage parameter is a mask.

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I removed the GETEXTENDEDSTYLE call and the negation code.
Negating the extended styles would have been a regression for callers that set the values themselves.


User32.SendMessageW(this, (User32.WM)TVM.SETEXTENDEDSTYLE, (int)extendedStyles, (int)extendedStyles);

static void SetExtendedStyle(ref TVS_EX extendedStyles, TVS_EX mask, bool value)
{
if (value)
{
extendedStyles |= mask;
}
else
{
extendedStyles &= ~mask;
}
}
}

// Replace the native control's ImageList with our current stateImageList
// set the value of internalStateImageList to the new list
private void UpdateNativeStateImageList()
Expand Down