Windows11 display scalin

[sorudals]

First of all, thank you for providing such a great library.

While using it, I encountered an issue and I am leaving this message to see if there is a solution.

When changing the Windows display scale, the height of the example qtquick code changes.

For example:
If you switch the scale like this: 100% > 225% > 100% > 225% > 100%,
you can visibly see the height of the window decrease each time.

Question:
Is there any way to fix this problem?

[wangwenx190]

Qt bug introduced in Qt 6.2, fixed in 6.4 or 6.5. Please upgrade your Qt version to a newer version.

[sorudals]

Thank you for your fast response!!

My qt version is 6.7.2

I tested with 6.6.3 and 6.7.2, and both results were the same

Should I downgrade to 6.5??

[SineStriker]

Thank you for your fast response!!

My qt version is 6.7.2

I tested with 6.6.3 and 6.7.2, and both results were the same

Should I downgrade to 6.5??

Does the problem still exist in Qt 6.6 or 6.7?

[sorudals]

Yes, it was.
Versions were 6.6.3 and 6.7.2

I didn't test with qwidget yet.

I'll test it tomorrow

[sorudals]

Sorry for late test.
I tested qwidget example with Qt 6.6.3 and checked decreasing of window height!

[wangwenx190]

Anyway, it's a Qt bug and it's I who pushed a fix for upstream Qt, so it should be fixed already. But now it seems it got broken again later for some reason.

[sorudals]

Is it related with this link??
qt/qtbase@17ab11c#diff-df8d4c1559d15c2e05198d3adb5a1ed9fe096a4584d0b35f7dc614cd20b680a5

[wangwenx190]

Is it related with this link?? qt/qtbase@17ab11c#diff-df8d4c1559d15c2e05198d3adb5a1ed9fe096a4584d0b35f7dc614cd20b680a5

It's commited by me indeed but not related to the current issue at all. Please check this commit which is the fix I mentioned above.

[sonysuqin]

Is it related with this link?? qt/qtbase@17ab11c#diff-df8d4c1559d15c2e05198d3adb5a1ed9fe096a4584d0b35f7dc614cd20b680a5

It's commited by me indeed but not related to the current issue at all. Please check this commit which is the fix I mentioned above.

我最近也碰到一样的问题，Win11+QT6.8.3，检查了对应版本的代码，确认你的代码是已经被合入，但是看到一些可能的逻辑问题：

void QWindowsWindow::handleDpiScaledSize(WPARAM wParam, LPARAM lParam, LRESULT *result)
{
// We want to keep QWindow's device independent size constant across the
// DPI change. To accomplish this, scale QPlatformWindow's native size
// by the change of DPI (e.g. 120 -> 144 = 1.2), also taking any scale
// factor rounding into account. The win32 window size includes the margins;
// add the margins for the new DPI to the window size.
const UINT dpi = UINT(wParam);
const qreal scale = dpiRelativeScale(dpi);
const QMargins margins = fullFrameMargins();
if (!(m_data.flags & Qt::FramelessWindowHint)) {
// We need to update the custom margins to match the current DPI, because
// we don't want our users manually hook into this message just to set a
// new margin, but here we can't call setCustomMargins() directly, that
// function will change the window geometry which conflicts with what we
// are currently doing.
m_data.customMargins *= scale;
}

const QSize windowSize = (geometry().size() * scale).grownBy((margins * scale) + customMargins());
SIZE *size = reinterpret_cast<SIZE *>(lParam);
size->cx = windowSize.width();
size->cy = windowSize.height();
*result = true; // Inform Windows that we've set a size

}

主要是这行的处理是否合理？

m_data.customMargins *= scale;

这行直接*= scale，是否意味着变成了物理像素？其他按照逻辑像素去获取并处理m_data.customMargins的地方是否会相应收到影响，进而出现这个问题？

[wangwenx190]

这里的scale是个相对值，是最新DPI相对于上一次DPI的比例，例如假设用户的缩放系数从125%切换到了150%，那么这个scale应该是1.2，意味着用户设置的自定义margin应该变成原来的1.2倍，这个1.2跟DPI的具体数值没有绑定关系，所以这行代码是没问题的。而且我测试过，在我的代码刚合入的时候，这个issue里提到的问题确实消失了。至于为什么后来又出现了，应该是别的地方有bug。反正我测试在qt6.9这个问题又不见了。

[sonysuqin]

我测了一下qt6.9.0，也有几率出这个问题，而且在双屏切换时问题更多，感觉不是很稳定，如果关闭QWINDOWKIT_ENABLE_WINDOWS_SYSTEM_BORDERS，这个问题是没有了，但是我看注释：
QWINDOWKIT_ENABLE_WINDOWS_SYSTEM_BORDERS

• If you don't want the system borders on Windows 10/11, you can DISABLE this option.
• If so, the Windows 10 top border issue will disappear. However, part of the client edge
  area will be occupied as the resizing margins.
  这个是说如果关闭的话在win10上客户区会缺标题栏那么高的一块儿吗？具体有多大副作用？

[wangwenx190]

我测了一下qt6.9.0，也有几率出这个问题，而且在双屏切换时问题更多，感觉不是很稳定

我用6.9测试没法复现，我也是双屏，两个屏幕DPI一样和不一样都测试过，都没遇到问题。如果你那边还能复现，说明触发问题的根本原因目前还没有找到。

这个是说如果关闭的话在win10上客户区会缺标题栏那么高的一块儿吗？

不是。win10开始窗口的resize区域视觉上是在窗口外部（除了顶部标题栏那块），这个区域在win10之前是不透明的，当系统缩放是100%时，宽度是8像素，视觉上就是那个窗口的边框。win10开始这个区域彻底透明了，原本8像素的窗口边框变成了一根1像素的线。如果你把那个开关关掉，相当于把resize区域转移到窗口内部了，范围还是8像素，围着窗口边缘一圈，这不过这一圈是沿着窗口边界向内扩展的。这一圈范围内的控件都没法接收鼠标事件（只有这8像素内的部分哈，其余部分还是正常的），因为要优先提供resize功能。所以关掉这个开关后你窗口的内容要注意，不要放的太靠边了。要说“副作用”那有点太夸张了，没什么副作用，就是内部排版也注意。

[sonysuqin]

我在QWindowKit的win32windowcontext.cpp文件setInternalWindowFrameMargins方法里不调用platformWindow->setCustomMargins(margins)，和关闭QWINDOWKIT_ENABLE_WINDOWS_SYSTEM_BORDERS有什么区别吗？我发现这两个方式都能够避免这个问题。