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Fix incorrect conversion to straight alpha pixel formats

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Previously, QWaylandSharedMemoryFormatHelper::fromWaylandShmFormat(WL_SHM_FORMAT_ARGB8888) would
return Format_ARGB32, i.e. the non-premultiplied version, while, according to the wayland-devel
mailing list (https://lists.freedesktop.org/archives/wayland-devel/2017-August/034791.html), all
Wayland RGB-based pixel formats with alpha should have premultiplied alpha.

This patch makes sure we return the premultiplied variants for ARGB8888, as well as for ABGR8888.

Using a switch instead of the array also allows us more freedom to choose the preferred format in
other cases where multiple QImage formats map to the same wl_shm format.

While being wrapped and exported as QtWaylandClient::QWaylandShm::fromFormat (private API), this
conversion function doesn't seem to be used anywhere, so this patch shouldn't cause any changes in
behavior for projects that only use public API.

Change-Id: Ie09f9a339b4540dd0383a72b3c951eb8c93e3ab4
Reviewed-by: Pier Luigi Fiorini <pierluigi.fiorini@liri.io>
This commit is contained in:
Johan Klokkhammer Helsing 2019-08-16 12:54:56 +02:00
parent 0b803993e7
commit 7163c286e4
1 changed files with 20 additions and 11 deletions
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31
src/plugins/platforms/wayland/shared/qwaylandsharedmemoryformathelper_p.h
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@ -51,7 +51,26 @@ class QWaylandSharedMemoryFormatHelper
{
public:
static inline wl_shm_format fromQImageFormat(QImage::Format format);
static inline QImage::Format fromWaylandShmFormat(wl_shm_format format);
static inline QImage::Format fromWaylandShmFormat(wl_shm_format format)
{
switch (format) {
case WL_SHM_FORMAT_XRGB8888: return QImage::Format_RGB32;
case WL_SHM_FORMAT_ARGB8888: return QImage::Format_ARGB32_Premultiplied;
case WL_SHM_FORMAT_RGB565: return QImage::Format_RGB16;
case WL_SHM_FORMAT_XRGB1555: return QImage::Format_RGB555;
case WL_SHM_FORMAT_RGB888: return QImage::Format_RGB888;
case WL_SHM_FORMAT_XRGB4444: return QImage::Format_RGB444;
case WL_SHM_FORMAT_ARGB4444: return QImage::Format_ARGB4444_Premultiplied;
case WL_SHM_FORMAT_XBGR8888: return QImage::Format_RGBX8888;
case WL_SHM_FORMAT_ABGR8888: return QImage::Format_RGBA8888_Premultiplied;
case WL_SHM_FORMAT_XBGR2101010: return QImage::Format_BGR30;
case WL_SHM_FORMAT_ABGR2101010: return QImage::Format_A2BGR30_Premultiplied;
case WL_SHM_FORMAT_XRGB2101010: return QImage::Format_RGB30;
case WL_SHM_FORMAT_ARGB2101010: return QImage::Format_A2RGB30_Premultiplied;
case WL_SHM_FORMAT_C8: return QImage::Format_Alpha8;
default: return QImage::Format_Invalid;
}
}
static inline QVector<wl_shm_format> supportedWaylandFormats();
private:
@ -108,16 +127,6 @@ wl_shm_format QWaylandSharedMemoryFormatHelper::fromQImageFormat(QImage::Format
return array.data[format];
}
QImage::Format QWaylandSharedMemoryFormatHelper::fromWaylandShmFormat(wl_shm_format format)
{
Array array = getData();
for (size_t i = 0; i < array.size; i++) {
if (array.data[i] == format)
return QImage::Format(i);
}
return QImage::Format_Invalid;
}
QVector<wl_shm_format> QWaylandSharedMemoryFormatHelper::supportedWaylandFormats()
{
QVector<wl_shm_format> retFormats;