diff options
Diffstat (limited to 'src/plugins/platforms/xcb/qxcbbackingstore.cpp')
-rw-r--r-- | src/plugins/platforms/xcb/qxcbbackingstore.cpp | 17 |
1 files changed, 9 insertions, 8 deletions
diff --git a/src/plugins/platforms/xcb/qxcbbackingstore.cpp b/src/plugins/platforms/xcb/qxcbbackingstore.cpp index f9240a45cc..741317d766 100644 --- a/src/plugins/platforms/xcb/qxcbbackingstore.cpp +++ b/src/plugins/platforms/xcb/qxcbbackingstore.cpp @@ -641,17 +641,17 @@ void QXcbBackingStoreImage::flushPixmap(const QRegion ®ion, bool fullRegion) xcb_subimage.bit_order = m_xcb_image->bit_order; const bool needsByteSwap = xcb_subimage.byte_order != m_xcb_image->byte_order; + // Ensure that we don't send more than maxPutImageRequestDataBytes per request. + const auto maxPutImageRequestDataBytes = connection()->maxRequestDataBytes(sizeof(xcb_put_image_request_t)); for (const QRect &rect : region) { - // We must make sure that each request is not larger than max_req_size. - // Each request takes req_size + m_xcb_image->stride * height bytes. - static const uint32_t req_size = sizeof(xcb_put_image_request_t); - const uint32_t max_req_size = xcb_get_maximum_request_length(xcb_connection()); - const int rows_per_put = (max_req_size - req_size) / m_xcb_image->stride; + const quint32 stride = round_up_scanline(rect.width() * m_qimage.depth(), xcb_subimage.scanline_pad) >> 3; + const int rows_per_put = maxPutImageRequestDataBytes / stride; // This assert could trigger if a single row has more pixels than fit in - // a single PutImage request. However, max_req_size is guaranteed to be - // at least 16384 bytes. That should be enough for quite large images. + // a single PutImage request. In the absence of the BIG-REQUESTS extension + // the theoretical maximum lengths of maxPutImageRequestDataBytes can be + // roughly 256kB. Q_ASSERT(rows_per_put > 0); // If we upload the whole image in a single chunk, the result might be @@ -666,9 +666,10 @@ void QXcbBackingStoreImage::flushPixmap(const QRegion ®ion, bool fullRegion) while (height > 0) { const int rows = std::min(height, rows_per_put); const QRect subRect(x, y, width, rows); - const quint32 stride = round_up_scanline(width * m_qimage.depth(), xcb_subimage.scanline_pad) >> 3; const QImage subImage = native_sub_image(&m_flushBuffer, stride, m_qimage, subRect, needsByteSwap); + Q_ASSERT(static_cast<size_t>(subImage.sizeInBytes()) <= maxPutImageRequestDataBytes); + xcb_subimage.width = width; xcb_subimage.height = rows; xcb_subimage.data = const_cast<uint8_t *>(subImage.constBits()); |