Flameshot Version
Flameshot v14.0.0 (da6121b), compiled with Qt 6.2.4. The affected scaling path is also present on current master (369f9ed9).
Installation Type
Linux package manager (14.0.0-1) and a build from source for diagnosis/testing.
Operating System type and version
Ubuntu 22.04.5 LTS, GNOME 42.9, Wayland.
Description
On a GNOME Wayland mixed-DPI desktop, selecting the HiDPI monitor from the portal-based capture flow produces a blurred preview whose selection coordinates cover only the top-left quarter of the display.
The relevant geometry is:
HDMI-2: 2560x1440, DPR 1, position +2298+0eDP-1: 3840x2400, DPR 2, position +0+1440- GNOME portal screenshot: 4858x3840, DPR 1
Here, Qt 6.2 reports the HiDPI screen geometry in native coordinates (3840x2400), and the portal composite uses the same native-coordinate canvas. ScreenGrabber::cropToMonitor() therefore correctly crops 3840x2400 pixels, but then treats the portal scale of 1 as a mismatch with the screen DPR of 2 and upscales that crop to 7680x4800. Assigning DPR 2 after that makes the capture surface use the raw 3840x2400 geometry instead of its 1920x1200 device-independent size. This applies HiDPI scaling twice: the preview is blurred and pointer/selection coordinates cover only one quarter of it.
This is the same visible symptom described in #265 and is related to the mixed-DPI reports #227, #2849, and #3444. These reports are closed, several following #4498, but the GNOME Wayland native-coordinate case remains reproducible.
Steps to reproduce
- Use GNOME Wayland with one DPR 1 monitor and one DPR 2 monitor.
- Run
QT_QPA_PLATFORM=wayland flameshot gui.
- In GNOME's portal dialog, share the desktop screenshot.
- In Flameshot's "click to select a screen" preview, select the DPR 2 monitor.
- Try to make a region selection across that monitor.
Actual result: the preview is lower resolution/blurred, and selection works only in the top-left quarter.
Expected result: the HiDPI monitor is shown at its native sharpness and the full monitor is selectable.
Proposed fix
When GNOME Wayland returns a portal screenshot whose X and Y scale are both 1, keep the cropped pixels at their native resolution instead of scaling them to geometry * DPR. Then, when a Wayland screen's raw geometry size equals the screenshot's pixel size and DPR is greater than 1, size the capture surface and selection area using geometry / DPR.
I have tested this behavior on the hardware/configuration above; it restores a sharp preview and full-screen selection. A linked pull request contains the guarded implementation.
Screenshots or screen recordings
The geometry and scaling calculations above were captured with Flameshot's debug capture logging. I can provide additional logs if needed.
System Information
- Ubuntu 22.04.5 LTS
- GNOME Shell 42.9
- Wayland session
- Qt 6.2.4
- Mixed-DPI layout: external 2560x1440 at DPR 1 plus internal 3840x2400 at DPR 2
Flameshot Version
Flameshot v14.0.0 (da6121b), compiled with Qt 6.2.4. The affected scaling path is also present on current
master(369f9ed9).Installation Type
Linux package manager (
14.0.0-1) and a build from source for diagnosis/testing.Operating System type and version
Ubuntu 22.04.5 LTS, GNOME 42.9, Wayland.
Description
On a GNOME Wayland mixed-DPI desktop, selecting the HiDPI monitor from the portal-based capture flow produces a blurred preview whose selection coordinates cover only the top-left quarter of the display.
The relevant geometry is:
HDMI-2: 2560x1440, DPR 1, position +2298+0eDP-1: 3840x2400, DPR 2, position +0+1440Here, Qt 6.2 reports the HiDPI screen geometry in native coordinates (3840x2400), and the portal composite uses the same native-coordinate canvas.
ScreenGrabber::cropToMonitor()therefore correctly crops 3840x2400 pixels, but then treats the portal scale of 1 as a mismatch with the screen DPR of 2 and upscales that crop to 7680x4800. Assigning DPR 2 after that makes the capture surface use the raw 3840x2400 geometry instead of its 1920x1200 device-independent size. This applies HiDPI scaling twice: the preview is blurred and pointer/selection coordinates cover only one quarter of it.This is the same visible symptom described in #265 and is related to the mixed-DPI reports #227, #2849, and #3444. These reports are closed, several following #4498, but the GNOME Wayland native-coordinate case remains reproducible.
Steps to reproduce
QT_QPA_PLATFORM=wayland flameshot gui.Actual result: the preview is lower resolution/blurred, and selection works only in the top-left quarter.
Expected result: the HiDPI monitor is shown at its native sharpness and the full monitor is selectable.
Proposed fix
When GNOME Wayland returns a portal screenshot whose X and Y scale are both 1, keep the cropped pixels at their native resolution instead of scaling them to
geometry * DPR. Then, when a Wayland screen's raw geometry size equals the screenshot's pixel size and DPR is greater than 1, size the capture surface and selection area usinggeometry / DPR.I have tested this behavior on the hardware/configuration above; it restores a sharp preview and full-screen selection. A linked pull request contains the guarded implementation.
Screenshots or screen recordings
The geometry and scaling calculations above were captured with Flameshot's debug capture logging. I can provide additional logs if needed.
System Information