Fix mouse drag tracking in terminal applications#214
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kdj0c merged 2 commits intokmscon:mainfrom Jan 13, 2026
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Thanks for your contribution. It looks good to me, the only comment I have would be to add a define in uterm_input_internal.h: And use that when no button is pressed. |
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Thank you for the review! I have updated the commits to use Changes:
The code is now more readable and maintainable. |
When an application like Vim activates mouse tracking (SGR mode with any-event tracking), motion events during drag (button held + movement) were not including button state information. This caused visual selection in Vim to only update on button release instead of showing real-time feedback during drag. Changes: - Add BUTTON_NONE constant (255) to represent no button pressed - Add pressed_button field (uint8_t) to uterm_input_pointer struct to track which button is currently pressed (BUTTON_NONE, 0=left, 1=right, 2=middle) - Initialize pressed_button to BUTTON_NONE in uterm_input_dev initialization - Update pressed_button state in pointer_dev_button() on press/release - Include button state in UTERM_MOVED events sent by pointer_dev_send_move() - Now motion events during drag properly indicate which button is pressed This fixes the lag/delay in visual selection for applications using mouse tracking under kmscon, bringing behavior in line with X terminal emulators.
The previous patch tracked button state correctly but used the wrong encoding when forwarding motion events to libtsm. In X10/SGR mouse tracking protocol: - Button press/release events use button numbers: 0 (left), 1 (right), 2 (middle) - Motion with button pressed (drag) uses: button + 32 This commit adds the +32 offset in forward_pointer_event() for UTERM_MOVED events when a button is pressed, so libtsm correctly interprets them as drag events rather than hover motion. Now visual selection in Vim should update in real-time during mouse drag.
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Summary
This PR fixes mouse drag tracking in kmscon, allowing applications like Vim to properly display visual selection in real-time during mouse drag operations.
Problem
When applications activate mouse tracking (e.g., Vim with
set mouse=a ttymouse=sgr), visual selection would only update after releasing the mouse button, not during the drag itself. This worked fine in X terminal emulators but not in kmscon.Root Cause
kmscon was not tracking or transmitting button state during mouse motion events. When the user dragged with a button pressed:
Solution
Commit 1: Track button state
pressed_buttonfield touterm_input_pointerstructureUTERM_MOVEDeventsCommit 2: Encode drags correctly
Testing
Tested with Vim visual selection under kmscon:
Works with all modern mouse tracking modes (SGR, PIXEL, modes 1002/1003).
Related
This requires corresponding fixes in libtsm: kmscon/libtsm#11