When using the polygon or polyline drawing tool on a mobile touch device, tapping a new position to add the next point moves the previous point instead of creating a new one.
Steps to Reproduce
Open any PDF document on a mobile device (touch input)
Select the polygon or polyline tool
Tap and drag to place the first point (P1), then lift finger
Tap at a new position (P2) to add the next line segment
Expected Behavior
Lifting the finger should finalize P1's position. Tapping at P2 should add a new point, creating a line segment from P1 to P2.
Actual Behavior
Tapping at P2 moves the previous point (P1) to the P2 position instead of adding a new point. The point is never finalized on pointerup.
Root Cause Analysis
The polygon/polyline handler appears to be designed around the mouse interaction model, where hover (pointer movement without pointerdown) provides a preview of the next line segment. On touch devices, there is no hover state — every interaction starts with pointerdown, making it impossible to distinguish between "move existing point" and "add new point" using the same event model.
Suggested Improvement
Consider adding touch-specific handling for multi-point drawing tools, for example:
Treat every new pointerdown (after pointerup) as a new point addition rather than a point move
Use long-press to enter point adjustment mode
Or any other gesture differentiation that works for both mouse and touch inputs
Environment
EmbedPDF version: 2.8.0
Platform: Mobile WebView (iOS WKWebView / Android WebView)
Input: Touch (no mouse/stylus)
When using the polygon or polyline drawing tool on a mobile touch device, tapping a new position to add the next point moves the previous point instead of creating a new one.
Steps to Reproduce
Open any PDF document on a mobile device (touch input)
Select the polygon or polyline tool
Tap and drag to place the first point (P1), then lift finger
Tap at a new position (P2) to add the next line segment
Expected Behavior
Lifting the finger should finalize P1's position. Tapping at P2 should add a new point, creating a line segment from P1 to P2.
Actual Behavior
Tapping at P2 moves the previous point (P1) to the P2 position instead of adding a new point. The point is never finalized on pointerup.
Root Cause Analysis
The polygon/polyline handler appears to be designed around the mouse interaction model, where hover (pointer movement without pointerdown) provides a preview of the next line segment. On touch devices, there is no hover state — every interaction starts with pointerdown, making it impossible to distinguish between "move existing point" and "add new point" using the same event model.
Suggested Improvement
Consider adding touch-specific handling for multi-point drawing tools, for example:
Treat every new pointerdown (after pointerup) as a new point addition rather than a point move
Use long-press to enter point adjustment mode
Or any other gesture differentiation that works for both mouse and touch inputs
Environment
EmbedPDF version: 2.8.0
Platform: Mobile WebView (iOS WKWebView / Android WebView)
Input: Touch (no mouse/stylus)