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Fix drawing lags and allow drawing dots to canvas #107

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Fix drawing lags and allow drawing dots to canvas #107

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2663f9e
Fix lags when drawing graphical notes
shubertm Sep 28, 2025
2811af7
Allow drawing dots
shubertm Sep 28, 2025
36c661d
SVG dot
shubertm Sep 28, 2025
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23 changes: 16 additions & 7 deletions app/src/main/java/dev/arkbuilders/arkmemo/ui/views/NotesCanvas.kt
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Original file line number Diff line number Diff line change
Expand Up @@ -42,7 +42,6 @@ class NotesCanvas(context: Context, attrs: AttributeSet) : View(context, attrs)
return false
}

var finishDrawing = false
when (event.action) {
MotionEvent.ACTION_DOWN -> {
path.moveTo(x, y)
Expand All @@ -56,7 +55,10 @@ class NotesCanvas(context: Context, attrs: AttributeSet) : View(context, attrs)
}
currentX = x
currentY = y
val drawPath = DrawPath(path, viewModel.paint)
viewModel.onDrawPath(drawPath)
}

MotionEvent.ACTION_MOVE -> {
val x2 = (currentX + x) / 2
val y2 = (currentY + y) / 2
Expand All @@ -72,17 +74,24 @@ class NotesCanvas(context: Context, attrs: AttributeSet) : View(context, attrs)
currentX = x
currentY = y
}

MotionEvent.ACTION_UP, MotionEvent.ACTION_CANCEL -> {
if (x == currentX && y == currentY) {
path.lineTo(x, y)
viewModel.svg().apply {
addCommand(
SVGCommand.AbsLineTo(x, y).apply {
paintColor = viewModel.paint.color.getStrokeColor()
brushSizeId = viewModel.paint.strokeWidth.getBrushSizeId()
},
)
}
Comment on lines +79 to +88
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@coderabbitai coderabbitai bot Sep 28, 2025

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⚠️ Potential issue | 🟠 Major

Dot detection needs touch-jitter tolerance.

ACTION_UP coordinates often drift by a few pixels even on a stationary tap, so this strict equality rarely fires. When it doesn’t, we skip the lineTo/SVG command and the dot still vanishes after reload—undercutting the PR goal. Please gate this branch with a small tolerance (e.g., a few px or scaledTouchSlop) instead of raw equality.

-                if (x == currentX && y == currentY) {
+                if (
+                    kotlin.math.abs(x - currentX) <= DOT_TOLERANCE_PX &&
+                    kotlin.math.abs(y - currentY) <= DOT_TOLERANCE_PX
+                ) {

Add an appropriate constant (tuned for density/touch slop) near the class definition, for example:

private companion object {
    private const val DOT_TOLERANCE_PX = 4f
}
🤖 Prompt for AI Agents 
In app/src/main/java/dev/arkbuilders/arkmemo/ui/views/NotesCanvas.kt around
lines 79-88, the current dot-detection uses strict x == currentX && y ==
currentY which fails due to touch jitter; add a small tolerance constant near
the class definition (e.g., in a private companion object, either a fixed
DOT_TOLERANCE_PX or obtain ViewConfiguration.get(context).scaledTouchSlop
converted to pixels) and replace the equality check with a distance/tolerance
check (e.g., if (abs(x - currentX) <= DOT_TOLERANCE_PX && abs(y - currentY) <=
DOT_TOLERANCE_PX) or squared-distance comparison) so the touch-up branch fires
for near-identical coordinates and the SVG dot command is preserved.

}
path = Path()
finishDrawing = true
}
}

if (!finishDrawing) {
val drawPath = DrawPath(path, viewModel.paint)
viewModel.onDrawPath(drawPath)
invalidate()
}
invalidate()

return true
}
Expand Down