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feat(pdf-viewer): implement pan lock to disable horizontal movement (#9)

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- Add `isScrollLocked` state to `PdfViewerScreen` to toggle panning behavior.
- Replace "Import SVG" debug icon with a Lock/Unlock toggle in the Top App Bar.
- Update `PdfVerticalReader` and `PdfPageComposable` to strictly zero out X-axis pan deltas and fling velocities when locked.
- Maintain zoom and vertical scrolling functionality while panning is locked.
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Aryan 2026-02-26 20:05:45 +05:30 • committed by GitHub
parent f2daebe0a5
commit ea31765612
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3 changed files with 34 additions and 35 deletions
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36
app/src/main/java/com/aryan/reader/pdf/PdfViewerScreen.kt
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@ -102,6 +102,8 @@ import androidx.compose.material.icons.filled.FullscreenExit
import androidx.compose.material.icons.filled.Info
import androidx.compose.material.icons.filled.KeyboardArrowDown
import androidx.compose.material.icons.filled.KeyboardArrowUp
import androidx.compose.material.icons.filled.Lock
import androidx.compose.material.icons.filled.LockOpen
import androidx.compose.material.icons.filled.Menu
import androidx.compose.material.icons.filled.MoreVert
import androidx.compose.material.icons.filled.Save
@ -588,6 +590,7 @@ fun PdfViewerScreen(
var showBars by remember { mutableStateOf(true) }
var isFullScreen by remember { mutableStateOf(false) }
var documentPassword by remember { mutableStateOf<String?>(null) }
var isScrollLocked by remember { mutableStateOf(false) }
var showPasswordDialog by remember { mutableStateOf(false) }
var isPasswordError by remember { mutableStateOf(false) }
LocalView.current
@ -3208,6 +3211,7 @@ fun PdfViewerScreen(
virtualPage = virtualPage,
totalPages = totalDisplayPages,
isDarkMode = isPdfDarkMode,
isScrollLocked = isScrollLocked,
onScaleChanged = { newScale ->
if (pagerState.currentPage == pageIndex) {
currentPageScale = newScale
@ -3597,6 +3601,7 @@ fun PdfViewerScreen(
state = verticalReaderState,
pdfDocument = docHolder,
isDarkMode = isPdfDarkMode,
isScrollLocked = isScrollLocked,
totalPages = totalDisplayPages,
pageAspectRatios = ratiosHolder,
virtualPages = virtualPages,
@ -4016,6 +4021,14 @@ fun PdfViewerScreen(
)
}
IconButton(onClick = { isScrollLocked = !isScrollLocked }) {
Icon(
imageVector = if (isScrollLocked) Icons.Default.Lock else Icons.Default.LockOpen,
contentDescription = if (isScrollLocked) "Unlock Panning" else "Lock Panning",
tint = MaterialTheme.colorScheme.onSurfaceVariant
)
}
IconButton(onClick = { isFullScreen = true }) {
Icon(
imageVector = Icons.Default.Fullscreen,
@ -4066,29 +4079,6 @@ fun PdfViewerScreen(
tint = Color(0xFFE91E63)
)
}
IconButton(onClick = {
val page = if (displayMode == DisplayMode.PAGINATION) pagerState.currentPage else verticalReaderState.currentPage
val demoAnnos = DemoAnnotationGenerator.generateDemoAnnotations(page)
val existing = allAnnotations[page] ?: emptyList()
allAnnotations = allAnnotations + (page to (existing + demoAnnos))
demoAnnos.forEach { annot ->
undoStack.add(HistoryAction.Add(page, annot))
}
redoStack.clear()
coroutineScope.launch {
snackbarHostState.showSnackbar("Demo annotations injected!")
}
}) {
Icon(
imageVector = Icons.Default.Edit,
contentDescription = "Inject Demo Annotations",
tint = Color(0xFF2E7D32)
)
}
}
Box {