Improved PDF vertical reader zoom and orientation handling (#98)
- Implemented `fitZoom` calculation to properly center and scale pages, especially in landscape orientation. - Updated `clampValues` and animation bounds to ensure content is correctly centered when zoomed out. - Refined double-tap-to-zoom logic to toggle between `fitZoom`, 1x, and 2.5x scales. - Replaced manual frame-based zooming with `Animatable.animateTo` for smoother transitions. - Added `configChanges` to `MainActivity` in `AndroidManifest.xml` to handle orientation and screen size changes manually. - Reduced delays and improved reliability of initial page snapping in `PdfViewerScreen`.
This commit is contained in:
Aryan
GitHub
parent
c9dc3ce8c2
commit
a9c791120d
3 changed files with 136 additions and 107 deletions
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@ -47,6 +47,7 @@
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android:name=".MainActivity"
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android:exported="true"
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android:theme="@style/Theme.Reader"
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android:configChanges="orientation|screenSize|screenLayout|keyboardHidden"
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android:launchMode="singleTask">
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<intent-filter>
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<action android:name="android.intent.action.MAIN" />
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@ -260,13 +260,10 @@ internal fun PdfVerticalReader(
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val dividerHeightPx = with(density) { dividerHeightDp.toPx() }
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val layoutState = remember(ratios, screenWidth, screenHeight, density) {
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// Return a wrapper object containing both list and total height to ensure
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// atomicity
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data class LayoutResult(val pages: List<PdfPageLayout>, val totalHeight: Float)
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var currentY = 0.0
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// Special case for single page centering
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if (ratios.size == 1) {
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val ratio = ratios[0]
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val safeRatio = if (ratio <= 0f) 1f else ratio
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@ -278,7 +275,6 @@ internal fun PdfVerticalReader(
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val pages = ratios.mapIndexed { index, ratio ->
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val safeRatio = if (ratio <= 0f) 1f else ratio
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// Use double for calculation
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val pageHeightDouble = screenWidth.toDouble() / safeRatio.toDouble()
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val pageHeight = pageHeightDouble.toFloat()
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@ -297,9 +293,7 @@ internal fun PdfVerticalReader(
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info
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}
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// Calculate exact total height based on the double accumulator
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val totalH = if (pages.isNotEmpty()) {
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// Determine the bottom of the last element strictly
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val last = pages.last()
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last.y + last.height
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} else {
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@ -314,58 +308,85 @@ internal fun PdfVerticalReader(
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Timber.tag(SCROLL_BOUNDS_TAG)
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.d("Layout Recalculated. Page Count: ${layoutInfo.size}, TotalDocHeight: $totalDocHeight")
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val zoomAnimatable = remember { Animatable(1f) }
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val panXAnimatable = remember { Animatable(0f) }
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val panYAnimatable = remember { Animatable(0f) }
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var previousLayoutPages by remember { mutableStateOf<List<PdfPageLayout>?>(null) }
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val currentScaleProvider = remember(zoomAnimatable) { { zoomAnimatable.value } }
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SideEffect {
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val prevPages = previousLayoutPages
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val currentPages = layoutState.pages
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if (prevPages != null && prevPages.size == currentPages.size) {
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val anchorIndex = state.firstVisiblePage.coerceIn(currentPages.indices)
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val oldY = prevPages[anchorIndex].y
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val newY = currentPages[anchorIndex].y
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val delta = newY - oldY
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if (abs(delta) > 0.1f) {
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val currentZoom = zoomAnimatable.value
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val shiftInScreenPixels = delta * currentZoom
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val targetPanY = panYAnimatable.value - shiftInScreenPixels
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scope.launch { panYAnimatable.snapTo(targetPanY) }
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val fitZoom = remember(ratios, screenWidth, screenHeight) {
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if (ratios.isEmpty() || screenWidth == 0f || screenHeight == 0f) 1f
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else {
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val firstRatio = ratios.firstOrNull { it > 0f } ?: 1f
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val baseHeight = screenWidth / firstRatio
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if (screenWidth > screenHeight) {
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((screenHeight - 32f) / baseHeight).coerceAtMost(1f)
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} else {
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1f
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}
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}
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previousLayoutPages = currentPages
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}
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val zoomAnimatable = remember { Animatable(fitZoom) }
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val panXAnimatable = remember { Animatable(if ((screenWidth * fitZoom) < screenWidth) (screenWidth - (screenWidth * fitZoom)) / 2f else 0f) }
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val panYAnimatable = remember { Animatable(0f) }
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var previousScreenWidth by remember { mutableFloatStateOf(0f) }
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LaunchedEffect(screenWidth, screenHeight) {
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if (previousScreenWidth > 0f && previousScreenWidth != screenWidth) {
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if (zoomAnimatable.value <= 1.1f) {
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val centeredX = if ((screenWidth * fitZoom) < screenWidth) {
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(screenWidth - (screenWidth * fitZoom)) / 2f
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} else 0f
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zoomAnimatable.snapTo(fitZoom)
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panXAnimatable.snapTo(centeredX)
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onZoomChange(fitZoom)
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}
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}
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previousScreenWidth = screenWidth
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}
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var isInitialLayout by remember { mutableStateOf(true) }
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val currentScaleProvider = remember(zoomAnimatable) { { zoomAnimatable.value } }
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LaunchedEffect(layoutState.pages) {
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if (!isInitialLayout) {
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val targetPageIdx = state.currentPage
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val newLayout = layoutState.pages
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val pageLayout = newLayout.getOrNull(targetPageIdx)
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if (pageLayout != null) {
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val currentZoom = zoomAnimatable.value
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val targetPanY = headerHeightPx - (pageLayout.y * currentZoom)
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val zoomedDocHeight = layoutState.totalHeight * currentZoom
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val minPanY = (screenHeight - footerHeightPx - zoomedDocHeight).coerceAtMost(headerHeightPx)
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val finalPanY = targetPanY.coerceIn(minPanY, headerHeightPx)
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Timber.tag("PdfZoomDiagnostics").i("Layout changed (Orientation/Size). Snapping to Page $targetPageIdx at PanY: $finalPanY")
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panYAnimatable.snapTo(finalPanY)
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}
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}
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isInitialLayout = false
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}
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fun clampValues(
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targetZoom: Float, targetPanX: Float, targetPanY: Float
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): Triple<Float, Float, Float> {
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val constrainedZoom = targetZoom.coerceIn(1f, 5f)
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val constrainedZoom = targetZoom.coerceIn(fitZoom, 5f)
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val zoomedDocWidth = screenWidth * constrainedZoom
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val zoomedDocHeight = totalDocHeight * constrainedZoom
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val maxPanX = 0f
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val minPanX = -(zoomedDocWidth - screenWidth).coerceAtLeast(0f)
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val minPanY = (screenHeight - footerHeightPx - zoomedDocHeight).coerceAtMost(
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headerHeightPx
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)
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val constrainedX = targetPanX.coerceIn(minPanX, maxPanX)
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val constrainedY = targetPanY.coerceIn(minPanY, headerHeightPx)
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if (constrainedZoom > 1.01f) {
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Timber.tag("PdfZoomIssue").v(
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"Clamp: Zoom=$constrainedZoom, targetY=$targetPanY, finalY=$constrainedY, " +
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"boundsY=[$minPanY, $headerHeightPx], zoomedHeight=$zoomedDocHeight"
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)
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val constrainedX = if (zoomedDocWidth < screenWidth) {
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(screenWidth - zoomedDocWidth) / 2f
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} else {
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val maxPanX = 0f
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val minPanX = -(zoomedDocWidth - screenWidth)
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targetPanX.coerceIn(minPanX, maxPanX)
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}
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val minPanY = if (zoomedDocHeight < (screenHeight - headerHeightPx - footerHeightPx)) {
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headerHeightPx
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} else {
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(screenHeight - footerHeightPx - zoomedDocHeight).coerceAtMost(headerHeightPx)
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}
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val constrainedY = targetPanY.coerceIn(minPanY, headerHeightPx)
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return Triple(constrainedZoom, constrainedX, constrainedY)
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}
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@ -629,6 +650,7 @@ internal fun PdfVerticalReader(
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val currentZoom = zoomAnimatable.value
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val zoomedDocHeight = totalDocHeight * currentZoom
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val zoomedDocWidth = screenWidth * currentZoom
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val isAnimating = zoomAnimatable.isRunning || panYAnimatable.isRunning || panXAnimatable.isRunning
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@ -637,11 +659,21 @@ internal fun PdfVerticalReader(
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val extraScrollForIme = if (isTextEditing) imeBottom.toFloat() else 0f
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val minPanY = (screenHeight - effectiveFooterPx - zoomedDocHeight - extraScrollForIme).coerceAtMost(headerHeightPx)
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val minPanX = -(screenWidth * currentZoom - screenWidth).coerceAtLeast(0f)
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val minPanX: Float
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val maxPanX: Float
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if (zoomedDocWidth < screenWidth) {
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val centeredX = (screenWidth - zoomedDocWidth) / 2f
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minPanX = centeredX
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maxPanX = centeredX
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} else {
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minPanX = -(zoomedDocWidth - screenWidth)
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maxPanX = 0f
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}
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if (!isAnimating) {
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panYAnimatable.updateBounds(lowerBound = minPanY, upperBound = headerHeightPx)
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panXAnimatable.updateBounds(lowerBound = minPanX, upperBound = 0f)
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panXAnimatable.updateBounds(lowerBound = minPanX, upperBound = maxPanX)
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} else {
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panYAnimatable.updateBounds(
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lowerBound = minOf(panYAnimatable.lowerBound ?: minPanY, minPanY),
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@ -649,7 +681,7 @@ internal fun PdfVerticalReader(
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)
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panXAnimatable.updateBounds(
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lowerBound = minOf(panXAnimatable.lowerBound ?: minPanX, minPanX),
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upperBound = 0f
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upperBound = maxOf(panXAnimatable.upperBound ?: maxPanX, maxPanX)
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)
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}
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}
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@ -706,7 +738,12 @@ internal fun PdfVerticalReader(
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val onDoubleTapToZoom: (Offset) -> Unit = { tapScreenOffset ->
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val currentZoom = zoomAnimatable.value
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val targetZoom = if (currentZoom < 1.1f) 2.5f else 1f
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val targetZoom = when {
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currentZoom < 0.95f -> 1f
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currentZoom < 2.45f -> 2.5f
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else -> fitZoom
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}
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val startPanX = panXAnimatable.value
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val startPanY = panYAnimatable.value
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@ -719,46 +756,41 @@ internal fun PdfVerticalReader(
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val pivotContentX = (tapScreenOffset.x - startPanX) / currentZoom
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val pivotContentY = (tapScreenOffset.y - startPanY) / currentZoom
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val durationMillis = 400L
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val startTimeNanos = withFrameNanos { it }
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val durationNanos = durationMillis * 1_000_000L
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val rawNextPanX = tapScreenOffset.x - (pivotContentX * targetZoom)
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val rawNextPanY = tapScreenOffset.y - (pivotContentY * targetZoom)
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while (true) {
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val now = withFrameNanos { it }
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val elapsedNanos = now - startTimeNanos
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val progress = (elapsedNanos.toFloat() / durationNanos).coerceIn(0f, 1f)
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val easedProgress = FastOutSlowInEasing.transform(progress)
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val (finalZoom, finalX, finalY) = clampCamera(targetZoom, rawNextPanX, rawNextPanY)
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val nextZoom = androidx.compose.ui.util.lerp(currentZoom, targetZoom, easedProgress)
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panXAnimatable.updateBounds(
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lowerBound = minOf(panXAnimatable.lowerBound ?: finalX, finalX, startPanX),
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upperBound = maxOf(panXAnimatable.upperBound ?: finalX, finalX, startPanX)
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)
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panYAnimatable.updateBounds(
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lowerBound = minOf(panYAnimatable.lowerBound ?: finalY, finalY, startPanY),
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upperBound = maxOf(panYAnimatable.upperBound ?: finalY, finalY, startPanY)
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)
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val rawNextPanX = tapScreenOffset.x - (pivotContentX * nextZoom)
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val rawNextPanY = tapScreenOffset.y - (pivotContentY * nextZoom)
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val (clampedZoom, clampedX, clampedY) = clampCamera(nextZoom, rawNextPanX, rawNextPanY)
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panXAnimatable.updateBounds(
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lowerBound = minOf(panXAnimatable.lowerBound ?: clampedX, clampedX),
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upperBound = maxOf(panXAnimatable.upperBound ?: clampedX, clampedX)
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)
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panYAnimatable.updateBounds(
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lowerBound = minOf(panYAnimatable.lowerBound ?: clampedY, clampedY),
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upperBound = maxOf(panYAnimatable.upperBound ?: clampedY, clampedY)
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)
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zoomAnimatable.snapTo(clampedZoom)
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panXAnimatable.snapTo(clampedX)
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panYAnimatable.snapTo(clampedY)
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if (progress >= 1f) break
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coroutineScope {
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launch { zoomAnimatable.animateTo(finalZoom, animationSpec = tween(400, easing = FastOutSlowInEasing)) }
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launch { panXAnimatable.animateTo(finalX, animationSpec = tween(400, easing = FastOutSlowInEasing)) }
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launch { panYAnimatable.animateTo(finalY, animationSpec = tween(400, easing = FastOutSlowInEasing)) }
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}
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onZoomChange(zoomAnimatable.value)
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val finalZoom = zoomAnimatable.value
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panXAnimatable.updateBounds(
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lowerBound = -(screenWidth * finalZoom - screenWidth).coerceAtLeast(0f),
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upperBound = 0f
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)
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val zoomedDocWidth = screenWidth * finalZoom
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val finalMinX: Float
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val finalMaxX: Float
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if (zoomedDocWidth < screenWidth) {
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val centeredX = (screenWidth - zoomedDocWidth) / 2f
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finalMinX = centeredX
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finalMaxX = centeredX
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} else {
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finalMinX = -(zoomedDocWidth - screenWidth)
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finalMaxX = 0f
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}
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panXAnimatable.updateBounds(lowerBound = finalMinX, upperBound = finalMaxX)
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val zDocH = totalDocHeight * finalZoom
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val minScrollY = (screenHeight - footerHeightPx - zDocH).coerceAtMost(headerHeightPx)
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panYAnimatable.updateBounds(lowerBound = minScrollY, upperBound = headerHeightPx)
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@ -1032,7 +1064,7 @@ internal fun PdfVerticalReader(
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val oldZoom = accumulatedZoom
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val rawTargetZoom = oldZoom * effectiveZoomChange
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val constrainedZoom = rawTargetZoom.coerceIn(1f, 5f)
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val constrainedZoom = rawTargetZoom.coerceIn(fitZoom, 5f)
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val prevCentroid = centroid - panChange
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val contentPivotX = (prevCentroid.x - accumulatedPanX) / oldZoom
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@ -1046,13 +1078,6 @@ internal fun PdfVerticalReader(
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val rawNewPanX = centroid.x - (contentPivotX * constrainedZoom)
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val rawNewPanY = centroid.y - (contentPivotY * constrainedZoom)
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if (effectiveZoomChange > 1.0f) {
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Timber.tag("PdfZoomIssue").d(
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"PinchIn FIXED: ZoomFactor=$effectiveZoomChange, CentroidY=${centroid.y}, " +
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"OldPanY=$accumulatedPanY, ResultRawPanY=$rawNewPanY"
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)
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}
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val (finalZoom, finalX, finalY) = clampCamera(
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constrainedZoom, rawNewPanX, rawNewPanY
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)
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@ -1103,7 +1128,7 @@ internal fun PdfVerticalReader(
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scope.launch {
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isFlinging = true
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try {
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if (accumulatedZoom !in 1f..5f) {
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if (accumulatedZoom !in fitZoom..5f) {
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zoomAnimatable.animateTo(
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finalZoom, animationSpec = tween(300)
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)
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@ -1111,8 +1136,18 @@ internal fun PdfVerticalReader(
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onZoomChange(zoomAnimatable.targetValue)
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val zoomedDocWidth = screenWidth * finalZoom
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val zoomedDocHeight = totalDocHeight * finalZoom
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val maxPanX = 0f
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val minPanX = -(zoomedDocWidth - screenWidth).coerceAtLeast(0f)
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val flingMinX: Float
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val flingMaxX: Float
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if (zoomedDocWidth < screenWidth) {
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val centeredX = (screenWidth - zoomedDocWidth) / 2f
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flingMinX = centeredX
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flingMaxX = centeredX
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} else {
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flingMinX = -(zoomedDocWidth - screenWidth)
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flingMaxX = 0f
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}
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val minPanY =
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(screenHeight - footerHeightPx - zoomedDocHeight).coerceAtMost(
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headerHeightPx
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@ -1121,11 +1156,9 @@ internal fun PdfVerticalReader(
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Timber.tag(SCROLL_BOUNDS_TAG)
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.d("- totalDocHeight: $totalDocHeight, zoom: $finalZoom -> zoomedDocHeight: $zoomedDocHeight")
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Timber.tag(SCROLL_BOUNDS_TAG)
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.d("- Fling bounds set to Y: [$minPanY, $headerHeightPx]")
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panXAnimatable.updateBounds(minPanX, maxPanX)
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panYAnimatable.updateBounds(
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minPanY, headerHeightPx
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)
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.d("- Fling bounds set to Y:[$minPanY, $headerHeightPx]")
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panXAnimatable.updateBounds(flingMinX, flingMaxX)
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panYAnimatable.updateBounds(minPanY, headerHeightPx)
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coroutineScope {
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launch {
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@ -2147,8 +2147,6 @@ fun PdfViewerScreen(
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Timber.tag("PdfPositionDebug").i("UI: Restoration Start | Target: $targetPage | Mode: $displayMode | Total: $pageCount")
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try {
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delay(200)
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when (displayMode) {
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DisplayMode.PAGINATION -> {
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if (pagerState.currentPage != targetPage) {
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@ -2157,14 +2155,11 @@ fun PdfViewerScreen(
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initialScrollDone = true
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}
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DisplayMode.VERTICAL_SCROLL -> {
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var retries = 0
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while (verticalReaderState.snapToPageHandler == null && retries < 20) {
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delay(50)
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retries++
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while (verticalReaderState.snapToPageHandler == null) {
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delay(16)
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}
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Timber.tag("PdfPositionDebug").d("UI: Executing Vertical snapToPage($targetPage) after $retries retries")
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Timber.tag("PdfPositionDebug").d("UI: Executing Vertical snapToPage($targetPage)")
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verticalReaderState.snapToPage(targetPage)
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delay(100)
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initialScrollDone = true
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}
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}
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