Control PDF page navigation and zoom level in KPDF

Use KPdfViewerState to navigate pages and adjust zoom programmatically, and configure swipe and pinch-to-zoom gestures through KPdfViewerConfig.

KPdfViewerState exposes navigation and zoom as simple method calls, so you can wire them to any button, gesture handler, or keyboard shortcut in your UI. Gesture-based navigation and pinch-to-zoom are configured separately in KPdfViewerConfig before the viewer is created.

Page navigation

Call nextPage, previousPage, or goToPage on the viewer state. Each call updates currentPageIndex, which KPdfViewer observes and reacts to automatically.

Row(horizontalArrangement = Arrangement.spacedBy(8.dp)) {
    Button(onClick = { viewerState.previousPage() }) {
        Text("Previous")
    }

    Button(onClick = { viewerState.nextPage() }) {
        Text("Next")
    }

    Button(onClick = { viewerState.goToPage(9) }) {
        Text("Jump to page 10")
    }
}

goToPage takes a 0-based index, so page 10 is index 9.

You can read the current page at any time from the state flow:

val currentPage by viewerState.currentPageIndex.collectAsState()

Swipe-to-navigate

To let users swipe between pages, enable enableSwipe in your KPdfViewerConfig:

val config = remember {
    KPdfViewerConfig.builder()
        .enableSwipe(true)
        .build()
}

Set it to false if you want to restrict navigation to programmatic calls only.

Zoom controls

Call zoomIn, zoomOut, resetZoom, or setZoom to change the zoom level. Changes propagate to KPdfViewer through the currentZoom state flow.

Row(horizontalArrangement = Arrangement.spacedBy(8.dp)) {
    Button(onClick = { viewerState.zoomOut() }) {
        Text("Zoom out")
    }

    Button(onClick = { viewerState.zoomIn() }) {
        Text("Zoom in")
    }

    Button(onClick = { viewerState.resetZoom() }) {
        Text("Reset")
    }
}

To jump to a specific zoom factor, call setZoom directly:

Button(onClick = { viewerState.setZoom(2.5f) }) {
    Text("Set 250%")
}

You can also read the live zoom value:

val zoom by viewerState.currentZoom.collectAsState()
Text("Zoom: ${(zoom * 100).toInt()}%")

Pinch-to-zoom and zoom range

Configure pinch-to-zoom and its limits in KPdfViewerConfig:

val config = remember {
    KPdfViewerConfig.builder()
        .enableZoom(true)
        .zoomRange(minZoom = 1f, maxZoom = 4f)
        .doubleTapZoom(2.5f)
        .build()
}

Option	Description
enableZoom	Enables pinch-to-zoom gestures on the viewer surface
zoomRange	Sets the minimum and maximum zoom factors
doubleTapZoom	Zoom factor applied when the user double-taps a page

resetZoom resets the zoom to minZoom from the configured zoomRange. If you want a “fit page” behaviour, set minZoom to 1f (the default) and call resetZoom.