Add buttons to toggle zoom and change number of pages on-screen

app/src/main/java/com/lhw/pdf/MainActivity.kt

@@ -2,11 +2,8 @@ package com.lhw.pdf
 
 import android.app.Presentation
 import android.content.Context
-import android.graphics.Bitmap
-import android.graphics.pdf.PdfRenderer
 import android.media.MediaRouter
 import android.os.Bundle
-import android.os.ParcelFileDescriptor
 import android.util.DisplayMetrics
 import android.view.Display
 import android.view.Menu
@@ -29,14 +26,17 @@ import com.lhw.pdf.databinding.ActivityMainBinding
 import java.io.File
 import java.io.FileOutputStream
 import java.io.InputStream
+import kotlin.math.max
 import kotlin.math.min
 
 class MainActivity : AppCompatActivity() {
-
     private lateinit var appBarConfiguration: AppBarConfiguration
     private lateinit var binding: ActivityMainBinding
     private val thumbnailWidth = 500
     private val thumbnailHeight = 700
+    private var renderAutoCrop = true
+    private var pagesPerLandscape = 3F
+    private val presentationDisplayMetrics = DisplayMetrics()
     private lateinit var pdfDocument: PdfDocument
     private lateinit var presentationScroll: HorizontalScrollView
     private lateinit var presentationLayout: LinearLayout
@@ -61,6 +61,18 @@ class MainActivity : AppCompatActivity() {
 
     }
 
+    private fun updatePresentationImages() {
+        val maxHeight: Int = presentationDisplayMetrics.heightPixels
+        val maxWidth: Int = min(maxHeight*5/7, (presentationDisplayMetrics.widthPixels/pagesPerLandscape).toInt())
+        pdfDocument.renderPagesPresentation(maxWidth, maxHeight, renderAutoCrop)
+        presentationLayout.removeAllViewsInLayout()
+        for (bitmap in pdfDocument.bitmapPagesPresentation.values) {
+            val img = ImageView(this)
+            img.setImageBitmap(bitmap)
+            presentationLayout.addView(img)
+        }
+    }
+
     private fun presentationView() {
         val mediaRouter = getSystemService(Context.MEDIA_ROUTER_SERVICE) as MediaRouter
         val presentationDisplay = mediaRouter.getSelectedRoute(MediaRouter.ROUTE_TYPE_LIVE_VIDEO)?.presentationDisplay
@@ -73,21 +85,14 @@ class MainActivity : AppCompatActivity() {
                 }
             }
 
-            val metrics = DisplayMetrics()
-            presentationDisplay.getMetrics(metrics)
-            val maxHeight: Int = metrics.heightPixels
-            val maxWidth: Int = min(maxHeight*5/7, metrics.widthPixels)
-            pdfDocument.renderPagesPresentation(maxWidth, maxHeight)
+            @Suppress("DEPRECATION")
+            presentationDisplay.getMetrics(presentationDisplayMetrics)
             presentationLayout = LinearLayout(presentation.context)
-            for (bitmap in pdfDocument.bitmapPagesPresentation.values) {
-                val img = ImageView(this)
-                img.setImageBitmap(bitmap)
-                presentationLayout.addView(img)
-            }
             presentationScroll = HorizontalScrollView(presentation.context)
             presentationScroll.addView(presentationLayout)
             val layoutParams = WindowManager.LayoutParams()
             presentation.addContentView(presentationScroll, layoutParams)
+            updatePresentationImages()
             presentation.show()
         }
     }
@@ -102,24 +107,6 @@ class MainActivity : AppCompatActivity() {
 
         setSupportActionBar(binding.appBarMain.toolbar)
 
-        binding.appBarMain.fab.setOnClickListener { view ->
-            Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
-                .setAction("Action", null)
-                .setAnchorView(R.id.fab).show()
-        }
-        val drawerLayout: DrawerLayout = binding.drawerLayout
-        val navView: NavigationView = binding.navView
-        val navController = findNavController(R.id.nav_host_fragment_content_main)
-        // Passing each menu ID as a set of Ids because each
-        // menu should be considered as top level destinations.
-        appBarConfiguration = AppBarConfiguration(
-            setOf(
-                R.id.nav_home, R.id.nav_gallery, R.id.nav_slideshow
-            ), drawerLayout
-        )
-        setupActionBarWithNavController(navController, appBarConfiguration)
-        navView.setupWithNavController(navController)
-
         initializePdfDocument()
         pdfDocument.renderThumbnails(thumbnailWidth, thumbnailHeight)
         val container = binding.appBarMain.contentMain.thumbnailsLayout
@@ -137,6 +124,41 @@ class MainActivity : AppCompatActivity() {
                 0
             )
         }
+
+        binding.appBarMain.crop.setOnClickListener { view ->
+            renderAutoCrop = !renderAutoCrop
+            val s = if (renderAutoCrop) "On" else "Off"
+            Snackbar.make(view, "Toggling Auto Crop $s", Snackbar.LENGTH_LONG)
+                .setAction("Action", null)
+                .setAnchorView(R.id.crop).show()
+            updatePresentationImages()
+        }
+        binding.appBarMain.zoomIn.setOnClickListener { view ->
+            pagesPerLandscape = max(pagesPerLandscape - 0.5F, 1F)
+            Snackbar.make(view, "Aiming for $pagesPerLandscape pages at a time", Snackbar.LENGTH_LONG)
+                .setAction("Action", null)
+                .setAnchorView(R.id.zoom_in).show()
+            updatePresentationImages()
+        }
+        binding.appBarMain.zoomOut.setOnClickListener { view ->
+            pagesPerLandscape = min(pagesPerLandscape + 0.5F, 10F)
+            Snackbar.make(view, "Aiming for $pagesPerLandscape pages at a time", Snackbar.LENGTH_LONG)
+                .setAction("Action", null)
+                .setAnchorView(R.id.zoom_out).show()
+            updatePresentationImages()
+        }
+        val drawerLayout: DrawerLayout = binding.drawerLayout
+        val navView: NavigationView = binding.navView
+        val navController = findNavController(R.id.nav_host_fragment_content_main)
+        // Passing each menu ID as a set of Ids because each
+        // menu should be considered as top level destinations.
+        appBarConfiguration = AppBarConfiguration(
+            setOf(
+                R.id.nav_home, R.id.nav_gallery, R.id.nav_slideshow
+            ), drawerLayout
+        )
+        setupActionBarWithNavController(navController, appBarConfiguration)
+        navView.setupWithNavController(navController)
     }
 
     override fun onCreateOptionsMenu(menu: Menu): Boolean {

app/src/main/java/com/lhw/pdf/PdfDocument.kt

@@ -134,11 +134,11 @@ class PdfDocument(private val fileCached: File, private val autoCrop: Boolean =
         }
     }
 
-    fun renderPagesMain(width: Int, height: Int) {
-        renderPagesToMap(bitmapPagesMain, width, height, true)
+    fun renderPagesMain(width: Int, height: Int, crop: Boolean = true) {
+        renderPagesToMap(bitmapPagesMain, width, height, crop)
     }
 
-    fun renderPagesPresentation(width: Int, height: Int) {
-        renderPagesToMap(bitmapPagesPresentation, width, height, true)
+    fun renderPagesPresentation(width: Int, height: Int, crop: Boolean = true) {
+        renderPagesToMap(bitmapPagesPresentation, width, height, crop)
     }
 }

app/src/main/res/layout/app_bar_main.xml

@@ -23,12 +23,38 @@
     <include android:id="@+id/content_main" layout="@layout/content_main" />
 
     <com.google.android.material.floatingactionbutton.FloatingActionButton
-        android:id="@+id/fab"
+        android:id="@+id/crop"
         android:layout_width="wrap_content"
         android:layout_height="wrap_content"
         android:layout_gravity="bottom|end"
         android:layout_marginEnd="@dimen/fab_margin"
         android:layout_marginBottom="16dp"
-        app:srcCompat="@android:drawable/ic_dialog_email" />
+        android:importantForAccessibility="no"
+        app:maxImageSize="48dp"
+        app:srcCompat="@android:drawable/ic_menu_crop" />
+
+    <com.google.android.material.floatingactionbutton.FloatingActionButton
+        android:id="@+id/zoom_in"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:layout_gravity="bottom|start"
+        android:layout_marginStart="96dp"
+        android:layout_marginBottom="16dp"
+        android:importantForAccessibility="no"
+        app:maxImageSize="48dp"
+        app:srcCompat="@android:drawable/ic_menu_zoom" />
+
+    <com.google.android.material.floatingactionbutton.FloatingActionButton
+        android:id="@+id/zoom_out"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:layout_gravity="bottom|start"
+        android:layout_marginStart="16dp"
+        android:layout_marginBottom="16dp"
+        android:importantForAccessibility="no"
+        android:rotationY="180"
+        android:rotationX="180"
+        app:maxImageSize="48dp"
+        app:srcCompat="@android:drawable/ic_menu_zoom" />
 
 </androidx.coordinatorlayout.widget.CoordinatorLayout>