Add full-screen notification image viewer

app/src/main/java/se/ajpanton/notificationlog/ImageViewerDialogFragment.kt

@@ -0,0 +1,121 @@
+package se.ajpanton.notificationlog
+
+import android.app.Dialog
+import android.graphics.Bitmap
+import android.graphics.BitmapFactory
+import android.graphics.Color
+import android.graphics.drawable.ColorDrawable
+import android.os.Bundle
+import android.view.Gravity
+import android.view.View
+import android.view.ViewGroup
+import android.view.Window
+import android.widget.FrameLayout
+import android.widget.ProgressBar
+import android.widget.TextView
+import androidx.core.os.bundleOf
+import androidx.core.view.WindowCompat
+import androidx.core.view.WindowInsetsCompat
+import androidx.core.view.WindowInsetsControllerCompat
+import androidx.fragment.app.DialogFragment
+import se.ajpanton.notificationlog.data.EncryptedImageStore
+
+/** Full-screen image viewer kept within MainActivity so opening it does not re-lock the app. */
+class ImageViewerDialogFragment : DialogFragment() {
+    private lateinit var root: FrameLayout
+    private lateinit var image: ZoomImageView
+    private lateinit var progress: ProgressBar
+    private var controlsVisible = false
+
+    override fun onCreateDialog(savedInstanceState: Bundle?): Dialog {
+        root = FrameLayout(requireContext()).apply { setBackgroundColor(Color.BLACK) }
+        image = ZoomImageView(requireContext()).apply {
+            visibility = View.GONE
+            onSingleTap = ::toggleSystemControls
+        }
+        progress = ProgressBar(requireContext()).apply { isIndeterminate = true }
+        root.addView(image, FrameLayout.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.MATCH_PARENT))
+        root.addView(progress, FrameLayout.LayoutParams(ViewGroup.LayoutParams.WRAP_CONTENT, ViewGroup.LayoutParams.WRAP_CONTENT, Gravity.CENTER))
+        return Dialog(requireContext()).apply {
+            requestWindowFeature(Window.FEATURE_NO_TITLE)
+            setContentView(root)
+        }
+    }
+
+    override fun onStart() {
+        super.onStart()
+        dialog?.window?.apply {
+            setLayout(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.MATCH_PARENT)
+            setBackgroundDrawable(ColorDrawable(Color.BLACK))
+            WindowCompat.setDecorFitsSystemWindows(this, false)
+            addFlags(android.view.WindowManager.LayoutParams.FLAG_SECURE)
+        }
+        hideSystemControls()
+        loadImage(requireArguments().getString(ARGUMENT_IMAGE_ID)!!)
+    }
+
+    private fun loadImage(imageId: String) {
+        val targetWidth = resources.displayMetrics.widthPixels
+        val targetHeight = resources.displayMetrics.heightPixels
+        val appContext = requireContext().applicationContext
+        Thread {
+            val bitmap = runCatching {
+                EncryptedImageStore(appContext).read(imageId)?.let { bytes ->
+                    decodeForViewer(bytes, targetWidth, targetHeight)
+                }
+            }.getOrNull()
+            activity?.runOnUiThread {
+                if (!isAdded) return@runOnUiThread
+                progress.visibility = View.GONE
+                if (bitmap == null) {
+                    root.addView(TextView(requireContext()).apply {
+                        text = "[image]"
+                        setTextColor(Color.WHITE)
+                        textSize = 18f
+                    }, FrameLayout.LayoutParams(ViewGroup.LayoutParams.WRAP_CONTENT, ViewGroup.LayoutParams.WRAP_CONTENT, Gravity.CENTER))
+                } else {
+                    image.setImageBitmap(bitmap)
+                    image.visibility = View.VISIBLE
+                }
+            }
+        }.start()
+    }
+
+    private fun decodeForViewer(bytes: ByteArray, targetWidth: Int, targetHeight: Int): Bitmap? {
+        val bounds = BitmapFactory.Options().apply { inJustDecodeBounds = true }
+        BitmapFactory.decodeByteArray(bytes, 0, bytes.size, bounds)
+        var sampleSize = 1
+        while (bounds.outWidth / sampleSize > targetWidth * MAX_SCREEN_SCALE ||
+            bounds.outHeight / sampleSize > targetHeight * MAX_SCREEN_SCALE
+        ) sampleSize *= 2
+        return BitmapFactory.decodeByteArray(bytes, 0, bytes.size, BitmapFactory.Options().apply { inSampleSize = sampleSize })
+    }
+
+    private fun toggleSystemControls() {
+        if (controlsVisible) hideSystemControls() else showSystemControls()
+    }
+
+    private fun hideSystemControls() {
+        val window = dialog?.window ?: return
+        WindowInsetsControllerCompat(window, root).apply {
+            systemBarsBehavior = WindowInsetsControllerCompat.BEHAVIOR_SHOW_TRANSIENT_BARS_BY_SWIPE
+            hide(WindowInsetsCompat.Type.systemBars())
+        }
+        controlsVisible = false
+    }
+
+    private fun showSystemControls() {
+        val window = dialog?.window ?: return
+        WindowInsetsControllerCompat(window, root).show(WindowInsetsCompat.Type.systemBars())
+        controlsVisible = true
+    }
+
+    companion object {
+        private const val ARGUMENT_IMAGE_ID = "image_id"
+        private const val MAX_SCREEN_SCALE = 4
+
+        fun newInstance(imageId: String) = ImageViewerDialogFragment().apply {
+            arguments = bundleOf(ARGUMENT_IMAGE_ID to imageId)
+        }
+    }
+}

app/src/main/java/se/ajpanton/notificationlog/ViewLogsFragment.kt

@@ -198,6 +198,11 @@ class ViewLogsFragment : Fragment(R.layout.fragment_view_logs) {
                                 maxHeight = dp(240)
                                 contentDescription = "Notification image"
                                 setPadding(0, dp(4), 0, 0)
+                                setOnClickListener {
+                                    if (isAdded) {
+                                        ImageViewerDialogFragment.newInstance(imageId).show(parentFragmentManager, IMAGE_VIEWER_TAG)
+                                    }
+                                }
                             })
                         }
                     }
@@ -285,5 +290,6 @@ class ViewLogsFragment : Fragment(R.layout.fragment_view_logs) {
         const val SCROLL_TO_TOP_THRESHOLD_DP = 120
         const val LOAD_MORE_THRESHOLD_DP = 480
         const val PAGE_SIZE = 80
+        const val IMAGE_VIEWER_TAG = "image-viewer"
     }
 }

app/src/main/java/se/ajpanton/notificationlog/ZoomImageView.kt

@@ -0,0 +1,132 @@
+package se.ajpanton.notificationlog
+
+import android.content.Context
+import android.graphics.Bitmap
+import android.graphics.Matrix
+import android.graphics.RectF
+import android.util.AttributeSet
+import android.view.GestureDetector
+import android.view.MotionEvent
+import android.view.ScaleGestureDetector
+import androidx.appcompat.widget.AppCompatImageView
+
+/** A fit-to-screen image which supports pinch zoom and one-finger panning. */
+class ZoomImageView @JvmOverloads constructor(
+    context: Context,
+    attributes: AttributeSet? = null,
+) : AppCompatImageView(context, attributes) {
+    var onSingleTap: (() -> Unit)? = null
+
+    private val transform = Matrix()
+    private val bounds = RectF()
+    private var minimumScale = 1f
+    private var currentScale = 1f
+    private var lastX = 0f
+    private var lastY = 0f
+    private var dragging = false
+    private val scaleDetector = ScaleGestureDetector(context, object : ScaleGestureDetector.SimpleOnScaleGestureListener() {
+        override fun onScale(detector: ScaleGestureDetector): Boolean {
+            val scale = (currentScale * detector.scaleFactor).coerceIn(minimumScale, minimumScale * MAX_ZOOM)
+            transform.postScale(scale / currentScale, scale / currentScale, detector.focusX, detector.focusY)
+            currentScale = scale
+            constrain()
+            return true
+        }
+    })
+    private val gestureDetector = GestureDetector(context, object : GestureDetector.SimpleOnGestureListener() {
+        override fun onSingleTapConfirmed(event: MotionEvent): Boolean {
+            onSingleTap?.invoke()
+            return true
+        }
+
+        override fun onDoubleTap(event: MotionEvent): Boolean {
+            val target = if (currentScale > minimumScale * 1.1f) minimumScale else minimumScale * DOUBLE_TAP_ZOOM
+            transform.postScale(target / currentScale, target / currentScale, event.x, event.y)
+            currentScale = target
+            constrain()
+            return true
+        }
+    })
+
+    init {
+        scaleType = ScaleType.MATRIX
+    }
+
+    override fun setImageBitmap(bitmap: Bitmap?) {
+        super.setImageBitmap(bitmap)
+        post(::resetToFit)
+    }
+
+    override fun onSizeChanged(width: Int, height: Int, oldWidth: Int, oldHeight: Int) {
+        super.onSizeChanged(width, height, oldWidth, oldHeight)
+        resetToFit()
+    }
+
+    override fun onTouchEvent(event: MotionEvent): Boolean {
+        scaleDetector.onTouchEvent(event)
+        gestureDetector.onTouchEvent(event)
+        when (event.actionMasked) {
+            MotionEvent.ACTION_DOWN -> {
+                lastX = event.x
+                lastY = event.y
+                dragging = false
+            }
+            MotionEvent.ACTION_MOVE -> if (!scaleDetector.isInProgress) {
+                val dx = event.x - lastX
+                val dy = event.y - lastY
+                if (dx != 0f || dy != 0f) {
+                    dragging = true
+                    transform.postTranslate(dx, dy)
+                    constrain()
+                }
+                lastX = event.x
+                lastY = event.y
+            }
+            MotionEvent.ACTION_UP, MotionEvent.ACTION_CANCEL -> {
+                if (dragging) performClick()
+            }
+        }
+        return true
+    }
+
+    override fun performClick(): Boolean = super.performClick()
+
+    private fun resetToFit() {
+        val drawable = drawable ?: return
+        if (width == 0 || height == 0 || drawable.intrinsicWidth <= 0 || drawable.intrinsicHeight <= 0) return
+        minimumScale = minOf(width.toFloat() / drawable.intrinsicWidth, height.toFloat() / drawable.intrinsicHeight)
+        currentScale = minimumScale
+        transform.reset()
+        transform.postScale(minimumScale, minimumScale)
+        transform.postTranslate(
+            (width - drawable.intrinsicWidth * minimumScale) / 2f,
+            (height - drawable.intrinsicHeight * minimumScale) / 2f,
+        )
+        imageMatrix = transform
+    }
+
+    private fun constrain() {
+        val drawable = drawable ?: return
+        bounds.set(0f, 0f, drawable.intrinsicWidth.toFloat(), drawable.intrinsicHeight.toFloat())
+        transform.mapRect(bounds)
+        val dx = when {
+            bounds.width() <= width -> width / 2f - bounds.centerX()
+            bounds.left > 0f -> -bounds.left
+            bounds.right < width -> width - bounds.right
+            else -> 0f
+        }
+        val dy = when {
+            bounds.height() <= height -> height / 2f - bounds.centerY()
+            bounds.top > 0f -> -bounds.top
+            bounds.bottom < height -> height - bounds.bottom
+            else -> 0f
+        }
+        transform.postTranslate(dx, dy)
+        imageMatrix = transform
+    }
+
+    private companion object {
+        const val MAX_ZOOM = 6f
+        const val DOUBLE_TAP_ZOOM = 2.5f
+    }
+}