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Zhuinden/InvertViewLayout.kt

Forked from bleeding182/InvertViewLayout.kt
Created June 22, 2018 19:54
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Revisions

  1. @bleeding182 bleeding182 revised this gist Jun 22, 2018. 1 changed file with 2 additions and 0 deletions.
    2 changes: 2 additions & 0 deletions InvertViewLayout.kt
    View file
    Original file line number Diff line number Diff line change
    @@ -1,3 +1,4 @@
    package com.davidmedenjak.overlappinginvertview

    import android.content.Context
    import android.graphics.*
    @@ -18,6 +19,7 @@ class InvertViewLayout(context: Context, attrs: AttributeSet? = null) : FrameLay
    }

    init {
    // https://stackoverflow.com/q/5941926/1837367
    val mx = floatArrayOf(-1.0f, 0.0f, 0.0f, 1.0f, 0.0f, 0.0f, -1.0f, 0.0f, 1.0f, 0.0f, 0.0f, 0.0f, -1.0f, 1.0f, 0.0f, 1.0f, 1.0f, 1.0f, 1.0f, 0.0f)
    val cm = ColorMatrix(mx)

  2. @bleeding182 bleeding182 created this gist Jun 22, 2018.
    56 changes: 56 additions & 0 deletions InvertViewLayout.kt
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    Original file line number Diff line number Diff line change
    @@ -0,0 +1,56 @@

    import android.content.Context
    import android.graphics.*
    import android.util.AttributeSet
    import android.view.View
    import android.widget.FrameLayout


    class InvertViewLayout(context: Context, attrs: AttributeSet? = null) : FrameLayout(context, attrs) {
    lateinit var backgroundView: View
    lateinit var overlay: View
    lateinit var bitmap: Bitmap

    val inversePaint: Paint = Paint()
    val rectPaint: Paint = Paint().apply {
    isAntiAlias = true
    color = Color.RED
    }

    init {
    val mx = floatArrayOf(-1.0f, 0.0f, 0.0f, 1.0f, 0.0f, 0.0f, -1.0f, 0.0f, 1.0f, 0.0f, 0.0f, 0.0f, -1.0f, 1.0f, 0.0f, 1.0f, 1.0f, 1.0f, 1.0f, 0.0f)
    val cm = ColorMatrix(mx)

    inversePaint.colorFilter = ColorMatrixColorFilter(cm)

    }

    override fun onLayout(changed: Boolean, left: Int, top: Int, right: Int, bottom: Int) {
    super.onLayout(changed, left, top, right, bottom)
    backgroundView = getChildAt(0)
    overlay = getChildAt(1)

    bitmap = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888)
    }

    override fun drawChild(canvas: Canvas, child: View, drawingTime: Long): Boolean {
    if (child !== overlay) {
    return super.drawChild(canvas, child, drawingTime)
    }

    val overlayCanvas = Canvas(bitmap)
    val result = super.drawChild(overlayCanvas, child, drawingTime)

    canvas.save()
    canvas.clipRect(backgroundView.left, backgroundView.top, backgroundView.right, backgroundView.bottom)
    canvas.drawBitmap(bitmap, 0F, 0F, inversePaint)
    canvas.restore()

    canvas.save()
    canvas.clipOutRect(backgroundView.left, backgroundView.top, backgroundView.right, backgroundView.bottom)
    canvas.drawBitmap(bitmap, 0F, 0F, null)
    canvas.restore()
    return result
    }

    }
    37 changes: 37 additions & 0 deletions layout.xml
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    @@ -0,0 +1,37 @@
    <?xml version="1.0" encoding="utf-8"?>
    <android.support.constraint.ConstraintLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.davidmedenjak.overlappinginvertview.MainActivity">

    <com.davidmedenjak.overlappinginvertview.InvertViewLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:background="#999999">

    <View
    android:layout_width="100dp"
    android:layout_height="100dp"
    android:layout_marginStart="50dp"
    android:layout_marginTop="50dp"
    android:background="@android:color/black"/>

    <TextView
    style="@style/TextAppearance.AppCompat.Display1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_marginStart="0sp"
    android:layout_marginTop="100dp"
    android:text="Hello World!"
    android:textColor="@android:color/black"
    android:textSize="50sp"
    app:layout_constraintBottom_toBottomOf="parent"
    app:layout_constraintLeft_toLeftOf="parent"
    app:layout_constraintRight_toRightOf="parent"
    app:layout_constraintTop_toTopOf="parent"/>

    </com.davidmedenjak.overlappinginvertview.InvertViewLayout>
    </android.support.constraint.ConstraintLayout>