Add library module

app/build.gradle

@@ -49,6 +49,8 @@ android {
 
 dependencies {
 
+    implementation project(":scratchview")
+
     implementation 'androidx.core:core-ktx:1.6.0'
     implementation 'androidx.appcompat:appcompat:1.3.1'
     implementation 'com.google.android.material:material:1.4.0'

app/src/main/java/com/vivek/scratchcardeffect/ui/screens/ScratchCardScreen.kt

@@ -1,15 +1,16 @@
 package com.vivek.scratchcardeffect.ui.screens
 
-import android.view.MotionEvent
-import androidx.compose.foundation.Canvas
+import androidx.compose.foundation.Image
 import androidx.compose.foundation.background
 import androidx.compose.foundation.layout.Box
+import androidx.compose.foundation.layout.Column
 import androidx.compose.foundation.layout.fillMaxSize
 import androidx.compose.foundation.layout.size
 import androidx.compose.foundation.shape.RoundedCornerShape
 import androidx.compose.material.Icon
 import androidx.compose.material.IconButton
 import androidx.compose.material.MaterialTheme
+import androidx.compose.material.Text
 import androidx.compose.material.icons.Icons
 import androidx.compose.material.icons.filled.Clear
 import androidx.compose.runtime.Composable
@@ -19,20 +20,15 @@ import androidx.compose.ui.Alignment
 import androidx.compose.ui.ExperimentalComposeUiApi
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.draw.clip
-import androidx.compose.ui.draw.clipToBounds
 import androidx.compose.ui.geometry.Offset
-import androidx.compose.ui.geometry.Rect
-import androidx.compose.ui.graphics.ClipOp
 import androidx.compose.ui.graphics.Color
 import androidx.compose.ui.graphics.ImageBitmap
 import androidx.compose.ui.graphics.Path
-import androidx.compose.ui.graphics.drawscope.clipPath
-import androidx.compose.ui.input.pointer.pointerInteropFilter
 import androidx.compose.ui.res.imageResource
-import androidx.compose.ui.unit.IntSize
 import androidx.compose.ui.unit.dp
 import com.vivek.scratchcardeffect.R
 import com.vivek.scratchcardeffect.models.DraggedPath
+import com.vivek.scratchview.ScratchingCanvas
 
 @ExperimentalComposeUiApi
 @Composable
@@ -64,69 +60,24 @@ fun ScratchCardScreen() {
         // Scratch Card Implementation
         ScratchingCanvas(
             overlayImage = overlayImage,
-            baseImage = baseImage,
-            modifier = Modifier.align(Alignment.Center),
+            modifier = Modifier
+                .align(Alignment.Center)
+                .size(200.dp)
+                .clip(RoundedCornerShape(size = 16.dp)),
             movedOffset = movedOffsetState.value,
             onMovedOffset = { x, y ->
                 movedOffsetState.value = Offset(x, y)
             },
             currentPath = currentPathState.value.path,
             currentPathThickness = currentPathState.value.width,
-        )
-    }
-}
-
-@ExperimentalComposeUiApi
-@Composable
-fun ScratchingCanvas(
-    overlayImage: ImageBitmap,
-    baseImage: ImageBitmap,
-    modifier: Modifier = Modifier,
-    movedOffset: Offset?,
-    onMovedOffset: (Float, Float) -> Unit,
-    currentPath: Path,
-    currentPathThickness: Float,
-) {
-    Canvas(
-        modifier = modifier
-            .size(220.dp)
-            .clipToBounds()
-            .clip(RoundedCornerShape(size = 16.dp))
-            .pointerInteropFilter {
-                when (it.action) {
-                    MotionEvent.ACTION_DOWN -> {
-                        println("CurrentPath/ACTION_DOWN: (${it.x}, ${it.y})")
-                        currentPath.moveTo(it.x, it.y)
-                    }
-                    MotionEvent.ACTION_MOVE -> {
-                        println("MovedOffset/ACTION_MOVE: (${it.x}, ${it.y})")
-                        onMovedOffset(it.x, it.y)
-                    }
-                }
-                true
+            background = {
+                Image(bitmap = baseImage, contentDescription = "", modifier = Modifier.size(220.dp))
+               /* Column(modifier = Modifier.align(Alignment.Center)) {
+                    Text(text = "Hello")
+                    Text(text = "Android")
+                }*/
             }
-    ) {
-        val canvasWidth = size.width.toInt()
-        val canvasHeight = size.height.toInt()
-        val imageSize = IntSize(width = canvasWidth, height = canvasHeight)
-
-        // Overlay Image to be scratched
-        drawImage(
-            image = overlayImage,
-            dstSize = imageSize
         )
-
-        movedOffset?.let {
-            currentPath.addOval(oval = Rect(it, currentPathThickness))
-        }
-
-        clipPath(path = currentPath, clipOp = ClipOp.Intersect) {
-            // Base Image after scratching
-            drawImage(
-                image = baseImage,
-                dstSize = imageSize
-            )
-        }
     }
 }
 

app/src/main/java/com/vivek/scratchcardeffect/utils/Utils.kt

@@ -0,0 +1,16 @@
+package com.vivek.scratchcardeffect.utils
+
+import android.graphics.Bitmap
+import android.graphics.Canvas
+import android.view.View
+
+fun View.takeScreenShot() : Bitmap {
+    val bitmap = Bitmap.createBitmap(
+        this.width,
+        this.height,
+        Bitmap.Config.ARGB_8888
+    )
+    val canvas = Canvas(bitmap)
+    this.draw(canvas)
+    return bitmap
+}

build.gradle

@@ -9,7 +9,7 @@ buildscript {
     }
     dependencies {
         classpath 'com.android.tools.build:gradle:7.0.3'
-        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:1.5.21"
+        classpath 'org.jetbrains.kotlin:kotlin-gradle-plugin:1.5.21'
 
         // NOTE: Do not place your application dependencies here; they belong
         // in the individual module build.gradle files

scratchview/.gitignore

@@ -0,0 +1 @@
+/build

scratchview/build.gradle

@@ -0,0 +1,54 @@
+plugins {
+    id 'com.android.library'
+    id 'org.jetbrains.kotlin.android'
+}
+
+android {
+    compileSdk 31
+
+    defaultConfig {
+        minSdk 21
+        targetSdk 31
+
+        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
+        consumerProguardFiles "consumer-rules.pro"
+    }
+
+    buildTypes {
+        release {
+            minifyEnabled false
+            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
+        }
+    }
+    compileOptions {
+        sourceCompatibility JavaVersion.VERSION_1_8
+        targetCompatibility JavaVersion.VERSION_1_8
+    }
+    kotlinOptions {
+        jvmTarget = '1.8'
+        useIR = true
+    }
+    buildFeatures {
+        compose true
+    }
+    composeOptions {
+        kotlinCompilerExtensionVersion compose_version
+        kotlinCompilerVersion '1.5.21'
+    }
+}
+
+dependencies {
+
+    implementation 'androidx.core:core-ktx:1.6.0'
+    implementation 'androidx.appcompat:appcompat:1.3.1'
+    implementation 'com.google.android.material:material:1.4.0'
+    testImplementation 'junit:junit:4.13.2'
+    androidTestImplementation 'androidx.test.ext:junit:1.1.3'
+    androidTestImplementation 'androidx.test.espresso:espresso-core:3.4.0'
+
+    implementation "androidx.compose.ui:ui:$compose_version"
+    implementation "androidx.compose.material:material:$compose_version"
+    implementation "androidx.compose.ui:ui-tooling-preview:$compose_version"
+    implementation 'androidx.lifecycle:lifecycle-runtime-ktx:2.3.1'
+    implementation 'androidx.activity:activity-compose:1.3.1'
+}

scratchview/proguard-rules.pro

@@ -0,0 +1,21 @@
+# Add project specific ProGuard rules here.
+# You can control the set of applied configuration files using the
+# proguardFiles setting in build.gradle.
+#
+# For more details, see
+#   http://developer.android.com/guide/developing/tools/proguard.html
+
+# If your project uses WebView with JS, uncomment the following
+# and specify the fully qualified class name to the JavaScript interface
+# class:
+#-keepclassmembers class fqcn.of.javascript.interface.for.webview {
+#   public *;
+#}
+
+# Uncomment this to preserve the line number information for
+# debugging stack traces.
+#-keepattributes SourceFile,LineNumberTable
+
+# If you keep the line number information, uncomment this to
+# hide the original source file name.
+#-renamesourcefileattribute SourceFile

scratchview/src/androidTest/java/com/vivek/scratchview/ExampleInstrumentedTest.kt

@@ -0,0 +1,24 @@
+package com.vivek.scratchview
+
+import androidx.test.platform.app.InstrumentationRegistry
+import androidx.test.ext.junit.runners.AndroidJUnit4
+
+import org.junit.Test
+import org.junit.runner.RunWith
+
+import org.junit.Assert.*
+
+/**
+ * Instrumented test, which will execute on an Android device.
+ *
+ * See [testing documentation](http://d.android.com/tools/testing).
+ */
+@RunWith(AndroidJUnit4::class)
+class ExampleInstrumentedTest {
+    @Test
+    fun useAppContext() {
+        // Context of the app under test.
+        val appContext = InstrumentationRegistry.getInstrumentation().targetContext
+        assertEquals("com.vivek.scratchview.test", appContext.packageName)
+    }
+}

scratchview/src/main/AndroidManifest.xml

@@ -0,0 +1,5 @@
+<?xml version="1.0" encoding="utf-8"?>
+<manifest xmlns:android="http://schemas.android.com/apk/res/android"
+    package="com.vivek.scratchview">
+
+</manifest>

scratchview/src/main/java/com/vivek/scratchview/Capturable.kt

@@ -0,0 +1,50 @@
+package com.vivek.scratchview
+
+import android.graphics.Bitmap
+import androidx.compose.material.MaterialTheme
+import androidx.compose.material.Surface
+import androidx.compose.runtime.*
+import androidx.compose.ui.platform.ComposeView
+import androidx.compose.ui.platform.LocalContext
+import androidx.compose.ui.viewinterop.AndroidView
+import androidx.core.view.drawToBitmap
+
+/**
+ * Adds ability to capture the [Composable] component in the form of [Bitmap]
+ *
+ * @param captureRequestKey Unique key for capture request
+ * @param onBitmapCaptured Callback providing captured [Bitmap] of a [content]
+ * @param content Composable content to be captured
+ */
+@Composable
+fun Capturable(
+    captureRequestKey: Any? = null,
+    onBitmapCaptured: (Bitmap) -> Unit,
+    content: @Composable () -> Unit
+) {
+    val latestCapturedCallback by rememberUpdatedState(onBitmapCaptured)
+
+    val context = LocalContext.current
+    val view = remember { ComposeView(context) }
+
+    AndroidView(
+        factory = {
+            view.apply {
+                setContent {
+                    Surface(color = MaterialTheme.colors.background) {
+                        content()
+                    }
+                }
+            }
+        }
+    )
+
+    // If key is changed it means it's requested to capture a Bitmap
+    LaunchedEffect(captureRequestKey) {
+        if (captureRequestKey != null) {
+            view.post {
+                latestCapturedCallback(view.drawToBitmap())
+            }
+        }
+    }
+}