[ADD/#28] CustomShadow 구현

core/build.gradle.kts

@@ -60,6 +60,7 @@ dependencies {
 
     // Compose Preview
     debugImplementation(libs.compose.ui.tooling)
+    implementation(libs.androidx.ui.tooling.preview)
 
     // Test Dependency
     testImplementation(libs.junit)

core/src/main/java/com/terning/core/extension/Modifier.kt

@@ -1,14 +1,25 @@
 package com.terning.core.extension
 
 import android.annotation.SuppressLint
+import android.graphics.BlurMaskFilter
 import androidx.compose.foundation.clickable
 import androidx.compose.foundation.gestures.detectTapGestures
 import androidx.compose.foundation.interaction.MutableInteractionSource
+import androidx.compose.runtime.Composable
 import androidx.compose.runtime.remember
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.composed
+import androidx.compose.ui.draw.drawBehind
 import androidx.compose.ui.focus.FocusManager
+import androidx.compose.ui.graphics.Color
+import androidx.compose.ui.graphics.Paint
+import androidx.compose.ui.graphics.drawscope.drawIntoCanvas
+import androidx.compose.ui.graphics.toArgb
 import androidx.compose.ui.input.pointer.pointerInput
+import androidx.compose.ui.platform.LocalDensity
+import androidx.compose.ui.unit.Dp
+import androidx.compose.ui.unit.dp
+import com.terning.core.designsystem.theme.Grey200
 
 @SuppressLint("ModifierFactoryUnreferencedReceiver")
 inline fun Modifier.noRippleClickable(crossinline onClick: () -> Unit): Modifier = composed {
@@ -25,3 +36,55 @@ fun Modifier.addFocusCleaner(focusManager: FocusManager): Modifier {
         })
     }
 }
+
+@Composable
+fun Modifier.customShadow(
+    color: Color = Grey200,
+    shadowRadius: Dp = 0.dp,
+    shadowWidth: Dp = 2.dp,
+    offsetX: Dp = 0.dp,
+    offsetY: Dp = 0.dp,
+) = composed {
+    val paint: Paint = remember { Paint() }
+    val density = LocalDensity.current
+    val radius = shadowRadius + shadowWidth
+    val blurRadiusPx = with(density) { radius.toPx() }
+    val maskFilter = remember {
+        BlurMaskFilter(blurRadiusPx, BlurMaskFilter.Blur.NORMAL)
+    }
+    drawBehind {
+        drawIntoCanvas { canvas ->
+            val frameworkPaint = paint.asFrameworkPaint()
+            if (radius != 0.dp) {
+                frameworkPaint.maskFilter = maskFilter
+            }
+            frameworkPaint.color = color.toArgb()
+
+            val leftPixel = offsetX.toPx()
+            val topPixel = offsetY.toPx()
+            val rightPixel = size.width + leftPixel
+            val bottomPixel = size.height + topPixel
+
+            if (radius > 0.dp) {
+                val radiusPx = radius.toPx()
+                canvas.drawRoundRect(
+                    left = leftPixel,
+                    top = topPixel,
+                    right = rightPixel,
+                    bottom = bottomPixel,
+                    radiusX = radiusPx,
+                    radiusY = radiusPx,
+                    paint = paint,
+                )
+            } else {
+                canvas.drawRect(
+                    left = leftPixel,
+                    top = topPixel,
+                    right = rightPixel,
+                    bottom = bottomPixel,
+                    paint = paint,
+                )
+            }
+        }
+    }
+}