add ImageScope

Author: SmartToolFactory

image/src/main/java/com/smarttoolfactory/image/ImageScope.kt

@@ -0,0 +1,123 @@
+package com.smarttoolfactory.image
+
+import android.graphics.Bitmap
+import androidx.compose.foundation.Canvas
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.Stable
+import androidx.compose.runtime.remember
+import androidx.compose.ui.graphics.Canvas
+import androidx.compose.ui.graphics.ImageBitmap
+import androidx.compose.ui.graphics.asAndroidBitmap
+import androidx.compose.ui.graphics.asImageBitmap
+import androidx.compose.ui.layout.ContentScale
+import androidx.compose.ui.unit.Constraints
+import androidx.compose.ui.unit.Density
+import androidx.compose.ui.unit.Dp
+import androidx.compose.ui.unit.IntRect
+
+
+/**
+ * Receiver scope being used by the children parameter of [ImageWithConstraints]
+ */
+@Stable
+interface ImageScope {
+    /**
+     * The constraints given by the parent layout in pixels.
+     *
+     * Use [minWidth], [maxWidth], [minHeight] or [maxHeight] if you need value in [Dp].
+     */
+    val constraints: Constraints
+
+    /**
+     * The minimum width in [Dp].
+     *
+     * @see constraints for the values in pixels.
+     */
+    val minWidth: Dp
+
+    /**
+     * The maximum width in [Dp].
+     *
+     * @see constraints for the values in pixels.
+     */
+    val maxWidth: Dp
+
+    /**
+     * The minimum height in [Dp].
+     *
+     * @see constraints for the values in pixels.
+     */
+    val minHeight: Dp
+
+    /**
+     * The maximum height in [Dp].
+     *
+     * @see constraints for the values in pixels.
+     */
+    val maxHeight: Dp
+
+    /**
+     * Width of area inside BoxWithConstraints that is scaled based on [ContentScale]
+     * This is width of the [Canvas] draw draws [ImageBitmap]
+     */
+    val imageWidth: Dp
+
+    /**
+     * Height of area inside BoxWithConstraints that is scaled based on [ContentScale]
+     * This is height of the [Canvas] draw draws [ImageBitmap]
+     */
+    val imageHeight: Dp
+
+    /**
+     * [IntRect] that covers boundaries of [ImageBitmap]
+     */
+    val rect: IntRect
+}
+
+internal data class ImageScopeImpl(
+    private val density: Density,
+    override val constraints: Constraints,
+    override val imageWidth: Dp,
+    override val imageHeight: Dp,
+    override val rect: IntRect,
+) : ImageScope {
+
+    override val minWidth: Dp get() = with(density) { constraints.minWidth.toDp() }
+
+    override val maxWidth: Dp
+        get() = with(density) {
+            if (constraints.hasBoundedWidth) constraints.maxWidth.toDp() else Dp.Infinity
+        }
+
+    override val minHeight: Dp get() = with(density) { constraints.minHeight.toDp() }
+
+    override val maxHeight: Dp
+        get() = with(density) {
+            if (constraints.hasBoundedHeight) constraints.maxHeight.toDp() else Dp.Infinity
+        }
+}
+
+@Composable
+internal fun ImageScope.getScaledImageBitmap(
+    bitmap: ImageBitmap,
+    contentScale: ContentScale
+): ImageBitmap {
+
+    val scaledBitmap =
+        remember(bitmap, rect, imageWidth, imageHeight, contentScale) {
+            // This bitmap is needed when we crop original bitmap due to scaling mode
+            // and aspect ratio result of cropping
+            // We might have center section of the image after cropping, and
+            // because of that thumbLayout either should have rectangle and some
+            // complex calculation for srcOffset and srcSide along side with touch offset
+            // or we can create a new bitmap that only contains area bounded by rectangle
+            Bitmap.createBitmap(
+                bitmap.asAndroidBitmap(),
+                rect.left,
+                rect.top,
+                rect.width,
+                rect.height
+            ).asImageBitmap()
+        }
+    return scaledBitmap
+}