Added isOpaque to MagickImage.

src/magick-image.ts

@@ -100,6 +100,13 @@ export interface IMagickImage extends IDisposable {
     readonly height: number;
     interpolate: PixelInterpolateMethod;
     readonly interlace: Interlace;
+
+    /**
+     * Gets a value indicating whether none of the pixels in the image have an alpha value other
+     * than OpaqueAlpha (QuantumRange).
+     */
+    readonly isOpaque: boolean;
+
     label: string | null;
     orientation: OrientationType;
     page: MagickGeometry;
@@ -509,6 +516,12 @@ export class MagickImage extends NativeInstance implements IMagickImage {
 
     get interlace(): Interlace { return ImageMagick._api._MagickImage_Interlace_Get(this._instance); }
 
+    get isOpaque(): boolean {
+        return Exception.usePointer(exception => {
+            return this.toBool(ImageMagick._api._MagickImage_IsOpaque_Get(this._instance, exception));
+        });
+    }
+
     get interpolate(): PixelInterpolateMethod { return ImageMagick._api._MagickImage_Interpolate_Get(this._instance); }
     set interpolate(value: PixelInterpolateMethod) { ImageMagick._api._MagickImage_Interpolate_Set(this._instance, value); }
 

tests/magick-image/is-opaque.spec.ts

@@ -0,0 +1,18 @@
+// Copyright Dirk Lemstra https://github.com/dlemstra/magick-wasm.
+// Licensed under the Apache License, Version 2.0.
+
+import { TestImages } from '@test/test-images';
+
+describe('MagickImage#hasAlpha', () => {
+    it('should return true when the image is fully opaque', async () => {
+        TestImages.imageMagickJpg.use(image => {
+            expect(image.isOpaque).toBe(true);
+        });
+    });
+
+    it('should return false when the image contains a (semi) transparent pixel', async () => {
+        TestImages.redPng.use(image => {
+            expect(image.isOpaque).toBe(false);
+        });
+    });
+});