1 files changed, 60 insertions, 0 deletions
diff --git a/library/src/main/java/com/davemorrissey/labs/subscaleview/decoder/ImageRegionDecoder.java b/library/src/main/java/com/davemorrissey/labs/subscaleview/decoder/ImageRegionDecoder.java
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index 0000000..22ee955
--- /dev/null
+++ b/library/src/main/java/com/davemorrissey/labs/subscaleview/decoder/ImageRegionDecoder.java
@@ -0,0 +1,60 @@
+package com.davemorrissey.labs.subscaleview.decoder;
+
+import android.content.Context;
+import android.graphics.Bitmap;
+import android.graphics.Point;
+import android.graphics.Rect;
+import android.net.Uri;
+
+/**
+ * Interface for image decoding classes, allowing the default {@link android.graphics.BitmapRegionDecoder}
+ * based on the Skia library to be replaced with a custom class.
+ */
+public interface ImageRegionDecoder {
+
+    /**
+     * Initialise the decoder. When possible, perform initial setup work once in this method. The
+     * dimensions of the image must be returned. The URI can be in one of the following formats:
+     * <br>
+     * File: <code>file:///scard/picture.jpg</code>
+     * <br>
+     * Asset: <code>file:///android_asset/picture.png</code>
+     * <br>
+     * Resource: <code>android.resource://com.example.app/drawable/picture</code>
+     * @param context Application context. A reference may be held, but must be cleared on recycle.
+     * @param uri URI of the image.
+     * @return Dimensions of the image.
+     * @throws Exception if initialisation fails.
+     */
+    Point init(Context context, Uri uri) throws Exception;
+
+    /**
+     * <p>
+     * Decode a region of the image with the given sample size. This method is called off the UI
+     * thread so it can safely load the image on the current thread. It is called from
+     * {@link android.os.AsyncTask}s running in an executor that may have multiple threads, so
+     * implementations must be thread safe. Adding <code>synchronized</code> to the method signature
+     * is the simplest way to achieve this, but bear in mind the {@link #recycle()} method can be
+     * called concurrently.
+     * </p><p>
+     * See {@link SkiaImageRegionDecoder} and {@link SkiaPooledImageRegionDecoder} for examples of
+     * internal locking and synchronization.
+     * </p>
+     * @param sRect Source image rectangle to decode.
+     * @param sampleSize Sample size.
+     * @return The decoded region. It is safe to return null if decoding fails.
+     */
+    Bitmap decodeRegion(Rect sRect, int sampleSize);
+
+    /**
+     * Status check. Should return false before initialisation and after recycle.
+     * @return true if the decoder is ready to be used.
+     */
+    boolean isReady();
+
+    /**
+     * This method will be called when the decoder is no longer required. It should clean up any resources still in use.
+     */
+    void recycle();
+
+}