Implement configuration for image loading

We support just two variables in the configuration: gravity and width.
Image will be place left, center or right aligned, and width will be
WRAP_CONTENT or MATCH_PARENT

library-image-loader/src/main/java/ru/noties/markwon/il/AsyncDrawableLoader.java

@@ -36,6 +36,7 @@ import okhttp3.Response;
 import okhttp3.ResponseBody;
 import pl.droidsonroids.gif.GifDrawable;
 import ru.noties.markwon.spans.AsyncDrawable;
+import ru.noties.markwon.spans.configuration.image.ImageConfig;
 
 public class AsyncDrawableLoader implements AsyncDrawable.Loader {
 
@@ -58,6 +59,7 @@ public class AsyncDrawableLoader implements AsyncDrawable.Loader {
     private final ExecutorService executorService;
     private final Handler mainThread;
     private final Drawable errorDrawable;
+    private final ImageConfig imageConfig;
 
     private final Map<String, Future<?>> requests;
 
@@ -67,6 +69,7 @@ public class AsyncDrawableLoader implements AsyncDrawable.Loader {
         this.executorService = builder.executorService;
         this.mainThread = new Handler(Looper.getMainLooper());
         this.errorDrawable = builder.errorDrawable;
+        this.imageConfig = builder.imageConfig;
         this.requests = new HashMap<>(3);
     }
 
@@ -146,7 +149,7 @@ public class AsyncDrawableLoader implements AsyncDrawable.Loader {
                         public void run() {
                             final AsyncDrawable asyncDrawable = reference.get();
                             if (asyncDrawable != null && asyncDrawable.isAttached()) {
-                                asyncDrawable.setResult(out);
+                                asyncDrawable.setResult(out, imageConfig);
                             }
                         }
                     });
@@ -345,6 +348,7 @@ public class AsyncDrawableLoader implements AsyncDrawable.Loader {
         private Resources resources;
         private ExecutorService executorService;
         private Drawable errorDrawable;
+        private ImageConfig imageConfig;
 
         public Builder client(@NonNull OkHttpClient client) {
             this.client = client;
@@ -366,6 +370,11 @@ public class AsyncDrawableLoader implements AsyncDrawable.Loader {
             return this;
         }
 
+        public Builder imageConfig(ImageConfig imageConfig) {
+            this.imageConfig = imageConfig;
+            return this;
+        }
+
         public AsyncDrawableLoader build() {
             if (client == null) {
                 client = new OkHttpClient();
@@ -377,6 +386,9 @@ public class AsyncDrawableLoader implements AsyncDrawable.Loader {
                 // we will use executor from okHttp
                 executorService = client.dispatcher().executorService();
             }
+            if(imageConfig == null){
+                imageConfig = new ImageConfig();
+            }
             return new AsyncDrawableLoader(this);
         }
     }

library/src/main/java/ru/noties/markwon/spans/AsyncDrawable.java

@@ -12,25 +12,26 @@ import android.support.annotation.Nullable;
 
 import ru.noties.markwon.renderer.html.ImageSize;
 import ru.noties.markwon.renderer.html.ImageSizeResolver;
+import ru.noties.markwon.spans.configuration.image.ImageConfig;
+import ru.noties.markwon.spans.configuration.image.ImageGravity;
+import ru.noties.markwon.spans.configuration.image.ImageWidth;
 
 public class AsyncDrawable extends Drawable {
 
-    public interface Loader {
-
-        void load(@NonNull String destination, @NonNull AsyncDrawable drawable);
-
-        void cancel(@NonNull String destination);
-    }
-
     private final String destination;
+
     private final Loader loader;
+
     private final ImageSize imageSize;
+
     private final ImageSizeResolver imageSizeResolver;
 
     private Drawable result;
+
     private Callback callback;
 
     private int canvasWidth;
+
     private float textSize;
 
     public AsyncDrawable(@NonNull String destination, @NonNull Loader loader) {
@@ -91,7 +92,7 @@ public class AsyncDrawable extends Drawable {
         }
     }
 
-    public void setResult(@NonNull Drawable result) {
+    public void setResult(@NonNull Drawable result, @NonNull ImageConfig imageConfig) {
 
         // if we have previous one, detach it
         if (this.result != null) {
@@ -101,7 +102,7 @@ public class AsyncDrawable extends Drawable {
         this.result = result;
         this.result.setCallback(callback);
 
-        final Rect bounds = resolveBounds();
+        final Rect bounds = resolveBounds(imageConfig);
         result.setBounds(bounds);
         setBounds(bounds);
 
@@ -168,10 +169,11 @@ public class AsyncDrawable extends Drawable {
     }
 
     /**
+     * @param imageConfig
      * @since 1.0.1
      */
     @NonNull
-    private Rect resolveBounds() {
+    private Rect resolveBounds(@NonNull ImageConfig imageConfig) {
         final Rect rect;
         if (imageSizeResolver == null
             || imageSize == null) {
@@ -179,6 +181,43 @@ public class AsyncDrawable extends Drawable {
         } else {
             rect = imageSizeResolver.resolveImageSize(imageSize, result.getBounds(), canvasWidth, textSize);
         }
-        return rect;
+        return adjustBounds(rect, imageConfig);
+    }
+
+    private Rect adjustBounds(Rect bounds, ImageConfig imageConfig) {
+        final ImageGravity gravity = imageConfig.getGravity();
+        final ImageWidth imageWidth = imageConfig.getImageWidth();
+
+        if (imageWidth == ImageWidth.MatchParent) {
+            final float aspectRatio = (float) bounds.width() / bounds.height();
+            bounds.left = 0;
+            bounds.right = canvasWidth;
+            bounds.bottom = (int) (bounds.top + bounds.height() * aspectRatio);
+        } else {
+            switch (gravity) {
+                case Left:
+                    //left is unchanged
+                    break;
+                case Right:
+                    bounds.left = canvasWidth - bounds.width();
+                    bounds.right = canvasWidth;
+                    break;
+                case Center:
+                    final int center = canvasWidth / 2;
+                    final int imageRadius = bounds.width() / 2;
+                    bounds.left = center - imageRadius;
+                    bounds.right = center + imageRadius;
+                    break;
+            }
+        }
+
+        return bounds;
+    }
+
+    public interface Loader {
+
+        void load(@NonNull String destination, @NonNull AsyncDrawable drawable);
+
+        void cancel(@NonNull String destination);
     }
 }

library/src/main/java/ru/noties/markwon/spans/configuration/image/ImageConfig.kt

@@ -0,0 +1,25 @@
+package ru.noties.markwon.spans.configuration.image
+
+/**
+ * Configuration for images
+ *
+ * Can set two parameters: image width style and horizontal gravity
+ *
+ * @property imageWidth Width of the image to be displayed (WRAP_CONTENT or MATCH_PARENT)
+ * @property gravity Horizontal gravity (left, right or center)
+ */
+class ImageConfig @JvmOverloads constructor(
+        val imageWidth: ImageWidth = ImageWidth.Wrap,
+        val gravity: ImageGravity = ImageGravity.Left
+)
+
+enum class ImageGravity {
+    Left,
+    Center,
+    Right
+}
+
+enum class ImageWidth {
+    Wrap,
+    MatchParent
+}