Fix #1020: Rendering of Svg images from server.

app/src/sharedTest/java/org/oppia/app/parser/HtmlParserTest.kt

@@ -151,16 +151,6 @@ class HtmlParserTest {
     assertThat(bulletSpan1).isNotNull()
   }
 
-  class FakeImageLoader : ImageLoader {
-    override fun load(imageUrl: String, target: CustomTarget<Bitmap>) {
-
-    }
-  }
-
-  private fun getResources(): Resources {
-    return ApplicationProvider.getApplicationContext<Context>().resources
-  }
-
   @Qualifier annotation class TestDispatcher
 
   // TODO(#89): Move this to a common test application component.

utility/build.gradle

@@ -47,6 +47,7 @@ dependencies {
   implementation(
       'androidx.appcompat:appcompat:1.0.2',
       'androidx.lifecycle:lifecycle-livedata-ktx:2.2.0-alpha03',
+      'com.caverock:androidsvg-aar:1.4',
       'com.github.bumptech.glide:glide:4.9.0',
       'com.google.dagger:dagger:2.24',
       "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version",

utility/src/main/java/org/oppia/util/parser/GlideImageLoader.kt

@@ -2,7 +2,10 @@ package org.oppia.util.parser
 
 import android.content.Context
 import android.graphics.Bitmap
+import android.graphics.Picture
 import com.bumptech.glide.Glide
+import com.bumptech.glide.load.engine.DiskCacheStrategy
+import com.bumptech.glide.request.RequestOptions
 import com.bumptech.glide.request.target.CustomTarget
 import javax.inject.Inject
 import org.oppia.util.caching.AssetRepository
@@ -14,6 +17,7 @@ class GlideImageLoader @Inject constructor(
   @CacheAssetsLocally private val cacheAssetsLocally: Boolean,
   private val assetRepository: AssetRepository
 ) : ImageLoader {
+
   override fun load(imageUrl: String, target: CustomTarget<Bitmap>) {
     val model: Any = if (cacheAssetsLocally) {
       object : ImageAssetFetcher {
@@ -27,4 +31,22 @@ class GlideImageLoader @Inject constructor(
       .load(model)
       .into(target)
   }
+
+  override fun loadSvg(imageUrl: String, target: CustomTarget<Picture>) {
+    val model: Any = if (cacheAssetsLocally) {
+      object : ImageAssetFetcher {
+        override fun fetchImage(): ByteArray = assetRepository.loadRemoteBinaryAsset(imageUrl)()
+
+        override fun getImageIdentifier(): String = imageUrl
+      }
+    } else imageUrl
+
+    // TODO(#45): Ensure the image caching flow is properly hooked up.
+    Glide.with(context)
+      .`as`(Picture::class.java)
+      .fitCenter()
+      .apply(RequestOptions.diskCacheStrategyOf(DiskCacheStrategy.NONE))
+      .load(model)
+      .into(target)
+  }
 }

utility/src/main/java/org/oppia/util/parser/ImageLoader.kt

@@ -1,10 +1,13 @@
 package org.oppia.util.parser
 
 import android.graphics.Bitmap
+import android.graphics.Picture
 import com.bumptech.glide.request.target.CustomTarget
 
 /** Loads an image from the provided URL into the specified target, optionally caching it. */
 interface ImageLoader {
 
   fun load(imageUrl: String, target: CustomTarget<Bitmap>)
+
+  fun loadSvg(imageUrl: String, target: CustomTarget<Picture>)
 }

utility/src/main/java/org/oppia/util/parser/RepositoryGlideModule.kt

@@ -1,17 +1,22 @@
 package org.oppia.util.parser
 
 import android.content.Context
+import android.graphics.Picture
 import com.bumptech.glide.Glide
 import com.bumptech.glide.Registry
 import com.bumptech.glide.annotation.GlideModule
 import com.bumptech.glide.module.AppGlideModule
+import com.caverock.androidsvg.SVG
 import java.io.InputStream
 import org.oppia.util.caching.AssetRepository
 
 /** Custom [AppGlideModule] to enable loading images from [AssetRepository] via Glide. */
 @GlideModule
 class RepositoryGlideModule : AppGlideModule() {
   override fun registerComponents(context: Context, glide: Glide, registry: Registry) {
-    registry.prepend(ImageAssetFetcher::class.java, InputStream::class.java, RepositoryModelLoader.Factory())
+    // TODO(#1039): Introduce custom type OppiaImage for rendering Bitmap and Svg.
+    registry.register(SVG::class.java, Picture::class.java, SvgDrawableTranscoder())
+      .append(InputStream::class.java, SVG::class.java, SvgDecoder())
+      .append(ImageAssetFetcher::class.java, InputStream::class.java, RepositoryModelLoader.Factory())
   }
 }

utility/src/main/java/org/oppia/util/parser/SvgDecoder.kt

@@ -0,0 +1,31 @@
+package org.oppia.util.parser
+
+import com.bumptech.glide.load.Options
+import com.bumptech.glide.load.ResourceDecoder
+import com.bumptech.glide.load.engine.Resource
+import com.bumptech.glide.load.resource.SimpleResource
+import com.caverock.androidsvg.SVG
+import com.caverock.androidsvg.SVGParseException
+import java.io.IOException
+import java.io.InputStream
+
+/** Decodes an SVG internal representation from an {@link InputStream}. */
+class SvgDecoder : ResourceDecoder<InputStream?, SVG?> {
+
+  override fun handles(source: InputStream, options: Options): Boolean {
+    return true
+  }
+
+  override fun decode(
+    source: InputStream,
+    width: Int,
+    height: Int,
+    options: Options
+  ): Resource<SVG?>? {
+    return try {
+      SimpleResource(source.use { SVG.getFromInputStream(it) })
+    } catch (ex: SVGParseException) {
+      throw IOException("Cannot load SVG from stream", ex)
+    }
+  }
+}

utility/src/main/java/org/oppia/util/parser/SvgDrawableTranscoder.kt

@@ -0,0 +1,20 @@
+package org.oppia.util.parser
+
+import android.graphics.Picture
+import com.bumptech.glide.load.Options
+import com.bumptech.glide.load.engine.Resource
+import com.bumptech.glide.load.resource.SimpleResource
+import com.bumptech.glide.load.resource.transcode.ResourceTranscoder
+import com.caverock.androidsvg.SVG
+
+/** SvgDrawableTranscoder converts SVG to PictureDrawable. */
+class SvgDrawableTranscoder : ResourceTranscoder<SVG?, Picture?> {
+  override fun transcode(
+    toTranscode: Resource<SVG?>,
+    options: Options
+  ): Resource<Picture?>? {
+    val svg: SVG = toTranscode.get()
+    val picture = svg.renderToPicture()
+    return SimpleResource(picture)
+  }
+}

utility/src/main/java/org/oppia/util/parser/UrlImageParser.kt

@@ -3,9 +3,11 @@ package org.oppia.util.parser
 import android.content.Context
 import android.graphics.Bitmap
 import android.graphics.Canvas
+import android.graphics.Picture
 import android.graphics.Rect
 import android.graphics.drawable.BitmapDrawable
 import android.graphics.drawable.Drawable
+import android.graphics.drawable.PictureDrawable
 import android.text.Html
 import android.view.ViewTreeObserver
 import android.widget.TextView
@@ -36,21 +38,41 @@ class UrlImageParser private constructor(
   override fun getDrawable(urlString: String): Drawable {
     val imageUrl = String.format(imageDownloadUrlTemplate, entityType, entityId, urlString)
     val urlDrawable = UrlDrawable()
-    val target = BitmapTarget(urlDrawable)
-    imageLoader.load(
-      gcsPrefix + gcsResource + imageUrl,
-      target
-    )
+    // TODO(#1039): Introduce custom type OppiaImage for rendering Bitmap and Svg.
+    if (imageUrl.endsWith("svg", ignoreCase = true)) {
+      val target = SvgTarget(urlDrawable)
+      imageLoader.loadSvg(
+        gcsPrefix + gcsResource + imageUrl,
+        target
+      )
+    } else {
+      val target = BitmapTarget(urlDrawable)
+      imageLoader.load(
+        gcsPrefix + gcsResource + imageUrl,
+        target
+      )
+    }
     return urlDrawable
   }
 
-  private inner class BitmapTarget(private val urlDrawable: UrlDrawable) : CustomTarget<Bitmap>() {
+  private inner class BitmapTarget(urlDrawable: UrlDrawable) : CustomImageTarget<Bitmap>(
+    urlDrawable, { resource -> BitmapDrawable(context.resources, resource) }
+  )
+
+  private inner class SvgTarget(urlDrawable: UrlDrawable) : CustomImageTarget<Picture>(
+    urlDrawable, { resource -> PictureDrawable(resource) }
+  )
+
+  private open inner class CustomImageTarget<T>(
+    private val urlDrawable: UrlDrawable,
+    private val drawableFactory: (T) -> Drawable
+  ) : CustomTarget<T>() {
     override fun onLoadCleared(placeholder: Drawable?) {
       // No resources to clear.
     }
 
-    override fun onResourceReady(resource: Bitmap, transition: Transition<in Bitmap>?) {
-      val drawable = BitmapDrawable(context.resources, resource)
+    override fun onResourceReady(resource: T, transition: Transition<in T>?) {
+      val drawable = drawableFactory(resource)
       htmlContentTextView.post {
         htmlContentTextView.width {
           val drawableHeight = drawable.intrinsicHeight
@@ -60,7 +82,8 @@ class UrlImageParser private constructor(
           } else {
             0
           }
-          val rect = Rect(initialDrawableMargin, 0, drawableWidth + initialDrawableMargin, drawableHeight)
+          val rect =
+            Rect(initialDrawableMargin, 0, drawableWidth + initialDrawableMargin, drawableHeight)
           drawable.bounds = rect
           urlDrawable.bounds = rect
           urlDrawable.drawable = drawable