Bug 1878599 - Allow to insert text on text control from dropping external application on Geckoview. r=masayuki,geckoview-reviewers,owlish

Android's drag and drop API will set a dropped item on `drop` event. But other
platforms will be set during `dragstart` event.

Editor's drag and drop event listener checks current dropped item on some
events such as `dragover` event in
`EditorEventListener::DragEventHasSupportingData`. Since there is no way to
set dropped item on `dragover` event, GeckoView will set temporary dropped
item with MIME type.

Differential Revision: https://phabricator.services.mozilla.com/D200618

mobile/android/geckoview/src/androidTest/assets/www/dnd.html

@@ -22,5 +22,6 @@
     <div id="drop" style="border: 1px solid red; width: 200px; height: 100px">
       drop
     </div>
+    <textarea id="textarea" style="width: 200px; height: 100px"></textarea>
   </body>
 </html>

mobile/android/geckoview/src/androidTest/java/org/mozilla/geckoview/test/DragAndDropTest.kt

@@ -13,6 +13,7 @@ import androidx.test.ext.junit.runners.AndroidJUnit4
 import androidx.test.filters.MediumTest
 import androidx.test.filters.SdkSuppress
 import org.hamcrest.Matchers.equalTo
+import org.json.JSONObject
 import org.junit.Test
 import org.junit.runner.RunWith
 import org.mozilla.geckoview.test.rule.GeckoSessionTestRule.WithDisplay
@@ -41,12 +42,14 @@ class DragAndDropTest : BaseSessionTest() {
             fieldY.set(dragEvent, y)
         }
 
+        val clipData = ClipData.newPlainText("label", "foo")
         if (action == DragEvent.ACTION_DROP) {
-            val clipData = ClipData.newPlainText("label", "foo")
             val fieldClipData = DragEvent::class.java.getDeclaredField("mClipData")
             fieldClipData.setAccessible(true)
             fieldClipData.set(dragEvent, clipData)
+        }
 
+        if (action != DragEvent.ACTION_DRAG_ENDED) {
             var clipDescription = clipData.getDescription()
             val fieldClipDescription = DragEvent::class.java.getDeclaredField("mClipDescription")
             fieldClipDescription.setAccessible(true)
@@ -56,6 +59,22 @@ class DragAndDropTest : BaseSessionTest() {
         return dragEvent
     }
 
+    fun sendDragEvent(startX: Float, startY: Float, endY: Float) {
+        // Android doesn't fire MotionEvent during drag and drop.
+        val dragStartEvent = createDragEvent(DragEvent.ACTION_DRAG_STARTED)
+        mainSession.panZoomController.onDragEvent(dragStartEvent)
+        val dragEnteredEvent = createDragEvent(DragEvent.ACTION_DRAG_ENTERED)
+        mainSession.panZoomController.onDragEvent(dragEnteredEvent)
+        listOf(startY, endY).forEach {
+            val dragLocationEvent = createDragEvent(DragEvent.ACTION_DRAG_LOCATION, startX, it)
+            mainSession.panZoomController.onDragEvent(dragLocationEvent)
+        }
+        val dropEvent = createDragEvent(DragEvent.ACTION_DROP, startX, endY)
+        mainSession.panZoomController.onDragEvent(dropEvent)
+        val dragEndedEvent = createDragEvent(DragEvent.ACTION_DRAG_ENDED)
+        mainSession.panZoomController.onDragEvent(dragEndedEvent)
+    }
+
     @WithDisplay(width = 300, height = 300)
     @Test
     fun dragStartTest() {
@@ -94,20 +113,42 @@ class DragAndDropTest : BaseSessionTest() {
             """.trimIndent(),
         )
 
-        // Android doesn't fire MotionEvent during drag and drop.
+        sendDragEvent(100.0F, 150.0F, 250.0F)
-        val dragStartEvent = createDragEvent(DragEvent.ACTION_DRAG_STARTED)
-        mainSession.panZoomController.onDragEvent(dragStartEvent)
-        val dragEnteredEvent = createDragEvent(DragEvent.ACTION_DRAG_ENTERED)
-        mainSession.panZoomController.onDragEvent(dragEnteredEvent)
-        listOf(150.0F, 250.0F).forEach {
-            val dragLocationEvent = createDragEvent(DragEvent.ACTION_DRAG_LOCATION, 100.0F, it)
-            mainSession.panZoomController.onDragEvent(dragLocationEvent)
-        }
-        val dropEvent = createDragEvent(DragEvent.ACTION_DROP, 100.0F, 250.0F)
-        mainSession.panZoomController.onDragEvent(dropEvent)
-        val dragEndedEvent = createDragEvent(DragEvent.ACTION_DRAG_ENDED)
-        mainSession.panZoomController.onDragEvent(dragEndedEvent)
 
         assertThat("drop event is fired correctly", promise.value as String, equalTo("foo"))
     }
+
+    @WithDisplay(width = 300, height = 500)
+    @Test
+    fun dropFromExternalToTextControlTest() {
+        mainSession.loadTestPath(DND_HTML_PATH)
+        sessionRule.waitForPageStop()
+
+        val promiseDragOver = mainSession.evaluatePromiseJS(
+            """
+          new Promise(
+              r => document.querySelector('textarea').addEventListener(
+                       'dragover',
+                       e => r({ types: e.dataTransfer.types, data: e.dataTransfer.getData('text/plain') }),
+                       { once: true }))
+            """.trimIndent(),
+        )
+
+        val promiseSetValue = mainSession.evaluatePromiseJS(
+            """
+          new Promise(
+              r => document.querySelector('textarea').addEventListener(
+                       'input',
+                       e => r(document.querySelector('textarea').value),
+                       { once: true }))
+            """.trimIndent(),
+        )
+
+        sendDragEvent(100.0F, 250.0F, 450.0F)
+
+        var value = promiseDragOver.value as JSONObject
+        assertThat("dataTransfer type is text/plain", value.getJSONArray("types").getString(0), equalTo("text/plain"))
+        assertThat("dataTransfer set empty string during dragover event", value.getString("data"), equalTo(""))
+        assertThat("input event is fired correctly", promiseSetValue.value as String, equalTo("foo"))
+    }
 }

mobile/android/geckoview/src/main/java/org/mozilla/gecko/GeckoDragAndDrop.java

@@ -29,6 +29,10 @@ public class GeckoDragAndDrop {
   /** The drag/drop data is nsITransferable and stored into nsDragService. */
   private static final String MIMETYPE_NATIVE = "application/x-moz-draganddrop";
 
+  private static final String[] sSupportedMimeType = {
+    MIMETYPE_NATIVE, ClipDescription.MIMETYPE_TEXT_HTML, ClipDescription.MIMETYPE_TEXT_PLAIN
+  };
+
   private static ClipData sDragClipData;
   private static float sX;
   private static float sY;
@@ -71,6 +75,12 @@ public class GeckoDragAndDrop {
       this.text = null;
     }
 
+    @WrapForJNI(skip = true)
+    public DropData(final String mimeType) {
+      this.mimeType = mimeType;
+      this.text = "";
+    }
+
     @WrapForJNI(skip = true)
     public DropData(final String mimeType, final String text) {
       this.mimeType = mimeType;
@@ -133,7 +143,7 @@ public class GeckoDragAndDrop {
   }
 
   /**
-   * Create drop data by DragEvent.ACTION_DROP. This ClipData will be stored into nsDragService as
+   * Create drop data by DragEvent. This ClipData will be stored into nsDragService as
    * nsITransferable. If this type has MIMETYPE_NATIVE, this is already stored into nsDragService.
    * So do nothing.
    *
@@ -141,15 +151,27 @@ public class GeckoDragAndDrop {
    * @return DropData that is from ClipData. If null, no data that we can convert to Gecko's type.
    */
   public static DropData createDropData(final DragEvent event) {
+    final ClipDescription description = event.getClipDescription();
+
+    if (event.getAction() == DragEvent.ACTION_DRAG_ENTERED) {
+      // Android API cannot get real dragging item until drop event. So we set MIME type only.
+      for (final String mimeType : sSupportedMimeType) {
+        if (description.hasMimeType(mimeType)) {
+          return new DropData(mimeType);
+        }
+      }
+      return null;
+    }
+
     if (event.getAction() != DragEvent.ACTION_DROP) {
       return null;
     }
+
     final ClipData clip = event.getClipData();
     if (clip == null || clip.getItemCount() == 0) {
       return null;
     }
 
-    final ClipDescription description = event.getClipDescription();
     if (description.hasMimeType(MIMETYPE_NATIVE)) {
       if (DEBUG) {
         Log.d(LOGTAG, "Drop data is native nsITransferable. Do nothing");

widget/android/nsDragService.cpp

@@ -257,10 +257,6 @@ void nsDragService::SetDropData(
   }
 
   nsString buffer(aDropData->Text()->ToString());
-  if (buffer.IsEmpty()) {
-    dragService->SetData(nullptr);
-    return;
-  }
   nsCOMPtr<nsISupports> wrapper;
   nsPrimitiveHelpers::CreatePrimitiveForData(
       mime, buffer.get(), buffer.Length() * 2, getter_AddRefs(wrapper));

widget/android/nsWindow.cpp

@@ -2636,6 +2636,10 @@ void nsWindow::OnDragEvent(int32_t aAction, int64_t aTime, float aX, float aY,
 
   if (message == eDragEnter) {
     dragService->StartDragSession();
+    // For compatibility, we have to set temporary data.
+    auto dropData =
+        mozilla::java::GeckoDragAndDrop::DropData::Ref::From(aDropData);
+    nsDragService::SetDropData(dropData);
   }
 
   nsCOMPtr<nsIDragSession> dragSession;