Support dragging texts into Android WebView.

content/browser/android/content_view_core_impl.cc

 // Copyright 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/browser/android/content_view_core_impl.h"
 
 #include <stddef.h>
 
 #include "base/android/jni_android.h"
 #include "base/android/jni_array.h"
@@ skipping 36 matching lines @@
 #include "content/public/browser/ssl_host_state_delegate.h"
 #include "content/public/browser/web_contents.h"
 #include "content/public/common/content_client.h"
 #include "content/public/common/content_switches.h"
 #include "content/public/common/menu_item.h"
 #include "content/public/common/user_agent.h"
 #include "jni/ContentViewCore_jni.h"
 #include "third_party/WebKit/public/web/WebInputEvent.h"
 #include "ui/android/view_android.h"
 #include "ui/android/window_android.h"
+#include "ui/base/dragdrop/drop_target_event.h"
+#include "ui/base/dragdrop/os_exchange_data_provider_android.h"
 #include "ui/events/android/motion_event_android.h"
 #include "ui/gfx/android/java_bitmap.h"
 #include "ui/gfx/geometry/point_conversions.h"
 #include "ui/gfx/geometry/size_conversions.h"
 #include "ui/gfx/geometry/size_f.h"
 
 using base::android::AttachCurrentThread;
 using base::android::ConvertJavaStringToUTF16;
 using base::android::ConvertJavaStringToUTF8;
 using base::android::ConvertUTF16ToJavaString;
@@ skipping 1335 matching lines @@
                                               const JavaParamRef<jobject>& jobj,
                                               jboolean opaque) {
   if (GetRenderWidgetHostViewAndroid()) {
     if (opaque)
       GetRenderWidgetHostViewAndroid()->SetBackgroundColorToDefault();
     else
       GetRenderWidgetHostViewAndroid()->SetBackgroundColor(SK_ColorTRANSPARENT);
   }
 }
 
+void ContentViewCoreImpl::OnDragEntered(
+    JNIEnv* env,
+    const base::android::JavaParamRef<jobject>& jobj,
+    int x,
+    int y,
+    int screen_x,
+    int screen_y) {
+  WebContentsViewAndroid* wcva = static_cast<WebContentsViewAndroid*>(
+      static_cast<WebContentsImpl*>(web_contents())->GetView());
+
+  ui::OSExchangeData data(new ui::OSExchangeDataProviderAndroid());

[dcheng, 2016/02/25 01:18:49]

Will there be a followup patch to address the fact that the types are not
plumbed through?

[hush (inactive), 2016/02/25 02:40:48]

Types are sort of plumbed through. We only support "string" format for now. So
we will return true for OSExchangeData::HasString and false for other types.
Webview won't get any drag drop related events if the drop data type is not
text. (See AwContents#onDragEvent. Returning false on "ACTION_DRAG_STARTED" will
ensure there won't be any subsequence DragEvents)


Yes, there will be a followup to support dragging image file URIs into webview.

[dcheng, 2016/02/25 21:13:38]

I don't think I follow: I don't see how the types are plumbed through at all
atm. Since we don't know what the contents of the drop are yet,
OSExchangeDataProviderAndroid will be unpopulated. So PrepareDropData will
always prepare a drop data that's empty.

[hush (inactive), 2016/02/27 01:47:22]

Sorry yeah you're right. I just updated the logic here. I will set an empty
string when on DRAG_ENTERED event to indicate the data type is string.

+  ui::DropTargetEvent event(
+      data, gfx::Point(x, y), gfx::Point(screen_x, screen_y),
+      ui::DragDropTypes::DRAG_COPY);  // Android drag and drop does only copy.
+
+  wcva->OnDragEntered(event);
+}
+
+void ContentViewCoreImpl::OnDragUpdated(
+    JNIEnv* env,
+    const base::android::JavaParamRef<jobject>& jobj,
+    int x,
+    int y,
+    int screen_x,
+    int screen_y) {
+  WebContentsViewAndroid* wcva = static_cast<WebContentsViewAndroid*>(
+      static_cast<WebContentsImpl*>(web_contents())->GetView());
+
+  ui::OSExchangeData data(new ui::OSExchangeDataProviderAndroid());
+  ui::DropTargetEvent event(
+      data, gfx::Point(x, y), gfx::Point(screen_x, screen_y),
+      ui::DragDropTypes::DRAG_COPY);  // Android drag and drop does only copy.
+
+  wcva->OnDragUpdated(event);
+}
+
+void ContentViewCoreImpl::OnPerformDrop(
+    JNIEnv* env,
+    const base::android::JavaParamRef<jobject>& jobj,
+    int x,
+    int y,
+    int screen_x,
+    int screen_y,
+    const base::android::JavaParamRef<jstring>& content) {
+  base::string16 text_to_drop = ConvertJavaStringToUTF16(env, content);
+
+  WebContentsViewAndroid* wcva = static_cast<WebContentsViewAndroid*>(
+      static_cast<WebContentsImpl*>(web_contents())->GetView());
+
+  ui::OSExchangeData data(new ui::OSExchangeDataProviderAndroid());
+  data.SetString(text_to_drop);
+  ui::DropTargetEvent event(data, gfx::Point(x, y),
+                            gfx::Point(screen_x, screen_y),
+                            ui::DragDropTypes::DRAG_COPY);
+
+  wcva->OnPerformDrop(event);
+}
+
+void ContentViewCoreImpl::OnDragExited(
+    JNIEnv* env,
+    const base::android::JavaParamRef<jobject>& jobj) {
+  WebContentsViewAndroid* wcva = static_cast<WebContentsViewAndroid*>(
+      static_cast<WebContentsImpl*>(web_contents())->GetView());
+  wcva->OnDragExited();
+}
+
 void ContentViewCoreImpl::RequestTextSurroundingSelection(
     int max_length,
     const base::Callback<
         void(const base::string16& content, int start_offset, int end_offset)>&
         callback) {
   DCHECK(!callback.is_null());
   RenderFrameHost* focused_frame = web_contents_->GetFocusedFrame();
   if (!focused_frame)
     return;
   if (GetRenderWidgetHostViewAndroid()) {
@@ skipping 99 matching lines @@
     return ScopedJavaLocalRef<jobject>();
 
   return view->GetJavaObject();
 }
 
 bool RegisterContentViewCore(JNIEnv* env) {
   return RegisterNativesImpl(env);
 }
 
 }  // namespace content