Move DiffLayer to the API

Change-Id: Iad673de4501ece0cf12f4f3e58ec67b4838f8718

polygerrit-ui/app/api/diff.ts

@@ -245,3 +245,41 @@ export declare interface MovedLinkClickedEventDetail {
   side: Side;
   lineNum: LineNumber;
 }
+
+export enum GrDiffLineType {
+  ADD = 'add',
+  BOTH = 'both',
+  BLANK = 'blank',
+  REMOVE = 'remove',
+}
+
+/** Describes a line to be rendered in a diff. */
+export declare interface GrDiffLine {
+  readonly type: GrDiffLineType;
+  /** The line number on the left side of the diff - 0 means none.  */
+  beforeNumber: LineNumber;
+  /** The line number on the right side of the diff - 0 means none.  */
+  afterNumber: LineNumber;
+}
+
+/**
+ * Interface to implemented to define a new layer in the diff.
+ *
+ * Layers can affect how the text of the diff or its line numbers
+ * are rendered.
+ */
+export declare interface DiffLayer {
+  /**
+   * Called during rendering and allows annotating the diff text or line number
+   * by mutating those elements.
+   *
+   * @param textElement The rendered text of one side of the diff.
+   * @param lineNumberElement The rendered line number of one side of the diff.
+   * @param line Describes the line that should be annotated.
+   */
+  annotate(
+    textElement: HTMLElement,
+    lineNumberElement: HTMLElement,
+    line: GrDiffLine
+  ): void;
+}

polygerrit-ui/app/elements/diff/gr-diff/gr-diff-line.ts

@@ -15,20 +15,17 @@
  * limitations under the License.
  */
 
-import {LineNumber} from '../../../api/diff';
+import {
+  GrDiffLine as GrDiffLineApi,
+  GrDiffLineType,
+  LineNumber,
+} from '../../../api/diff';
 
-export {LineNumber};
+export {GrDiffLineType, LineNumber};
 
 export const FILE = 'FILE';
 
-export enum GrDiffLineType {
-  ADD = 'add',
-  BOTH = 'both',
-  BLANK = 'blank',
-  REMOVE = 'remove',
-}
-
-export class GrDiffLine {
+export class GrDiffLine implements GrDiffLineApi {
   constructor(
     readonly type: GrDiffLineType,
     public beforeNumber: LineNumber = 0,

polygerrit-ui/app/types/types.ts

@@ -14,9 +14,9 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
+import {DiffLayer as DiffLayerApi} from '../api/diff';
 import {DiffViewMode, MessageTag, Side} from '../constants/constants';
 import {IronA11yAnnouncer} from '@polymer/iron-a11y-announcer/iron-a11y-announcer';
-import {GrDiffLine} from '../elements/diff/gr-diff/gr-diff-line';
 import {FlattenedNodesObserver} from '@polymer/polymer/lib/utils/flattened-nodes-observer';
 import {PaperInputElement} from '@polymer/paper-input/paper-input';
 import {
@@ -150,8 +150,7 @@ export type DiffLayerListener = (
   side: Side
 ) => void;
 
-export interface DiffLayer {
-  annotate(el: HTMLElement, lineEl: HTMLElement, line: GrDiffLine): void;
+export interface DiffLayer extends DiffLayerApi {
   addListener?(listener: DiffLayerListener): void;
   removeListener?(listener: DiffLayerListener): void;
 }