RPP: improve keyboard experience of annotations

This CL makes it so that when you tab into the annotation, you are
immediately placed into edit mode, and the cursor is put at the end of
the annotation.

This *sort of* worked for clicking with the mouse, but with the keyboard
you have to do a bit more work to get the cursor to display at the right
point. Because by default it will not appear.

Fixed: 406549702
Change-Id: I328d70763a09fc60a0c4258586fc97ba3d2f5658
Reviewed-on: https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/6401393
Commit-Queue: Jack Franklin <jacktfranklin@chromium.org>
Auto-Submit: Jack Franklin <jacktfranklin@chromium.org>
Reviewed-by: Alina Varkki <alinavarkki@chromium.org>

Author: jackfranklin

front_end/panels/timeline/overlays/components/EntryLabelOverlay.ts

@@ -261,7 +261,8 @@ export class EntryLabelOverlay extends HTMLElement {
     // We do not want to create multi-line labels.
     // Therefore, if the new key is `Enter` key, treat it
     // as the end of the label input and blur the input field.
-    if (event.key === Platform.KeyboardUtilities.ENTER_KEY || event.key === Platform.KeyboardUtilities.ESCAPE_KEY) {
+    if ((event.key === Platform.KeyboardUtilities.ENTER_KEY || event.key === Platform.KeyboardUtilities.ESCAPE_KEY) &&
+        this.#isLabelEditable) {
       // Note that we do not stop the event propagating here; this is on
       // purpose because we need it to bubble up into TimelineFlameChartView's
       // handler. That updates the state and deals with the keydown.
@@ -276,7 +277,6 @@ export class EntryLabelOverlay extends HTMLElement {
       // safe to call this just in case the blur() didn't actually trigger.
       this.#inputField.blur();
       this.setLabelEditabilityAndRemoveEmptyLabel(false);
-
       return false;
     }
 
@@ -307,19 +307,10 @@ export class EntryLabelOverlay extends HTMLElement {
     }
 
     const pastedText = clipboardData.getData('text');
-
     const newText = this.#inputField.textContent + pastedText;
     const trimmedText = newText.slice(0, EntryLabelOverlay.MAX_LABEL_LENGTH + 1);
-
     this.#inputField.textContent = trimmedText;
-
-    // Reset the selection to the end
-    const selection = window.getSelection();
-    const range = document.createRange();
-    range.selectNodeContents(this.#inputField);
-    range.collapse(false);
-    selection?.removeAllRanges();
-    selection?.addRange(range);
+    this.#placeCursorAtInputEnd();
   }
 
   set entryLabelVisibleHeight(entryLabelVisibleHeight: number) {
@@ -449,8 +440,9 @@ export class EntryLabelOverlay extends HTMLElement {
     }
     this.#isLabelEditable = editable;
     this.#render();
-    // If the label is editable, focus cursor on it
-    if (editable) {
+    // If the label is editable, focus cursor on it & put the cursor at the end
+    if (editable && this.#inputField) {
+      this.#placeCursorAtInputEnd();
       this.#focusInputBox();
     }
     // On MacOS when clearing the input box it is left with a new line, so we
@@ -463,6 +455,23 @@ export class EntryLabelOverlay extends HTMLElement {
     }
   }
 
+  /**
+   * Places the user's cursor at the end of the input. We do this when the user
+   * focuses the input with either the keyboard or mouse, and when they paste in
+   * text, so that the cursor is placed in a useful position to edit.
+   */
+  #placeCursorAtInputEnd(): void {
+    if (!this.#inputField) {
+      return;
+    }
+    const selection = window.getSelection();
+    const range = document.createRange();
+    range.selectNodeContents(this.#inputField);
+    range.collapse(false);
+    selection?.removeAllRanges();
+    selection?.addRange(range);
+  }
+
   set callTree(callTree: Utils.AICallTree.AICallTree|null) {
     this.#callTree = callTree;
   }
@@ -706,7 +715,12 @@ export class EntryLabelOverlay extends HTMLElement {
             <span
               class="input-field"
               role="textbox"
-              @dblclick=${() => this.setLabelEditabilityAndRemoveEmptyLabel(true)}
+              @focus=${() => {
+                this.setLabelEditabilityAndRemoveEmptyLabel(true);
+              }}
+              @dblclick=${() => {
+                this.setLabelEditabilityAndRemoveEmptyLabel(true);
+              }}
               @blur=${() => this.setLabelEditabilityAndRemoveEmptyLabel(false)}
               @keydown=${this.#handleLabelInputKeyDown}
               @paste=${this.#handleLabelInputPaste}
@@ -718,6 +732,7 @@ export class EntryLabelOverlay extends HTMLElement {
                 }}
               contenteditable=${this.#isLabelEditable ? 'plaintext-only' : false}
               jslog=${VisualLogging.textField('timeline.annotations.entry-label-input').track({keydown: true, click: true})}
+              tabindex="0"
             ></span>
             ${(() => {
               switch (this.#shouldRenderAIButton()) {