Always reset screenshot preview to alpha=1

It's possible for the screenshot process to not get shut down as
soon as the UI disappears. If this occurs after a shared transition
(which sets the preview to alpha=0 to hide it as part of the
transition), the preview gets stuck at alpha=0 and isn't visible.
Always resetting the screenshot view and setting alpha=1 guarantees
that regardless of the state of the screenshot process, we always
start from a clean slate.

Bug: 242862442
Test: forced the screenshot process to stay up by never running
the finish callback in ScreenshotHelper, verified that we get the
invisible-preview behavior and that it's fixed with this change

Change-Id: I9b795928cba93f8cef19244105db2c7f31c0973b

packages/SystemUI/src/com/android/systemui/screenshot/ScreenshotController.java

@@ -555,6 +555,8 @@ public class ScreenshotController {
                 mScreenshotView.announceForAccessibility(
                         mContext.getResources().getString(R.string.screenshot_saving_title)));
 
+        mScreenshotView.reset();
+
         if (mScreenshotView.isAttachedToWindow()) {
             // if we didn't already dismiss for another reason
             if (!mScreenshotView.isDismissing()) {
@@ -564,7 +566,6 @@ public class ScreenshotController {
                 Log.d(TAG, "saveScreenshot: screenshotView is already attached, resetting. "
                         + "(dismissing=" + mScreenshotView.isDismissing() + ")");
             }
-            mScreenshotView.reset();
         }
         mPackageName = topComponent == null ? "" : topComponent.getPackageName();
         mScreenshotView.setPackageName(mPackageName);

packages/SystemUI/src/com/android/systemui/screenshot/ScreenshotView.java

@@ -1006,6 +1006,7 @@ public class ScreenshotView extends FrameLayout implements
         // Clear any references to the bitmap
         mScreenshotPreview.setImageDrawable(null);
         mScreenshotPreview.setVisibility(View.INVISIBLE);
+        mScreenshotPreview.setAlpha(1f);
         mScreenshotPreviewBorder.setAlpha(0);
         mPendingSharedTransition = false;
         mActionsContainerBackground.setVisibility(View.GONE);