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Commit 1b9b7b46 authored by Matthew DeVore's avatar Matthew DeVore
Browse files

DisplayTopology: use correct layout listener 

The GlobalLayoutListener was not being informed of the pane's size
change at the correct time. It was causing a paneless UI to flash very
briefly when opening the ExternalDisplayPreferenceFragment. This was
hard to see in most situations, but when replacing the fragment with
a new ExternalDisplayPreferenceFragment it became very obvious (this
may be necessary to implement b/409354332).

We also got informed twice, because the resize of the pane when creating
a new TopologyScale caused a new notification. This made us need a
flag to indicate whether refresh was necessary. Instead, we use the
old/new values in the OnLayoutListener to decide if the scale needs to
be reconstructed.

Flag: com.android.settings.flags.display_topology_pane_in_display_list
Bug: b/400934884
Bug: b/409354332
Test: verify with a Log call that refreshPane is called ONCE when opening the fragment
Test: verify with a Log call that refreshPane is called ONCE when changing width of fragment
Change-Id: Ibde4efae2d72d18c49535e75b00a13d6fc07a75e
parent 6dc042d6

src/com/android/settings/connecteddevice/display/DisplayTopologyPreference.kt

+26 −22
Original line number Diff line number Diff line
@@ -25,8 +25,9 @@ import android.graphics.PointF 
import android.graphics.RectF

import android.hardware.display.DisplayTopology

import android.util.DisplayMetrics

import android.util.Log

import android.view.MotionEvent

import android.view.ViewTreeObserver

import android.view.View

import android.widget.FrameLayout

import android.widget.TextView
@@ -43,8 +44,7 @@ import kotlin.math.abs 
 * when there is one or more extended display attached.

 */

class DisplayTopologyPreference(val injector: ConnectedDisplayInjector)

        : Preference(injector.context!!), ViewTreeObserver.OnGlobalLayoutListener,

          GroupSectionDividerMixin {

        : Preference(injector.context!!), GroupSectionDividerMixin {

    @VisibleForTesting lateinit var mPaneContent : FrameLayout

    @VisibleForTesting lateinit var mPaneHolder : FrameLayout

    @VisibleForTesting lateinit var mTopologyHint : TextView
@@ -63,14 +63,25 @@ class DisplayTopologyPreference(val injector: ConnectedDisplayInjector) 
     */

    @VisibleForTesting val accidentalDragTimeLimitMs = 800L



    /**

     * This is needed to prevent a repopulation of the pane causing another

     * relayout and vice-versa ad infinitum.

     */

    private var mPaneNeedsRefresh = false



    private val mTopologyListener = Consumer<DisplayTopology> { applyTopology(it) }



    private val mPaneContentLayoutListener = object : View.OnLayoutChangeListener {

        override fun onLayoutChange(v: View,

                newLeft: Int, newTop: Int, newRight: Int, newBottom: Int,

                oldLeft: Int, oldTop: Int, oldRight: Int, oldBottom: Int) {

            val oldWidth = oldRight - oldLeft

            val newWidth = newRight - newLeft

            // The width will change e.g. when first displaying the topology UI (oldWidth is 0) or

            // when the window is resized. We ignore when the height is changed because we don't

            // specify the height in terms of layout, but specify it algorithmically via

            // TopologyScale, which uses the width and the topology to calculate a height.

            if (oldWidth != newWidth) {

                Log.i(TAG, "Width changed from $oldWidth to $newWidth - refresh pane")

                refreshPane()

            }

        }

    }



    init {

        layoutResource = R.layout.display_topology_preference
@@ -90,20 +101,16 @@ class DisplayTopologyPreference(val injector: ConnectedDisplayInjector) 
            if (newPane == mPaneContent) {

                return

            }

            mPaneContent.viewTreeObserver.removeOnGlobalLayoutListener(this)

            mPaneContent.removeOnLayoutChangeListener(mPaneContentLayoutListener)

        }

        mPaneContent = newPane

        mPaneHolder = holder.itemView as FrameLayout

        mTopologyHint = holder.findViewById(R.id.topology_hint) as TextView

        mPaneContent.viewTreeObserver.addOnGlobalLayoutListener(this)

        mPaneContent.addOnLayoutChangeListener(mPaneContentLayoutListener)

    }



    override fun onAttached() {

        super.onAttached()

        // We don't know if topology changes happened when we were detached, as it is impossible to

        // listen at that time (we must remove listeners when detaching). Setting this flag makes

        // the following onGlobalLayout call refresh the pane.

        mPaneNeedsRefresh = true

        injector.registerTopologyListener(mTopologyListener)

    }
@@ -118,13 +125,6 @@ class DisplayTopologyPreference(val injector: ConnectedDisplayInjector) 
        injector.unregisterTopologyListener(mTopologyListener)

    }



    override fun onGlobalLayout() {

        if (mPaneNeedsRefresh) {

            mPaneNeedsRefresh = false

            refreshPane()

        }

    }



    /**

     * Holds information about the current system topology.

     * @param positions list of displays comprised of the display ID and position
@@ -350,4 +350,8 @@ class DisplayTopologyPreference(val injector: ConnectedDisplayInjector) 


        return true

    }



    companion object {

        val TAG = "DisplayTopologyPreference"

    }

}

tests/robotests/src/com/android/settings/connecteddevice/display/DisplayTopologyPreferenceTest.kt

+2 −2
Original line number Diff line number Diff line
@@ -117,7 +117,7 @@ class DisplayTopologyPreferenceTest { 
    @Test

    fun disabledTopology() {

        preference.onAttached()

        preference.onGlobalLayout()

        preference.refreshPane()



        assertThat(preference.mPaneContent.childCount).isEqualTo(0)

        // TODO(b/352648432): update test when we show the main display even when
@@ -180,7 +180,7 @@ class DisplayTopologyPreferenceTest { 
        preference.mPaneContent.right = 640



        preference.onAttached()

        preference.onGlobalLayout()

        preference.refreshPane()

    }



    /**