TopologyScale values for scaling the topology pane

import com.android.settings.R

import android.content.Context

import android.graphics.Point

import android.graphics.PointF

import android.graphics.RectF

import androidx.preference.Preference

import java.util.Locale

import kotlin.math.max

import kotlin.math.min

/**

 * Contains the parameters needed for transforming global display coordinates to and from topology

 * pane coordinates. This is necessary for implementing an interactive display topology pane. The

 * pane allows dragging and dropping display blocks into place to define the topology. Conversion to

 * pane coordinates is necessary when rendering the original topology. Conversion in the other

 * direction, to display coordinates, is necessary for resolve a drag position to display space.

 *

 * The topology pane coordinates are integral and represent the relative position from the upper-

 * left corner of the pane. It uses a scale optimized for showing all displays with minimal or no

 * scrolling. The display coordinates are floating point and the origin can be in any position. In

 * practice the origin will be the upper-left coordinate of the primary display.

 */

class TopologyScale(paneWidth : Int, displaysPos : Collection<RectF>) {

    /** Scale of block sizes to real-world display sizes. Should be less than 1. */

    val blockRatio : Float

    /** Height of topology pane needed to allow all display blocks to appear with some padding. */

    val paneHeight : Int

    /** Pane's X view coordinate that corresponds with topology's X=0 coordinate. */

    val originPaneX : Int

    /** Pane's Y view coordinate that corresponds with topology's Y=0 coordinate. */

    val originPaneY : Int

    init {

        val displayBounds = RectF(

                Float.MAX_VALUE, Float.MAX_VALUE, Float.MIN_VALUE, Float.MIN_VALUE)

        var smallestDisplayDim = Float.MAX_VALUE

        // displayBounds is the smallest rect encompassing all displays, in display space.

        // smallestDisplayDim is the size of the smallest display edge, in display space.

        for (pos in displaysPos) {

            displayBounds.union(pos)

            smallestDisplayDim = minOf(smallestDisplayDim, pos.height(), pos.width())

        }

        // Set height according to the width and the aspect ratio of the display bounds.

        // 0.05 is a reasonable limit to the size of display blocks. It appears to match the

        // ratio used in the ChromeOS topology editor. It prevents blocks from being too large,

        // which would make dragging and dropping awkward.

        val rawBlockRatio = min(0.05, paneWidth.toDouble() * 0.6 / displayBounds.width())

        // If the `ratio` is set too low because one of the displays will have an edge less than

        // 48dp long, increase it such that the smallest edge is that long. This may override the

        // 0.05 limit since it is more important than it.

        blockRatio = max(48.0 / smallestDisplayDim, rawBlockRatio).toFloat()

        // Essentially, we just set the pane height based on the pre-determined pane width and the

        // aspect ratio of the display bounds. But we may need to increase it slightly to achieve

        // 20% padding above and below the display bounds - this is where the 0.6 comes from.

        paneHeight = max(

                paneWidth.toDouble() / displayBounds.width() * displayBounds.height(),

                displayBounds.height() * blockRatio / 0.6).toInt()

        // Set originPaneXY (the location of 0,0 in display space in the pane's coordinate system)

        // such that the display bounds rect is centered in the pane.

        // It is unlikely that either of these coordinates will be negative since blockRatio has

        // been chosen to allow 20% padding around each side of the display blocks. However, the

        // a11y requirement applied above (48.0 / smallestDisplayDim) may cause the blocks to not

        // fit. This should be rare in practice, and can be worked around by moving the settings UI

        // to a larger display.

        val blockMostLeft = (paneWidth - displayBounds.width() * blockRatio) / 2

        val blockMostTop = (paneHeight - displayBounds.height() * blockRatio) / 2

        originPaneX = (blockMostLeft - displayBounds.left * blockRatio).toInt()

        originPaneY = (blockMostTop - displayBounds.top * blockRatio).toInt()

    }

    /** Transforms coordinates in view pane space to display space. */

    fun paneToDisplayCoor(panePos : Point) : PointF {

        return PointF(

                (panePos.x - originPaneX).toFloat() / blockRatio,

                (panePos.y - originPaneY).toFloat() / blockRatio)

    }

    /** Transforms coordinates in display space to view pane space. */

    fun displayToPaneCoor(displayPos : PointF) : Point {

        return Point(

                (displayPos.x * blockRatio).toInt() + originPaneX,

                (displayPos.y * blockRatio).toInt() + originPaneY)

    }

    override fun toString() : String {

        return String.format(

                Locale.ROOT,

                "{TopoScale blockRatio=%f originPaneXY=%d,%d paneHeight=%d}",

                blockRatio, originPaneX, originPaneY, paneHeight)

    }

}

const val PREFERENCE_KEY = "display_topology_preference"

/**

/*

 * Copyright (C) 2024 The Android Open Source Project

 *

 * Licensed under the Apache License, Version 2.0 (the "License");

 * you may not use this file except in compliance with the License.

 * You may obtain a copy of the License at

 *

 *      http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 */

package com.android.settings.connecteddevice.display

import android.graphics.Point

import android.graphics.PointF

import android.graphics.RectF

import org.junit.Assert.assertEquals

import org.junit.Test

import org.junit.runner.RunWith

import org.robolectric.RobolectricTestRunner

fun assertPointF(x: Float, y: Float, delta: Float, actual: PointF) {

    assertEquals(x, actual.x, delta)

    assertEquals(y, actual.y, delta)

}

@RunWith(RobolectricTestRunner::class)

class TopologyScaleTest {

    @Test

    fun oneDisplay4to3Aspect() {

        val scale = TopologyScale(

                /* paneWidth= */ 640,

                listOf(RectF(0f, 0f, 640f, 480f)))

        // blockRatio is higher than 0.05 in order to make the smallest display edge (480 dp) 48dp

        // in the pane.

        assertEquals(

                "{TopoScale blockRatio=0.100000 originPaneXY=288,216 paneHeight=480}", "" + scale)

        assertEquals(Point(352, 264), scale.displayToPaneCoor(PointF(640f, 480f)))

        assertEquals(Point(320, 240), scale.displayToPaneCoor(PointF(320f, 240f)))

        assertEquals(PointF(640f, 480f), scale.paneToDisplayCoor(Point(352, 264)))

    }

    @Test

    fun twoUnalignedDisplays() {

        val scale = TopologyScale(

                /* paneWidth= */ 300,

                listOf(RectF(0f, 0f, 1920f, 1200f), RectF(1920f, -300f, 3840f, 900f)))

        assertEquals(

                "{TopoScale blockRatio=0.046875 originPaneXY=60,37 paneHeight=117}", "" + scale)

        assertEquals(Point(78, 55), scale.displayToPaneCoor(PointF(400f, 400f)))

        assertEquals(Point(42, 37), scale.displayToPaneCoor(PointF(-400f, 0f)))

        assertPointF(-384f, 106.6666f, 0.001f, scale.paneToDisplayCoor(Point(42, 42)))

    }

    @Test

    fun twoDisplaysBlockRatioBumpedForGarSizeMinimumHorizontal() {

        val scale = TopologyScale(

                /* paneWidth= */ 192,

                listOf(RectF(0f, 0f, 240f, 320f), RectF(-240f, -320f, 0f, 0f)))

        // blockRatio is higher than 0.05 in order to make the smallest display edge (240 dp) 48dp

        // in the pane.

        assertEquals(

                "{TopoScale blockRatio=0.200000 originPaneXY=96,128 paneHeight=256}", "" + scale)

        assertEquals(Point(192, 256), scale.displayToPaneCoor(PointF(480f, 640f)))

        assertEquals(Point(96, 64), scale.displayToPaneCoor(PointF(0f, -320f)))

        assertPointF(220f, -430f, 0.001f, scale.paneToDisplayCoor(Point(140, 42)))

    }

}