desktopMain.androidx.compose.ui.window.WindowLocationTracker.desktop.kt Maven / Gradle / Ivy

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Compose UI primitives. This library contains the primitives that form the Compose UI Toolkit, such as drawing, measurement and layout.

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/*
 * Copyright 2022 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 androidx.compose.ui.window

import java.awt.GraphicsConfiguration
import java.awt.GraphicsEnvironment
import java.awt.Point
import java.awt.Toolkit
import java.awt.Window
import java.awt.event.WindowEvent
import java.awt.event.WindowFocusListener

/**
 * Track position of all opened windows and provide an appropriate location for new created windows.
 *
 * Needed to place windows in cascade, and on the same screen.
 *
 * Singleton because we have only the single platform.
 * We basically override the standard behaviour of the window manager.
 */
internal object WindowLocationTracker {
    private val cascadeOffset = Point(48, 48)

    private var lastFocusedWindows = mutableSetOf()

    private val focusListener = object : WindowFocusListener {
        override fun windowGainedFocus(e: WindowEvent) {
            // put window on the top of the set
            lastFocusedWindows.remove(e.window)
            lastFocusedWindows.add(e.window)
        }

        override fun windowLostFocus(e: WindowEvent) = Unit
    }

    fun onWindowCreated(window: Window) {
        window.addWindowFocusListener(focusListener)
    }

    fun onWindowDisposed(window: Window) {
        window.removeWindowFocusListener(focusListener)
        lastFocusedWindows.remove(window)
    }

    val lastActiveGraphicsConfiguration: GraphicsConfiguration? get() =
        lastFocusedWindows.lastOrNull()?.graphicsConfiguration

    fun getCascadeLocationFor(window: Window): Point {
        val lastWindow = lastFocusedWindows.lastOrNull()
        val graphicsConfiguration = lastWindow?.graphicsConfiguration ?:
            GraphicsEnvironment.getLocalGraphicsEnvironment().defaultScreenDevice?.defaultConfiguration

        return if (graphicsConfiguration != null) {
            val screenBounds = graphicsConfiguration.bounds
            val screenInsets = Toolkit.getDefaultToolkit().getScreenInsets(graphicsConfiguration)
            val screenLeftTop = screenBounds.leftTop + Point(screenInsets.left, screenInsets.top)
            val screenRightBottom = screenBounds.rightBottom - Point(screenInsets.right, screenInsets.bottom)

            val lastLocation = lastWindow?.location ?: screenLeftTop
            var location = lastLocation + cascadeOffset
            val rightBottom = location + window.size.rightBottom
            if (rightBottom.x > screenRightBottom.x || rightBottom.y > screenRightBottom.y) {
                location = screenLeftTop + cascadeOffset
            }
            location
        } else {
            cascadeOffset
        }
    }
}