System UI: Make opposite corners static when dragging on a corner (00279cf0) · Commits · e / os / android_frameworks_base

packages/SystemUI/src/com/android/systemui/screencapture/ui/compose/RegionBox.kt

+128 −132

Original line number	Diff line number	Diff line
		@@ -33,82 +33,112 @@ import androidx.compose.runtime.setValue
		import androidx.compose.ui.Alignment
		import androidx.compose.ui.Modifier
		import androidx.compose.ui.geometry.Offset
		import androidx.compose.ui.geometry.Rect
		import androidx.compose.ui.geometry.Size
		import androidx.compose.ui.graphics.graphicsLayer
		import androidx.compose.ui.input.pointer.pointerInput
		import androidx.compose.ui.layout.onSizeChanged
		import androidx.compose.ui.platform.LocalDensity
		import androidx.compose.ui.unit.Dp
		import androidx.compose.ui.unit.dp
		import androidx.compose.ui.unit.max
		import androidx.compose.ui.unit.min

		/** An enum to identify each of the four corners of the rectangle. */
		enum class Corner {
		TopLeft,
		TopRight,
		BottomLeft,
		BottomRight,
		/**
		* An enum to identify each of the four corners of the rectangle.
		*
		* @param alignment The alignment of the corner within the box.
		*/
		enum class Corner(val alignment: Alignment) {
		TopLeft(Alignment.TopStart),
		TopRight(Alignment.TopEnd),
		BottomLeft(Alignment.BottomStart),
		BottomRight(Alignment.BottomEnd),
		}

		/**
		* A stateful composable that manages the size of a resizable RegionBox.
		* A stateful composable that manages the size and position of a resizable RegionBox.
		*
		* @param initialWidth The initial width of the box.
		* @param initialHeight The initial height of the box.
		* @param onDragEnd A callback function that is invoked with the final width and height when the
		* user finishes a drag gesture.
		* @param onDragEnd A callback function that is invoked with the final offset, width, and height
		* when the user finishes a drag gesture.
		* @param initialOffset The initial top-left offset of the box. Default is (0, 0), which is the
		* parent's top-left corner.
		* @param modifier The modifier to be applied to the composable.
		*/
		@Composable
		fun RegionBox(
		initialWidth: Dp,
		initialHeight: Dp,
		onDragEnd: (width: Dp, height: Dp) -> Unit,
		onDragEnd: (offset: Offset, width: Dp, height: Dp) -> Unit,
		initialOffset: Offset = Offset.Zero,
		modifier: Modifier = Modifier,
		) {
		// The minimum size allowed for the rectangle.
		// TODO(b/422565042): change when its value is finalized.
		val MIN_SIZE = 48.dp
		val minSize = 48.dp

		// The current state of the box.
		var width by remember { mutableStateOf(initialWidth) }
		var height by remember { mutableStateOf(initialHeight) }
		val density = LocalDensity.current
		val minSizePx = remember(density) { with(density) { minSize.toPx() } }

		val onDrag: (dragAmount: Offset, corner: Corner, maxWidth: Dp, maxHeight: Dp) -> Unit =
		{ dragAmount, corner, maxWidth, maxHeight ->
		val (dragX, dragY) = dragAmount
		// State for the region box's geometry.
		var rect by remember {
		mutableStateOf(
		with(density) {
		// Calculate the potential new width and height based on the drag amount.
		// The width and height are increased or decreased by twice the drag amount as the
		// drag is calculated from the center of the box, so we need to add twice the drag
		// amount to account for both sides of the box.
		val newWidth =
		when (corner) {
		Corner.TopLeft,
		Corner.BottomLeft -> width - (dragX.toDp() * 2)
		Corner.TopRight,
		Corner.BottomRight -> width + (dragX.toDp() * 2)
		// offset is how far from the parent's top-left corner the box should be placed.
		Rect(offset = initialOffset, size = Size(initialWidth.toPx(), initialHeight.toPx()))
		}
		val newHeight =
		when (corner) {
		Corner.TopLeft,
		Corner.TopRight -> height - (dragY.toDp() * 2)
		Corner.BottomLeft,
		Corner.BottomRight -> height + (dragY.toDp() * 2)
		)
		}

		// The new width and height cannot be smaller than the minimum allowed, or bigger
		// than the screen size.
		width = max(min(newWidth, maxWidth), MIN_SIZE)
		height = max(min(newHeight, maxHeight), MIN_SIZE)
		val onDrag: (dragAmount: Offset, corner: Corner, maxWidth: Float, maxHeight: Float) -> Unit =
		{ dragAmount, corner, maxWidth, maxHeight ->
		// Used for calculating the new dimensions based on which corner is dragged.
		var newLeft = rect.left
		var newTop = rect.top
		var newRight = rect.right
		var newBottom = rect.bottom

		val (dragX, dragY) = dragAmount

		// Handle horizontal drag for resizing.
		if (corner == Corner.TopLeft \|\| corner == Corner.BottomLeft) {
		val potentialNewLeft = rect.left + dragX
		val rightLimitForMinWidth = rect.right - minSizePx

		newLeft = potentialNewLeft.coerceIn(0f, rightLimitForMinWidth)
		} else {
		val potentialNewRight = rect.right + dragX
		val leftLimitForMinWidth = rect.left + minSizePx

		newRight = potentialNewRight.coerceIn(leftLimitForMinWidth, maxWidth)
		}

		// Handle vertical drag for resizing.
		if (corner == Corner.TopLeft \|\| corner == Corner.TopRight) {
		val potentialNewTop = rect.top + dragY
		val bottomLimitForMinHeight = rect.bottom - minSizePx

		newTop = potentialNewTop.coerceIn(0f, bottomLimitForMinHeight)
		} else {
		val potentialNewBottom = rect.bottom + dragY
		val topLimitForMinHeight = rect.top + minSizePx

		newBottom = potentialNewBottom.coerceIn(topLimitForMinHeight, maxHeight)
		}

		rect = Rect(newLeft, newTop, newRight, newBottom)
		}

		ResizableRectangle(
		width = width,
		height = height,
		rect = rect,
		onDrag = onDrag,
		onDragEnd = { onDragEnd(width, height) },
		onDragEnd = {
		onDragEnd(
		Offset(rect.left, rect.top),
		with(density) { rect.width.toDp() },
		with(density) { rect.height.toDp() },
		)
		},
		modifier = modifier,
		)
		}
		@@ -116,28 +146,27 @@ fun RegionBox(
		/**
		* A box with border lines and centered corner knobs that can be resized.
		*
		* @param width The current width of the box.
		* @param height The current height of the box.
		* @param rect The current geometry of the region box.
		* @param onDrag Callback invoked when a knob is dragged.
		* @param onDragEnd Callback invoked when a drag gesture finishes.
		* @param modifier The modifier to be applied to the composable.
		*/
		@Composable
		private fun ResizableRectangle(
		width: Dp,
		height: Dp,
		onDrag: (dragAmount: Offset, corner: Corner, maxWidth: Dp, maxHeight: Dp) -> Unit,
		rect: Rect,
		onDrag: (dragAmount: Offset, corner: Corner, maxWidth: Float, maxHeight: Float) -> Unit,
		onDragEnd: () -> Unit,
		modifier: Modifier = Modifier,
		) {
		// The diameter of the resizable knob on each corner of the region box.
		val KNOB_DIAMETER = 8.dp
		val knobDiameter = 8.dp
		// The width of the border stroke around the region box.
		val BORDER_STROKE_WIDTH = 4.dp
		val borderStrokeWidth = 4.dp

		// Must remember the screen size for the drag logic. Initial values are set to 0.
		var screenWidth by remember { mutableStateOf(0.dp) }
		var screenHeight by remember { mutableStateOf(0.dp) }
		var screenWidth by remember { mutableStateOf(0f) }
		var screenHeight by remember { mutableStateOf(0f) }

		val density = LocalDensity.current

		// The box that contains the whole screen.
		@@ -148,91 +177,57 @@ private fun ResizableRectangle(
		// .onSizeChanged gives us the final size of this box, which is the screen size,
		// after it has been drawn.
		.onSizeChanged { sizeInPixels ->
		screenWidth = with(density) { sizeInPixels.width.toDp() }
		screenHeight = with(density) { sizeInPixels.height.toDp() }
		},
		contentAlignment = Alignment.Center,
		screenWidth = sizeInPixels.width.toFloat()
		screenHeight = sizeInPixels.height.toFloat()
		}
		) {
		// The box container for the region box and its knobs.
		Box(modifier = Modifier.size(width, height)) {
		Box(
		modifier =
		Modifier.graphicsLayer(translationX = rect.left, translationY = rect.top)
		.size(
		width = with(density) { rect.width.toDp() },
		height = with(density) { rect.height.toDp() },
		)
		) {
		// The main box for the region selection.
		Box(
		modifier =
		Modifier.fillMaxSize()
		.border(BORDER_STROKE_WIDTH, MaterialTheme.colorScheme.onSurfaceVariant)
		.border(borderStrokeWidth, MaterialTheme.colorScheme.onSurfaceVariant)
		)

		// The offset is half of the knob diameter so that it is centered.
		val knobOffset = KNOB_DIAMETER / 2
		val knobOffset = knobDiameter / 2

		// Top left knob
		Knob(
		diameter = KNOB_DIAMETER,
		modifier =
		Modifier.align(Alignment.TopStart)
		.offset(x = -knobOffset, y = -knobOffset)
		.pointerInput(Unit) {
		detectDragGestures(
		onDragEnd = onDragEnd,
		onDrag = { change, dragAmount ->
		change.consume()
		onDrag(dragAmount, Corner.TopLeft, screenWidth, screenHeight)
		},
		)
		},
		)
		// Create knobs by looping through the Corner enum values
		Corner.entries.forEach { corner ->
		val xOffset: Dp
		val yOffset: Dp

		// Top right knob
		Knob(
		diameter = KNOB_DIAMETER,
		modifier =
		Modifier.align(Alignment.TopEnd)
		.offset(x = knobOffset, y = -knobOffset)
		.pointerInput(Unit) {
		detectDragGestures(
		onDragEnd = onDragEnd,
		onDrag = { change, dragAmount ->
		change.consume()
		onDrag(dragAmount, Corner.TopRight, screenWidth, screenHeight)
		},
		)
		},
		)
		if (corner == Corner.TopLeft \|\| corner == Corner.BottomLeft) {
		xOffset = -knobOffset
		} else {
		xOffset = knobOffset
		}

		// Bottom left knob
		Knob(
		diameter = KNOB_DIAMETER,
		modifier =
		Modifier.align(Alignment.BottomStart)
		.offset(x = -knobOffset, y = knobOffset)
		.pointerInput(Unit) {
		detectDragGestures(
		onDragEnd = onDragEnd,
		onDrag = { change, dragAmount ->
		change.consume()
		onDrag(dragAmount, Corner.BottomLeft, screenWidth, screenHeight)
		},
		)
		},
		)
		if (corner == Corner.TopLeft \|\| corner == Corner.TopRight) {
		yOffset = -knobOffset
		} else {
		yOffset = knobOffset
		}

		// Bottom right knob
		Knob(
		diameter = KNOB_DIAMETER,
		diameter = knobDiameter,
		modifier =
		Modifier.align(Alignment.BottomEnd)
		.offset(x = knobOffset, y = knobOffset)
		.pointerInput(Unit) {
		Modifier.align(corner.alignment)
		.offset(x = xOffset, y = yOffset)
		.pointerInput(corner, screenWidth, screenHeight) {
		detectDragGestures(
		onDragEnd = onDragEnd,
		onDrag = { change, dragAmount ->
		change.consume()
		onDrag(
		dragAmount,
		Corner.BottomRight,
		screenWidth,
		screenHeight,
		)
		onDrag(dragAmount, corner, screenWidth, screenHeight)
		},
		)
		},
		@@ -240,6 +235,7 @@ private fun ResizableRectangle(
		}
		}
		}
		}

		/**
		* The circular knob on each corner of the box used for dragging each corner.