66 lines
2.1 KiB
Kotlin

package center.sciprog.maps.features
import androidx.compose.runtime.MutableState
import androidx.compose.runtime.getValue
import androidx.compose.runtime.mutableStateOf
import androidx.compose.runtime.setValue
import androidx.compose.ui.geometry.Offset
import androidx.compose.ui.unit.*
/**
* A state holder for current canvas size and view point. Allows transformation from coordinates to pixels and back
*/
public abstract class CanvasState<T: Any>(
public val viewConfig: ViewConfig<T>
){
public abstract val space: CoordinateSpace<T>
private var canvasSizeState: MutableState<DpSize?> = mutableStateOf(null)
private var viewPointState: MutableState<ViewPoint<T>?> = mutableStateOf(null)
public var canvasSize: DpSize
get() = canvasSizeState.value ?: DpSize(512.dp, 512.dp)
set(value) {
canvasSizeState.value = value
viewConfig.onCanvasSizeChange(value)
}
public var viewPoint: ViewPoint<T>
get() = viewPointState.value ?: space.defaultViewPoint
set(value) {
viewPointState.value = value
viewConfig.onViewChange(viewPoint)
}
public val zoom: Float get() = viewPoint.zoom
// Selection rectangle. If null - no selection
public var selectRect: DpRect? by mutableStateOf(null)
public abstract fun Rectangle<T>.toDpRect(): DpRect
public abstract fun ViewPoint<T>.moveBy(x: Dp, y: Dp): ViewPoint<T>
public abstract fun computeViewPoint(rectangle: Rectangle<T>): ViewPoint<T>
public abstract fun DpOffset.toCoordinates(): T
public abstract fun T.toDpOffset(): DpOffset
public fun toCoordinates(offset: Offset, density: Density): T = with(density){
val dpOffset = DpOffset(offset.x.toDp(), offset.y.toDp())
dpOffset.toCoordinates()
}
public fun toOffset(coordinates: T, density: Density): Offset = with(density){
val dpOffset = coordinates.toDpOffset()
return Offset(dpOffset.x.toPx(), dpOffset.y.toPx())
}
}
public val DpRect.topLeft: DpOffset get() = DpOffset(left, top)
public val DpRect.bottomRight: DpOffset get() = DpOffset(right, bottom)