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/**
* @license
* Copyright 2011 Google LLC
* SPDX-License-Identifier: Apache-2.0
*/
/**
* @fileoverview A database of all the rendered connections that could
* possibly be connected to (i.e. not collapsed, etc).
* Sorted by y coordinate.
* @author [email protected] (Neil Fraser)
*/
'use strict';
goog.provide('Blockly.ConnectionDB');
goog.require('Blockly.constants');
goog.require('Blockly.RenderedConnection');
goog.requireType('Blockly.IConnectionChecker');
/**
* Database of connections.
* Connections are stored in order of their vertical component. This way
* connections in an area may be looked up quickly using a binary search.
* @param {!Blockly.IConnectionChecker} checker The workspace's
* connection type checker, used to decide if connections are valid during a
* drag.
* @constructor
*/
Blockly.ConnectionDB = function(checker) {
/**
* Array of connections sorted by y position in workspace units.
* @type {!Array.<!Blockly.RenderedConnection>}
* @private
*/
this.connections_ = [];
/**
* The workspace's connection type checker, used to decide if connections are
* valid during a drag.
* @type {!Blockly.IConnectionChecker}
* @private
*/
this.connectionChecker_ = checker;
};
/**
* Add a connection to the database. Should not already exist in the database.
* @param {!Blockly.RenderedConnection} connection The connection to be added.
* @param {number} yPos The y position used to decide where to insert the
* connection.
* @package
*/
Blockly.ConnectionDB.prototype.addConnection = function(connection, yPos) {
var index = this.calculateIndexForYPos_(yPos);
this.connections_.splice(index, 0, connection);
};
/**
* Finds the index of the given connection.
*
* Starts by doing a binary search to find the approximate location, then
* linearly searches nearby for the exact connection.
* @param {!Blockly.RenderedConnection} conn The connection to find.
* @param {number} yPos The y position used to find the index of the connection.
* @return {number} The index of the connection, or -1 if the connection was
* not found.
* @private
*/
Blockly.ConnectionDB.prototype.findIndexOfConnection_ = function(conn, yPos) {
if (!this.connections_.length) {
return -1;
}
var bestGuess = this.calculateIndexForYPos_(yPos);
if (bestGuess >= this.connections_.length) {
// Not in list
return -1;
}
yPos = conn.y;
// Walk forward and back on the y axis looking for the connection.
var pointerMin = bestGuess;
var pointerMax = bestGuess;
while (pointerMin >= 0 && this.connections_[pointerMin].y == yPos) {
if (this.connections_[pointerMin] == conn) {
return pointerMin;
}
pointerMin--;
}
while (pointerMax < this.connections_.length &&
this.connections_[pointerMax].y == yPos) {
if (this.connections_[pointerMax] == conn) {
return pointerMax;
}
pointerMax++;
}
return -1;
};
/**
* Finds the correct index for the given y position.
* @param {number} yPos The y position used to decide where to
* insert the connection.
* @return {number} The candidate index.
* @private
*/
Blockly.ConnectionDB.prototype.calculateIndexForYPos_ = function(yPos) {
if (!this.connections_.length) {
return 0;
}
var pointerMin = 0;
var pointerMax = this.connections_.length;
while (pointerMin < pointerMax) {
var pointerMid = Math.floor((pointerMin + pointerMax) / 2);
if (this.connections_[pointerMid].y < yPos) {
pointerMin = pointerMid + 1;
} else if (this.connections_[pointerMid].y > yPos) {
pointerMax = pointerMid;
} else {
pointerMin = pointerMid;
break;
}
}
return pointerMin;
};
/**
* Remove a connection from the database. Must already exist in DB.
* @param {!Blockly.RenderedConnection} connection The connection to be removed.
* @param {number} yPos The y position used to find the index of the connection.
* @throws {Error} If the connection cannot be found in the database.
*/
Blockly.ConnectionDB.prototype.removeConnection = function(connection, yPos) {
var index = this.findIndexOfConnection_(connection, yPos);
if (index == -1) {
throw Error('Unable to find connection in connectionDB.');
}
this.connections_.splice(index, 1);
};
/**
* Find all nearby connections to the given connection.
* Type checking does not apply, since this function is used for bumping.
* @param {!Blockly.RenderedConnection} connection The connection whose
* neighbours should be returned.
* @param {number} maxRadius The maximum radius to another connection.
* @return {!Array.<!Blockly.RenderedConnection>} List of connections.
*/
Blockly.ConnectionDB.prototype.getNeighbours = function(connection, maxRadius) {
var db = this.connections_;
var currentX = connection.x;
var currentY = connection.y;
// Binary search to find the closest y location.
var pointerMin = 0;
var pointerMax = db.length - 2;
var pointerMid = pointerMax;
while (pointerMin < pointerMid) {
if (db[pointerMid].y < currentY) {
pointerMin = pointerMid;
} else {
pointerMax = pointerMid;
}
pointerMid = Math.floor((pointerMin + pointerMax) / 2);
}
var neighbours = [];
/**
* Computes if the current connection is within the allowed radius of another
* connection.
* This function is a closure and has access to outside variables.
* @param {number} yIndex The other connection's index in the database.
* @return {boolean} True if the current connection's vertical distance from
* the other connection is less than the allowed radius.
*/
function checkConnection_(yIndex) {
var dx = currentX - db[yIndex].x;
var dy = currentY - db[yIndex].y;
var r = Math.sqrt(dx * dx + dy * dy);
if (r <= maxRadius) {
neighbours.push(db[yIndex]);
}
return dy < maxRadius;
}
// Walk forward and back on the y axis looking for the closest x,y point.
pointerMin = pointerMid;
pointerMax = pointerMid;
if (db.length) {
while (pointerMin >= 0 && checkConnection_(pointerMin)) {
pointerMin--;
}
do {
pointerMax++;
} while (pointerMax < db.length && checkConnection_(pointerMax));
}
return neighbours;
};
/**
* Is the candidate connection close to the reference connection.
* Extremely fast; only looks at Y distance.
* @param {number} index Index in database of candidate connection.
* @param {number} baseY Reference connection's Y value.
* @param {number} maxRadius The maximum radius to another connection.
* @return {boolean} True if connection is in range.
* @private
*/
Blockly.ConnectionDB.prototype.isInYRange_ = function(index, baseY, maxRadius) {
return (Math.abs(this.connections_[index].y - baseY) <= maxRadius);
};
/**
* Find the closest compatible connection to this connection.
* @param {!Blockly.RenderedConnection} conn The connection searching for a compatible
* mate.
* @param {number} maxRadius The maximum radius to another connection.
* @param {!Blockly.utils.Coordinate} dxy Offset between this connection's
* location in the database and the current location (as a result of
* dragging).
* @return {!{connection: Blockly.RenderedConnection, radius: number}}
* Contains two properties: 'connection' which is either another
* connection or null, and 'radius' which is the distance.
*/
Blockly.ConnectionDB.prototype.searchForClosest = function(conn, maxRadius,
dxy) {
if (!this.connections_.length) {
// Don't bother.
return {connection: null, radius: maxRadius};
}
// Stash the values of x and y from before the drag.
var baseY = conn.y;
var baseX = conn.x;
conn.x = baseX + dxy.x;
conn.y = baseY + dxy.y;
// calculateIndexForYPos_ finds an index for insertion, which is always
// after any block with the same y index. We want to search both forward
// and back, so search on both sides of the index.
var closestIndex = this.calculateIndexForYPos_(conn.y);
var bestConnection = null;
var bestRadius = maxRadius;
var temp;
// Walk forward and back on the y axis looking for the closest x,y point.
var pointerMin = closestIndex - 1;
while (pointerMin >= 0 && this.isInYRange_(pointerMin, conn.y, maxRadius)) {
temp = this.connections_[pointerMin];
if (this.connectionChecker_.canConnect(conn, temp, true, bestRadius)) {
bestConnection = temp;
bestRadius = temp.distanceFrom(conn);
}
pointerMin--;
}
var pointerMax = closestIndex;
while (pointerMax < this.connections_.length &&
this.isInYRange_(pointerMax, conn.y, maxRadius)) {
temp = this.connections_[pointerMax];
if (this.connectionChecker_.canConnect(conn, temp, true, bestRadius)) {
bestConnection = temp;
bestRadius = temp.distanceFrom(conn);
}
pointerMax++;
}
// Reset the values of x and y.
conn.x = baseX;
conn.y = baseY;
// If there were no valid connections, bestConnection will be null.
return {connection: bestConnection, radius: bestRadius};
};
/**
* Initialize a set of connection DBs for a workspace.
* @param {!Blockly.IConnectionChecker} checker The workspace's
* connection checker, used to decide if connections are valid during a drag.
* @return {!Array.<!Blockly.ConnectionDB>} Array of databases.
*/
Blockly.ConnectionDB.init = function(checker) {
// Create four databases, one for each connection type.
var dbList = [];
dbList[Blockly.INPUT_VALUE] = new Blockly.ConnectionDB(checker);
dbList[Blockly.OUTPUT_VALUE] = new Blockly.ConnectionDB(checker);
dbList[Blockly.NEXT_STATEMENT] = new Blockly.ConnectionDB(checker);
dbList[Blockly.PREVIOUS_STATEMENT] = new Blockly.ConnectionDB(checker);
return dbList;
};