pixel-editor/js/_rectSelect.js

var isRectSelecting = false;
let startX;
let startY;
let endX;
let endY;

/** Starts the selection: saves the canvas, sets the start coordinates
 * 
 * @param {*} mouseEvent 
 */
function startRectSelection(mouseEvent) {
    // Saving the canvas
    new HistoryStates.EditCanvas();
    // Putting the vfx layer on top of everything
    VFXCanvas.style.zIndex = MAX_Z_INDEX;

    // Saving the start coords of the rect
    let cursorPos = getCursorPosition(mouseEvent);
    startX = Math.round(cursorPos[0] / zoom) - 0.5;
    startY = Math.round(cursorPos[1] / zoom) - 0.5;

    // Avoiding external selections
    if (startX < 0) {
        startX = 0;
    }
    else if (startX > currentLayer.canvas.width) {
        startX = currentLayer.canvas.width;
    }

    if (startY < 0) {
        startY = 0;
    }
    else if (startY > currentLayer.canvas.height) {
        startY = currentLayer.canvas.height;
    }

    // Drawing the rect
    drawRect(startX, startY);
    selectionCanceled = false;
}

/** Updates the selection
 * 
 * @param {*} mouseEvent 
 */
function updateRectSelection(mouseEvent) {
	let pos = getCursorPosition(mouseEvent);

	// Drawing the rect
	drawRect(Math.round(pos[0] / zoom) + 0.5, Math.round(pos[1] / zoom) + 0.5);
}

/** Ends the selection: sets the end coordiantes
 * 
 * @param {*} mouseEvent 
 */
function endRectSelection(mouseEvent) {
	// Getting the end position
	let currentPos = getCursorPosition(mouseEvent);
	endX = Math.round(currentPos[0] / zoom) + 0.5;
	endY = Math.round(currentPos[1] / zoom) + 0.5;

	// Inverting end and start (start must always be the top left corner)
	if (endX < startX) {
		let tmp = endX;
		endX = startX;
		startX = tmp;
	}
	// Same for the y
	if (endY < startY) {
		let tmp = endY;
		endY = startY;
		startY = tmp;
	}

	// Selecting the move tool
	currentTool = tool.moveselection;
	currentToolTemp = currentTool;

	// Resetting this
	isRectSelecting = false;

	// Updating the cursor
	currentTool.updateCursor();
}

/** Cuts the selection from its canvas and puts it in the tmp layer so it can be moved
 * 
 * @param {*} mousePosition 
 */
function cutSelection(mousePosition) {
	// Getting the selected pixels
	imageDataToMove = currentLayer.context.getImageData(startX, startY, endX - startX + 1, endY - startY + 1);
    
	currentLayer.context.clearRect(startX - 0.5, startY - 0.5, endX - startX + 1, endY - startY + 1);
	// Moving those pixels from the current layer to the tmp layer
	TMPLayer.context.putImageData(imageDataToMove, startX + 1, startY);
}

/** Draws a dashed rectangle representing the selection
 * 
 * @param {*} x Current end x coordinate of the selection
 * @param {*} y Current end y coordinate of the selection
 */
function drawRect(x, y) {
    // Getting the vfx context
    let vfxContext = VFXCanvas.getContext('2d');

    // Clearing the vfx canvas
    vfxContext.clearRect(0, 0, VFXCanvas.width, VFXCanvas.height);
    vfxContext.lineWidth = 1;
    vfxContext.strokeStyle = 'black';
    vfxContext.setLineDash([4]);

    // Drawing the rect
    vfxContext.beginPath();
    vfxContext.rect(startX, startY, x - startX, y - startY);

    vfxContext.stroke();
}

function applyChanges() {
    VFXCanvas.style.zIndex = MIN_Z_INDEX;
}

// Checks whether the pointer is inside the selected area or not
function cursorInSelectedArea() {
    // Getting the cursor position
    let cursorPos = getCursorPosition(currentMouseEvent);
    // Getting the coordinates relatively to the canvas
    let x = cursorPos[0] / zoom;
    let y = cursorPos[1] / zoom;

    // This is to avoid rightX or topY being less than leftX or bottomY
    let leftX = Math.min(startX, endX);
    let rightX = Math.max(startX, endX);
    let topY = Math.max(startY, endY);
    let bottomY = Math.min(startY, endY);

    if (leftX <= x && x <= rightX) {
        if (bottomY <= y && y <= topY) {
            return true;
        }

        return false;
    }

    return false;
}

/** Moves the rect ants to the specified position 
 * 
 * @param {*} x X coordinate of the rect ants
 * @param {*} y Y coordinat of the rect ants
 * @param {*} width Width of the selection
 * @param {*} height Height of the selectin
 */
function moveSelection(x, y, width, height) {
    // Getting the vfx context
    let vfxContext = VFXCanvas.getContext('2d');

    // Clearing the vfx canvas
    vfxContext.clearRect(0, 0, VFXCanvas.width, VFXCanvas.height);
    vfxContext.lineWidth = 1;
    vfxContext.setLineDash([4]);

    // Fixing the coordinates
    startX = Math.round(Math.round(x) - 0.5 - Math.round(width / 2)) + 0.5;
    startY = Math.round(Math.round(y) - 0.5 - Math.round(height / 2)) + 0.5;
    endX = startX + Math.round(width);
    endY = startY + Math.round(height);

    // Drawing the rect
    vfxContext.beginPath();
    vfxContext.rect(startX, startY, width, height);

    vfxContext.stroke();
}