pixel-editor/js/_mouseEvents.js

var currentMouseEvent;
var lastMouseMovePos;

//mousedown - start drawing
window.addEventListener("mousedown", function (mouseEvent) {
	// Saving the event in case something else needs it
	currentMouseEvent = mouseEvent;
	canDraw = true;

	//if no document has been created yet, or this is a dialog open, or the currentLayer is locked
	if (!documentCreated || dialogueOpen || currentLayer.isLocked || !currentLayer.isVisible) return;
	//prevent right mouse clicks and such, which will open unwanted menus
	//mouseEvent.preventDefault();

	lastMouseClickPos = getCursorPosition(mouseEvent);

	dragging = true;
	//left or right click ?
	if (mouseEvent.which == 1) {
		if (spacePressed)
			currentTool = tool.pan;
		else if (mouseEvent.altKey)
			currentTool = tool.eyedropper;
		else if (mouseEvent.target.className == 'drawingCanvas' &&
			(currentTool.name == 'pencil' || currentTool.name == 'eraser' || currentTool.name == 'rectangle'))
		    new HistoryStateEditCanvas();
		else if (currentTool.name == 'moveselection') {
			if (!cursorInSelectedArea() && 
				((mouseEvent.target.id == 'canvas-view') || mouseEvent.target.className == 'drawingCanvas')) {
				tool.pencil.switchTo();
				canDraw = false;
			}
		}
		
		currentTool.updateCursor();

		if (!currentLayer.isLocked && !currentLayer.isVisible && canDraw) {
			draw(mouseEvent);
		}
	}
	else if (currentTool.name == 'pencil' && mouseEvent.which == 3) {
		currentTool = tool.resizebrush;
		tool.pencil.previousBrushSize = tool.pencil.brushSize;
	}
	else if (currentTool.name == 'eraser' && mouseEvent.which == 3) {
	    currentTool = tool.resizeeraser;
	    tool.eraser.previousBrushSize = tool.eraser.brushSize;
    }
	else if (currentTool.name == 'rectangle' && mouseEvent.which == 3) {
		currentTool = tool.resizerectangle;
		tool.rectangle.previousBrushSize = tool.rectangle.brushSize;
	}

	if (currentTool.name == 'eyedropper' && mouseEvent.target.className == 'drawingCanvas')
	    eyedropperPreview.style.display = 'block';

	return false;
}, false);



//mouseup - end drawing
window.addEventListener("mouseup", function (mouseEvent) {
	// Saving the event in case something else needs it
	currentMouseEvent = mouseEvent;

	closeMenu();
	
	if (currentLayer != null && !isChildOfByClass(mouseEvent.target, "layers-menu-entry")) {
		currentLayer.closeOptionsMenu();	
	}

	if (!documentCreated || dialogueOpen || !currentLayer.isVisible || currentLayer.isLocked) return;

	if (currentTool.name == 'eyedropper' && mouseEvent.target.className == 'drawingCanvas') {
		var cursorLocation = getCursorPosition(mouseEvent);
		var selectedColor = getEyedropperColor(cursorLocation);
		var newColor = rgbToHex(selectedColor[0],selectedColor[1],selectedColor[2]);

		currentGlobalColor = "#" + newColor;

		for (let i=1; i<layers.length - 1; i++) {
			layers[i].context.fillStyle = currentGlobalColor;
		}

		var colors = document.getElementsByClassName('color-button');
	    for (var i = 0; i < colors.length; i++) {

	      //if picked color matches this color
	      if (newColor == colors[i].jscolor.toString()) {
	        //remove current color selection
	        var selectedColor = document.querySelector("#colors-menu li.selected")
	        if (selectedColor) selectedColor.classList.remove("selected");

	      	//set current color

			for (let i=2; i<layers.length; i++) {
				layers[i].context.fillStyle = '#' + newColor;
			}

	      	//make color selected
	      	colors[i].parentElement.classList.add('selected');

	        //hide eyedropper
	        eyedropperPreview.style.display = 'none';
	      }
	    }
	}
	else if (currentTool.name == 'fill' && mouseEvent.target.className == 'drawingCanvas') {

		//get cursor postion
		var cursorLocation = getCursorPosition(mouseEvent);

		//offset to match cursor point
		cursorLocation[0] += 2;
		cursorLocation[1] += 12;

    	//fill starting at the location
		fill(cursorLocation);
		currentLayer.updateLayerPreview();
	}
	else if (currentTool.name == 'zoom' && mouseEvent.target.className == 'drawingCanvas') {
		let mode;
		if (mouseEvent.which == 1){
			mode = "in";
        }
    }
    else if (currentTool == 'zoom' && mouseEvent.target.className == 'drawingCanvas') {
        let mode;
        if (mouseEvent.which == 1){
            mode = 'in';
        }
        else if (mouseEvent.which == 3){
            mode = 'out';
        }

        changeZoom(layers[0], mode, getCursorPosition(mouseEvent));

        for (let i=1; i<layers.length; i++) {
            layers[i].copyData(layers[0]);
        }
	}
	else if (currentTool.name == 'rectselect' && isRectSelecting) {
		endRectSelection(mouseEvent);
	}
	else if (currentTool.name == 'rectangle' && isDrawingRect) {
		endRectDrawing(mouseEvent);
		currentLayer.updateLayerPreview();
	}

	dragging = false;
	currentTool = currentToolTemp;

	currentTool.updateCursor();


}, false);

// TODO: Make it snap to the pixel grid
function setPreviewPosition(preview, cursor, size){
    preview.style.left = (
        currentLayer.canvas.offsetLeft
        + Math.floor(cursor[0]/zoom) * zoom
        - Math.floor(size / 2) * zoom
    ) + 'px';
    preview.style.top = (
        currentLayer.canvas.offsetTop
        + Math.floor(cursor[1]/zoom) * zoom
        - Math.floor(size / 2) * zoom
    ) + 'px';
}


// OPTIMIZABLE: redundant || mouseEvent.target.className in currentTool ifs

//mouse is moving on canvas
window.addEventListener("mousemove", draw, false);
function draw (mouseEvent) {
	lastMouseMovePos = getCursorPosition(mouseEvent);
	// Saving the event in case something else needs it
	currentMouseEvent = mouseEvent;

	var cursorLocation = lastMouseMovePos;

	//if a document hasnt yet been created or the current layer is locked, exit this function
	if (!documentCreated || dialogueOpen || !currentLayer.isVisible || currentLayer.isLocked) return;

	// Moving brush preview
	currentTool.moveBrushPreview(cursorLocation);
	// Hiding eyedropper, will be shown if it's needed
	eyedropperPreview.style.display = 'none';

	if (currentTool.name == 'pencil') {
		//hide brush preview outside of canvas / canvas view
		if (mouseEvent.target.className == 'drawingCanvas'|| mouseEvent.target.className == 'drawingCanvas')
		  brushPreview.style.visibility = 'visible';
		else
		  brushPreview.style.visibility = 'hidden';

		//draw line to current pixel
		if (dragging) {
			if (mouseEvent.target.className == 'drawingCanvas' || mouseEvent.target.className == 'drawingCanvas') {
				line(Math.floor(lastMouseClickPos[0]/zoom),Math.floor(lastMouseClickPos[1]/zoom),Math.floor(cursorLocation[0]/zoom),Math.floor(cursorLocation[1]/zoom), tool.pencil.brushSize);
				lastMouseClickPos = cursorLocation;
			}
		}

		//get lightness value of color
		var selectedColor = currentLayer.context.getImageData(Math.floor(cursorLocation[0]/zoom),Math.floor(cursorLocation[1]/zoom),1,1).data;
		var colorLightness = Math.max(selectedColor[0],selectedColor[1],selectedColor[2])

		//for the darkest 50% of colors, change the brush preview to dark mode
		if (colorLightness>127) brushPreview.classList.remove('dark');
		else brushPreview.classList.add('dark');

		currentLayer.updateLayerPreview();
	}
	// Decided to write a different implementation in case of differences between the brush and the eraser tool
	else if (currentTool.name == 'eraser') {
        //hide brush preview outside of canvas / canvas view
        if (mouseEvent.target.className == 'drawingCanvas' || mouseEvent.target.className == 'drawingCanvas')
            brushPreview.style.visibility = 'visible';
        else
            brushPreview.style.visibility = 'hidden';

        //draw line to current pixel
        if (dragging) {
            if (mouseEvent.target.className == 'drawingCanvas' || mouseEvent.target.className == 'drawingCanvas') {
                line(Math.floor(lastMouseClickPos[0]/zoom),Math.floor(lastMouseClickPos[1]/zoom),Math.floor(cursorLocation[0]/zoom),Math.floor(cursorLocation[1]/zoom), currentTool.brushSize);
                lastMouseClickPos = cursorLocation;
            }
        }

        currentLayer.updateLayerPreview();
	}
	else if (currentTool.name == 'rectangle')
	{
		//hide brush preview outside of canvas / canvas view
		if (mouseEvent.target.className == 'drawingCanvas'|| mouseEvent.target.className == 'drawingCanvas')
		  brushPreview.style.visibility = 'visible';
		else
		  brushPreview.style.visibility = 'hidden';

		if (!isDrawingRect && dragging) {
			startRectDrawing(mouseEvent);
		}
		else if (dragging){
			updateRectDrawing(mouseEvent);
		}
	}
	else if (currentTool.name == 'pan' && dragging) {
	    // Setting first layer position
        setCanvasOffset(layers[0].canvas, layers[0].canvas.offsetLeft + (cursorLocation[0] - lastMouseClickPos[0]), layers[0].canvas.offsetTop + (cursorLocation[1] - lastMouseClickPos[1]));
        // Copying that position to the other layers
        for (let i=1; i<layers.length; i++) {
            layers[i].copyData(layers[0]);
        }
    }
    else if (currentTool.name == 'eyedropper' && dragging && mouseEvent.target.className == 'drawingCanvas') {
    	let selectedColor = getEyedropperColor(cursorLocation);

        eyedropperPreview.style.borderColor = '#'+rgbToHex(selectedColor[0],selectedColor[1],selectedColor[2]);
        eyedropperPreview.style.display = 'block';

        eyedropperPreview.style.left = cursorLocation[0] + currentLayer.canvas.offsetLeft - 30 + 'px';
        eyedropperPreview.style.top = cursorLocation[1] + currentLayer.canvas.offsetTop - 30 + 'px';

        var colorLightness = Math.max(selectedColor[0],selectedColor[1],selectedColor[2]);

        //for the darkest 50% of colors, change the eyedropper preview to dark mode
        if (colorLightness>127) eyedropperPreview.classList.remove('dark');
        else eyedropperPreview.classList.add('dark');
    }
    else if (currentTool.name == 'resizebrush' && dragging) {
        //get new brush size based on x distance from original clicking location
        var distanceFromClick = cursorLocation[0] - lastMouseClickPos[0];
        //var roundingAmount = 20 - Math.round(distanceFromClick/10);
        //this doesnt work in reverse...  because... it's not basing it off of the brush size which it should be
        var brushSizeChange = Math.round(distanceFromClick/10);
        var newBrushSize = tool.pencil.previousBrushSize + brushSizeChange;

        //set the brush to the new size as long as its bigger than 1
        tool.pencil.brushSize = Math.max(1,newBrushSize);

        //fix offset so the cursor stays centered
        tool.pencil.moveBrushPreview(lastMouseClickPos);
        currentTool.updateCursor();
    }
    else if (currentTool.name == 'resizeeraser' && dragging) {
        //get new brush size based on x distance from original clicking location
        var distanceFromClick = cursorLocation[0] - lastMouseClickPos[0];
        //var roundingAmount = 20 - Math.round(distanceFromClick/10);
        //this doesnt work in reverse...  because... it's not basing it off of the brush size which it should be
        var eraserSizeChange = Math.round(distanceFromClick/10);
        var newEraserSizeChange = tool.eraser.previousBrushSize + eraserSizeChange;

        //set the brush to the new size as long as its bigger than 1
		tool.eraser.brushSize = Math.max(1,newEraserSizeChange);
		
		//fix offset so the cursor stays centered
		tool.eraser.moveBrushPreview(lastMouseClickPos);
        currentTool.updateCursor();
    }
    else if (currentTool.name == 'resizerectangle' && dragging) {
    	//get new brush size based on x distance from original clicking location
        var distanceFromClick = cursorLocation[0] - lastMouseClickPos[0];
        //var roundingAmount = 20 - Math.round(distanceFromClick/10);
        //this doesnt work in reverse...  because... it's not basing it off of the brush size which it should be
        var rectangleSizeChange = Math.round(distanceFromClick/10);
        var newRectangleSize = tool.rectangle.previousBrushSize + rectangleSizeChange;

        //set the brush to the new size as long as its bigger than 1
        tool.rectangle.brushSize = Math.max(1,newRectangleSize);

		//fix offset so the cursor stays centered
		tool.rectangle.moveBrushPreview(lastMouseClickPos);
        currentTool.updateCursor();
    }
    else if (currentTool.name == 'rectselect') {
    	if (dragging && !isRectSelecting && mouseEvent.target.className == 'drawingCanvas') {
    		isRectSelecting = true;
    		startRectSelection(mouseEvent);
    	}
    	else if (dragging && isRectSelecting) {
    		updateRectSelection(mouseEvent);
    	}
    	else if (isRectSelecting) {
    		endRectSelection();
    	}
    }
    else if (currentTool.name == 'moveselection') {
    	// Updating the cursor (move if inside rect, cross if not)
    	currentTool.updateCursor();

        // If I'm dragging, I move the preview
        if (dragging && cursorInSelectedArea()) {
            updateMovePreview(getCursorPosition(mouseEvent));
        }
    }
}

//mousewheel scroll
canvasView.addEventListener("wheel", function(mouseEvent){
	let mode;
	if (mouseEvent.deltaY < 0){
		mode = 'in';
	}
	else if (mouseEvent.deltaY > 0) {
		mode = 'out';
	}

	// Changing zoom and position of the first layer
	changeZoom(layers[0], mode, getCursorPosition(mouseEvent));

	for (let i=1; i<layers.length; i++) {
		// Copying first layer's data into the other layers
		layers[i].copyData(layers[0]);
	}
});