GetsCalledEachMouseClick.java

    event = new MousePressEvent() {
            @Override
            public void call(int key, int action) {
                if(action == GLFW.GLFW_PRESS && key == GLFW.GLFW_MOUSE_BUTTON_LEFT) {
                    for(ItemRenderHolder holder:items) {
                        holder.setOldSlot();
                        if(MathUtils.isClose(range, (float) Input.getMouseX(), holder.pos.x)) {
                            if(MathUtils.isClose(range, (float) (win.getYSize() - Input.getMouseY()), holder.pos.y))
                                holder.isHolding = true;
                        }
                    }
                } else if(action == GLFW.GLFW_RELEASE && key == GLFW.GLFW_MOUSE_BUTTON_LEFT) {
                    items.forEach(holder -> {
                        if(holder.isHolding) {
                            holder.isHolding = false;
                            holder.pos.x = MathUtils.mapMulti(holder.pos.x-offset.x, offset2) + offset.x;
                            holder.pos.y = MathUtils.mapMulti(holder.pos.y-offset.y, offset2) + offset.y;
                            holder.recalcSlot();
                            items.forEach(holder1 -> {
                                if(!holder.equals(holder1)) {
                                    if(holder.slot.x == holder1.slot.x && holder.slot.y == holder1.slot.y) {
                                        if(holder.itemStack.item.id == holder1.itemStack.item.id) {
                                            holder.itemStack.count += holder1.itemStack.count;
                                            toRemove = items.indexOf(holder1);
                                            shouldRemove = true;
                                        } else {
                                            holder.returnBack();
                                        }
                                    }
                                }
                            });
                            if(holder.slot.x > 8 || holder.slot.y > 2 || holder.slot.x < 0 || holder.slot.y < 0) {
                                holder.returnBack();
                            }
                        }
                    });
                    if(shouldRemove) {
                        items.remove(toRemove);
                        shouldRemove = false;
                    }
                }
            }
        };