AScrollbar.h

/*
 * AUI Framework - Declarative UI toolkit for modern C++20
 * Copyright (C) 2020-2024 Alex2772 and Contributors
 *
 * SPDX-License-Identifier: MPL-2.0
 *
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/.
 */
 
//
// Created by alex2 on 06.12.2020.
//
 
#pragma once
 
#include <AUI/Util/ALayoutDirection.h>
#include <AUI/Common/ATimer.h>
#include "AViewContainer.h"
#include "ASpacerExpanding.h"
 
class API_AUI_VIEWS AScrollbar;
 
class AScrollbarButton: public AView {
public:
    AScrollbarButton() {
 
    }
};
class AScrollbarHandle: public AView {friend class API_AUI_VIEWS AScrollbar;
private:
    int mScrollOffset = 0;
    bool mDragging = false;
 
public:
    void setSize(glm::ivec2 size) override;
    void onPointerMove(glm::vec2 pos, const APointerMoveEvent& event) override;
    void onPointerPressed(const APointerPressedEvent& event) override;
    void onPointerReleased(const APointerReleasedEvent& event) override;
    void setOverridenSize(int overridenSize) {
        mOverridenSize = overridenSize;
    }
 
private:
    explicit AScrollbarHandle(AScrollbar& scrollbar) : mScrollbar(scrollbar) {}
 
    AScrollbar& mScrollbar;
    int mOverridenSize;
};
 
class AScrollbarOffsetSpacer: public ASpacerExpanding {
public:
    AScrollbarOffsetSpacer(): ASpacerExpanding(0, 0) {
 
    }
 
    int getMinimumWidth() override {
        return 0;
    }
 
    int getMinimumHeight() override {
        return 0;
    }
};

class API_AUI_VIEWS AScrollbar: public AViewContainerBase {
    friend class AScrollbarHandle;
public:
 
    explicit AScrollbar(ALayoutDirection direction = ALayoutDirection::VERTICAL);
 
    [[nodiscard]] int getCurrentScroll() const {
        return mCurrentScroll;
    }
 
    void setScrollDimensions(size_t viewportSize, size_t fullSize);
    void updateScrollHandleSize();
    void setScroll(int scroll);
 
    void scroll(int delta) noexcept {
        setScroll(mCurrentScroll + delta);
    }
 
    void onScroll(float& delta);
 
    void onScroll(const AScrollEvent& event) override;

    void setStickToEnd(bool stickToEnd) {
        if (stickToEnd) {
            mStickToEnd = StickToEnd{
                .locked = true,
            };
            scrollToEnd();
        } else {
            mStickToEnd.reset();
        }
    }
 
    void setAppearance(ass::ScrollbarAppearance::AxisValue appearance) {
        mAppearance = appearance;
    }
 
    void scrollToStart() {
        setScroll(0);
    }
 
    void scrollToEnd();
 
    float getAvailableSpaceForSpacer();
 
    void updateScrollHandleOffset(int max);
 
    void onPointerPressed(const APointerPressedEvent& event) override;
 
    void setSize(glm::ivec2 size) override;
 
    static const _<ATimer>& buttonTimer();
 

    std::size_t getMaxScroll() const noexcept {
        if (mFullSize <= mViewportSize) {
            return 0;
        }
 
        return mFullSize - mViewportSize;
    }
 
signals:
 
    emits<int> scrolled;
 
    emits<int> updatedMaxScroll;
 
    emits<> triggeredManually;
 
protected:
    ALayoutDirection mDirection;
    _<ASpacerExpanding> mOffsetSpacer;
    _<AScrollbarHandle> mHandle;
    _<AScrollbarButton> mForwardButton;
    _<AScrollbarButton> mBackwardButton;
 
    size_t mViewportSize = 0, mFullSize = 0;
    int mCurrentScroll = 0;
 
    void setOffset(size_t o);
 
    void scrollForward();
    void scrollBackward();
 
    void handleScrollbar(int s);
 
 
private:
    struct StickToEnd {
        bool locked = true;
    };
    AOptional<StickToEnd> mStickToEnd;
    ass::ScrollbarAppearance::AxisValue mAppearance = ass::ScrollbarAppearance::ON_DEMAND;
};