RetroShare/retroshare-gui/src/gui/gxschannels/GxsChannelPostThumbnail.h

/*******************************************************************************
 * retroshare-gui/src/gui/gxschannels/GxsChannelPostThumbnail.h                *
 *                                                                             *
 * Copyright 2020 by Retroshare Team   <retroshare.project@gmail.com>          *
 *                                                                             *
 * This program is free software: you can redistribute it and/or modify        *
 * it under the terms of the GNU Affero General Public License as              *
 * published by the Free Software Foundation, either version 3 of the          *
 * License, or (at your option) any later version.                             *
 *                                                                             *
 * This program is distributed in the hope that it will be useful,             *
 * but WITHOUT ANY WARRANTY; without even the implied warranty of              *
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the                *
 * GNU Affero General Public License for more details.                         *
 *                                                                             *
 * You should have received a copy of the GNU Affero General Public License    *
 * along with this program. If not, see <https://www.gnu.org/licenses/>.       *
 *                                                                             *
 *******************************************************************************/

#pragma once

#include <string>

#include <QWidget>
#include <QLabel>
#include <QLayout>

#include "retroshare/rsgxschannels.h"
#include "retroshare/rsidentity.h"

#include "gui/gxs/GxsIdDetails.h"
#include "gui/common/FilesDefs.h"

// Class to provide a label in which the image can be zoomed/moved. The widget size is fixed by the GUI and the user can move/zoom the image
// inside the window formed by the widget. When happy, the view-able part of the image can be extracted.

class ZoomableLabel: public QLabel
{
    Q_OBJECT

public:
    ZoomableLabel(QWidget *parent): QLabel(parent),mUseStyleSheet(true),mZoomFactor(1.0),mCenterX(0.0),mCenterY(0.0),mZoomEnabled(true) {}

    void setPicture(const QPixmap& pix);
    void setEnableZoom(bool b) { mZoomEnabled = b; }
    void reset();
    QPixmap extractCroppedScaledPicture() const;
    void updateView();

    const QPixmap& originalImage() const { return mFullImage ; }

signals:
    void clicked();

protected:
    void mousePressEvent(QMouseEvent *ev) override;
    void mouseReleaseEvent(QMouseEvent *ev) override;
    void mouseMoveEvent(QMouseEvent *ev) override;
    void resizeEvent(QResizeEvent *ev) override;
    void wheelEvent(QWheelEvent *me) override;

    void enterEvent(QEvent * /* ev */ ) override { if(mUseStyleSheet) setStyleSheet("QLabel { border: 2px solid #039bd5; }");}
    void leaveEvent(QEvent * /* ev */ ) override { if(mUseStyleSheet) setStyleSheet("QLabel { border: 2px solid #CCCCCC; border-radius: 3px; }");}

    bool mUseStyleSheet;

    QPixmap mFullImage;

    float mZoomFactor;
    float mCenterX;
    float mCenterY;
    int   mLastX,mLastY;
    bool  mMoving;
    bool  mZoomEnabled;
};

// Class to paint the thumbnails with title

class ChannelPostThumbnailView: public QWidget
{
	Q_OBJECT

public:
    typedef enum {
        ASPECT_RATIO_UNKNOWN = 0x00,
        ASPECT_RATIO_2_3     = 0x01,
        ASPECT_RATIO_1_1     = 0x02,
        ASPECT_RATIO_16_9    = 0x03,
    } AspectRatio;

	// This variable determines the zoom factor on the text below thumbnails. 2.0 is mostly correct for all screen.
    static constexpr float THUMBNAIL_OVERSAMPLE_FACTOR = 2.0;

    static constexpr uint32_t FLAG_NONE      = 0x00;
    static constexpr uint32_t FLAG_SHOW_TEXT = 0x01;
    static constexpr uint32_t FLAG_ALLOW_PAN = 0x02;
    static constexpr uint32_t FLAG_SCALE_FONT= 0x04;

	// Size of thumbnails as a function of the height of the font. An aspect ratio of 3/4 is good.

	static const int THUMBNAIL_W  = 4;
	static const int THUMBNAIL_H  = 6;

    static constexpr char *CHAN_DEFAULT_IMAGE = ":images/thumb-default-video.png";

    virtual ~ChannelPostThumbnailView();
    ChannelPostThumbnailView(QWidget *parent=NULL,uint32_t flags=FLAG_ALLOW_PAN | FLAG_SHOW_TEXT | FLAG_SCALE_FONT);
    ChannelPostThumbnailView(const RsGxsChannelPost& post,uint32_t flags,QWidget *parent=NULL);

    void init(const RsGxsChannelPost& post);

    void setAspectRatio(AspectRatio r);
    void setPixmap(const QPixmap& p,bool guess_aspect_ratio) ;
    QPixmap getCroppedScaledPicture() const { return mPostImage->extractCroppedScaledPicture() ; }

    void setText(const QString& s);

    // This is used to allow to render the widget into a pixmap without the white space that Qt adds vertically. There is *no way* apparently
    // to get rid of that bloody space. It depends on the aspect ratio of the image and it only shows up when the text label is shown.
    // The label however has a correct size. It seems that Qt doesn't like widgets with horizontal aspect ratio and forces the size accordingly.

    QSize actualSize() const ;

    /*!
     * \brief bestAspectRatio
     * 			Computes the preferred aspect ratio for the image in the post. The default is 1:1.
     * \return the prefered aspect ratio
     */
    AspectRatio bestAspectRatio() ;
private:
    static const float DEFAULT_SIZE_IN_FONT_HEIGHT ;
    static const float FONT_SCALE_FACTOR ;

    float thumbnail_w() const;
    float thumbnail_h() const;

    ZoomableLabel *mPostImage;
    QLabel *mPostTitle;
    uint32_t mFlags;
    AspectRatio mAspectRatio;
};