Inheriting from Slider class

General JUCE discussion
1

Hi jules,

I’m building a custom linear slider class, which should especially be able to paint itself using arbitrary images.

I’d like to inherit from the Slider class (to keep the Slider’s internal behaviour) and adapt slider’s sliderRect (and therefore sliderRegionSize and sliderRegionStart) according to images “properties”. However, these members are private…

Would it be possible to make them protected (i’ve done this temporarily) ? Or is there another way to implement a self-drawing custom slider ?

Thanx in advance !

2

You should really be using the LookAndFeel class to do a custom slider - if you find that that’s not flexible enough, let me know how you think it could be made better.

3

In fact, i need to change sliderRect values to match with my images.
For example, if use a image for the thumb so that the current slider value corresponds to the vertical middle of my image.
I need to tell the base Slider class that sliderRegionSize corresponds to my track image size less thumb size and that sliderRegionStart to a halp thumb size.

So, something like that :

SliderRect is private, therefore not accessible in lookAndFeel methods.

4

you can take inspiration from this slider (derived from the Slider class, but doesn’t use the look and feel, and uses some internal images instead)

/*
 ==============================================================================

 This file is part of the JUCETICE project - Copyright 2007 by Lucio Asnaghi.

 JUCETICE is based around the JUCE library - "Jules' Utility Class Extensions"
 Copyright 2007 by Julian Storer.

 ------------------------------------------------------------------------------

 JUCE and JUCETICE can be redistributed and/or modified under the terms of
 the GNU General Public License, as published by the Free Software Foundation;
 either version 2 of the License, or (at your option) any later version.

 JUCE and JUCETICE are distributed in the hope that they will be useful,
 but WITHOUT ANY WARRANTY; without even the implied warranty of
 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 GNU General Public License for more details.

 You should have received a copy of the GNU General Public License
 along with JUCE and JUCETICE; if not, visit www.gnu.org/licenses or write to
 Free Software Foundation, Inc., 59 Temple Place, Suite 330,
 Boston, MA 02111-1307 USA

 ==============================================================================
 */


//==============================================================================
/**
     An image based slider.
*/
class ImageSlider : public Slider
{
public:

    //==============================================================================
    enum SliderOrientation
    {
        LinearHorizontal = 0,
        LinearVertical   = 1
    };

    //==============================================================================
    /** Constructor */
    ImageSlider (const String& sliderName);

    /** Destructor */
    ~ImageSlider();

    //==============================================================================
    void setOrientation (const SliderOrientation isVertical);

    //==============================================================================
    void setThumbImage (Image* newImage);
    void setThumbOffsetInImage (const int newMinOffset, const int newMaxOffset);

        //==============================================================================
    /** @internal */
    void paint (Graphics& g);

private:

    //==============================================================================
    /** Image handle resources */
    static const char*  fader_horizontal;
    static const int    fader_horizontal_size;
    static const char*  fader_vertical;
    static const int    fader_vertical_size;

    int minOffset, maxOffset;
    Image* thumbImage;
};




/*
 ==============================================================================

 This file is part of the JUCETICE project - Copyright 2007 by Lucio Asnaghi.

 JUCETICE is based around the JUCE library - "Jules' Utility Class Extensions"
 Copyright 2007 by Julian Storer.

 ------------------------------------------------------------------------------

 JUCE and JUCETICE can be redistributed and/or modified under the terms of
 the GNU General Public License, as published by the Free Software Foundation;
 either version 2 of the License, or (at your option) any later version.

 JUCE and JUCETICE are distributed in the hope that they will be useful,
 but WITHOUT ANY WARRANTY; without even the implied warranty of
 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 GNU General Public License for more details.

 You should have received a copy of the GNU General Public License
 along with JUCE and JUCETICE; if not, visit www.gnu.org/licenses or write to
 Free Software Foundation, Inc., 59 Temple Place, Suite 330,
 Boston, MA 02111-1307 USA

 ==============================================================================
 */

#include "jucetice_ImageSlider.h"


//==============================================================================
ImageSlider::ImageSlider (const String& sliderName)
  : Slider (sliderName),
    minOffset (0),
    maxOffset (0),
    thumbImage (0)
{
    setOrientation (ImageSlider::LinearVertical);
}

ImageSlider::~ImageSlider()
{
    if (thumbImage)
        ImageCache::release (thumbImage);
}

//==============================================================================
void ImageSlider::setOrientation (const SliderOrientation orientation)
{
    if (orientation == ImageSlider::LinearHorizontal)
    {
        setSliderStyle (Slider::LinearHorizontal);
        setThumbImage (ImageCache::getFromMemory (ImageSlider::fader_horizontal,
                                                  ImageSlider::fader_horizontal_size));
        setThumbOffsetInImage (4, 4); // used if the thumb is smaller than
                                        // the size of its image, for example
                                        // if the thumb have a inner shadow
    }
    else if (orientation == ImageSlider::LinearVertical)
    {
        setSliderStyle (Slider::LinearVertical);
        setThumbImage (ImageCache::getFromMemory (ImageSlider::fader_vertical,
                                                  ImageSlider::fader_vertical_size));
        setThumbOffsetInImage (4, 4); // used if the thumb is smaller than
                                        // the size of its image, for example
                                        // if the thumb have a inner shadow
    }
}

//==============================================================================
void ImageSlider::setThumbImage (Image* newImage)
{
    thumbImage = newImage;
}

void ImageSlider::setThumbOffsetInImage (const int newMinOffset, const int newMaxOffset)
{
    minOffset = newMinOffset;
    maxOffset = newMaxOffset;
}

//==============================================================================
void ImageSlider::paint (Graphics& g)
{
    float x = 0, y = 0;
    int minX, maxX;
    const bool sliderEnabled = isEnabled();
    const bool hightlight = isMouseOverOrDragging();

    if (getSliderStyle() == Slider::LinearVertical)
    {
        x = (getWidth () - thumbImage->getWidth()) / 2;
        y = (getHeight () - thumbImage->getHeight()) * (1.0f - valueToProportionOfLength (getValue()));
        minX = minOffset;
        maxX = getHeight() - maxOffset;

        // draw background line
        g.setColour (Colours::black.withAlpha (sliderEnabled ? 0.5f : 0.3f));
        g.drawVerticalLine (getWidth() / 2,
                            minX, jmax ((int) y + minOffset, minX));
        g.drawVerticalLine (getWidth() / 2,
                            jmin ((int)y + thumbImage->getHeight() - maxOffset, maxX), maxX);
    }
    else if (getSliderStyle() == Slider::LinearHorizontal)
    {
        x = (getWidth () - thumbImage->getWidth()) * valueToProportionOfLength (getValue());
        y = (getHeight () - thumbImage->getHeight()) / 2;
        minX = minOffset;
        maxX = getWidth() - maxOffset;

        // draw background line
        g.setColour (Colours::black.withAlpha (sliderEnabled ? 0.5f : 0.3f));
        g.drawHorizontalLine (getHeight() / 2,
                                minX, jmax ((int) x + minOffset, minX));
        g.drawHorizontalLine (getHeight() / 2,
                                jmin ((int) x + thumbImage->getWidth() - maxOffset, maxX), maxX);
    }

    if (thumbImage)
    {
        if (! sliderEnabled)
            g.setOpacity (0.6f);
        else
            g.setOpacity (1.0f);

        // draw thumb image
        g.drawImage (thumbImage,
                        (int) x, (int) y, thumbImage->getWidth(), thumbImage->getHeight(),
                        0, 0, thumbImage->getWidth(), thumbImage->getHeight());

        if (sliderEnabled && hightlight)
        {
            // g.setColour (Colours::yellow.withAlpha (0.25f));
            // g.fillRect ((int) x, (int) y, thumbImage->getWidth(), thumbImage->getHeight());
        }
    }
}


//==============================================================================
static const unsigned char temp1[] = {137,80,78,71,13,10,26,10,0,0,0,13,73,72,68,82,0,0,0,24,0,0,0,15,8,6,0,0,0,254,164,15,219,0,0,0,6,98,75,71,
  68,0,255,0,255,0,255,160,189,167,147,0,0,0,9,112,72,89,115,0,0,11,19,0,0,11,19,1,0,154,156,24,0,0,0,7,116,73,77,69,
  7,215,3,14,16,36,13,247,239,181,191,0,0,1,187,73,68,65,84,56,203,213,148,221,110,211,64,16,133,191,93,219,113,32,70,212,49,229,231,130,
  86,165,42,80,94,142,39,224,9,120,48,238,145,42,168,194,5,106,65,105,73,90,215,78,213,198,206,122,135,11,79,132,228,70,194,149,184,97,165,213,
  104,87,51,115,118,230,156,89,248,223,151,249,135,254,210,55,192,232,14,54,248,244,1,88,219,6,144,110,128,57,157,151,23,167,63,231,233,60,207,1,
  33,8,66,30,12,99,70,15,71,28,127,159,178,251,34,229,89,246,24,231,5,196,179,188,185,225,243,209,132,31,103,191,88,148,87,124,252,240,254,57,
  80,3,75,96,21,118,1,146,100,100,231,23,19,142,190,30,147,101,41,73,146,16,199,49,105,154,50,249,244,133,253,157,109,14,118,158,82,57,8,44,
  12,44,204,46,11,78,166,51,198,217,19,128,61,160,4,114,160,8,59,229,7,214,66,24,89,162,65,132,181,33,54,8,48,166,45,116,24,133,88,107,
  105,0,47,128,7,111,160,105,60,198,128,115,13,192,59,96,170,249,150,225,6,2,218,108,34,109,59,229,222,194,217,83,155,3,177,237,230,247,162,188,
  24,243,135,211,251,105,45,5,30,1,67,192,222,1,16,143,113,206,179,170,87,120,239,240,190,65,124,91,70,237,26,68,4,11,88,211,114,96,13,4,
  65,155,70,109,168,10,180,128,233,182,72,202,235,107,198,227,45,14,223,188,198,88,105,57,0,242,60,231,237,203,140,198,57,190,157,156,227,61,8,66,
  125,123,203,217,249,12,16,138,162,0,112,42,81,15,200,29,128,221,237,173,125,237,227,33,240,10,24,3,131,30,179,32,42,207,43,96,1,84,128,15,
  55,56,214,42,179,181,18,230,90,182,249,11,128,215,151,47,52,182,4,170,176,243,130,70,145,47,245,174,0,98,5,232,179,26,29,176,245,28,84,102,
  195,55,17,0,145,170,96,160,103,211,179,69,58,29,84,186,235,223,56,246,168,17,206,84,69,211,0,0,0,0,73,69,78,68,174,66,96,130,0,0};
const char* ImageSlider::fader_horizontal = (const char*) temp1;
const int ImageSlider::fader_horizontal_size = 558;

static const unsigned char temp2[] = {137,80,78,71,13,10,26,10,0,0,0,13,73,72,68,82,0,0,0,15,0,0,0,24,8,6,0,0,0,37,5,167,105,0,0,0,6,98,75,71,
  68,0,255,0,255,0,255,160,189,167,147,0,0,0,9,112,72,89,115,0,0,11,19,0,0,11,19,1,0,154,156,24,0,0,1,197,73,68,65,84,
  56,203,197,148,219,110,211,64,16,134,191,217,181,227,64,34,81,39,42,136,11,90,149,138,67,121,255,119,224,30,169,64,21,132,170,2,74,75,220,184,
  117,211,180,118,236,29,46,216,36,198,78,137,196,13,150,70,214,206,206,191,115,252,7,254,215,39,255,120,167,15,25,136,23,219,56,235,18,4,84,128,
  54,193,242,45,201,46,251,253,158,49,6,4,196,169,138,58,36,155,205,216,223,221,57,4,10,32,7,22,65,11,252,35,137,147,203,17,65,104,86,202,
  178,116,12,6,59,0,7,64,6,76,129,172,9,182,73,154,114,252,249,132,176,19,130,42,136,176,40,22,28,189,121,13,112,4,140,189,109,17,108,170,
  197,112,24,99,76,224,83,20,156,43,17,163,0,47,125,254,215,192,180,21,182,181,1,253,126,31,99,237,170,60,206,85,191,207,48,0,18,32,2,108,
  203,243,163,110,68,20,69,136,200,170,214,234,116,217,150,14,16,120,145,22,184,247,184,71,28,199,173,100,210,52,109,245,63,104,246,247,228,116,204,232,
  253,39,186,225,250,170,40,43,222,190,24,182,30,108,121,222,127,30,115,184,183,139,49,235,86,169,42,85,89,214,7,134,141,97,63,27,62,225,213,222,
  83,170,154,206,0,95,206,46,182,123,46,157,146,151,224,180,6,22,112,142,237,96,212,97,13,80,51,182,6,20,221,14,190,159,207,233,24,112,242,167,
  231,226,238,110,59,248,195,241,136,201,244,154,170,90,187,182,214,112,126,49,249,43,88,1,253,126,254,147,179,241,4,145,141,20,214,90,66,106,154,38,
  55,217,21,81,199,98,132,149,132,129,97,126,59,195,211,177,122,136,207,161,159,223,3,224,157,255,199,62,194,18,184,2,190,2,31,129,211,13,172,162,
  240,156,93,82,47,241,91,165,2,110,188,62,3,242,38,184,2,238,129,212,79,82,10,116,253,156,56,191,65,50,175,207,101,195,254,178,158,61,145,23,
  83,219,97,203,7,114,160,248,5,194,64,164,44,166,64,137,52,0,0,0,0,73,69,78,68,174,66,96,130,0,0};
const char* ImageSlider::fader_vertical = (const char*) temp2;
const int ImageSlider::fader_vertical_size = 549;

this could be adapted to use your sliders graphics :slight_smile:

5

You should be able to do it with a lookandfeel - LookAndFeel::getSliderThumbRadius() sets the thumb size, I think.

6

Thanx Kraken for the ImageSlider Class example,
Thanx Jules for the tip.

using getSliderThumbRadius () seems to be a good solution !!

7

I,m in a similar situation. I,ve subclassed the slider and added my methods to it, all working nicely. But now I need to call one of my methods in LookandFeel::drawLinearSlider to change the way it looks based on my properties, but it does not allow me because the slider passed though in drawLinearSlider is of the type Slider and not my subclassed slider.

I,ve tried implementing the paint method in my class and call LookandFeel::drawLinearSlider from there but then I also run into problems with private members.

Can anyone offer a clean solution for this? Maybe a dynamic cast on the slider in LookandFeel::drawLinearSlider?

8

Yes, you could certainly do a dynamic cast there, that’d work fine.

9

Yes the dynamic cast did the trick, we always figured that a dynamic cast is a last resort solution?

10

No - there’s nothing wrong with a few dynamic casts IMHO.