I want to be able to make a custom horizontal slider using an image film strip like the rotary image. I’m not able to find any examples of it online. Has anyone implemented this before?
I implemented an “EndlessSlider” that seems like it might be similar to what you are after - this basically takes an image and transforms it across the Component view according to slider events from the user. In the PolarDesigner plugin, we use this as a ‘trim’ to adjust all bands equally, but you could of course use it for whatever your needs are. Mine is vertical, but you can adjust for horizontal easily enough …
//
// EndlessSlider.h
// PolarDesigner - All
//
// Created by Jay Vaughan on 23.02.22.
// Copyright © 2022 Austrian Audio. All rights reserved.
//
// This Component implements an 'endless slider', which can be useful for implementing
// 'trim' controls, i.e. for applying trim to a set of EQ's, volume sliders, etc.
//
// To adjust the rate of trim, use the EndlessSlider.step value in the slider inc/dec
// callbacks.
#ifndef EndlessSlider_h
#define EndlessSlider_h
class EndlessSlider : public Slider {
public:
EndlessSlider () :
Slider()
{
setChangeNotificationOnlyOnRelease(false);
sliderImage = getImageFromAssets("scrollImage.png");
setTextBoxStyle (Slider::NoTextBox, false, 0, 0);
setSliderStyle (Slider::LinearBarVertical);
setScrollWheelEnabled(true);
};
// Trim step value - modify it freely as needed
double step = 0.012725f;
// set these callbacks where you use this class in order to get inc/dec messages
std::function<void()> sliderIncremented;
std::function<void()> sliderDecremented;
// calculate whether to callback to an increment or decrement, and update UI
void mouseDrag(const MouseEvent &e) override
{
int currentMoved;
static int lastMoved;
if (e.mouseWasDraggedSinceMouseDown()) {
currentMoved = e.getDistanceFromDragStartY();
sliderImageTransform = (AffineTransform::translation ((float) (sliderImage.getWidth()),
(float) (sliderImage.getHeight()) + currentMoved)
.followedBy (getTransform()));
if ((currentMoved > lastMoved)){
sliderDecremented();
} else
if (currentMoved < lastMoved) {
sliderIncremented();
}
lastMoved = currentMoved;
repaint();
}
}
void paint (Graphics&g) override
{
Rectangle<int> bounds = getLocalBounds();
Path endlessPath;
g.setColour(getRandomColour());
g.setFillType(juce::FillType(sliderImage, sliderImageTransform));
g.fillRect(bounds);
}
void mouseExit (const MouseEvent& e) override
{
repaint();
}
~EndlessSlider () {}
void resized() override
{
Slider::resized();
auto& lf = getLookAndFeel();
auto layout = lf.getSliderLayout (*this);
sliderRect = layout.sliderBounds;
}
private:
Rectangle<int> sliderRect;
Image sliderImage;
AffineTransform sliderImageTransform;
// utility functions - from DemoRunner utilities
static juce::Colour getRandomColour()
{
auto& random = juce::Random::getSystemRandom();
return juce::Colour ((juce::uint8) random.nextInt (256),
(juce::uint8) random.nextInt (256),
(juce::uint8) random.nextInt (256));
}
// creats a usable image asset from a file stream
inline std::unique_ptr<InputStream> createAssetInputStream (const char* resourcePath)
{
#if JUCE_ANDROID
ZipFile apkZip (File::getSpecialLocation (File::invokedExecutableFile));
return std::unique_ptr<InputStream> (apkZip.createStreamForEntry (apkZip.getIndexOfFileName ("assets/" + String (resourcePath))));
#else
#if JUCE_IOS
auto assetsDir = File::getSpecialLocation (File::currentExecutableFile)
.getParentDirectory().getChildFile ("Assets");
#elif JUCE_MAC
auto assetsDir = File::getSpecialLocation (File::currentExecutableFile)
.getParentDirectory().getParentDirectory().getChildFile ("Resources").getChildFile ("Assets");
#endif
auto resourceFile = assetsDir.getChildFile (resourcePath);
jassert (resourceFile.existsAsFile());
return resourceFile.createInputStream();
#endif
}
// creates an image asset from cache if possible
inline Image getImageFromAssets (const char* assetName)
{
auto hashCode = (String (assetName) + "@endless_slider_assets").hashCode64();
auto img = ImageCache::getFromHashCode (hashCode);
if (img.isNull())
{
std::unique_ptr<InputStream> juceIconStream (createAssetInputStream (assetName));
if (juceIconStream == nullptr)
return {};
img = ImageFileFormat::loadFrom (*juceIconStream);
ImageCache::addImageToCache (img, hashCode);
}
return img;
}
};
#endif /* EndlessSlider_h */
This is open source, btw … see our Plugin repositories here: Austrian Audio · GitHub
Thanks austrianaudioJV.
At the moment I have something I am developing but it doesn’t seem to stretch the image correctly to fit the container. Here is my code.
void knobTesting::drawLinearSlider(juce::Graphics &g, int x, int y, int width, int height,
float sliderPos, float minSliderPos, float maxSliderPos, const juce::Slider::SliderStyle,
juce::Slider &s)
{
if (img1.isValid())
{
//std::cout << "Positions: " + x;
const int imgWidth = img1.getWidth();
const int imgHeight = img1.getHeight();
const int frames = imgHeight/ 201;
const double sliderValuePos = (s.getValue() - s.getMinimum()) / (s.getMaximum() - s.getMinimum());
const int frameId = (int)ceil(sliderValuePos * ((double)frames - 1.0));
const double frameHeight = imgHeight/201;
const float centerX = x + width * 0.5f;
const float centerY = y + height * 0.5f;
const float rx = centerX - (width/2) - 1.0f;
const float ry = centerY - width;
g.drawImage(img1,
(int)rx,
(int)ry,
width,
frameHeight,
0,
frameId*frameHeight,
imgWidth,
frameHeight);
}
else
{
static const float textPpercent = 0.35f;
juce::Rectangle<float> text_bounds(1.0f + width * (1.0f - textPpercent) / 2.0f,
0.5f * height, width * textPpercent, 0.5f * height);
g.setColour(juce::Colours::white);
g.drawFittedText(juce::String("No Image"), text_bounds.getSmallestIntegerContainer(),
juce::Justification::horizontallyCentred | juce::Justification::centred, 1);
}
}
I would advise not using the manual methods to resize the image for your needs, but rather apply a Transform to it. This is a lot more performant and also more likely to give you the results you need. Remember you can do all sorts of operations in the Transform … see my code for an example, which is useful inasmuch as it wraps the image (the source image is only 6 pixels wide) across the Transform being applied. You can also do your stretching that way too …