Brightness.cpp

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// Copyright (c) 2008-2019 OpenShot Studios, LLC
//
// SPDX-License-Identifier: LGPL-3.0-or-later
 
#include "Brightness.h"
#include "Exceptions.h"
 
using namespace openshot;
 
Brightness::Brightness() : brightness(0.0), contrast(3.0) {
    // Init effect properties
    init_effect_details();
}
 
// Default constructor
Brightness::Brightness(Keyframe new_brightness, Keyframe new_contrast) : brightness(new_brightness), contrast(new_contrast)
{
    // Init effect properties
    init_effect_details();
}
 
// Init effect settings
void Brightness::init_effect_details()
{
    InitEffectInfo();
 
    info.class_name = "Brightness";
    info.name = "Brightness & Contrast";
    info.description = "Adjust the brightness and contrast of the frame's image.";
    info.has_audio = false;
    info.has_video = true;
}
 
// This method is required for all derived classes of EffectBase, and returns a
// modified openshot::Frame object
std::shared_ptr<openshot::Frame> Brightness::GetFrame(std::shared_ptr<openshot::Frame> frame, int64_t frame_number)
{
    // Get the frame's image
    std::shared_ptr<QImage> frame_image = frame->GetImage();
 
    // Get keyframe values for this frame
    float brightness_value = brightness.GetValue(frame_number);
    float contrast_value = contrast.GetValue(frame_number);
 
    // Loop through pixels
    unsigned char *pixels = (unsigned char *) frame_image->bits();
    int pixel_count = frame_image->width() * frame_image->height();
 
    #pragma omp parallel for
    for (int pixel = 0; pixel < pixel_count; ++pixel)
    {
        // Compute contrast adjustment factor
        float factor = (259 * (contrast_value + 255)) / (255 * (259 - contrast_value));
 
        // Calculate alpha % (to be used for removing pre-multiplied alpha value)
        int A = pixels[pixel * 4 + 3];
        float alpha_percent = A / 255.0;
 
        // Get RGB values, and remove pre-multiplied alpha
        unsigned char R = pixels[pixel * 4 + 0] / alpha_percent;
        unsigned char G = pixels[pixel * 4 + 1] / alpha_percent;
        unsigned char B = pixels[pixel * 4 + 2] / alpha_percent;
 
        // Apply constrained contrast adjustment
        R = constrain((factor * (R - 128)) + 128);
        G = constrain((factor * (G - 128)) + 128);
        B = constrain((factor * (B - 128)) + 128);
 
        // Adjust brightness and write constrained values back to image
        pixels[pixel * 4 + 0] = constrain(R + (255 * brightness_value));
        pixels[pixel * 4 + 1] = constrain(G + (255 * brightness_value));
        pixels[pixel * 4 + 2] = constrain(B + (255 * brightness_value));
 
        // Pre-multiply the alpha back into the color channels
        pixels[pixel * 4 + 0] *= alpha_percent;
        pixels[pixel * 4 + 1] *= alpha_percent;
        pixels[pixel * 4 + 2] *= alpha_percent;
    }
 
    // return the modified frame
    return frame;
}
 
// Generate JSON string of this object
std::string Brightness::Json() const {
 
    // Return formatted string
    return JsonValue().toStyledString();
}
 
// Generate Json::Value for this object
Json::Value Brightness::JsonValue() const {
 
    // Create root json object
    Json::Value root = EffectBase::JsonValue(); // get parent properties
    root["type"] = info.class_name;
    root["brightness"] = brightness.JsonValue();
    root["contrast"] = contrast.JsonValue();
 
    // return JsonValue
    return root;
}
 
// Load JSON string into this object
void Brightness::SetJson(const std::string value) {
 
    // Parse JSON string into JSON objects
    try
    {
        const Json::Value root = openshot::stringToJson(value);
        // Set all values that match
        SetJsonValue(root);
    }
    catch (const std::exception& e)
    {
        // Error parsing JSON (or missing keys)
        throw InvalidJSON("JSON is invalid (missing keys or invalid data types)");
    }
}
 
// Load Json::Value into this object
void Brightness::SetJsonValue(const Json::Value root) {
 
    // Set parent data
    EffectBase::SetJsonValue(root);
 
    // Set data from Json (if key is found)
    if (!root["brightness"].isNull())
        brightness.SetJsonValue(root["brightness"]);
    if (!root["contrast"].isNull())
        contrast.SetJsonValue(root["contrast"]);
}
 
// Get all properties for a specific frame
std::string Brightness::PropertiesJSON(int64_t requested_frame) const {
 
    // Generate JSON properties list
    Json::Value root = BasePropertiesJSON(requested_frame);
 
    // Keyframes
    root["brightness"] = add_property_json("Brightness", brightness.GetValue(requested_frame), "float", "", &brightness, -1.0, 1.0, false, requested_frame);
    root["contrast"] = add_property_json("Contrast", contrast.GetValue(requested_frame), "float", "", &contrast, -128, 128.0, false, requested_frame);
 
    // Return formatted string
    return root.toStyledString();
}