Mask.cpp

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// Copyright (c) 2008-2019 OpenShot Studios, LLC
//
// SPDX-License-Identifier: LGPL-3.0-or-later
 
#include "Mask.h"
 
#include "Exceptions.h"
 
#include "ReaderBase.h"
#include <array>
#include <omp.h>
 
using namespace openshot;
 
Mask::Mask() : replace_image(false) {
    // Init effect properties
    init_effect_details();
}
 
// Default constructor
Mask::Mask(ReaderBase *mask_reader, Keyframe mask_brightness, Keyframe mask_contrast) :
        brightness(mask_brightness), contrast(mask_contrast), replace_image(false)
{
    // Init effect properties
    init_effect_details();
 
    // Keep ownership local by cloning externally-provided readers.
    if (mask_reader)
        MaskReader(CreateReaderFromJson(mask_reader->JsonValue()));
}
 
// Init effect settings
void Mask::init_effect_details()
{
    InitEffectInfo();
 
    info.class_name = "Mask";
    info.name = "Alpha Mask / Wipe Transition";
    info.description = "Uses a grayscale mask image to gradually wipe / transition between 2 images.";
    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> Mask::GetFrame(std::shared_ptr<openshot::Frame> frame, int64_t frame_number) {
    // Get frame image first
    std::shared_ptr<QImage> frame_image = frame->GetImage();
    if (!frame_image || frame_image->isNull())
        return frame;
 
    // No reader (bail on applying the mask)
    auto original_mask = ResolveMaskImage(frame_image, frame_number);
    if (!original_mask || original_mask->isNull())
        return frame;
 
    // Grab raw pointers and dimensions one time
    unsigned char* pixels      = reinterpret_cast<unsigned char*>(frame_image->bits());
    unsigned char* mask_pixels = reinterpret_cast<unsigned char*>(original_mask->bits());
    const int num_pixels        = original_mask->width() * original_mask->height();
 
    // Evaluate brightness and contrast keyframes just once
    double contrast_value   = contrast.GetValue(frame_number);
    double brightness_value = brightness.GetValue(frame_number);
 
    int brightness_adj = static_cast<int>(255 * brightness_value);
    float contrast_factor = 20.0f / std::max(0.00001f, 20.0f - static_cast<float>(contrast_value));
    const bool output_mask = replace_image;
    const auto clamp_u8 = [](int value) -> unsigned char {
        if (value < 0) return 0;
        if (value > 255) return 255;
        return static_cast<unsigned char>(value);
    };
    // Precompute gray->adjusted-gray mapping for this frame's brightness/contrast.
    std::array<unsigned char, 256> adjusted_gray{};
    for (int gray = 0; gray < 256; ++gray) {
        const int adjusted = static_cast<int>(contrast_factor * ((gray + brightness_adj) - 128) + 128);
        adjusted_gray[gray] = clamp_u8(adjusted);
    }
    // 8-bit multiply lookup for premultiplied alpha channel scaling.
    static const std::array<std::array<unsigned char, 256>, 256> mul_lut = [] {
        std::array<std::array<unsigned char, 256>, 256> lut{};
        for (int alpha = 0; alpha < 256; ++alpha) {
            for (int value = 0; value < 256; ++value) {
                lut[alpha][value] = static_cast<unsigned char>((value * alpha) / 255);
            }
        }
        return lut;
    }();
 
    // Separate loops keep the hot path branch-free per pixel.
    if (output_mask) {
        #pragma omp parallel for if(num_pixels >= 16384) schedule(static)
        for (int i = 0; i < num_pixels; ++i) {
            const int idx = i * 4;
            const int R = mask_pixels[idx + 0];
            const int G = mask_pixels[idx + 1];
            const int B = mask_pixels[idx + 2];
            const int A = mask_pixels[idx + 3];
 
            const int gray = ((R * 11) + (G * 16) + (B * 5)) >> 5;
            const int diff = A - adjusted_gray[gray];
            const unsigned char new_val = clamp_u8(diff);
            pixels[idx + 0] = new_val;
            pixels[idx + 1] = new_val;
            pixels[idx + 2] = new_val;
            pixels[idx + 3] = new_val;
        }
    } else if (mask_invert) {
        #pragma omp parallel for if(num_pixels >= 16384) schedule(static)
        for (int i = 0; i < num_pixels; ++i) {
            const int idx = i * 4;
            const int R = mask_pixels[idx + 0];
            const int G = mask_pixels[idx + 1];
            const int B = mask_pixels[idx + 2];
            const int A = mask_pixels[idx + 3];
 
            const int gray = ((R * 11) + (G * 16) + (B * 5)) >> 5;
            int alpha = A - adjusted_gray[gray];
            if (alpha < 0) alpha = 0;
            else if (alpha > 255) alpha = 255;
            alpha = 255 - alpha;
 
            // Premultiplied RGBA → multiply each channel by alpha
            pixels[idx + 0] = mul_lut[alpha][pixels[idx + 0]];
            pixels[idx + 1] = mul_lut[alpha][pixels[idx + 1]];
            pixels[idx + 2] = mul_lut[alpha][pixels[idx + 2]];
            pixels[idx + 3] = mul_lut[alpha][pixels[idx + 3]];
        }
    } else {
        #pragma omp parallel for if(num_pixels >= 16384) schedule(static)
        for (int i = 0; i < num_pixels; ++i) {
            const int idx = i * 4;
            const int R = mask_pixels[idx + 0];
            const int G = mask_pixels[idx + 1];
            const int B = mask_pixels[idx + 2];
            const int A = mask_pixels[idx + 3];
 
            const int gray = ((R * 11) + (G * 16) + (B * 5)) >> 5;
            int alpha = A - adjusted_gray[gray];
            if (alpha < 0) alpha = 0;
            else if (alpha > 255) alpha = 255;
 
            // Premultiplied RGBA → multiply each channel by alpha
            pixels[idx + 0] = mul_lut[alpha][pixels[idx + 0]];
            pixels[idx + 1] = mul_lut[alpha][pixels[idx + 1]];
            pixels[idx + 2] = mul_lut[alpha][pixels[idx + 2]];
            pixels[idx + 3] = mul_lut[alpha][pixels[idx + 3]];
        }
    }
 
    // return the modified frame
    return frame;
}
 
// Generate JSON string of this object
std::string Mask::Json() const {
 
    // Return formatted string
    return JsonValue().toStyledString();
}
 
// Generate Json::Value for this object
Json::Value Mask::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();
    root["replace_image"] = replace_image;
 
    // return JsonValue
    return root;
}
 
// Load JSON string into this object
void Mask::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 Mask::SetJsonValue(const Json::Value root) {
    Json::Value normalized_root = root;
    // Legacy compatibility: keep accepting "reader" on Mask effects.
    if (!normalized_root["reader"].isNull() && normalized_root["mask_reader"].isNull())
        normalized_root["mask_reader"] = normalized_root["reader"];
 
    // Set parent data
    EffectBase::SetJsonValue(normalized_root);
 
    // Set data from Json (if key is found)
    if (!normalized_root["replace_image"].isNull())
        replace_image = normalized_root["replace_image"].asBool();
    if (!normalized_root["brightness"].isNull())
        brightness.SetJsonValue(normalized_root["brightness"]);
    if (!normalized_root["contrast"].isNull())
        contrast.SetJsonValue(normalized_root["contrast"]);
 
}
 
// Get all properties for a specific frame
std::string Mask::PropertiesJSON(int64_t requested_frame) const {
 
    // Generate JSON properties list
    Json::Value root = BasePropertiesJSON(requested_frame);
 
    // Add replace_image choices (dropdown style)
    root["replace_image"] = add_property_json("Replace Image", replace_image, "int", "", NULL, 0, 1, false, requested_frame);
    root["replace_image"]["choices"].append(add_property_choice_json("Yes", true, replace_image));
    root["replace_image"]["choices"].append(add_property_choice_json("No", false, replace_image));
 
    // 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, 0, 20, false, requested_frame);
 
    // Return formatted string
    return root.toStyledString();
}
 
void Mask::Reader(ReaderBase *new_reader) {
    if (!new_reader) {
        MaskReader(NULL);
        return;
    }
 
    // Keep ownership local by cloning externally-provided readers.
    MaskReader(CreateReaderFromJson(new_reader->JsonValue()));
}