src/renderer.cpp

#include "rive/math/mat2d.hpp"
#include "rive/renderer.hpp"

using namespace rive;

Mat2D rive::computeAlignment(Fit fit, Alignment alignment, const AABB& frame, const AABB& content) {
    float contentWidth = content.width();
    float contentHeight = content.height();
    float x = -content.left() - contentWidth / 2.0 - (alignment.x() * contentWidth / 2.0);
    float y = -content.top() - contentHeight / 2.0 - (alignment.y() * contentHeight / 2.0);

    float scaleX = 1.0, scaleY = 1.0;

    switch (fit) {
        case Fit::fill: {
            scaleX = frame.width() / contentWidth;
            scaleY = frame.height() / contentHeight;
            break;
        }
        case Fit::contain: {
            float minScale =
                std::fmin(frame.width() / contentWidth, frame.height() / contentHeight);
            scaleX = scaleY = minScale;
            break;
        }
        case Fit::cover: {
            float maxScale =
                std::fmax(frame.width() / contentWidth, frame.height() / contentHeight);
            scaleX = scaleY = maxScale;
            break;
        }
        case Fit::fitHeight: {
            float minScale = frame.height() / contentHeight;
            scaleX = scaleY = minScale;
            break;
        }
        case Fit::fitWidth: {
            float minScale = frame.width() / contentWidth;
            scaleX = scaleY = minScale;
            break;
        }
        case Fit::none: {
            scaleX = scaleY = 1.0;
            break;
        }
        case Fit::scaleDown: {
            float minScale =
                std::fmin(frame.width() / contentWidth, frame.height() / contentHeight);
            scaleX = scaleY = minScale < 1.0 ? minScale : 1.0;
            break;
        }
    }

    Mat2D translation;
    translation[4] = frame.left() + frame.width() / 2.0 + (alignment.x() * frame.width() / 2.0);
    translation[5] = frame.top() + frame.height() / 2.0 + (alignment.y() * frame.height() / 2.0);

    return translation * Mat2D::fromScale(scaleX, scaleY) * Mat2D::fromTranslate(x, y);
}

void Renderer::translate(float tx, float ty) { this->transform(Mat2D(1, 0, 0, 1, tx, ty)); }

void Renderer::scale(float sx, float sy) { this->transform(Mat2D(sx, 0, 0, sy, 0, 0)); }

void Renderer::rotate(float radians) {
    const float s = std::sin(radians);
    const float c = std::cos(radians);
    this->transform(Mat2D(c, s, -s, c, 0, 0));
}