PixelCanvasGeometry.h

Go to the documentation of this file.

// SPDX-FileCopyrightText: 2026 Valentin Eloy
// SPDX-License-Identifier: GPL-3.0-or-later
 
#pragma once
 
#include <optional>
#include <utility>
 
#include "HMI/Editor/ThumbnailGeometry.h"

 
namespace hmi {

inline constexpr int PIXEL_CANVAS_MIN_ZOOM = 1;
inline constexpr int PIXEL_CANVAS_MAX_ZOOM = 32;

inline constexpr int PIXEL_CANVAS_GRID_VISIBLE_MIN_ZOOM = 4;

struct PixelCanvasView {
    int zoom = 8;
    int panX = 0;  
    int panY = 0;  
    int zoomDenominator = 1;
 
    [[nodiscard]] friend bool operator==(const PixelCanvasView&,
                                         const PixelCanvasView&) noexcept = default;
};

struct PixelScreenRect {
    double x = 0.0;
    double y = 0.0;
    double width = 0.0;
    double height = 0.0;
};

[[nodiscard]] PixelScreenRect imagePixelScreenRect(const PixelCanvasView& view, int x,
                                                   int y) noexcept;

[[nodiscard]] std::optional<std::pair<int, int>> screenToImagePixel(const PixelCanvasView& view,
                                                                    int imageWidth, int imageHeight,
                                                                    double screenX,
                                                                    double screenY) noexcept;

[[nodiscard]] constexpr int clampPixelCanvasZoom(int zoom) noexcept {
    if (zoom < PIXEL_CANVAS_MIN_ZOOM) {
        return PIXEL_CANVAS_MIN_ZOOM;
    }
    if (zoom > PIXEL_CANVAS_MAX_ZOOM) {
        return PIXEL_CANVAS_MAX_ZOOM;
    }
    return zoom;
}

[[nodiscard]] constexpr int pixelCanvasZoomIn(int zoom) noexcept {
    return clampPixelCanvasZoom(zoom + 1);
}

[[nodiscard]] constexpr int pixelCanvasZoomOut(int zoom) noexcept {
    return clampPixelCanvasZoom(zoom - 1);
}

[[nodiscard]] constexpr bool pixelCanvasGridVisible(int zoom) noexcept {
    return zoom >= PIXEL_CANVAS_GRID_VISIBLE_MIN_ZOOM;
}

inline constexpr int PIXEL_CANVAS_MAX_DENOMINATOR = 8;

[[nodiscard]] constexpr bool isValidPixelCanvasDenominator(int denominator) noexcept {
    return denominator == 1 || denominator == 2 || denominator == 4 ||
           denominator == PIXEL_CANVAS_MAX_DENOMINATOR;
}

[[nodiscard]] constexpr double pixelCanvasScale(const PixelCanvasView& view) noexcept {
    if (view.zoom <= 0 || view.zoomDenominator <= 0) {
        return 0.0;
    }
    return static_cast<double>(view.zoom) / static_cast<double>(view.zoomDenominator);
}

[[nodiscard]] constexpr PixelCanvasView pixelCanvasZoomIn(const PixelCanvasView& view) noexcept {
    PixelCanvasView next = view;
    if (next.zoomDenominator > 1) {
        next.zoomDenominator /= 2;
        return next;
    }
    next.zoom = clampPixelCanvasZoom(next.zoom + 1);
    return next;
}

[[nodiscard]] constexpr PixelCanvasView pixelCanvasZoomOut(const PixelCanvasView& view) noexcept {
    PixelCanvasView next = view;
    if (next.zoom > PIXEL_CANVAS_MIN_ZOOM) {
        next.zoom = clampPixelCanvasZoom(next.zoom - 1);
        return next;
    }
    if (next.zoomDenominator < PIXEL_CANVAS_MAX_DENOMINATOR) {
        next.zoomDenominator *= 2;
    }
    return next;
}

[[nodiscard]] constexpr bool pixelCanvasGridVisible(const PixelCanvasView& view) noexcept {
    return view.zoomDenominator == 1 && view.zoom >= PIXEL_CANVAS_GRID_VISIBLE_MIN_ZOOM;
}

struct PixelCanvasRealSize {
    int width = 0;
    int height = 0;
};

[[nodiscard]] PixelCanvasRealSize pixelCanvasRealSize(int imageWidth, int imageHeight, int zoom,
                                                      double scaleFactor) noexcept;

[[nodiscard]] PixelCanvasRealSize pixelCanvasRealSize(int imageWidth, int imageHeight,
                                                      const PixelCanvasView& view,
                                                      double scaleFactor) noexcept;
 
}  // namespace hmi