feat: canvas from texture atlas element

src/graphics/core/Atlas.cpp

@@ -49,6 +49,14 @@ ImageData* Atlas::getImage() const {
     return image.get();
 }
 
+std::shared_ptr<Texture> Atlas::shareTexture() const {
+    return texture;
+}
+
+std::shared_ptr<ImageData> Atlas::shareImageData() const {
+    return image;
+}
+
 void AtlasBuilder::add(const std::string& name, std::unique_ptr<ImageData> image) {
     entries.push_back(atlasentry{name, std::shared_ptr<ImageData>(image.release())});
     names.insert(name);

src/graphics/core/Atlas.hpp

@@ -14,8 +14,8 @@ class ImageData;
 class Texture;
 
 class Atlas {
-    std::unique_ptr<Texture> texture;
-    std::unique_ptr<ImageData> image;
+    std::shared_ptr<Texture> texture;
+    std::shared_ptr<ImageData> image;
     std::unordered_map<std::string, UVRegion> regions;
 public:
     /// @param image atlas raster
@@ -36,6 +36,9 @@ public:
 
     Texture* getTexture() const;
     ImageData* getImage() const;
+
+    std::shared_ptr<Texture> shareTexture() const;
+    std::shared_ptr<ImageData> shareImageData() const;
 };
 
 struct atlasentry {

src/graphics/core/ImageData.cpp

@@ -95,6 +95,17 @@ void ImageData::blit(const ImageData& image, int x, int y) {
     throw std::runtime_error("mismatching format");
 }
 
+std::unique_ptr<ImageData> ImageData::cropped(int x, int y, int width, int height) const {
+    width = std::min<int>(width, this->width - x);
+    height = std::min<int>(height, this->height - y);
+    if (width <= 0 || height <= 0) {
+        throw std::runtime_error("invalid crop dimensions");
+    }
+    auto subImage = std::make_unique<ImageData>(format, width, height);
+    subImage->blitMatchingFormat(*this, -x, -y);
+    return subImage;
+}
+
 static bool clip_line(int& x1, int& y1, int& x2, int& y2, int width, int height) {
     const int left = 0;
     const int right = width;

src/graphics/core/ImageData.hpp

@@ -33,6 +33,8 @@ public:
     void extrude(int x, int y, int w, int h);
     void fixAlphaColor();
 
+    std::unique_ptr<ImageData> cropped(int x, int y, int width, int height) const;
+
     ubyte* getData() const {
         return data.get();
     }

src/graphics/core/Texture.cpp

@@ -54,6 +54,12 @@ void Texture::reload(const ubyte* data) {
     glBindTexture(GL_TEXTURE_2D, 0);
 }
 
+void Texture::reloadPartial(const ImageData& image, uint x, uint y, uint w, uint h) {
+    glBindTexture(GL_TEXTURE_2D, id);
+    glTexSubImage2D(GL_TEXTURE_2D, 0, x, y, w, h, GL_RGBA, GL_UNSIGNED_BYTE, image.getData());
+    glBindTexture(GL_TEXTURE_2D, 0);
+}
+
 std::unique_ptr<ImageData> Texture::readData() {
     auto data = std::make_unique<ubyte[]>(width * height * 4);
     glBindTexture(GL_TEXTURE_2D, id);

src/graphics/core/Texture.hpp

@@ -19,6 +19,7 @@ public:
     virtual void bind() const;
     virtual void unbind() const;
     void reload(const ubyte* data);
+    void reloadPartial(const ImageData& image, uint x, uint y, uint w, uint h);
 
     void setNearestFilter();