feat: autoresize (extend/shrink) canvas element

src/graphics/core/ImageData.cpp

@@ -470,6 +470,32 @@ void ImageData::addColor(const ImageData& other, int multiplier) {
     }
 }
 
+void ImageData::extend(int newWidth, int newHeight) {
+    size_t comps;
+    switch (format) {
+        case ImageFormat::rgb888: comps = 3; break;
+        case ImageFormat::rgba8888: comps = 4; break;
+        default:
+            throw std::runtime_error("only unsigned byte formats supported");    
+    }
+    auto newData = std::make_unique<ubyte[]>(newWidth * newHeight * comps);
+    for (uint y = 0; y < newHeight; y++) {
+        for (uint x = 0; x < newWidth; x++) {
+            for (size_t c = 0; c < comps; c++) {
+                if (x < width && y < height) {
+                    newData[(y * newWidth + x) * comps + c] =
+                        data[(y * width + x) * comps + c];
+                } else {
+                    newData[(y * newWidth + x) * comps + c] = 0;
+                }
+            }
+        }
+    }
+    data = std::move(newData);
+    width = newWidth;
+    height = newHeight;
+}
+
 void ImageData::addColor(const glm::ivec4& color, int multiplier) {
     uint comps;
     switch (format) {

src/graphics/core/ImageData.hpp

@@ -36,6 +36,7 @@ public:
     void mulColor(const ImageData& other);
     void addColor(const glm::ivec4& color, int multiplier);
     void addColor(const ImageData& other, int multiplier);
+    void extend(int newWidth, int newHeight);
 
     std::unique_ptr<ImageData> cropped(int x, int y, int width, int height) const;
 

src/graphics/core/Texture.cpp

@@ -44,10 +44,10 @@ void Texture::unbind() const {
 void Texture::reload(const ImageData& image) {
     width = image.getWidth();
     height = image.getHeight();
-    reload(image.getData());
+    reload(image.getData(), width, height);
 }
 
-void Texture::reload(const ubyte* data) {
+void Texture::reload(const ubyte* data, uint width, uint height) {
     glBindTexture(GL_TEXTURE_2D, id);
     glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0,
         GL_RGBA, GL_UNSIGNED_BYTE, static_cast<const GLvoid*>(data));

src/graphics/core/Texture.hpp

@@ -18,7 +18,7 @@ public:
 
     virtual void bind() const;
     virtual void unbind() const;
-    void reload(const ubyte* data);
+    void reload(const ubyte* data, uint w, uint h);
     void reloadPartial(const ImageData& image, uint x, uint y, uint w, uint h);
 
     void setNearestFilter();