Large map draw function

draw.h

// x, y, w, h specify what region of the screen to update.
// mZoom specifies the zoom level to draw the map at (1 = 1:1, 2 = only every other pixel is shown, etc)
// mOriginX/Y specifies what position on the map is currently at the screen's top right corner.

    void draw(int32_t x, int32_t y, int32_t w, int32_t h) {
        tft.setAddrWindow(x, y, x+w-1, y+h-1);
        //
        x *= mZoom;
        y *= mZoom;
        x += mOriginX;
        y += mOriginY;
        w *= mZoom;
        h *= mZoom;
        //
        File file = SD.open("yeg-big.lcd");
        int32_t ImWidth = 2048;
        int32_t ImHeight = 2048;
        //
        for (int32_t row = y; row < y+h; row += mZoom) {
            uint16_t pixels[w*mZoom];
            file.seek((ImWidth*2)*row + 2*x);
            file.read((uint8_t*)pixels, 2*w*mZoom);
            for (int i = 0; i < w; i += mZoom)
                tft.pushColor((pixels[i] >> 8) | (pixels[i] << 8));
        }
        //
        file.close();
    }