SDL2_image rendering not working properly - c++

Question

I am trying to render an image using SDL_image v2.0.0, in SDL2.
I have an image called Red.png in my res/img/ folder. When I try to load the texture, and use SDL_QueryTexture() it gets the size and everything just fine. But when it comes to rendering the actual image, Ive put a rectangle outline to know where the image is, but there is no image in the box.
The class I use to load and render the texture:
class LTexture
{
public:
~LTexture()
{
SDL_DestroyTexture(image_);
renderer_ = nullptr;
image_ = nullptr;
}
void init(SDL_Renderer* renderer)
{
printf("init texture\n");
renderer_ = renderer;
}
void loadBMP(std::string filename)
{
printf("load texture\n");
image_ = IMG_LoadTexture(renderer_, ("res/img/"+filename).c_str());
SDL_QueryTexture(image_, NULL, NULL, &imgrect.w, &imgrect.h);
}
void render(int x, int y)
{
imgrect.x = x;
imgrect.y = y;
SDL_SetRenderDrawColor(renderer_, 128, 128, 128, 255);
if (image_ != nullptr && renderer_ != nullptr)
{
printf("%i, %i\n", imgrect.x, imgrect.y);
SDL_RenderDrawRect(renderer_, &imgrect);
SDL_RenderCopy(renderer_, image_, &imgrect, &imgrect);
}
}
bool isLoaded()
{
return image_ != nullptr;
}
private:
SDL_Renderer* renderer_ = nullptr;
SDL_Texture* image_ = nullptr;
SDL_Rect imgrect;
};
I know it correctly gets the renderer and loads the image because the DrawRect function works, and if you didn't guess by the name, Red.png is a red rectangle.

Answer 1

Pass nullptr in for srcrect in your SDL_RenderCopy() call:
SDL_RenderCopy(renderer_, image_, nullptr, &imgrect);
Right now if x and/or y are larger than image_ SDL will clip srcrect to the extents of image_, end up with an empty rect, and do nothing.
Example:
#include <SDL2/SDL.h>
#include <SDL2/SDL_image.h>
#include <cstdlib>
#include <string>
class LTexture
{
public:
LTexture()
: renderer_( nullptr )
, image_( nullptr )
{ }
~LTexture()
{
SDL_DestroyTexture(image_);
renderer_ = nullptr;
image_ = nullptr;
}
void init(SDL_Renderer* renderer)
{
printf("init texture\n");
renderer_ = renderer;
}
void loadBMP(std::string filename)
{
printf("load texture\n");
image_ = IMG_LoadTexture(renderer_, filename.c_str());
SDL_QueryTexture(image_, NULL, NULL, &imgrect.w, &imgrect.h);
}
void render(int x, int y)
{
imgrect.x = x;
imgrect.y = y;
SDL_SetRenderDrawColor(renderer_, 128, 128, 128, 255);
if (image_ != nullptr && renderer_ != nullptr)
{
printf("%i, %i\n", imgrect.x, imgrect.y);
SDL_RenderDrawRect(renderer_, &imgrect);
SDL_RenderCopy(renderer_, image_, nullptr, &imgrect);
}
}
bool isLoaded()
{
return image_ != nullptr;
}
private:
SDL_Renderer* renderer_;
SDL_Texture* image_;
SDL_Rect imgrect;
};
int main( int argc, char** argv )
{
SDL_Init( SDL_INIT_EVERYTHING );
IMG_Init( IMG_INIT_PNG );
SDL_Window * window = SDL_CreateWindow
(
"SDL2",
SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED,
300, 300,
SDL_WINDOW_SHOWN
);
SDL_Renderer* renderer = SDL_CreateRenderer
(
window,
0,
SDL_RENDERER_ACCELERATED
);
LTexture tex;
tex.init( renderer );
tex.loadBMP( "red.png" );
bool running = true;
while( running )
{
SDL_Event ev;
while( SDL_PollEvent( &ev ) )
{
if ( ev.type == SDL_QUIT )
running = false;
}
SDL_SetRenderDrawColor( renderer, 0, 0, 0, 255 );
SDL_RenderFillRect( renderer, NULL );
tex.render( 50, 50 );
SDL_RenderPresent( renderer );
SDL_Delay( 33 );
}
SDL_DestroyRenderer( renderer );
SDL_DestroyWindow( window );
IMG_Quit();
SDL_Quit();
return 0;
}
red.png for reference:

Answer 2

I don't know if this is still actual, but I have problems using SDL_RENDERER_ACCELERATED flag (under Linuix Mint), when I use SW acceleration, SDL_Render* works.