Screen Shot for Off Screen Frame Buffer

[aaghiijnnuz]

I want to take a screen shot for a off screen framebuffer. This is what I am doing.

1. I create texture like this and use createFrameBuffer by passing this texturehandle.
   bgfx::TextureHandle subviewTexBlit = bgfx::createTexture2D(width, height, false, 1, bgfx::Texture::Format::RGBA8, BGFX_TEXTURE_RT);

2. I set my framebuffer to my view and submit what I want to show to this view. just like this:
   bgfx::setviewframebuffer(0,my frame buffer handle)
   ......
   bgfx::submit()
   bgfx::frame

3. I add a button outside the bgfx, such as windows default button. This button is set to call screen shot methods in bgfx just like the step 4.

4. I hope to get the data from the frame buffer and save it as png in local. The code is like this:
   bgfx::TextureHandle subviewTexBlit = bgfx::createTexture2D(width, height, false, 1, bgfx::Texture::Format::RGBA8, BGFX_TEXTURE_BLIT_DST| BGFX_TEXTURE_READ_BACK);
   bgfx::blit(0, subviewTexBlit, 0, 0, bgfx::gettexture(my frame buffer));
   void* data = malloc(my texture size in the step 4)
   bgfx::readtexture(new texture, data)
   call bimg to save data as png

After this four step, i get empty in my data pointer memory. can some one help me? Thanks

also, i modify my code like #2376 (comment). It do not work.

[aaghiijnnuz]

bgfx::readtexture(new texture, data) is only available after centain frame is called