openglplayground/Widget.cc

#include <vector>

#define GLM_FORCE_RADIANS
#include <glm/gtc/packing.hpp>

#include "Widget.hh"
#include "texture.hh"
#include "shaders.hh"

Widget::Widget(int width, int height, std::string name)
  : name_(std::move(name)), width_(width), height_(height),
    background_(nullptr),
    bg_(SDL_Color{0, 0, 0, 0}), fg_(SDL_Color{255, 255, 255, 255}),
    padLeft_(0), padTop_(0), padRight_(0), padBottom_(0),
    alignHoriz_(ALIGN_LEFT), alignVert_(ALIGN_TOP),
    renderTop_(0), renderLeft_(0),
    renderTexValid_(false), renderAttribsValid_(false),
    renderTex_(nullptr), vaID_(0)
{
  if (width_ == WRAP_CONTENT)
    realWidth_ = 0;
  else
    realWidth_ = width_;

  if (height_ == WRAP_CONTENT)
    realHeight_ = 0;
  else
    realHeight_ = height_;
}

Widget::~Widget()
{
  glDeleteVertexArrays(1, &vaID_);
}

void Widget::setSize(int width, int height)
{
  if ((width_ != width) || (height_ != height)) {
    width_ = width;
    height_ = height;
  
    if (width_ != WRAP_CONTENT)
      if (realWidth_ != width_) {
	realWidth_ = width_;
      }

    if (height_ != WRAP_CONTENT)
      if (realHeight_ != height_) {
	realHeight_ = height_;
      }

    layout();
  }
}

void Widget::setBackground(SDL_Surface* surf)
{
  if (background_ != surf) {
    background_ = surf;
    invalidateGL();
  }
}

void Widget::setBackgroundColor(SDL_Color bg)
{
  if (bg_ != bg) {
    bg_ = bg;
    invalidateGL();
  }
}

void Widget::setForegroundColor(SDL_Color fg)
{
  if (fg_ != fg) {
    fg_ = fg;
    invalidateGL();
  }
}

void Widget::setPadding(int left, int top, int right, int bottom)
{
  if ((padLeft_ != left) ||
      (padTop_ != top) ||
      (padRight_ != right) ||
      (padBottom_ != bottom)) {
    padLeft_ = left;
    padTop_ = top;
    padRight_ = right;
    padBottom_ = bottom;

    layout();
  }
}

void Widget::setAlignment(int horiz, int vert) {
  if ((alignHoriz_ != horiz) ||
      (alignVert_ != vert)) {
    alignHoriz_ = horiz;
    alignVert_ = vert;

    invalidateGL();
  }
}

void Widget::setParent(Widget *parent)
{
  parent_ = parent;
}
 
void Widget::setGLRenderPos(int left, int top)
{
  if ((top != renderTop_) ||
      (left != renderLeft_)) {
    renderAttribsValid_ = false;
    renderTop_ = top;
    renderLeft_ = left;
  }
}

void Widget::render(SDL_Surface *dst, SDL_Rect *dstRect) const
{
  if (background_) {
    if (SDL_BlitScaled(background_, nullptr, dst, dstRect) != 0)
      throw SDLException{};
  } else {
    // Skip completely transparent background
    if (bg_.a == 0)
      return;

    // Simply write completely intransparent bg
    if (bg_.a == 255) {
      SDLSurfaceScopedLock lock{dst};
      if (SDL_FillRect(dst, dstRect,
		       SDL_MapRGBA(dst->format, bg_.r, bg_.g, bg_.b, bg_.a)) != 0)
	throw SDLException{};

      return;
    }

    // Do proper blending blit for all other bgs
    int w = dstRect?dstRect->w:dst->w;
    int h = dstRect?dstRect->h:dst->h;
    
    uint32_t rmask, gmask, bmask, amask;
    int bpp;
    if (!SDL_PixelFormatEnumToMasks(dst->format->format,
				    &bpp, &rmask, &gmask, &bmask, &amask))
      throw SDLException{};
    
    SDLSurfaceUPtr tmp{SDL_CreateRGBSurface(0, w, h, bpp,
					    rmask, gmask, bmask, amask)};
    if (!tmp)
      throw SDLException{};

    {
      SDLSurfaceScopedLock lock{tmp};
      if (SDL_FillRect(tmp.get(), nullptr,
		       SDL_MapRGBA(tmp->format, bg_.r, bg_.g, bg_.b, bg_.a)) != 0)
	throw SDLException{};
    }

    if (SDL_BlitSurface(tmp.get(), nullptr, dst, dstRect) != 0)
      throw SDLException{};
  } 
}

SDL_Rect Widget::calcContentRect(SDL_Surface *dst, SDL_Rect *dstRect, SDL_Rect contentRect) const
{
  SDL_Rect rect;
  
  if (dstRect) {
    rect.x = dstRect->x + padLeft_;
    rect.y = dstRect->y + padTop_;
    rect.w = dstRect->w - (padLeft_ + padRight_);
    rect.h = dstRect->h - (padTop_ + padBottom_);
  } else {
    rect.x = padLeft_;
    rect.y = padTop_;
    rect.w = dst->w - padLeft_ - padRight_;
    rect.h = dst->h - padTop_ - padBottom_;
  }

  if (contentRect.w < rect.w) {
    auto space = rect.w - contentRect.w;
    if (alignHoriz_ == ALIGN_RIGHT) {
      rect.x += space;
      rect.w -= space;
    } else if (alignHoriz_ == ALIGN_CENTER) {
      rect.x += space/2;
      rect.w -= space/2;
    }
  }

  if (contentRect.h < rect.h) {
    auto space = rect.h - contentRect.h;
    if (alignHoriz_ == ALIGN_BOTTOM) {
      rect.y += space;
      rect.h -= space;
    } else if (alignHoriz_ == ALIGN_CENTER) {
      rect.y += space/2;
      rect.h -= space/2;
    }
  }

  return rect;
}

void Widget::renderToGL() const
{
  const size_t NUM_TRIANGLES = 6;

  if (!renderTexValid_) {
    uint32_t rmask, gmask, bmask, amask;
    int bpp;
    if (!SDL_PixelFormatEnumToMasks(SDL_PIXELFORMAT_ABGR8888,
				    &bpp, &rmask, &gmask, &bmask, &amask))
      throw SDLException{};
  
    SDLSurfaceUPtr tmp(SDL_CreateRGBSurface(0, realWidth_, realHeight_, bpp,
					    rmask, gmask, bmask, amask));
    render(tmp.get(), nullptr);
    
    if (!renderTex_ || (renderTex_->getWidth() != realWidth_) ||
	(renderTex_->getHeight() != realHeight_)) {
      
      renderTex_ = make_unique<Texture2D>(tmp.get());

      // Texture resize invalidates vertex attributes
      renderAttribsValid_ = false;
    } else {
      renderTex_->copyFromSurface(tmp.get());
    }
    renderTexValid_ = true;
  } else
    renderTex_->bind();

  if (!renderAttribsValid_) {
    int t = renderTop_, l = renderLeft_, b = renderTop_+realHeight_,
      r = renderLeft_+realWidth_;
    std::vector<VertexAttribs> vertexAttribs{
      {{l, t}, {0, 0}},
      {{r, b}, {65535u, 65535u}},
      {{r, t}, {65535u, 0}},
      {{l, t}, {0, 0}},
      {{l, b}, {0, 65535u}},
      {{r, b}, {65535u, 65535u}}};
      
    if (!vbo_) {
      vbo_ = VBOManager::getInstance().alloc(sizeof(VertexAttribs)*NUM_TRIANGLES);
      glBindBuffer(GL_ARRAY_BUFFER, vbo_.getVBOId());
      glGenVertexArrays(1, &vaID_);
      glBindVertexArray(vaID_);
	
      glEnableVertexAttribArray(ATTRIB_VERTEX_POS);
      glVertexAttribPointer(ATTRIB_VERTEX_POS, 2, GL_SHORT, GL_FALSE, sizeof(VertexAttribs),
			    (void*)(vbo_.getOfs()+offsetof(VertexAttribs, vertex)));
	
      glEnableVertexAttribArray(ATTRIB_VERTEX_TC);
      glVertexAttribPointer(ATTRIB_VERTEX_TC, 2, GL_UNSIGNED_SHORT, GL_TRUE,
			    sizeof(VertexAttribs),
			    (void*)(vbo_.getOfs()+offsetof(VertexAttribs, texCoords)));
    } else {
      glBindBuffer(GL_ARRAY_BUFFER, vbo_.getVBOId());
      glBindVertexArray(vaID_);
    }
    glBufferSubData(GL_ARRAY_BUFFER, vbo_.getOfs(),
		    sizeof(VertexAttribs)*NUM_TRIANGLES,
		    static_cast<void const*>(vertexAttribs.data()));
    renderAttribsValid_ = true;
  } else
    glBindVertexArray(vaID_);
  
  glDrawArrays(GL_TRIANGLES, 0, NUM_TRIANGLES);
}