ScrollView.c

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/*
 * ObjectivelyMVC: Object oriented MVC framework for SDL3 and C.
 * Copyright (C) 2014 Jay Dolan <jay@jaydolan.com>
 *
 * This software is provided 'as-is', without any express or implied
 * warranty. In no event will the authors be held liable for any damages
 * arising from the use of this software.
 *
 * Permission is granted to anyone to use this software for any purpose,
 * including commercial applications, and to alter it and redistribute it
 * freely, subject to the following restrictions:
 *
 * 1. The origin of this software must not be misrepresented; you must not
 * claim that you wrote the original software. If you use this software
 * in a product, an acknowledgment in the product documentation would be
 * appreciated but is not required.
 *
 * 2. Altered source versions must be plainly marked as such, and must not be
 * misrepresented as being the original software.
 *
 * 3. This notice may not be removed or altered from any source distribution.
 */
 
#include <assert.h>
 
#include "ScrollView.h"
 
#define _Class _ScrollView
 
#pragma mark - Object
 
static void dealloc(Object *self) {
 
  ScrollView *this = (ScrollView *) self;
 
  release(this->contentView);
  release(this->scrollBar);
 
  super(Object, self, dealloc);
}
 
#pragma mark - View
 
static void awakeWithDictionary(View *self, const Dictionary *dictionary) {
 
  super(View, self, awakeWithDictionary, dictionary);
 
  ScrollView *this = (ScrollView *) self;
 
  View *contentView = NULL;
 
  const Inlet inlets[] = MakeInlets(
    MakeInlet("contentView", InletTypeView, &contentView, NULL),
    MakeInlet("scrollbarVisibility", InletTypeEnum, &this->scrollBarVisibility, (ident) ScrollBarVisibilityNames),
    MakeInlet("step", InletTypeFloat, &this->step, NULL)
  );
 
  $(self, bind, inlets, dictionary);
 
  if (contentView) {
    $(this, setContentView, contentView);
    release(contentView);
  }
}
 
static void applyStyle(View *self, const Style *style) {
 
  super(View, self, applyStyle, style);
 
  ScrollView *this = (ScrollView *) self;
 
  const Inlet inlets[] = MakeInlets(
    MakeInlet("scrollbar", InletTypeEnum, &this->scrollBarVisibility, (ident) ScrollBarVisibilityNames)
  );
 
  $(self, bind, inlets, (Dictionary *) style->attributes);
 
  $(self, setNeedsLayout);
}
 
static View *init(View *self) {
  return (View *) $((ScrollView *) self, initWithFrame, NULL);
}
 
static void layoutSubviews(View *self) {
 
  ScrollView *this = (ScrollView *) self;
 
  bool scrollBarHidden;
  switch (this->scrollBarVisibility) {
    case ScrollBarShow:
      scrollBarHidden = false;
      break;
    case ScrollBarHide:
      scrollBarHidden = true;
      break;
    default: {
      if (this->contentView == NULL) {
        scrollBarHidden = true;
      } else {
        const SDL_Size contentSize = $(this->contentView, size);
        const SDL_Rect bounds = $(self, bounds);
        scrollBarHidden = contentSize.h <= bounds.h;
      }
      break;
    }
  }
  
  $((View *) this->scrollBar, setVisibility,
    scrollBarHidden ? ViewVisibilityHidden : ViewVisibilityVisible);
 
  super(View, self, layoutSubviews);
 
  if (this->contentView) {
    this->contentView->frame.x = this->contentOffset.x;
    this->contentView->frame.y = this->contentOffset.y;
  }
}
 
#pragma mark - Control
 
static bool captureEvent(Control *self, const SDL_Event *event) {
 
  ScrollView *this = (ScrollView *) self;
 
  if (event->type == SDL_EVENT_MOUSE_MOTION && (event->motion.state & SDL_BUTTON_LMASK)) {
    self->state |= ControlStateHighlighted;
 
    SDL_Point offset = this->contentOffset;
 
    offset.x += event->motion.xrel;
    offset.y += event->motion.yrel;
 
    $(this, scrollToOffset, &offset);
    return true;
  } else if (event->type == SDL_EVENT_MOUSE_WHEEL) {
    SDL_Point offset = this->contentOffset;
 
    offset.x -= event->wheel.x * this->step;
    offset.y += event->wheel.y * this->step;
 
    $(this, scrollToOffset, &offset);
    return true;
  } else if (event->type == SDL_EVENT_MOUSE_BUTTON_UP && (event->button.button & SDL_BUTTON_LMASK)) {
 
    if ($(self, isHighlighted)) {
      self->state &= ~ControlStateHighlighted;
      return true;
    }
  }
 
  return super(Control, self, captureEvent, event);
}
 
#pragma mark - ScrollView
 
static ScrollView *initWithFrame(ScrollView *self, const SDL_Rect *frame) {
 
  self = (ScrollView *) super(Control, self, initWithFrame, frame);
  if (self) {
    self->step = 12.f;
 
    self->scrollBar = $(alloc(ScrollBar), initWithScrollView, self);
    assert(self->scrollBar);
 
    View *scrollBar = (View *) self->scrollBar;
    $(scrollBar, setVisibility, ViewVisibilityHidden);
 
    $((View *) self, addSubview, scrollBar);
  }
 
  return self;
}
 
static void scrollToOffset(ScrollView *self, const SDL_Point *offset) {
 
  if (self->contentView) {
    const SDL_Size contentSize = $(self->contentView, size);
    const SDL_Rect bounds = $((View *) self, bounds);
 
    if (contentSize.w > bounds.w) {
      self->contentOffset.x = clamp(offset->x, -(contentSize.w - bounds.w), 0);
    } else {
      self->contentOffset.x = 0;
    }
 
    if (contentSize.h > bounds.h) {
      self->contentOffset.y = clamp(offset->y, -(contentSize.h - bounds.h), 0);
    } else {
      self->contentOffset.y = 0;
    }
 
  } else {
    self->contentOffset.x = self->contentOffset.y = 0;
  }
 
  $((View *) self, setNeedsLayout);
  $((View *) self->scrollBar, setNeedsLayout);
}
 
static void setContentView(ScrollView *self, View *contentView) {
 
  if (contentView != self->contentView) {
 
    if (self->contentView) {
      $(self->contentView, removeClassName, "contentView");
      $((View *) self, removeSubview, self->contentView);
      self->contentView = release(self->contentView);
    }
 
    if (contentView) {
      $(contentView, addClassName, "contentView");
      $((View *) self, addSubview, contentView);
      self->contentView = retain(contentView);
    }
    
    $((View *) self, addSubview, (View *) self->scrollBar);
 
    $(self, scrollToOffset, &MakePoint(0, 0));
  }
}
 
static void setScrollBarVisibility(ScrollView *self, ScrollBarVisibility visibility) {
 
  View *this = (View *) self;
 
  $(this->style, addEnumAttribute, "scrollbar", ScrollBarVisibilityNames, visibility);
 
  $(this, invalidateStyle);
}
 
#pragma mark - Class lifecycle
 
static void initialize(Class *clazz) {
 
  ((ObjectInterface *) clazz->interface)->dealloc = dealloc;
 
  ((ViewInterface *) clazz->interface)->applyStyle = applyStyle;
  ((ViewInterface *) clazz->interface)->awakeWithDictionary = awakeWithDictionary;
  ((ViewInterface *) clazz->interface)->init = init;
  ((ViewInterface *) clazz->interface)->layoutSubviews = layoutSubviews;
 
  ((ControlInterface *) clazz->interface)->captureEvent = captureEvent;
 
  ((ScrollViewInterface *) clazz->interface)->initWithFrame = initWithFrame;
  ((ScrollViewInterface *) clazz->interface)->scrollToOffset = scrollToOffset;
  ((ScrollViewInterface *) clazz->interface)->setContentView = setContentView;
  ((ScrollViewInterface *) clazz->interface)->setScrollBarVisibility = setScrollBarVisibility;
}
 
Class *_ScrollView(void) {
  static Class *clazz;
  static Once once;
 
  do_once(&once, {
    clazz = _initialize(&(const ClassDef) {
      .name = "ScrollView",
      .superclass = _Control(),
      .instanceSize = sizeof(ScrollView),
      .interfaceSize = sizeof(ScrollViewInterface),
      .initialize = initialize,
    });
  });
 
  return clazz;
}
 
#undef _Class